EMERGENCY MEDICINE PRACTICE

EMERGENCY MEDICINE PRACTICE . EMPRACTICE NET A N E V I D E N C E - B A S E D A P P ROAC H T O E M E RG E N C Y M E D I C I N E July 2004 Diarrhea: I...
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EMERGENCY MEDICINE PRACTICE . EMPRACTICE NET A N E V I D E N C E - B A S E D A P P ROAC H T O E M E RG E N C Y M E D I C I N E

July 2004

Diarrhea: Identifying Serious Illness And Providing Relief

Volume 6, Number 7 Authors

It’s a stormy day, yet the ED is furiously busy. As you pick up your next patient’s chart, you glance at the chief complaint—diarrhea. “Why would anyone come out on a day like this, for something like that?” you wonder. Then your eye catches the patient’s age (60) and vital signs—temperature, 38.7˚C (101.7˚F); pulse, 124 beats per minute; respiratory rate, 24 breaths per minute; blood pressure, 102/50 mmHg. This man seems a bit sicker than the run-of-the-mill diarrhea patient. A quick glance into his room confirms your suspicion; he’s pale, sweaty, ill-looking. He clearly needs help. But is an extensive work-up really going to be cost-effective—and won’t it keep you from treating other patients in a timely manner? Besides, don’t most of these cases run their course with a little help from fluids and symptomatic treatment?

D

IARRHEA is a common condition that can stem from many causes. Fortunately, the care of the ED patient with diarrhea is usually straightforward—a targeted history and physical examination, followed by symptomatic remedies. However, the temptation to dismiss a case as “just diarrhea” can be quite dangerous, as serious disease processes can present with diarrhea as the chief complaint. Some patients require more systematic investigation or even hospitalization. Clinical judgment based on the current evidence can help guide a cost-effective work-up of patients with diarrhea that will identify patients with more severe etiologies or at risk for complications.

Critical Appraisal Of The Literature Given that diarrhea is such a ubiquitous part of the human condition, it’s not surprising that the literature on the subject is truly voluminous. Thousands of studies address the epidemiology, etiology, pathophysiology, evaluation, treatment, differential diagnosis, and other features of patients with diarrhea. Thankfully, a number of well-done reviews, meta-analyses, and position statements from expert medical organizations condense the findings, making the job of the practicing emergency physician caring for patients with diarrhea much easier.1-19 In general, the preponderance of evidence tends to support the following practices in patients with diarrhea: Associate Editor Andy Jagoda, MD, FACEP, Vice-Chair of Academic Affairs, Department of Emergency Medicine; Residency Program Director; Director, International Studies Program, Mount Sinai School of Medicine, New York, NY.

Editorial Board William J. Brady, MD, Associate Professor and Vice Chair, Department of Emergency Medicine, University of Virginia, Charlottesville, VA. Judith C. Brillman, MD, Professor, Department of Emergency Medicine, The University of

New Mexico Health Sciences Center School of Medicine, Albuquerque, NM. Francis M. Fesmire, MD, FACEP, Director, Heart-Stroke Center, Erlanger Medical Center; Assistant Professor of Medicine, UT College of Medicine, Chattanooga, TN. Valerio Gai, MD, Professor and Chair, Department of Emergency Medicine, University of Turin, Italy. Michael J. Gerardi, MD, FAAP, FACEP, Clinical Assistant Professor, Medicine, University of Medicine and Dentistry of New Jersey; Director, Pediatric Emergency Medicine, Children’s Medical Center,

Michael D. Burg, MD, FACEP Residency Program Director, Department of Emergency Medicine, Onze Lieve Vrouwe Gasthuis (Hospital), Amsterdam, The Netherlands. Hoori Hovanessian, MD, FACEP Assistant Clinical Professor, Department of Emergency Medicine, UCSF–Fresno, University Medical Center, Fresno, CA; Presbyterian Intercommunity Hospital, Whittier, CA. Peer Reviewers Andy Jagoda, MD, FACEP Vice-Chair of Academic Affairs, Department of Emergency Medicine; Residency Program Director; Director, International Studies Program, Mount Sinai School of Medicine, New York, NY. Earl J. Reisdorff, MD, FACEP Director of Medical Education, Ingham Regional Medical Center; Associate Professor, Michigan State University Emergency Medicine Residency, Lansing MI. CME Objectives Upon completing this article, you should be able to: 1. construct a broad differential diagnosis for diarrheal illness in adults and children; 2. describe aspects of a targeted history and physical examination for patients with diarrhea, including indications for diagnostic testing; 3. identify ED patients at high risk for serious or life-threatening diarrheal illnesses; and 4. describe treatment strategies for ED patients with diarrhea.

Date of original release: July 1, 2004. Date of most recent review: June 15, 2004. See “Physician CME Information” on back page.

Atlantic Health System; Department of Emergency Medicine, Morristown Memorial Hospital.

Attending, Massachusetts General Hospital; Faculty, Harvard Affiliated Emergency Medicine Residency, Boston, MA.

Michael A. Gibbs, MD, FACEP, Chief, Department of Emergency Medicine, Maine Medical Center, Portland, ME.

Michael S. Radeos, MD, MPH, Attending Physician, Department of Emergency Medicine, Lincoln Medical and Mental Health Center, Bronx, NY; Assistant Professor in Emergency Medicine, Weill College of Medicine, Cornell University, New York, NY.

Gregory L. Henry, MD, FACEP, CEO, Medical Practice Risk Assessment, Inc., Ann Arbor, MI; Clinical Professor, Department of Emergency Medicine, University of Michigan Medical School, Ann Arbor, MI; Past President, ACEP. Francis P. Kohrs, MD, MSPH, Lifelong Medical Care, Berkeley, CA.

Steven G. Rothrock, MD, FACEP, FAAP, Associate Professor of Emergency Medicine, University of Florida; Orlando Regional Medical Center; Medical Director of Orange County Emergency Medical Service, Orlando, FL.

Keith A. Marill, MD, Emergency

Alfred Sacchetti, MD, FACEP,

Research Director, Our Lady of Lourdes Medical Center, Camden, NJ; Assistant Clinical Professor of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA. Corey M. Slovis, MD, FACP, FACEP, Professor of Emergency Medicine and Chairman, Department of Emergency Medicine, Vanderbilt University Medical Center; Medical Director, Metro Nashville EMS, Nashville, TN. Charles Stewart, MD, FACEP, Colorado Springs, CO. Thomas E. Terndrup, MD, Professor and Chair, Department of Emergency Medicine, University of Alabama at Birmingham, Birmingham, AL.

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Etiology, Epidemiology, And Pathophysiology

• Evaluating the patient: The presence of a dry axilla supports the diagnosis of hypovolemia, and moist mucous membranes and a tongue without furrows argue against it. In adults, the capillary refill time and poor skin turgor have no proven diagnostic value.3 Acute body weight changes provide the best measures of dehydration in children. Mucous membrane hydration, capillary refill time, absence of tears, and alterations in mental status are the next best associated measures.4 Important features of the history include how the illness began; stool characteristics (frequency and quantity); travel history; occupation; day care center attendance or nursing home residence; whether the patient has ingested raw or undercooked meat, raw seafood, or raw milk; whether the patient’s contacts are ill; the patient’s sexual contacts, medications, and other medical conditions, if any.2,5 Red-flag findings include severe dehydration, bloody or febrile diarrhea, or illness in infants, elderly, or immunocompromised patients.5 Serial evaluations over several hours can improve the diagnostic accuracy in patients in whom the etiology is unclear.1

Etiology Diarrhea is a change in normal bowel movements characterized by an increase in the water content, volume, or frequency of stools. Fluid secretion into the gut and increased gut motility together produce both the increased stooling frequency and the increased stool liquidity.16,20 The passage of more than 200 grams of stool per day is considered to be diarrhea; two to three bowel movements per day is the upper limit of normal. An episode of diarrhea lasting 14 days or less is generally defined as “acute diarrhea,” while “persistent diarrhea” refers to episodes lasting longer than 14 days. “Chronic” diarrhea is generally defined as diarrhea that lasts more than 30 days.

Epidemiology Virtually every human being experiences diarrhea at some point. Causes may range from the mild to the life-threatening, although the clinical course is generally brief and selflimited in developed nations. However, worldwide, diarrheal illnesses are the second most common cause of death and the leading cause of death in children.21 Diarrhea is a common cause of morbidity even in the United States. The number of hospital admissions due to gastroenteritis in the United States is estimated to be 450,000 per year.20 Additionally, the U.S. prevalence of chronic diarrhea approaches 5%.22

• Laboratory testing: Routine testing for specific pathogens is not recommended.4 Reserve laboratory testing and stool cultures for select circumstances. Criteria vary but often include bloody diarrhea, weight loss, diarrhea leading to dehydration, fever, neurologic involvement, sudden onset of severe abdominal pain, persistent (> 7 days) diarrhea, or possible community-acquired diarrhea, traveler’s diarrhea, or nosocomial diarrhea.2,5 Maintain a lower threshold for ordering if the patient is pediatric, elderly, or immunocompromised.2

Pathophysiology Diarrhea is broadly categorized as one of two types—either secretory or osmotic. The poorly named secretory diarrhea actually occurs due to abnormal electrolyte transport across the intestinal epithelial cells. Increased secretion and/or decreased absorption result. The diarrhea is not related to the intestinal contents and therefore typically does not stop with fasting. Infection (e.g., cholera) is the most common cause of secretory diarrhea. The fluid losses can be enormous. Osmotic diarrhea results from the presence of nonabsorbable solute that exerts an osmotic pressure effect across the intestinal mucosa, resulting in excessive water output. Because the diarrhea is caused by the solute, it tends to stop during fasting. Sorbitol, a poorly absorbed sugar, is capable of causing osmotic diarrhea.20 Another way that diarrhea is commonly classified is as infectious vs. noninfectious or inflammatory vs. noninflammatory. Symptoms such as fever, bloody diarrhea, and severe cramping suggest an invasive bacterial pathogen such as Shigella, Salmonella, Yersinia, or Campylobacter. The presence of nausea and vomiting strongly suggests a viral agent, and prior antibiotic use suggests possible Clostridium difficile enteritis. Absence of these factors suggests a noninfectious cause. Inflammatory diarrhea can be bloody and associated with fever and abdominal cramps. The causes can be infectious or non-infectious. Non-inflammatory diarrhea tends to be watery and can be associated with nausea, vomiting, and abdominal cramps.

• Rehydration: Initiate rehydration (oral whenever possible).5 In children, clear liquids are not recommended as a substitute for oral rehydration solutions or regular diets to prevent or treat dehydration.4 • Diet: Refeeding of the usual diet at the earliest opportunity should be encouraged to prevent or limit dehydration. Very frequent (e.g., every 10-60 minutes), small feedings may be better tolerated if vomiting is present. The BRAT diet (bananas, rice, applesauce, and toast) affords no advantage unless these foods are part of the regular diet.4 • Medications: Antibiotic therapy can reduce illness duration by one or two days in most cases. Criteria for empiric antibiotic therapy vary, but consideration of risks must be weighed against any potential benefits. In children, antimicrobial therapies are recommended only when special risks or evidence of serious bacterial infection is present.4 Institute selective therapy for traveler’s diarrhea, shigellosis, and Campylobacter infection.5 Avoid administering antimotility agents with bloody diarrhea or proven infection with Shiga toxinproducing Escherichia coli.5 Anti-diarrheal agents and antiemetics are not recommended for use in children with acute gastroenteritis.4

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Entamoeba histolytica, and Cryptosporidium.2 Signs and symptoms such as bloody diarrhea, weight loss, diarrhea leading to dehydration, fever, prolonged diarrhea (3 or more unformed stools per day, persisting several days), neurologic involvement (such as paresthesias, motor weakness, cranial nerve palsies), and/or severe abdominal pain may suggest infectious causes and drive the need for laboratory testing, especially in young, elderly, or immunocompromised patients.2

The differential diagnosis of diarrhea with abdominal pain is vast. While patients who present with vomiting, diarrhea, and abdominal cramps and who have benign abdominal examinations may seem like clear-cut cases of gastroenteritis—and most patients will respond well given rehydration and antiemetics—it is important to be aware that the differential diagnosis includes more severe etiologies that require different management approaches. (See Table 1.)

Irritable Bowel Syndrome Infectious Enteritis

Patients with irritable bowel syndrome can have abdominal pain or discomfort, constipation, diarrhea, or an alternating course of constipation and diarrhea. A mucoid rectal discharge is present in about half of afflicted patients.23 Evaluation of these patients fails to produce an organic basis for the disease; patients do not experience weight loss, fever, or rectal bleeding. While symptoms vary from person to person, irritable bowel syndrome is typically characterized by abdominal pain or discomfort for at least 12 weeks out of the previous 12 months; abdominal pain that is relieved by having a bowel movement; and changes in frequency or appearance of stool when an episode starts. Eliciting a history suggestive of irritable bowel syndrome requires referral to exclude more serious disease processes.

Infectious causes of diarrhea are commonly seen in the ED. Ingestion of contaminated food or water is the typical culprit; recent travel, exposure to other ill persons, recent hospitalization, child care center attendance, and nursing home residence should all raise the index of suspicion. (See Table 2 on page 4.) Common bacterial agents include Campylobacter, Salmonella, and Shigella species, as well as E. coli. Viral infections may be caused by rotavirus, Norwalk virus, cytomegalovirus, herpes simplex virus, and viral hepatitis. In developed countries, parasitic diarrhea is generally only a concern among travelers and those with prolonged diarrhea. Parasites that cause diarrhea include Giardia lamblia,

Table 1. Typical Characteristics Of Different Etiologies Of Diarrhea. Infectious

watery diarrhea (compared to the voluminous amounts produced as a consequence of gastroenteritis), mild or absent fever

Viral gastroenteritis Diarrhea with aches, chills, cold symptoms, nausea or vomiting; history suggesting recent consumption of contaminated food or exposure to other ill persons, especially day care; with or without fever

Vascular Ischemic bowel disease Diarrhea, severe abdominal pain, older patient, history of peripheral vascular disease

Bacterial diarrhea or Giardia Diarrhea, history suggesting recent consumption of contaminated food, with or without fever (see Table 2 on page 4)

Malabsorption

Traveler’s diarrhea Recent foreign travel, prolonged illness (see also Table 3 on page 6)

e.g., celiac disease or lactose intolerance Diarrhea, gas, bloating, and stomach pains that seems to be triggered by certain foods

Functional bowel disorders

Medications

Irritable bowel syndrome Variable symptoms but prolonged course; bowel movements that alternate between constipation and diarrhea, especially if episodes are related to stress

Recent new medicine, especially antibiotics, high blood pressure medications, cancer drugs/radiation therapy, some herbal medicines

Intestinal obstruction Severe abdominal pain along with nausea, vomiting, and diarrhea

Toxins Radiation enteritis Tenesmus, bleeding, and diarrhea stemming from malabsorption; can persist for two or three months after treatment cessation

Fecal impaction/other blockage Chronic constipation followed by recent watery diarrhea

Inflammatory

Arsenic, mushroom poisoning, pesticides, etc. Varies; usually diarrhea is one of several symptoms

Inflammatory bowel disease (includes Crohn’s disease and ulcerative colitis) Frequent bowel movements mixed with blood or mucus

Other systemic conditions e.g., food allergies, colon cancer, hyperthyroidism Typically a longer course plus other suggestive symptoms; see also Table 3 on page 6

Appendicitis Vomiting that follows abdominal pain, small amounts of

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Differential Diagnosis

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Inflammatory Bowel Disease

Eliciting a family history of inflammatory bowel disease or other risk factors for it will allow rapid evaluation of this condition by referral to a gastroenterologist.24 The diagnosis rests on the clinical history, stool studies to exclude infection, and colonoscopy to determine the presence and extent of disease.

Inflammatory bowel disease is a general term that refers to illnesses that cause chronic inflammation in the intestines, typically causing diarrhea and abdominal cramps. The two major types of inflammatory bowel disease are Crohn’s disease and ulcerative colitis. Crohn’s disease is a chronic inflammation of the intestines that is usually confined to the ileum. It is characterized by abdominal cramps or pain, diarrhea (sometimes bloody), fever, and anorexia. The clinical course may be erratic, with frequent relapses interspersed with periods of symptom remission.24 Ulcerative colitis, which is also a chronic inflammatory disease, is confined to the colon and rectum. Patients with mild disease may present with fewer than four bowel movements per day, whereas patients with severe disease may experience more than six bowel movements per day along with weight loss, fever, and anemia. While the diarrhea is often bloody, many patients do not have grossly bloody stools, even with exacerbations. It too may be characterized by periods of remission. A documented history of inflammatory bowel disease will aid in providing patients appropriate evaluation and treatment. Some patients, however, will have episodic symptoms for years before being correctly diagnosed.

Ischemic Bowel Disease Ischemic bowel disease should be considered in adults with abdominal pain, especially if they are older than 50 years or have a history of peripheral vascular disease. Most patients with acute mesenteric ischemia will present with severe abdominal pain, although there can be a paucity of physical findings. The abdominal pain may be followed by a rapid and forceful bowel movement.25 Other patients may have chronic mesenteric ischemia with chronic intermittent abdominal pain of up to several months’ duration (intestinal angina) followed by an acute attack of pain. These patients may experience weight loss, as well as occasional diarrhea and bloating.26 Occult fecal blood is present in up to 75% of patients.27 Bloody diarrhea may occur in those with ischemic colitis (inflammation of the colon caused by insufficient blood flow to the colon); those with small bowel ischemia will have voluminous diarrhea.28 Individuals at increased risk for ischemic bowel disease include patients with

Table 2. Agents Causing Infectious Diarrhea And Their Associated Symptoms. Campylobacter jejuni

dysentery. Diarrhea containing blood and mucus, fever, abdominal cramps, chills, and vomiting; 12-50 hours from ingestion of bacteria; can last a few days to two weeks.

Symptoms: fever, headache and muscle pain followed by diarrhea (sometimes bloody), abdominal pain and nausea that appear 2-5 days after eating; may last 7-10 days.

Staphylococcus aureus

Clostridium perfringens

Symptoms: severe nausea, abdominal cramps, vomiting, and diarrhea occur 1-6 hours after eating; recovery within 2-3 days—longer if severe dehydration occurs.

Symptoms: diarrhea and gas pains may appear 8-24 hours after eating; usually last about one day, but less severe symptoms may persist for 1-2 weeks.

Vibrio parahaemolyticus

Escherichia coli 0157:H7

Symptoms: Diarrhea, abdominal cramps, nausea, vomiting, headache, fever, and chills; onset four hours to four days after eating; lasts about 2.5 days.

Symptoms: diarrhea or bloody diarrhea, abdominal cramps, nausea, and malaise; can begin 2-5 days after food is eaten, lasting about eight days. Very young patients can develop hemolytic uremic syndrome, which causes acute kidney failure. A similar illness, thrombotic thrombocytopenic purpura, may occur in older adults.

Cyclospora cayetanensis Symptoms: Nausea, vomiting, loss of appetite, and diarrhea; onset within two days; lasts one week to two months.

Cryptosporidium parvum

Listeria monocytogenes

Symptoms: Profuse watery diarrhea, abdominal pain, appetite loss, vomiting, and low-grade fever, onset within 1-12 days.

Symptoms: fever, chills, headache, backache, sometimes abdominal pain and diarrhea; onset from 7-30 days after eating, but most symptoms are reported 48-72 hours after consumption of contaminated food; primarily affects pregnant women and their fetuses, newborns, the elderly, people with cancer, and those with impaired immune systems; can cause fetal and infant death.

Giardia lamblia Symptoms: Sudden onset of explosive watery stools, abdominal cramps, anorexia, nausea, and vomiting; onset within 1-3 days.

Salmonella (many types)

Viral gastroenteritis from Norwalk and Norwalk-like viruses

Symptoms: stomach pain, diarrhea, nausea, chills, fever, and headache usually appear 8-72 hours after eating; may last 1-2 days; all age groups are susceptible, but symptoms are most severe for the elderly, the infirm, and infants.

Symptoms: Nausea, vomiting, diarrhea, abdominal pain, headache, and low-grade fever; onset within 1-2 days; lasts about 36 hours. Adapted from: U.S. Food and Drug Administration Center for Food Safety and Applied Nutrition Web site (http://www.cfsan.fda.gov/~dms/ qa-fdb12.html, http://www.cfsan.fda.gov/~dms/unwelcom.html).

Shigella (many types) Symptoms: disease referred to as “shigellosis” or bacillary

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Miscellaneous Causes Many other entities should be considered in the differential diagnosis of diarrhea, including melena, laxative abuse, partial bowel obstruction, various malabsorption syndromes (e.g., Whipple’s disease, small bowel bacterial overgrowth, celiac sprue), food allergy, rectosigmoid abscess, colon cancer, diverticulitis, hyperthyroidism, and pernicious anemia. Many medications (as well as herbal remedies) can cause diarrhea. In pediatric patients, ageappropriate problems such as intussusception and Meckel’s diverticulum should be considered in the differential diagnosis of diarrhea. Uncommon causes of diarrhea include mushroom poisoning, ciguatera fish poisoning, arsenic ingestion, and exposure to pesticides, sodium fluoride, thallium, or zinc. In most of these cases, diarrhea is part of a symptom complex, and other suggestive elements of the history are present.

Radiation Enteritis Radiation therapy is used to treat a number of urologic, gynecologic, and colorectal cancers. During the radiation treatment period, most patients experience tenesmus, bleeding, and diarrhea.30 Malabsorption from mucosal damage and bacterial overgrowth are two factors that contribute to these symptoms.26 Symptoms can start within hours of initial treatment and usually resolve two or three months after treatment cessation,30 although some patients may develop chronic problems necessitating surgery. The rectum is the most commonly inflamed site given its proximity to the irradiated tissue; the terminal ileum can also be irradiated in patients undergoing treatment for pelvic malignancies. Treatment of acute radiation enteritis involves temporary discontinuation of radiation therapy, selective intravenous fluid administration, and antimotility medications. Sucralfate may ameliorate the symptoms of radiation enteritis. In one double-blind placebo-controlled trial of patients with prostate or bladder cancer randomized to receive either oral sucralfate or placebo, those patients receiving sucralfate had improvement in the frequency and consistency of bowel movements, and fewer patients required treatment with anti-diarrheal preparations.31

Prehospital Care Initial prehospital assessment should focus on the patient’s vital signs and mental status. Transport hemodynamically stable patients without further intervention. Follow local EMS protocols for hypotension/shock for patients who are hemodynamically unstable; usually, this includes establishing at least one large-bore intravenous line and infusing crystalloid solution and expediting the transport of unstable patients for further evaluation and care. While gastrointestinal infections may be caused by a variety of agents, including bacteria, viruses, and protozoa, only a few agents have been documented in person-toperson transmission. Generally, adherence to either standard or contact precautions will minimize the risk of transmitting enteric pathogens.36

Appendicitis Patients with appendicitis can have vomiting as well as loose stools. Rectal irritation by an inflamed pelvic appendix can produce small amounts of watery diarrhea, as compared to the voluminous amounts produced as a consequence of gastroenteritis.32 In Rothrock et al’s study of 181 children younger than 13 years who were ultimately found to have appendicitis, 27% were initially misdiagnosed. Patients in this group were more likely to be younger, have vomiting before pain, and have diarrhea (in addition to constipation, dysuria, and upper respiratory tract symptoms).33 A retrospective case series review of 63 children younger than 3 years ultimately diagnosed with appendicitis found that 57% were initially misdiagnosed; diarrhea was commonly reported.34 A retrospective review of 87 patients with appendicitis revealed that six patients (7%) required more than one ED visit before their diagnosis was established. The initial diagnosis in two of these patients was gastroenteritis. These six patients were more likely to have a normal appetite, to have diarrhea, and to be afebrile.35 While most patients with appendicitis present with right lower quadrant abdominal pain, 15% of appendices are in atypical locations, causing pain in locations other than the right lower quadrant.32 Gastroenteritis can present with fevers higher (>103˚F) than those seen with appendicitis, and in general, vomiting and diarrhea precede abdominal pain, whereas vomiting follows abdominal pain in appendicitis. Because appendicitis will steadily worsen, while

July 2004 • EMPractice.net

Emergency Department Evaluation History History Of Present Illness Obtaining a thorough history is crucial. Certain issues are important to address during patient assessment. They include: • Type and volume of stools: Also note whether the stools contain any blood. (Note that melena may not be perceived by the patient to be “bloody”; ask about blackened stools as well. See also the March 2004 issue of Emergency Medicine Practice, “Gastrointestinal Bleeding: An Evidence-Based ED Approach To Risk Stratification.”) • Associated symptoms such as nausea, vomiting, abdominal pain, fever, and tenesmus: When vomiting is a prominent feature of the patient’s symptoms, viruses are the more likely etiologic agents.12,37 Fever greater than 38.5˚C (101.3˚F) is usually associated with intestinal inflammation due to invasive bacteria (e.g.,

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uncomplicated gastroenteritis generally resolves with fluids, a period of observation can help identify patients with appendicitis if the diagnosis is unclear.

hypovolemia, sepsis, cardiac arrhythmias, congestive heart failure, and those using vasoconstrictive medications or drugs (e.g., digitalis, pseudoephedrine, cocaine, amphetamines).29 Ischemia may progress to infarct unless detected and treated early.

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dance, and occupational hazards such as food handling or working with animals.

Shigella, Salmonella, or Campylobacter species), enteric viruses, or toxin-induced damage due to Clostridium difficile or Entamoeba histolytica.37

Past Medical History

• Character and location of any abdominal pain: Pain is common in patients with mesenteric ischemia, inflammatory bowel disease, and irritable bowel syndrome.22

The patient’s past medical history also provides essential information for the management of patients with diarrhea. Are you treating an otherwise healthy 20-year-old woman, a patient with HIV/AIDS, or a 70-year-old diabetic man with a history of congestive heart failure taking numerous medications? Is the patient undergoing cancer treatment? Consider pathogens that affect immunosuppressed hosts in patients receiving chemotherapy. Acute radiation enteritis is a concern in those who have undergone radiation treatment within the past six weeks. Inquire about other gastrointestinal ailments such as Crohn’s disease or ulcerative colitis.

• Duration of symptoms: Symptom duration can help narrow the differential diagnosis. Viral gastroenteritis usually lasts 12-60 hours.2 Thus, it is less likely that diarrhea lasting more than a couple of days or so is viral. Diarrhea lasting greater than two weeks often has a different etiology (see Table 3) than diarrhea that has been present for less than two weeks.37 • Weight loss: Determine whether the patient has lost weight. Patients with diarrhea may have weight loss because of both increased output and reduced intake. Substantial weight loss is more likely due to ischemia, neoplasm, or malabsorptive syndromes.22 Weight loss may be an indicator of dehydration in children.

Medications Obtaining a history of medication use—specifically including prescription, over-the-counter, and herbal preparations—is important, since many can cause diarrhea. Some of the more common offenders include laxatives, antibiotics, colchicine, and magnesium- or calcium-containing antacids. If there is a history of antibiotic use within the past three months, C. difficile-induced diarrhea is an important consideration.38 Diabetics using a relatively new class of hypoglycemic medications known as alpha-glucosidase inhibitors (e.g., acarbose, miglitol) may develop abdominal pain, bloating, and diarrhea. Artificial sweeteners containing sorbitol or mannitol are poorly absorbed and may cause diarrhea. Patients on enteral tube feedings may also develop diarrhea.28 The elderly are more likely to be on multiple medications and may be more susceptible to adverse effects.

• Indicators of dehydration: Asking about urine output, dizziness, thirst, and syncope—as well as asking family members or prehospital personnel about altered mental status—is useful in assessing the patient’s volume status. • Epidemiological risk factors: Further questions should focus on the patient’s recent diet, and specifically whether there has been any ingestion of seafood, raw or undercooked meat, eggs, or milk products. In addition, ask about recent foreign travel or local outings involving lake or stream swimming or visits to a farm, ill contacts, group living arrangements (e.g., nursing home, college dormitory) or day care atten-

Review Of Systems A brief review of systems is additionally helpful. A patient who is currently menstruating may have guaiacpositive stools secondary to stool sample contamination from menstrual blood. The patient’s pregnancy status is important for antibiotic selection, use of medications for symptomatic treatment of the diarrhea, and decisions about managing her hemodynamic status. Ask the patient about the ability to get to the bathroom on time. Some individuals complain of diarrhea when the real problem is fecal incontinence.

Table 3. Common Causes Of Diarrhea Persisting Longer Than Two Weeks. Parasites Cryptosporidium parvum, Cyclospora cayetanensis, Entamoeba histolytica, Giardia lamblia, microsporidia

Bacteria Campylobacter, Clostridium difficile, Escherichia coli, Listeria monocytogenes, Salmonella enteritidis, Shigella

Social History

Viral infections

The patient’s occupational history may be relevant if they work as a veterinarian, food handler, or day care center or nursing home employee. The patient’s sexual preference and whether they engage in receptive anal intercourse should be ascertained as this may expand the differential diagnosis to include AIDS-associated diarrhea as well as proctitis secondary to sexually transmitted diseases. Inquire about alcohol and drug use. Patients who abuse alcohol may present with various abdominal complaints, including diarrhea and melena. Opioid withdrawal frequently involves nausea, vomiting, and diarrhea. Patients with eating disorders or those attempting to lose weight should be questioned about laxative abuse.

HIV

Medications Antibiotics, high blood pressure medications, cancer drugs/ radiation therapy

Noninfectious food sources Food allergies; certain food additives (sorbitol, fructose, and others) are also implicated

Other systemic conditions Diabetes, thyroid and other endocrine diseases; malignancies/tumors; previous surgery of the abdomen or gastrointestinal tract; conditions causing reduced blood flow to the intestine such as ischemic bowel disease

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more timely results and are therefore more useful in the ED setting than stool cultures in identifying causes of inflammatory diarrhea. A selective approach to fecal leukocyte/ lactoferrin testing in patients with diarrhea is recommended, yet the precise approach remains a matter of dispute. Community-acquired or traveler’s diarrhea, nosocomial diarrhea, and diarrhea persisting more than seven days have been suggested by the Infectious Diseases Society of America as indications for testing.5 The utility of these tests lies in helping to determine whether antibiotic treatment is indicated.37 Occult blood, fecal leukocytes, and fecal lactoferrin are often found in the stools of patients with inflammatory diarrhea. The most common pathogens in patients with a positive test result include Shigella, Salmonella, Campylobacter, Aeromonas, Yersinia, non-cholera Vibrio species,40,41 and Clostridium difficile.42 Fecal leukocytes are generally seen in the stool of patients with shigellosis, salmonellosis, Campylobacter, enteroinvasive E. coli, enterohemorrhagic E. coli, or staphylococcal enterocolitis.43 Other conditions in which fecal leukocytes may be seen include Entamoeba histolytica enteritis, Crohn’s disease, ulcerative colitis, and pseudomembraneous colitis.44 Lactoferrin is a protein found in leukocytes. The fecal lactoferrin assay can measure levels of lactoferrin released from damaged or deteriorated leukocytes in stool specimens.43 Although more research is needed, some studies indicate that fecal lactoferrin is more sensitive than fecal leukocytes or occult blood as a screening tool for detecting invasive pathogens45,46 as well as for detecting other causes of inflammatory diarrhea such as ulcerative colitis and Crohn’s disease.47,48 The test is slightly costlier than fecal leukocyte testing, but it is quicker and easier to perform and is not limited by the need for a fresh stool specimen.49 Guaiac-positive stools, as well as the findings of fecal leukocytes and fecal lactoferrin, are all predictive of finding an identifiable bacterial pathogen on stool culture.37 In one prospective study of 873 patients, stool cultures were ordered in 549 episodes (62.6%), most frequently for patients with fever, more than 10 stools per day, or visibly bloody stools. Enteropathogens were identified in 168 episodes (30.6%).39 In another well-designed study of 1040 patients, the absence of occult blood in the stool was a reliable indicator for a lack of enteroinvasive bacteria.40

While patients with a chief complaint of diarrhea rarely present with an imminent life threat, the initial assessment of any ED patient should include a rapid assessment of the ABCs. Hypovolemic or septic shock may require the patient’s airway to be secured and the patient to be ventilated.

Secondary Survey A secondary survey allows for further assessment of the patient’s volume status as well as the presence or absence of systemic toxicity. Is the patient febrile? Is postural hypotension present? Are the mucus membranes dry? For infants, is the anterior fontanelle sunken? Is the pediatric patient producing any tears when crying? Note the patient’s skin turgor, jugular venous pressure, capillary refill, and the presence or absence of sunken eyes. Also, evaluate the patient’s mental status. Is the patient awake, alert, and able to answer questions? Is the patient lethargic or completely unresponsive? Other features of diagnostic significance include the presence of flushing or rashes on the skin, mouth ulcers, thyroid masses, wheezing, arthritis, heart murmurs, hepatomegaly or abdominal masses, ascites, and edema.16 The abdominal examination should include auscultation of bowel sounds as well as the presence or absence of tenderness or peritoneal signs. A rectal examination can determine whether the stools are grossly bloody, melanotic, or guaiac-positive. Given the fact that melanotic stools are usually liquid, the patient may refer to this type of stool simply as “diarrhea.” Thus, a rectal examination may play an important role in assessing the nature of the stools. Selected female patients may require a pelvic examination depending on the degree and location of their abdominal pain.

Diagnostic Studies Blood Tests Routine CBC counts or chemistry panels are unnecessary in most patients since diarrhea is a self-limited problem in most cases. A chemistry panel may reveal an electrolyte imbalance or the degree of dehydration in systemically ill patients, or in those with severe or persistent diarrhea. In patients with bloody diarrhea, obtain a CBC and platelet count to exclude hemolytic uremic syndrome. (Hemolytic uremic syndrome is discussed in further detail in the section on pediatric patients later in this article.) Eosinophilia on the leukocyte differential can point to food allergy, collagenvascular diseases, neoplasm, parasitic infections, or eosinophilic gastroenteritis or colitis.22 Such diagnostic testing should be reserved for select cases in which clinical or epidemiologic factors or disease severity suggest their need.5 Unfortunately, the literature does not provide clearcut indications for such testing.

Stool Culture While readily obtainable tests such as heme- or leukocytepositive stools can provide the ED practitioner with valuable information, stool cultures may be advisable under certain circumstances. The use of antibiotics in certain cases of bacterial diarrhea can produce undesirable outcomes, so determining the causative agent via stool cultures can be helpful. For instance, treatment of salmonellosis can prolong the carrier state and lead to a higher clinical relapse rate.28 The likelihood of hemolytic uremic syndrome in patients infected with E. coli 0157:H7 is increased with the use of antibiotics.50 Empiric antibiotic use may increase the risk

Fecal Leukocyte/Lactoferrin Testing Fecal leukocytes and fecal lactoferrin testing can provide

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Physical Examination Primary Survey

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patients who have been on antibiotics within the past three months (suggests C. difficile). Ideally, stool samples should be sent for culture within two hours after passage to allow for detection of certain pathogens that perish quickly. If the patient is unable to provide a stool sample, a rectal swab can be brought to the lab in transport media and then cultured.28 Routine stool cultures in most laboratories will identify Shigella, Campylobacter, and Salmonella.2 (In patients who develop diarrhea after three days of hospitalization, C. difficile testing will have a higher yield (15%-20%), whereas standard stool cultures will have poor yields.28)

of C. difficile colitis. Determination of antimicrobial susceptibility is also important given the emergence of resistance to some commonly used antibiotics. Finally, negative stool culture results may be important prerequisites for the diagnosis of certain ailments such as inflammatory bowel disease. Stool cultures can also play a role in identifying agents that have significant public health consequences. An outbreak of illness due to Salmonella enteritidis serves to illustrate this point. The state public health laboratory in Minnesota received a higher-than-expected number of reports of Salmonella isolates from local clinical laboratories in 1994. These reports ultimately led to the detection of a nationwide outbreak of Salmonella enteritidis infection due to contaminated ice cream that had been widely distributed (with patients afflicted in 41 states). An estimated 220,000 people were affected by this outbreak.51 Elimination of the contaminated product from the market potentially prevented the spread of this infection to thousands of others. These preventive measures were possible because stool cultures were obtained on the first patients who presented to their physicians with diarrhea. While these examples provide compelling evidence for obtaining stool cultures on patients with diarrhea, the yield on routinely obtained stool cultures is low. In six studies conducted between 1980 and 1997, stool cultures were positive in 1.5%-5.6% of cases.5 This translates to a cost of $952-$1200 for each positive culture obtained. Interestingly, in the study with a positive culture yield of 5.6%, 63% of the patients had grossly bloody stools, while 91% presented with a history of bloody diarrhea.52 Therefore, experts recommend restricting the use of stool cultures. In patients in whom vomiting is a prominent feature of their disease, viral agents are the likely etiology and stool cultures will have a low yield. Proposed criteria that suggest a higher yield from stool cultures include history of bloody stools (grossly bloody or heme-positive stools) or stools containing leukocytes or lactoferrin; immunocompromised patients; fever higher than 38.5˚C (101.3˚F); systemic illness or an illness that is clinically severe or persistent; and patients with severe abdominal pain.2,28,53 Selective cultures can be considered in specific circumstances such as bloody diarrhea in afebrile patients with a history of ingestion of unpasteurized juice or milk or undercooked beef (suggests enterohemorrhagic E. coli); patients who have consumed shellfish within 72 hours of the onset of illness (suggests Vibrio parahemolyticus); and

Stool Testing For Parasites In developed countries, testing for ova and parasites in patients with acute diarrhea is rarely indicated.54 Cases in which testing for ova and parasites may be appropriate include patients who present with diarrhea lasting more than 14 days, the immunocompromised, and patients who have not responded to antimicrobial therapy.2 Other situations in which to consider ova and parasite testing include a community outbreak of diarrhea with a suspected waterborne cause, exposure to infants at a day care center, patients with a history of travel to endemic areas such as Russia (Giardia, Cryptosporidium), Nepal (Cyclospora), or mountainous regions of North America (Giardia). In patients with chronic bloody diarrhea and a paucity of fecal leukocytes, consider amebiasis.5 As with routine stool cultures, stool culture for ova and parasites in patients in whom diarrhea develops three or more days after hospitalization has an extremely low yield.49

Endoscopy/Computed Tomography Lower gastrointestinal endoscopy should be considered in patients with rectal bleeding, severe abdominal pain, fever, as well as negative stool tests for pathogens or otherwise unexplained chronic diarrhea lasting longer than three weeks.20 Biopsy and evaluation of the colonic mucosa is crucial to exclude the presence of C. difficile pseudomembraneous colitis, inflammatory bowel disease, ischemic colitis, microscopic or collagenous colitis (types of inflammatory bowel disease), and malignancy.20 In one study, 809 HIV-negative patients with chronic non-bloody diarrhea underwent colonoscopy. Fifteen percent of these patients had an inflammatory cause of diarrhea, including microscopic colitis and, to a lesser extent, Crohn’s disease and ulcerative colitis.55

Key Points In The Management Of Patients With Diarrhea • For most patients, diarrheal illness is short and self-limited.

dependent on a complete history and physical examination rather than on extensive, costly laboratory testing.

• While the presence of abdominal discomfort and loose stools can be consistent with gastroenteritis, this symptom complex may also signal appendicitis, ischemic bowel disease, inflammatory bowel disease, radiation enteritis, irritable bowel syndrome, and a wide variety of other disorders.

• Treatment for many forms of diarrhea consists of rehydration and symptomatic relief. • Pediatric, elderly, chronically ill, or immunocompromised patients are at greatest risk for serious etiologies and/or complications, including dehydration. ▲

• Correct diagnosis of an acute diarrheal illness is largely

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Treatment Treatment decisions are influenced by several factors, including the patient’s hydration status, the need for symptomatic relief, and the likelihood of the presence of a bacterial pathogen.

Rehydration Rehydration can be accomplished by oral or intravenous fluid administration. In patients with moderate-to-severe dehydration, as well as those in whom vomiting disallows adequate oral fluid intake, intravenous hydration speeds up the recovery process. In many cases, rehydration can be achieved with oral rehydration solutions. Fluids used for rehydration should contain sodium, potassium, and glucose.28 Various commercial types of oral rehydration solutions (such as Pedialyte, Lytren, and Rehydrolyte) are available. Various home preparations have been proposed, although they are not recommended in children. Additionally, sports drinks, which are designed to replenish fluids and electrolytes lost by sweating, are inadequate to replace diarrheal sodium losses. These solutions can be effective if they are supplemented with another source of salt such as pretzels or crackers.16,22 The use of the “BRAT” diet (bananas, rice, applesauce, toast) is commonly recommended, although evidence-based data supporting its use are sparse. One evidence-based clinical practice guideline suggests that continued use of the patient’s preferred, usual, and age-appropriate diet should be encouraged, and that the BRAT diet offers no advantage unless those foods are part of the usual diet.4

Empiric Antibiotic Therapy Authorities disagree on the indications for empiric antibiotic therapy in diarrheal illness. When effective, antibiotics shorten the course of an acute diarrheal illness by one or two days. This potential benefit should be balanced against the risk of drug-induced side-effects. The expense of therapy and the broader societal issue of antibiotic resistance induced by antibiotic overuse should also be considered.5 Interestingly, although physicians often believe that patients expect antibiotics for a variety of ailments, one study found that patient satisfaction with medical care in the case of diarrheal illness correlates poorly with receiving antibiotics. An additional finding of this same study is that physicians are not adept at identifying which patients expect antibiotics.58 Empiric antibiotics should be considered for patients with acute dysentery or those with moderate-to-severe traveler’s diarrhea.5 Diarrhea lasting longer than two to two-and-a-half days has a higher probability of having a non-viral cause; thus, empiric antibiotics can be given in these cases as well. Other criteria for empiric antibiotic therapy include fever greater than 38.5˚C (101.3˚F) plus either leukocyte-, lactoferrin-, or hemoccult-positive stools.28 Table 4 on page 13 lists the pharmaceutical regimens recommended for patients with diarrheal illnesses. In most instances, fluoroquinolones for adults and trimethoprimsulfamethoxazole (TMP-SMX) for children are reasonable

Symptomatic Therapy Symptomatic therapy may be used in selected patients with diarrhea. Patients who are afebrile and have non-bloody diarrhea as well as most patients with chronic diarrhea associated with inflammatory bowel disease may benefit from the use of antimotility agents.28 Antimotility agents should generally be avoided in patients with high fever, sepsis, immunocompromise, bloody diarrhea, or suspected inflammatory diarrhea because of delayed clearance of

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enteric pathogens, prolonged fever, and toxic megacolon,28,53 although some argue that antimotility agents may be used in patients with nondysenteric forms of diarrhea caused by enteroinvasive pathogens as long as antibiotics are also prescribed. Agents available for diarrhea relief include loperamide, diphenoxylate, and bismuth subsalicylate. Loperamide is a commonly recommended antimotility agent because of its safety and efficacy profile. It slows intraluminal flow of liquid by inhibiting peristalsis, which allows for increased intestinal absorption of fluid and electrolytes, which in turn results in substantial stool volume reduction. When used with antibiotics in patients with traveler’s diarrhea or bacillary dysentery, loperamide can reduce the duration of diarrhea by one day.53 It is an opiate that does not penetrate the nervous system; thus, there are no CNS side-effects or potential for addiction. Diphenoxylate is less costly than loperamide; however, it is chemically related to meperidine, can penetrate the CNS, and may be habit-forming. Bismuth subsalicylate helps alleviate symptoms of dyspepsia, nausea, and diarrhea. It exerts its anti-diarrheal effects via an antisecretory mechanism, binding of bacterial toxins, and by its inherent antimicrobial activity. It helps alleviate nausea and vomiting by a topical effect on the gastric mucosa and is preferred when vomiting is a prominent complaint. It has been used effectively in children with diarrhea as well as in patients with traveler’s diarrhea.57

In patients with unexplained diarrhea and a negative colonoscopic examination, upper gastrointestinal tract infections (Giardia, bacterial overgrowth syndrome) and small bowel and pancreatic diseases resulting in malabsorption should be considered. Biopsies obtained by upper endoscopy can determine etiologies such as celiac sprue (which causes the malabsorption of gluten), Whipple’s disease (a malabsorption illness caused by Tropheryma whippelii), or other malabsorptive syndromes. CT scanning of the abdomen and pelvis may provide further information about small bowel and colonic disease or extrinsic disease processes such as pancreatic tumors that can cause diarrhea.56 Although these are not primary diagnostic considerations, a working knowledge of these options is important to facilitate the work-up of patients who present to the ED with persistent diarrhea and a negative initial evaluation.

Is the patient stable?

YES

NO





ABCs, resuscitate, then history and physical examination (Class I)

History and physical examination (Class I)



➤ Provide symptomatic therapy • • • • • •

Rehydration (IV or oral) (Class I) Antiemetics as needed (Class II) Antipyretics as needed (Class II) Antibiotics as indicated (Class II) Antimotility agents as indicated (Class II) Other symptomatic relief as needed (Class II)

➤ Diagnostic evaluation as indicated





Potentially serious diagnosis possible, or patient too ill to discharge

Acute, self-limited process likely



Patient too ill to discharge

Diagnosis clear and stable clinical state

Consult and/or admit (Class II)





Consult and/or admit (Class I)





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Clinical Pathway: Approach To Patients With Diarrhea

Discharge (Class I)

The evidence for recommendations is graded using the following scale. For complete definitions, see back page. Class I: Definitely recommended. Definitive, excellent evidence provides support. Class II: Acceptable and useful. Good evidence provides support. Class III: May be acceptable, possibly useful. Fair-to-good evidence provides support. Indeterminate: Continuing area of research.

This clinical pathway is intended to supplement, rather than substitute for, professional judgment and may be changed depending upon a patient’s individual needs. Failure to comply with this pathway does not represent a breach of the standard of care.

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Diarrhea (loose, watery bowel movements) is often caused by an infection. Many infections that cause diarrhea simply go away by themselves. Diarrhea can also be caused by other things, like medications, bleeding into the stomach or bowels, diseases of the bowels, appendicitis, and many others. Diarrhea can happen by itself or may happen with other symptoms, like cramps or pain in the stomach and bowel area, fever, vomiting, rash, or bleeding from the rear end. You can become dehydrated (lose too much water) because of diarrhea. at the pharmacy or supermarket. Let your child eat a regular diet as soon as possible. If your child is vomiting, try having him or her drink very small amounts of liquid until the vomiting stops.

Adults Signs of dehydration • You are very thirsty • You feel weak or dizzy • You faint or feel like you might faint • Your skin is dry or very loose • Your urine is dark

Do Not: • Don’t use water or sports drinks for your dehydrated child (use an oral rehydration solution instead) • Don’t withhold dairy products (milk, cheese, ice cream) from your child • Don’t have your child drink fruit juices like prune, apple, or grape juice (these can cause diarrhea)

How to avoid or treat dehydration For the first 1-2 days: Drink lots of fluids, such as caffeine-free sodas, sports drinks, and flavored mineral water, or an oral rehydration solution that you can buy at the supermarket or pharmacy. Nibble on salted crackers or pretzels (you need the salt) and drink some orange juice or eat some bananas (for the potassium, needed for the heart and muscles. You are probably drinking enough if you are not thirsty and your urine is pale yellow. After the first 1-2 days: Try plain potatoes, noodles, rice, boiled cereals, bread, and other similar items. Go back to your regular diet if the diarrhea is gone.

Medications Use all medications exactly as your doctor advises. You have been prescribed: • ______________________________ • ______________________________ • ______________________________ You may also use: • ______________________________ • ______________________________ • ______________________________

Do Not: • Don’t drink milk or eat dairy products (cheese, ice cream) for 2-3 days • Don’t drink caffeine (tea, cola, coffee) • Don’t drink alcohol • Don’t drink fruit juices like prune, apple, or grape juice (these can cause diarrhea)

Reasons to return to the Emergency Department: • You are dehydrated • You are vomiting and cannot eat or drink • You have a fever over _____˚ F ( _____˚ C ) • You have blood, pus, or mucus in your diarrhea or bowel movements • You have pain in the stomach or bowel area • You have bloody, black, or wine-colored diarrhea or bowel movements • Your sickness lasts more than _____ days • You are not getting better at home • You have any other problems that concern you

Children Signs of dehydration • Your child is very thirsty • Your child is very weak, sleepy, or cranky • Your child’s skin feels cool, doughy, or loose • Your child cries but does not make tears • Your child does not make as much urine as usual How to avoid or treat dehydration Use an oral rehydration solution that you can buy

See your own doctor in _____ days.

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Sample Discharge Instructions For Patients With Diarrhea

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Ten Pitfalls To Avoid 1. “The patient had nausea, vomiting, and diarrhea—typical gastroenteritis, right?” While that’s often the case, a more thorough evaluation is required. Gastrointestinal symptoms are notoriously nonspecific. Plus, a wide variety of extra-abdominal conditions can present with abdominal complaints (diabetic ketoacidosis, thyrotoxicosis, poisonings, pneumonia).

a diagnosis of viral gastroenteritis, which is often a wastebasket category and implies premature closure of the diagnostic thought process. 7. “In the ED, everybody with vomiting and diarrhea looks sick at first—but if they look better after rehydration, it’s usually okay to discharge them. This 65-year-old man looked pretty good after he was rehydrated. How was I supposed to know that he’d get worse at home? We can’t admit everyone.” It seems prudent to be more concerned about those at the extremes of age (the pediatric and geriatric set), immunocompromised individuals, and those with severe abdominal pain. Severe abdominal pain is not typically associated with gastroenteritis or most common enteric pathogens. Loose stools may also be present in patients with ischemic bowel disease. Consider this diagnosis in the elderly and in those with a history of vascular disease. C. difficile-associated diarrhea is a consideration in anyone who has been taking antibiotics during the past three months. Certain antibiotics (e.g., clindamycin) place the patient at particularly high risk for toxin-induced colitis.

2. “The patient had nausea, vomiting, and diarrhea. I diagnosed ‘viral gastroenteritis’ and discharged her in stable condition. She never told me that she recently returned from an overseas trip!” Travelers, patients recently discharged from the hospital, patients with recent medication use (especially antibiotics), and the immunocompromised are susceptible to a much wider range of etiologies. Inquire routinely about these aspects of their medical history. Patients often do not realize the significance of these factors. 3. “The patient reported diarrhea. He didn’t tell me his stool was black! How was I supposed to know that he had a gastrointestinal bleed?” Many patients either don’t know the characteristics of the stool they’re passing or fail to recognize the significance of various abnormalities (blood, mucus, melena). Ask the patient for specifics, and if any doubt remains about what is being passed, do a rectal examination.

8. “I didn’t give Mr. Jones an antimotility drug because I was always taught it might make the patient worse. I never expected him to become so dehydrated that he’d pass out!” While it’s true that there are cases in which antimotility drugs are contraindicated, they can be of significant benefit for both comfort and for preventing dehydration in most adults with diarrhea.

4. “The patient had nausea, vomiting, and diarrhea—typical gastroenteritis. How was I supposed to know it was appendicitis?” (Part 1) Unfortunately, there are no absolute guidelines. While appendicitis remains a primarily clinical diagnosis, quantifying might help. Appendicitis patients tend to have one or two emesis episodes after their abdominal pain begins, and they typically pass one or two loose stools. Those with gastroenteritis, on the other hand, tend to have multiple episodes of vomiting and voluminous loose stools.

9. “When I discharged Mrs. Smith, she was stable, taking oral fluids, and had no abdominal pain—but later she came back in shock, severely dehydrated. What could I have done differently?” Written discharge instructions that the patient and her family can understand and use are critically important. Key reasons to return to the ED include profuse diarrhea, dehydration (manifested by weakness, lethargy, altered mental status, syncope/near-syncope, thirst, decreased urine output), sustained fever, severe or persistent abdominal pain, bloody or mucoid stools, and the inability to take and retain oral fluids. (See also the “Sample Discharge Instructions For Patients With Diarrhea” on page 11.) Instructions must be clear and specific.

5. “The patient had nausea, vomiting, and diarrhea—typical gastroenteritis. How was I supposed to know it was appendicitis?” (Part 2) Serial abdominal examinations can be extremely helpful in identifying appendicitis. Patients with gastroenteritis generally improve with time and fluids. While the pulse and blood pressure of patients with appendicitis may improve with intravenous fluids, abdominal signs and symptoms like localized tenderness, guarding, and rebound typically persist.

10. “I know that diarrhea can occasionally have serious sequelae, but it simply isn’t practical to send everyone for follow-up!” That’s true, but be careful. In general, otherwise healthy patients whose symptoms resolve quickly do not require follow-up. But certain subsets of patients—such as those with chronic symptoms, the elderly, the very young, the immunocompromised, and those with co-morbid illnesses—should be referred for follow-up. And, as mentioned in the prior item, discharge instructions should be very clear about circumstances under which patients should seek further medical care. ▲

6. “The patient had nausea, vomiting, and diarrhea, but was otherwise unremarkable. I diagnosed ‘viral gastroenteritis’ and discharged her in stable condition. I had to diagnose something, right? Too bad she got worse and had to return to the ED a couple of days later.” Many entities seem like viral gastroenteritis that aren’t. If the diagnosis is unclear, stick to the facts and write “vomiting and diarrhea with dehydration” (or something similar) on the chart. Don’t paint yourself into a corner with

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choices.5 Empiric therapy with metronidazole (or other anti-Giardia agent) can also be considered in patients with diarrhea lasting 2-4 weeks, without systemic symptoms or dysentery.16 In suspected cases of C. difficile-associated diarrhea, the offending antibiotic should be stopped if possible and treatment with oral metronidazole begun. Metronidazole should be stopped if the assay for C. difficile toxin is negative.14 When empiric antibiotic therapy is not employed judiciously, it can be ineffective or even harmful. If vomiting is a prominent symptom of the illness, a viral source is more likely. Antibiotics should also not be used if the diarrhea is thought to be due to Shiga toxin-producing E. coli. This decision will involve physician judgment since no diagnostic test will yield an immediate result to help the clinician. Keep in mind that Shiga toxin-producing E. coli (E. coli 0157:H7 being the most common type) causes bloody diarrhea. E. coli 0157:H7 outbreaks have been associated with undercooked ground beef as well as with fresh produce such as unpasteurized apple cider, cabbage, and alfalfa sprouts.2

diarrhea include quinolones, TMP-SMX, as well as nonabsorbable or poorly absorbed antibiotics such as rifaximin and aztreonam.59,60 A comparison of two different doses of TMP-SMX with or without loperamide vs. loperamide alone in American adults with acute diarrhea in Mexico revealed that combination therapy with TMP-SMX and loperamide was the most efficacious regimen.61 Several studies have also provided data regarding the efficacy and safety of rifaximin for the treatment of traveler’s diarrhea. Adults with acute traveler’s diarrhea who took rifaximin vs. placebo for three days had earlier resolution of symptoms (average, slightly more than one day).62 A randomized, controlled trial comparing rifaximin with TMP-SMX revealed an 11% clinical failure rate with rifaximin vs. a 29% clinical failure rate with TMP-SMX.63 In another comparison of rifaximin with ciprofloxacin, no significant differences were noted between the two treatment groups.59 There is an increasing emergence of fluoroquinoloneresistant Campylobacter, with the rate of resistance exceeding 80% in Southern Asia.53 For patients with travel histories to this part of the world, erythromycin or azithromycin are alternatives.53

Traveler’s Diarrhea

Prevention Of Traveler’s Diarrhea

Antibiotics commonly used in the treatment of traveler’s

Advising patients on ways to minimize the risk of traveler’s diarrhea for future trips may be helpful, as well. Beverages should be carbonated or steaming hot. Uncarbonated water, bottled water, and even ice may be unsafe. Dry foods (bread), acidic foods (citrus), and foods with high sugar content (jellies, syrups) are safe. Buffet items and green, leafy vegetables (which are washed in water) should be avoided.57 Advise travelers to take along loperamide or bismuth subsalicylate as well as an antibiotic. (However, note that sulfa-based medications can produce photosensitivity.) One randomized, controlled comparison of bismuth subsalicylate with loperamide showed similar efficacy; however, the loperamide group passed fewer stools than the bismuth subsalicylate group.64 On the other hand, bismuth subsalicylate has the additional advantage of alleviating nausea and vomiting and has been shown to prevent traveler’s diarrhea. In a randomized, double-blind, placebo-controlled trial, diarrhea developed in 23% of students receiving bismuth subsalicylate compared with 61% of students taking a placebo. The treatment group experienced fewer intestinal complaints and were less likely to pass loose or watery stools. In subjects in whom diarrhea did occur, enteropathogens were identified less commonly in the treatment group (33%) compared to the placebo group (71%).57

Table 4. Empiric Antibiotic Therapy Regimens For Suspected Infectious Diarrhea. 1. Temperature greater than 38.5˚C (101.3˚F) and one of the following: • Guaiac-positive stools or presence of fecal leukocytes or fecal lactoferrin • Also, consider empiric antibiotics in patients with diarrhea lasting longer than 48 hours

Treatment: • A fluoroquinolone in adults • Trimethoprim-sulfamethoxazole in children Treatment period: 1-5 days

2. Moderate-to-severe traveler’s diarrhea Treatment: • A fluoroquinolone in adults • Trimethoprim-sulfamethoxazole in children Treatment period: 1-5 days

3. Diarrhea for 2-4 weeks without systemic symptoms or dysentery Treatment: • Consider a seven- to 10-day course of metronidazole or other anti-Giardia agent

4. Nosocomial diarrhea Treatment:

Special Circumstances

• Stop the suspected offending antibiotic • Metronidazole (first line) or vancomycin (in case of metronidazole failure or when metronidazole is contraindicated or not tolerated) Treatment period: 10 days if assay for C. difficile is positive. Stop antibiotic if assay for C. difficile is negative.

July 2004 • EMPractice.net

Immunocompromized Patients Patients with HIV/AIDS are especially prone to diarrheal illnesses. About half of North American AIDS patients will develop diarrhea at some point in their illness. The incidence of diarrhea in AIDS patients throughout the develop-

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ing world approaches 100%.65 While HIV/AIDS patients are at risk for all of the diarrheal ailments that afflict the immunocompetent population, they can develop enteric infections from a variety of unusual viral, parasitic, protozoal, and bacterial organisms. Malignancies affecting the gastrointestinal tract, such as lymphoma and Kaposi’s sarcoma, may produce diarrhea, as can many antiretroviral medications.65,66 Finally, many AIDS patients receive multiple or sustained courses of antibiotics, predisposing them to C. difficile-associated diarrhea.66 Therefore, it is important to maintain a broad differential diagnosis, consider a more aggressive diagnostic strategy, involve consultants early when appropriate, and consider hospitalization to improve diagnostic certainty through a combination of testing, observation, and consultant involvement. (See also the January 2002 issue of Emergency Medicine Practice, “HIV-Related Illnesses: The Challenge Of ED Management.”) Because certain symptoms may suggest particular organisms (see Table 5), the approach to the HIV/AIDS patient with diarrhea begins with the history. Definitive diagnosis, however, is likely to result from either microbiological studies or endoscopy.65,66 Begin by assessing the patient’s immune status. Ask about specific exposures (sexual practices, travel history, and medications including recent antibiotics). Inquire also about the stool characteristics (bloody, mucoid, watery) and all associated symptoms (e.g., fever, vomiting, abdominal pain or cramping, tenesmus, bloating, weight loss).65,66 What may seem like an acute bout of diarrhea may actually represent the beginning of chronic symptoms. Routine laboratory tests should be ordered based on the clinical situation.65 Many authorities recommend that in AIDS patients, a stool culture should be done, along with C. difficile toxin and ova and parasite testing.66 If these studies are negative, referral to a gastroenterologist for endoscopic investigations could be the next step in the patient’s evaluation.65,66 In the AIDS patient with chronic diarrhea and a negative microbiological work-up for infectious agents, authorities are divided on the best approach. Some advocate symptomatic care, some a course of empiric antibiotics, and still others suggest endoscopy with gastrointestinal mucosal biopsy; symptoms and

disease stage guide these decisions.17 Endoscopy often produces a definitive diagnosis in AIDS patients with chronic diarrhea and negative stool studies.67 ED treatment options include rehydration, antimotility agents, and empiric antibiotics, as discussed earlier in this article. Consultation or referral to the patient’s primary care provider or infectious disease specialist regarding antibiotic therapy or changes in antiretroviral therapy are advisable.

Elderly Patients Diarrheal illnesses are important causes of death and disability in the elderly. Not only are more serious etiologies more common in the elderly, the physiological stresses of diarrheal illness are more challenging for this population. Age-related declines in immune system functioning, physiologic changes of aging, medications (e.g., those that inhibit gastric acid secretion, antibiotics, vasoconstrictors, and others), and environmental factors (e.g., group living in nursing homes) all contribute to the elderly patient’s susceptibility to develop diarrhea.68 Furthermore, elderly patients with diarrhea are often profoundly dehydrated due to fluid losses associated with their illness, fever, an age-related disordered thirst mechanism, co-existing illnesses (e.g., diabetes mellitus), medications (e.g., diuretics) and limited access to fluids due to infirmity. Prompt, adequate rehydration is essential; however, intravenous rehydration of the elderly individual may be complicated by the presence of cardiovascular disease or renal dysfunction, thus limiting rapid, largevolume fluid administration.68 Ischemic colitis, diverticulitis, bacterial overgrowth, and colonic malignancies are all more common in the elderly and may present with loose stool.7,68,69 Infections— notably, C. difficile, E. coli 0157:H7 and Salmonella species— are more common in the elderly.68,70 Infectious diarrhea in the elderly is associated with a higher mortality rate.68 If medications are indicated for an elderly patient with diarrhea, be aware of drug interactions and side-effects, particularly if the patient is already on multiple medications. Antacids may reduce the potency of fluoroquinolones. Additionally, fluoroquinolones can increase theophylline and warfarin levels and can either increase or decrease phenytoin levels. Metronidazole can cause nausea and vomiting, exacerbating the situation for a patient who initially presented with a gastrointestinal complaint. Drinking alcohol while taking metronidazole must be strictly avoided since a disulfiram-like reaction can ensue. Also, warfarin, phenytoin, and phenobarbital metabolism may all increase in the patient on metronidazole, potentiating their effect.68 Be particularly cautious when evaluating elderly patients with diarrhea combined with abdominal pain. Elderly patients with abdominal pain tend to have more serious, often surgical, illnesses that present atypically or go unrecognized longer.69 (See also the premier issue of Emergency Medicine Practice, “Assessing Abdominal Pain In Adults: A Rational, Cost-Effective, And EvidenceBased Strategy.”) Specific surgical diagnoses to consider

Table 5. Diarrheal Syndromes In Patients With HIV/AIDS. Abdominal cramps, bloating, nausea Possible agents: Cryptosporidia, microsporidia, isospora, giardia, cyclospora, and Mycobacterium avium complex

Profuse watery diarrhea, weight loss, electrolyte disturbance (especially in advanced disease) Possible agent: Cryptosporidia

Bloody stools, fever, abdominal cramps Possible agents: Invasive bacteria, C. difficile, cytomegalovirus Adapted from: Sax PE. Opportunistic infections in HIV disease: down but not out. Infect Dis Clin North Am 2001;15(2):433-55.

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Pediatric Patients Diarrhea is very common in children, especially among those who attend day care. While most children in developed nations have mild, self-limited disease, pediatric patients are susceptible to more adverse outcomes— especially dehydration—than their healthy adult counterparts.21 In the United States, about 9% of all hospitalizations of children younger than 5 years are because of diarrhea.71 While pediatric patients are susceptible to more adverse outcomes from diarrheal illnesses, the approach is generally the same. As with adults, infectious causes predominate, although children have more of a predisposition to rotavirus. Another common non-infectious cause in children is the excessive consumption of sugary, clear liquids, which can cause copious, watery stools. The wary practitioner should also keep more serious diagnoses such as intussusception and Meckel’s diverticulum in mind. In most cases, prevention of dehydration is the primary consideration. Oral rehydration methods are preferred. After rehydration, recommend prompt resumption of a

Cost- And Time-Effective Strategies For Patients With Diarrhea 1. Consider minimizing testing in those with acute gastroenteritis by obtaining an adequate history and performing a sufficient physical examination. Routine laboratory testing is unhelpful for most patients with acute diarrheal illnesses. The white blood cell count is neither sensitive nor specific for any particular illness characterized by diarrhea. The white blood cell differential is often similarly unhelpful. Hemoglobin and hematocrit levels may be useful in those patients with blood loss, but otherwise are of limited to no value. Electrolytes are rarely disordered significantly in young patients with short periods of diarrhea. Renal function tests are a poor screen for dehydration. Urine-specific gravity may be somewhat more helpful, but easily observable clinical features like skin perfusion, vital signs, urine output, and thirst may be best of all. Caveat: The WBC count can be helpful in identifying C. difficile (which may require admission) or enteric fever. In addition, eosinophilia may indicate alternative diagnoses.

bloody stools, grossly bloody, or heme-positive stools), stool samples positive for leukocytes or lactoferrin, patients whose symptoms last longer than two days, and in all other patients to whom empiric antibiotics will be prescribed. 4. Do not order stool testing for ova and parasites in the ED. Testing for ova and parasites in patients with acute diarrhea is rarely indicated in the United States. 5. Oral rehydration is superior to intravenous rehydration in most patients able to tolerate oral intake. The cost difference is enormous in favor of oral rehydration— and it also provides one important indicator of the patient’s suitability for discharge (ability to tolerate oral fluids). In addition, several studies indicate faster recovery times with early refeeding. If the gut works, use it. Caveat: Intravenous rehydration with or without oral supplementation can be much quicker—which may be an important consideration in high-volume EDs.

2. Test for C. difficile toxin in those patients with a suggestive history, including antibiotic use in the past three months. This is one situation for which testing is truly indicated. Treatment for C. difficile is relatively inexpensive and effective. In this setting, test for the toxin; treat empirically pending the culture results if strong clinical suspicion is present.

6. Reassess, reassess, reassess and provide good discharge instructions. Prior to discharging any patient with gastrointestinal complaints, recheck the vital signs, repeat the abdominal examination, and document your findings. Make sure that all patients can take oral fluids without developing vomiting or other intolerable symptoms. Those who can’t are more likely to bounce back to the ED and may be quite unhappy about a second visit for the same illness. Finally, make sure that patients and their caregivers can comply with discharge instructions and understand reasons to return to the hospital. ▲

3. Order stool cultures selectively. In general, stool cultures are expensive, time-consuming, low yield, and not helpful to the emergency physician. Consider obtaining stool cultures only in patients with a temperature greater than 38.5˚C (101.3˚F), bloody stools (history of

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regular diet, supplemented with oral rehydration solution as tolerated. In vomiting children, frequent, small-volume oral intake is recommended.4 In children, as a general rule, pharmacologic agents should not be used to treat acute diarrhea.21 While some well-designed studies have shown statistically significant results for certain agents, the results were not clinically significant, and published evidence-based guidelines do not support their use in children.4,21 Antibiotic use may be considered in patients in high-risk categories or with serious bacterial infections.4 Hemolytic uremic syndrome is a complication of E. coli 0157:H7 infection that occurs primarily in children. While rare, it is the most common cause of acute kidney failure in infants and children. Early symptoms include vomiting and diarrhea (sometimes bloody), fever, and irritability or lethargy. Later, urine output, decreased consciousness, pallor, bruising, petechiae, or jaundice may occur. An enlarged liver or spleen may be present. Laboratory studies will show evidence of hemolytic anemia and acute renal failure. Administration of packed red blood cells may be necessary, and severe cases may require dialysis. Nevertheless, most children receiving treatment recover completely with no long-term consequences.

in the elderly patient with diarrhea include bowel obstruction, appendicitis, mesenteric ischemia, neoplasm, and diverticulitis.69

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Pregnant Patients

than those in the placebo group.77 It should be noted that the studies referenced above were conducted primarily in the developing world, where zinc deficiency in children is prevalent. In the United States, zinc administration to children with diarrheal illnesses is not a part of standard therapy.

Constipation is usually more of a problem than diarrhea during pregnancy; however, when diarrhea does occur, treatment principles are similar. Preventing dehydration in pregnant patients is a top priority, as it is dangerous for both mother and fetus. Replete disordered electrolytes as needed and provide symptomatic relief. Antibiotic and other medication use in the pregnant patient with diarrhea should be guided by an assessment of the individual patient’s riskbenefit ratio based on symptom severity and pregnancy risk category of the medication. Loperamide is the safest antimotility agent since it acts peripherally (unlike diphenoxlylate) and does not contain salicylates (unlike bismuth subsalicylate).72 Of the antibiotics generally used for diarrhea treatment, none are considered relatively safe in pregnancy except metronidazole (a Category B drug) after the first trimester if the benefits outweigh the risks. The quinolones and TMP-SMX are either to be avoided or used with caution depending on stage of pregnancy. If doubts exist about antibiotic use in the pregnant patient, the best approach is to coordinate treatment with the patient’s obstetrician-gynecologist or consult a medical reference that lists teratogenic agents.

Ramoplanin For C. difficile-Associated Diarrhea A new antibiotic, ramoplanin, is currently in Phase II development for C. difficile-associated diarrhea. This antibiotic also has activity against vancomycinresistant Enterococcus species and other enteric organisms.78 Ramoplanin is an oral agent and is not systemically absorbed.79

Disposition

Probiotics are microorganisms that some have used in a variety of settings and clinical circumstances to colonize the intestine to prevent or treat diarrhea. One recent meta-analysis of probiotic use in children hospitalized with acute gastroenteritis found that probiotics are a useful adjuvant along with rehydration therapy in acute gastroenteritis.73 Another meta-analysis of oral Lactobacillus (the most-studied probiotic) treatment of children with acute infectious diarrhea found that diarrhea duration was reduced an average of 0.7 days, and stool frequency decreased by an average of 1.6 per day.74 A third recent meta-analysis of probiotics for antibiotic-associated diarrhea found that diarrhea occurred in 23% of patients not receiving a probiotic agent and in 13% of patients receiving a probiotic.75 This meta-analysis involved children and adults. While probiotics are not standard therapy for adults or children with diarrhea in the United States, they are available over-the-counter in a variety of retail outlets, and patients may ask about their utility in diarrheal illnesses.

For patients with diarrheal illness, disposition decisions rely heavily on physician judgment. Clinically stable patients with benign physical examinations and diagnoses that present low risk for complications—the most common scenario—can be safely discharged with good follow-up instructions. Ill patients who fail to respond adequately to simple ED measures like rehydration and symptom relief may either be held in the ED or admitted to an observation area or to the hospital, depending on local resources and hospital policies. A brief hospital admission can provide dramatic improvement, especially for patients at the extremes of age or with serious co-morbidities. Patients who represent diagnostic dilemmas or who present atypically could require either a period of observation or immediate further investigation depending on the level of concern. Given the incredibly broad differential diagnosis of diarrheal illness, no definitive rules are available to guide decision-making. Again, maintain a heightened level of alertness when evaluating the very old and the very young, those with multiple or serious co-morbidities, and the immunocompromised. Patients with chronic diarrhea deserve special mention because they often need extensive evaluation to determine the cause of their symptoms. This diagnostic evaluation usually exceeds the scope of most ED capabilities. Coordination of care with a gastroenterologist is advised in these cases. The role of the emergency physician is to exclude serious illness, ensure patient stability, begin an investigation to exclude infectious causes of diarrhea, and provide timely referral for further evaluation.

Zinc

Preventive Measures

In 2000, a pooled analysis of randomized, controlled trials of zinc therapy in children under 5 years of age with diarrhea concluded that zinc supplementation reduces the duration and severity of acute and persistent diarrhea.76 A more recent randomized, controlled clinical trial studied the effects of zinc administration in children with diarrhea. This study was done in Nepalese children 6-35 months of age with acute diarrhea. Findings were that zinc supplementation substantially reduced diarrhea duration and that those in the zinc group were more likely to vomit

Emergency physicians should also teach patients and their families about simple preventive measures to reduce disease transmission, especially when a patient is being discharged with a transmissible diarrheal illness. Norwalklike viruses, in particular, are infectious in very low concentrations and are easily spread from person to person by droplets, or even by contaminated objects. Asymptomatic carriers can also transmit these viruses. In addition, infectious agents are easily spread among the institutionalized elderly due to poor personal hygiene (secondary to

Controversies/Cutting Edge Probiotics

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Guerrant RL, Van Gilder T, Steiner TS, et al; Infectious Diseases Society of America. Practice guidelines for the management of infectious diarrhea. Clin Infect Dis 2001 Feb 1;32(3):331-351. (Practice guideline) 6. No authors listed. Practice parameters for the treatment of sigmoid diverticulitis. The Standards Task Force. The American Society of Colon and Rectal Surgeons. Dis Colon Rectum 2000 Mar;43(3):289. (Practice guideline) 7. Wong WD, Wexner SD, Lowry A, et al. Practice parameters for the treatment of sigmoid diverticulitis—supporting documentation. The Standards Task Force. The American Society of Colon and Rectal Surgeons. Dis Colon Rectum 2000 Mar;43(3):290-297. (Practice guideline) 8. No authors listed. American Gastroenterological Association Medical Position Statement: guidelines on intestinal ischemia. Gastroenterology 2000 May;118(5):951-953. (Practice guideline) 9. Brandt LJ, Boley SJ. AGA technical review on intestinal ischemia. American Gastrointestinal Association. Gastroenterology 2000 May;118(5):954-968. (Review) 10. Hanauer SB, Sandborn W; Practice Parameters Committee of the American College of Gastroenterology. Management of Crohn’s disease in adults. Am J Gastroenterol 2001 Mar;96(3):635-643. (Practice guideline) 11. No authors listed; American Gastroenterology Association. American Gastroenterological Association medical position statement: irritable bowel syndrome. Gastroenterology 2002 Dec;123(6):2105-2107. (Practice guideline) 12. No authors listed. “Norwalk-like viruses”: public health consequences and outbreak management. MMWR Recomm Rep 2001 Jun 1:50(RR09);1-18. (Review) 13. Sampson HA, Sicherer SH, Birnbaum AH. AGA technical review on the evaluation of food allergy in gastrointestinal disorders. American Gastroenterological Association. Gastroenterology 2001 Mar;120(4):10261040. (Review) 14. Fekety R. Guidelines for the diagnosis and management of Clostridium difficile-associated diarrhea and colitis. American College of Gastroenterology, Practice Parameters Committee. Am J Gastroenterol 1997 May;92(5):739-750. (Practice guideline) 15. Andersson RE. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Br J Surg 2004 Jan;91(1):28-37. (Meta-analysis; 24 studies) 16. Fine KD, Schiller LR. AGA technical review on the evaluation and management of chronic diarrhea. Gastroenterology 1999 Jun;116(6):14641486. (Review) 17. No authors listed. American Gastroenterological Association medical position statement: guidelines for the management of malnutrition and cachexia, chronic diarrhea, and hepatobiliary disease in patients with human immunodeficiency virus infection. Gastroenterology 1996 Dec;111(6):1722-1723. (Practice guideline) 18. American College of Radiology, Expert Panel on Gastrointestinal Imaging. Imaging recommendations for patients with Crohn’s disease. Reston, VA: American College of Radiology; 2001. (Review) 19. Eisen GM, Dominitz JA, Faigel DO, et al; American Society for Gastrointestinal Endoscopy. Use of endoscopy in diarrheal illnesses. Gastrointest Endosc 2001 Dec;54(6):821-823. (Practice guideline) 20. Schiller LR, Sellin JH. Diarrhea. In: Feldman M, Friedman LS, Sleisenger MH, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 7th ed. Philadelphia: WB Saunders; 2002:131-153. (Textbook chapter) 21.* No authors listed. Practice parameter: the management of acute gastroenteritis in young children. American Academy of Pediatrics, Provisional Committee on Quality Improvement, Subcommittee on Acute Gastroenteritis. Pediatrics 1996 Mar;97(3):424-435. (Practice guideline) 22. No authors listed. American Gastroenterological Association medical position statement: guidelines for the evaluation and management of chronic diarrhea. Gastroenterology 1999 Jun;116(6):1461-1463. (Practice guideline) 23. Hasler WL. The irritable bowel syndrome. Med Clin North Am 2002 Nov;86(6):1525-1551. (Review) 24. Andres PG, Friedman LS. Epidemiology and the natural course of inflammatory bowel disease. Gastroenterol Clin North Am 1999 Jun;28(2):255-281, vii. (Review) 25. Burns BJ, Brandt LJ. Intestinal ischemia. Gastroenterol Clin North Am 2003 Dec;32(4):1127-1143. (Review) 26. Tabrez S, Roberts IM. Malabsorption and malnutrition. Prim Care 2001 Sep;28(3):505-522, v. (Review) 27. Brandt LJ, Boley SJ. Intestinal ischemia. In: Feldman M, Friedman LS, Sleisenger MH, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver

Summary A simple approach focused on obtaining a thorough history and performing a focused physical examination is generally sufficient for most ED patients presenting with diarrhea. Selective laboratory testing can be helpful but should not be the cornerstone of patient evaluation. Symptomatic treatment is simple and well-supported in the literature. Differentiating between those patients requiring symptomatic treatment prior to discharge, those needing hospitalization and more systematic investigation, and those with more serious disease processes masquerading as simple diarrhea remains the most essential element of the ED encounter. It is easy to confuse the common (gastroenteritis) with the rare (poisonings), the serious (appendicitis), and the deadly (gastrointestinal hemorrhage). If there is a doubt about the diagnosis, ED observation and repeated examinations can be helpful. Patients warranting a greater level of concern are the very young, the elderly, immunocompromised individuals, those with major comorbidities, and those with unusual or atypical presentations such as severe abdominal pain. ▲

References Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report. To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study, will be included in bold type following the reference, where available. In addition, the most informative references cited in the paper, as determined by the authors, will be noted by an asterisk (*) next to the number of the reference. 1.

2.

3.

4.*

No authors listed. Clinical policy: critical issues for the initial evaluation and management of patients presenting with a chief complaint of nontraumatic acute abdominal pain. Ann Emerg Med 2000 Oct;36(4):406-415. (Clinical policy) No authors listed; American Medical Association; Centers for Disease Control and Prevention; Center for Food Safety and Applied Nutrition, Food and Drug Administration; Food Safety and Inspection Service, U.S. Department of Agriculture. Diagnosis and management of foodborne illnesses: a primer for physicians. MMWR Recomm Rep 2001 Jan 26;50(RR-2):1-69. (Review) McGee S, Abernethy WB 3rd, Simel DL. The rational clinical examination. Is this patient hypovolemic? JAMA 1999 Mar 17;281(11):1022-1029. (Meta-analysis) Cincinnati Children’s Hospital Medical Center. Evidence based clinical practice guideline for children with acute gastroenteritis (AGE). Cincinnati (OH): Cincinnati Children’s Hospital Medical Center; 2001 Apr. (Practice guideline; 118 references)

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5.*

immobility, incontinence, and reduced mental alertness), and close living quarters. Hand-washing with soap is a simple, effective measure that can be used by caregivers of patients with diarrhea. This is especially important for caretakers of immunocompromised patients (those receiving cancer chemotherapy, immunosuppressive agents, long-term steroids, or those with HIV) as well as food handlers.

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N Engl J Med 1996 May 16;334(20):1281-1286. (Epidemiologic data) Eidlitz-Marcus T, Cohen YH, Nussinovitch M, et al. Comparative efficacy of two- and five-day courses of ceftriaxone for treatment of severe shigellosis in children. J Pediatr 1993 Nov;123(5):822-824. (Prospective, randomized; 40 patients) 53.* Thielman NM, Guerrant RL. Clinical practice. Acute infectious diarrhea. N Engl J Med 2004 Jan 1;350(1):38-47. (Review) 54. Siegel DL, Edelstein PH, Nachamkin I. Inappropriate testing for diarrheal diseases in the hospital. JAMA 1990 Feb 16;263(7):979-982. (Retrospective; 281 cases) 55. Fine KD, Seidel RH, Do K. The prevalence, anatomic distribution, and diagnosis of colonic causes of chronic diarrhea. Gastrointest Endosc 2000 Mar;51(3):318-326. (Prospective; 809 patients with chronic nonbloody diarrhea) 56.* Schiller LR. Diarrhea. Med Clin North Am 2000 Sep;84(5):1259-1274, x. (Review) 57. DuPont HL, Sullivan P, Evans DG, et al. Prevention of traveler’s diarrhea (emporiatric enteritis). Prophylactic administration of subsalicylate bismuth). JAMA 1980 Jan 18;243(3):237-241. (Randomized, controlled trial; 128 patients) 58. Karras DJ, Ong S, Moran GJ, et al; EMERGEncy ID NET Study Group. Antibiotic use for emergency department patients with acute diarrhea: Prescribing practices, patient expectations, and patient satisfaction. Ann Emerg Med 2003 Dec;42(6):835-842. (Multicenter, prospective; 104 patients) 59.* DuPont HL, Jiang ZD, Ericsson CD, et al. Rifaximin versus ciprofloxacin for the treatment of traveler’s diarrhea: a randomized, double-blind clinical trial. Clin Infect Dis 2001 Dec 1;33(11):1807-1815. (Randomized, controlled trial; 187 patients) 60. Ramzan NN. Traveler’s diarrhea. Gastroenterol Clin North Am 2001 Sep;30(3):665-678, viii. (Review) 61. Ericsson CD, DuPont HL, Mathewson JJ, et al. Treatment of traveler’s diarrhea with sulfamethoxazole and trimethoprim and loperamide. JAMA 1990 Jan 12;263(2):257-261. (Randomized, controlled trial; 227 patients) 62. Steffen R, Sack DA, Riopel L, et al. Therapy of travelers’ diarrhea with rifaximin on various continents. Am J Gastroenterol 2003 May;98(5):1073-1078. (Multicenter, randomized, controlled trial; 380 patients) 63. DuPont HL, Ericsson CD, Mathewson JJ, et al. Rifaximin: a nonabsorbed antimicrobial in the therapy of travelers’ diarrhea. Digestion 1998 Nov-Dec;59(6):708-714. (Multicenter, randomized, controlled trial; 72 patients) 64. Johnson PC, Ericsson CD, DuPont HL, et al. Comparison of loperamide with bismuth subsalicylate for the treatment of acute travelers’ diarrhea. JAMA 1986 Feb 14;255(6):757-760. (Randomized, controlled trial; 219 patients) 65. Cohen J, West AB, Bini EJ. Infectious diarrhea in human immunodeficiency virus. Gastroenterol Clin North Am 2001 Sep;30(3):637-664. (Review) 66. Sax PE. Opportunistic infections in HIV disease: down but not out. Infect Dis Clin North Am 2001 Jun;15(2):433-455. (Review) 67. Wei SC, Hung CC, Chen MY, et al. Endoscopy in acquired immunodeficiency syndrome patients with diarrhea and negative stool studies. Gastrointest Endosc 2000 Apr;51(4 Pt 1):427-432. (Prospective; 40 patients) 68. Slotwiner-Nie PK, Brandt LJ. Infectious diarrhea in the elderly. Gastroenterol Clin North Am 2001 Sep;30(3):625-635. (Review) 69. Hendrickson M, Naparst TR. Abdominal surgical emergencies in the elderly. Emerg Med Clin North Am 2003 Nov;21(4):937-969. (Review) 70. Kyne L, Hamel MB, Polavaram R, et al. Health care costs and mortality associated with nosocomial diarrhea due to Clostridium difficile. Clin Infect Dis 2002 Feb 1;34(3):346-353. (Prospective; 271 patients) 71. Cicirello HG, Glass RI. Current concepts of the epidemiology of diarrheal diseases. Semin Pediatr Infect Dis 1994;5:163-167. (Review) 72. Wald A. Constipation, diarrhea, and symptomatic hemorrhoids during pregnancy. Gastroenterol Clin North Am 2003 Mar;32(1):309-322, vii. (Review) 73. Szajewska H, Mrukowicz JZ. Probiotics in the treatment and prevention of acute infectious diarrhea in infants and children: a systematic review of published randomized, double-blind, placebocontrolled trials. J Pediatr Gastroenterol Nutr 2001 Oct;33 Suppl 2:S17-25. (Systematic review) 74. Van Niel CW, Feudtner C, Garrison MM, et al. Lactobacillus therapy for acute infectious diarrhea in children: a meta-analysis. Pediatrics 2002 Apr;109(4):678-684. (Meta-analysis) 75. Cremonini F, Di Caro S, Nista EC, et al. Meta-analysis: the effect of probiotic administration on antibiotic-associated diarrhoea. Aliment

Disease. 7th ed. Philadelphia: WB Saunders; 2002:2321-2340. (Textbook chapter) 28.* Gore JI, Surawicz C. Severe acute diarrhea. Gastroenterol Clin North Am 2003 Dec;32(4):1249-1267. (Review) 29. Osorio J, Farreras N, Ortiz De Zarate L, et al. Cocaine-induced mesenteric ischaemia. Dig Surg 2000;17(6):648-651. (Case report) 30. Saclarides TJ. Radiation injuries of the gastrointestinal tract. Surg Clin North Am 1997 Feb;77(1):261-268. (Review) 31. Henriksson R, Franzen L, Littbrand B. Effects of sucralfate on acute and late bowel discomfort following radiotherapy of pelvic cancer. J Clin Oncol 1992 Jun;10(6):969-975. (Randomized, controlled trial; 70 patients) 32. Irish MS, Pearl RH, Caty MG, et al. The approach to common abdominal diagnosis in infants and children. Pediatr Clin North Am 1998 Aug;45(4):729-772. (Review) 33. Rothrock SG, Skeoch G, Rush JJ, et al. Clinical features of misdiagnosed appendicitis in children. Ann Emerg Med 1991 Jan;20(1):45-50. (Retrospective; 181 patients) 34. Horwitz JR, Gursoy M, Jaksic T, et al. Importance of diarrhea as a presenting symptom of appendicitis in very young children. Am J Surg 1997 Feb;173(2):80-82. (Retrospective; 63 patients) 35. Reynolds SL. Missed appendicitis in a pediatric emergency department. Pediatr Emerg Care 1993 Feb;9(1):1-3. (Retrospective; 87 patients) 36. Bolyard EA, Tablan OC, Williams WW, et al. Guideline for infection control in healthcare personnel, 1998. Hospital Infection Control Practices Advisory Committee. Infect Control Hosp Epidemiol 1998 Jun;19(6):407-463. (Practice guideline) 37.* DuPont HL. Guidelines on acute infectious diarrhea in adults. The Practice Parameters Committee of the American College of Gastroenterology. Am J Gastroenterol 1997 Nov;92(11):1962-1975. (Practice guideline) 38. Brar HS, Surawicz CM. Pseudomembranous colitis: an update. Can J Gastroenterol 2000 Jan;14(1):51-56. (Review) 39. Talan D, Moran GJ, Newdow M, et al; EMERGEncy ID NET Study Group. Etiology of bloody diarrhea among patients presenting to United States emergency departments: prevalence of Escherichia coli 0157:H7 and other enteropathogens. Clin Infect Dis 2001 Feb 15;32(4):573-580. (Prospective; 873 patients) 40. McNeely WS, Dupont HL, Mathewson JJ, et al. Occult blood versus fecal leukocytes in the diagnosis of bacterial diarrhea: a study of U.S. travelers to Mexico and Mexican children. Am J Trop Med Hyg 1996 Oct;55(4):430-433. (Comparative; 1040 patients) 41. Harris JC, Dupont HL, Hornick RB. Fecal leukocytes in diarrheal illness. Ann Intern Med 1972 May;76(5):697-703. (169 patients with diarrhea) 42. Manabe YC, Vinetz JM, Moore RD, et al. Clostridium difficile colitis: an efficient clinical approach to diagnosis. Ann Intern Med 1995 Dec 1;123(11):835-840. (Prospective; 268 inpatients) 43. Turgeon DK, Fritsche TR. Laboratory approaches to infectious diarrhea. Gastroenterol Clin North Am 2001 Sep;30(3):693-707. (Review) 44. Lieberman JM. Rotavirus and other viral causes of gastroenteritis. Pediatr Ann 1994 Oct;23(10):529-532, 534-535. (Review) 45. Huicho L, Garaycochea V, Uchima N, et al. Fecal lactoferrin, fecal leukocytes and occult blood in the diagnostic approach to childhood invasive diarrhea. Pediatr Infect Dis J 1997 Jul;16(7):644-647. (Prospective; 125 patients with diarrhea) 46. Choi SW, Park CH, Silva TM, et al. To culture or not to culture: fecal lactoferrin screening for inflammatory bacterial diarrhea. J Clin Microbiol 1996 Apr;34(4):928-932. (Retrospective, cost-benefit analysis; 55 patients) 47. Fine KD, Ogunji F, George J, et al. Utility of a rapid fecal latex agglutination test detecting the neutrophil protein, lactoferrin, for diagnosing inflammatory causes of chronic diarrhea. Am J Gastroenterol 1998 Aug;93(8):1300-1305. (Non-random sample; 103 patients) 48. Kane SV, Sandborn WJ, Rufo PA, et al. Fecal lactoferrin is a sensitive and specific marker in identifying intestinal inflammation. Am J Gastroenterol 2003 Jun;98(6):1309-1314. (Prospective, comparative; 215 patients) 49. Hamer DH, Gorbach SL. Infectious diarrhea and bacterial food poisoning. In: Feldman M, Friedman LS, Sleisenger MH, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 7th ed. Philadelphia: WB Saunders; 2002:1864-1913. (Textbook chapter) 50. Wong CS, Jelacic S, Habeeb RL, et al. The risk of the hemolytic-uremic syndrome after antibiotic treatment of Escherichia coli 0157:H7 infections. N Engl J Med 2000 Jun 29;342(26):1930-1936. (Prospective cohort; 71 patients) 51. Hennessy TW, Hedberg CW, Slutsker L, et al. A national outbreak of Salmonella enteritidis infections from ice cream. The Investigation Team.

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78.

79.

Pharmacol Ther 2002 Aug;16(8):1461-1467. (Meta-analysis) Bhutta ZA, Bird SM, Black RE, et al. Therapeutic effects of oral zinc in acute and persistent diarrhea in children in developing countries: pooled analysis of randomized controlled trials. Am J Clin Nutr 2000 Dec;72(6):1516-1522. (Meta-analysis) Strand TA, Chandyo RK, Bahl R, et al. Effectiveness and efficacy of zinc for the treatment of acute diarrhea in young children. Pediatrics 2002 May;109(5):898-903. (Randomized, controlled trial; 1792 children) Wong MT, Kauffman CA, Standiford HC, et al; Ramoplanin VRE2 Clinical Study Group. Effective suppression of vancomycin-resistant Enterococcus species in asymptomatic gastrointestinal carriers by a novel glycolipodepsipeptide, ramoplanin. Clin Infect Dis 2001 Nov 1;33(9):1476-1482. (Multicenter, randomized, controlled trial; 68 patients) Montecalvo MA. Ramoplanin: a novel antimicrobial agent with the potential to prevent vancomycin-resistant enterococcal infection in high-risk patients. J Antimicrob Chemother 2003 Jun;51 Suppl 3:iii31-35. (Review)

Physician CME Questions 1.

2.

3.

4.

5.

6.

The presence of fever, cramping, and diarrhea is least likely to be associated with: a. bacterial diarrhea. b. inflammatory bowel disease. c. irritable bowel syndrome. d. appendicitis.

Which of the following can be ruled out as a cause of diarrhea persisting longer than two weeks in otherwise healthy U.S. ED patients? a. Norwalk virus b. Food allergies c. Giardia lamblia d. Ischemic bowel disease

8.

A thorough history of medication use in patients with diarrhea should include: a. recent antibiotic use. b. hypoglycemic medications. c. herbal medications. d. vasoconstrictive medications. e. all of the above.

9.

Which of the following laboratory tests should be routine in all patients with diarrhea? a. Chemistry panels b. Stool culture c. Fecal leukocyte/lactoferrin testing d. None of the above

10. In children with mild-to-moderate dehydration, the preferred rehydration method is: a. intravenous rehydration. b. rehydration via commercial oral rehydration solutions. c. rehydration via sports drinks. d. rehydration via consumption of clear liquids.

Which of the following symptoms are viral agents most likely to produce? a. Nausea/vomiting b. Bloody diarrhea c. Severe abdominal pain d. Bowel movements that alternate between constipation and diarrhea

11. Empiric antibiotic therapy should not be employed for: a. nosocomial diarrhea. b. moderate-to-severe traveler’s diarrhea. c. diarrhea due to E. coli 0157:H7. d. any of the above.

In most cases of diarrhea seen in U.S. EDs, the cause is: a. an infectious agent that does not require antibiotics. b. an infectious agent that requires antibiotics. c. inflammatory bowel disease. d. appendicitis.

12. Elderly patients: a. are more likely to have serious etiologies for diarrheal illnesses. b. are more likely to be profoundly dehydrated due to diarrheal illnesses. c. are more prone to drug interactions and side-effects. d. all of the above.

Abdominal pain, diarrhea, age greater than 50 years, and a history of peripheral vascular disease should raise particular concern about: a. ulcerative colitis. b. irritable bowel syndrome. c. appendicitis. d. ischemic bowel disease.

13. In children with diarrheal illnesses: a. infectious etiologies are unlikely. b. oral rehydration methods are preferred. c. loperamide is recommended. d. resumption of the child’s regular diet should be delayed until most of the symptoms have passed.

Of the following, which is most valuable in identifying/ruling out appendicitis in the ED? a. Stool culture b. WBC count c. Plain films d. Serial examinations

14. Lactobacillus: a. is a probiotic being studied for its ability to prevent and treat diarrhea. b. is available only by prescription. c. has been shown to be ineffective in several recent meta-analyses. d. is standard therapy for adults but not children in the United States.

Fecal leukocytes are present in: a. infectious causes of diarrhea only. b. non-infectious causes of diarrhea only. c. inflammatory causes of diarrhea, including infectious and non-infectious causes. d. non-inflammatory causes of diarrhea.

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Physician CME Information

15. Written discharge instructions should include key reasons to return to the ED, such as: a. profuse or bloody diarrhea. b. dehydration or inability to take and retain oral fluids. c. severe or persistent abdominal pain. d. sustained fever. e. all of the above.

This CME enduring material is sponsored by Mount Sinai School of Medicine and has been planned and implemented in accordance with the Essentials and Standards of the Accreditation Council for Continuing Medical Education. Credit may be obtained by reading each issue and completing the printed post-tests administered in December and June or online single-issue post-tests administered at EMPractice.net. Target Audience: This enduring material is designed for emergency medicine physicians. Needs Assessment: The need for this educational activity was determined by a survey of medical staff, including the editorial board of this publication; review of morbidity and mortality data from the CDC, AHA, NCHS, and ACEP; and evaluation of prior activities for emergency physicians.

16. Loperamide should not be used in: a. children less than 5 years. b. adults with traveler’s diarrhea. c. adults with bacillary dysentery. d. all of the above.

Date of Original Release: This issue of Emergency Medicine Practice was published July 1, 2004. This activity is eligible for CME credit through July 1, 2007. The latest review of this material was June 15, 2004. Discussion of Investigational Information: As part of the newsletter, faculty may be presenting investigational information about pharmaceutical products that is outside Food and Drug Administration approved labeling. Information presented as part of this activity is intended solely as continuing medical education and is not intended to promote off-label use of any pharmaceutical product. Disclosure of Off-Label Usage: This issue of Emergency Medicine Practice discusses no off-label use of any pharmaceutical product.

Coming in Future Issues: Hand Injuries • Herbal Toxicities • The Suicidal Patient

Faculty Disclosure: In compliance with all ACCME Essentials, Standards, and Guidelines, all faculty for this CME activity were asked to complete a full disclosure statement. The information received is as follows: Dr. Burg reports that he is a shareholder in Genome Therapeutics, makers of ramoplanin. Dr. Hovanessian, Dr. Jagoda, and Dr. Reisdorff report no significant financial interest or other relationship with the manufacturer(s) of any commercial product(s) discussed in this educational presentation.

Class Of Evidence Definitions Each action in the clinical pathways section of Emergency Medicine Practice receives a score based on the following definitions. Class I • Always acceptable, safe • Definitely useful • Proven in both efficacy and effectiveness Level of Evidence: • One or more large prospective studies are present (with rare exceptions) • High-quality meta-analyses • Study results consistently positive and compelling Class II • Safe, acceptable • Probably useful Level of Evidence: • Generally higher levels of evidence • Non-randomized or retrospective studies: historic, cohort, or case-control studies • Less robust RCTs • Results consistently positive Class III • May be acceptable • Possibly useful • Considered optional or alternative treatments Level of Evidence: • Generally lower or intermediate levels of evidence

• Case series, animal studies, consensus panels • Occasionally positive results

Accreditation: Mount Sinai School of Medicine is accredited by the Accreditation Council for Continuing Medical Education to sponsor continuing medical education for physicians.

Indeterminate • Continuing area of research • No recommendations until further research

Credit Designation: Mount Sinai School of Medicine designates this educational activity for up to 4 hours of Category 1 credit toward the AMA Physician’s Recognition Award. Each physician should claim only those hours of credit actually spent in the educational activity. Emergency Medicine Practice is approved by the American College of Emergency Physicians for 48 hours of ACEP Category 1 credit (per annual subscription). Emergency Medicine Practice has been approved by the American Academy of Family Physicians as having educational content acceptable for Prescribed credit. Term of approval covers issues published within one year from the distribution date of July 1, 2003. This issue has been reviewed and is acceptable for up to 4 Prescribed credits. Credit may be claimed for one year from the date of this issue. Emergency Medicine Practice has been approved for 48 Category 2-B credit hours by the American Osteopathic Association.

Level of Evidence: • Evidence not available • Higher studies in progress • Results inconsistent, contradictory • Results not compelling Significantly modified from: The Emergency Cardiovascular Care Committees of the American Heart Association and representatives from the resuscitation councils of ILCOR: How to Develop EvidenceBased Guidelines for Emergency Cardiac Care: Quality of Evidence and Classes of Recommendations; also: Anonymous. Guidelines for cardiopulmonary resuscitation and emergency cardiac care. Emergency Cardiac Care Committee and Subcommittees, American Heart Association. Part IX. Ensuring effectiveness of community-wide emergency cardiac care. JAMA 1992;268(16):2289-2295.

Earning Credit: Two Convenient Methods • Print Subscription Semester Program: Paid subscribers with current and valid licenses in the United States who read all CME articles during each Emergency Medicine Practice six-month testing period, complete the post-test and the CME Evaluation Form distributed with the December and June issues, and return it according to the published instructions are eligible for up to 4 hours of Category 1 credit toward the AMA Physician’s Recognition Award (PRA) for each issue. You must complete both the post-test and CME Evaluation Form to receive credit. Results will be kept confidential. CME certificates will be delivered to each participant scoring higher than 70%. • Online Single-Issue Program: Paid subscribers with current and valid licenses in the United States who read this Emergency Medicine Practice CME article and complete the online post-test and CME Evaluation Form at EMPractice.net are eligible for up to 4 hours of Category 1 credit toward the AMA Physician’s Recognition Award (PRA). You must complete both the post-test and CME Evaluation Form to receive credit. Results will be kept confidential. CME certificates may be printed directly from the Web site to each participant scoring higher than 70%.

Emergency Medicine Practice is not affiliated with any pharmaceutical firm or medical device manufacturer. President and CEO: Robert Williford. Publisher: Heidi Frost. Research Editors: Ben Abella, MD, University of Chicago; Richard Kwun, MD, Mount Sinai School of Medicine.

Direct all editorial or subscription-related questions to EB Practice, LLC: 1-800-249-5770 • Fax: 1-770-500-1316 • Non-U.S. subscribers, call: 1-678-366-7933 EB Practice, LLC • 305 Windlake Court • Alpharetta, GA 30022 E-mail: [email protected] • Web Site: EMPractice.net Emergency Medicine Practice (ISSN 1524-1971) is published monthly (12 times per year) by EB Practice, LLC, 305 Windlake Court, Alpharetta, GA 30022. Opinions expressed are not necessarily those of this publication. Mention of products or services does not constitute endorsement. This publication is intended as a general guide and is intended to supplement, rather than substitute, professional judgment. It covers a highly technical and complex subject and should not be used for making specific medical decisions. The materials contained herein are not intended to establish policy, procedure, or standard of care. Emergency Medicine Practice is a trademark of EB Practice, LLC. Copyright 2004 EB Practice, LLC. All rights reserved. No part of this publication may be reproduced in any format without written consent of EB Practice, LLC. Subscription price: $299, U.S. funds. (Call for international shipping prices.)

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