It s Not Just Amputation Anymore. Advancements in the Treatment of Frostbite. Kathryn Moser, RN, AG-ACNP, EMT-Basic

It’s Not Just Amputation Anymore. Advancements in the Treatment of Frostbite. Kathryn Moser, RN, AG-ACNP, EMT-Basic Abstract Frostbite is an injury t...
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It’s Not Just Amputation Anymore. Advancements in the Treatment of Frostbite. Kathryn Moser, RN, AG-ACNP, EMT-Basic

Abstract Frostbite is an injury to the skin and underlying tissues as a result of environmental cold exposure resulting from ice crystal formation in the skin causing cell death, spasm and constriction of blood vessels, and formation of blood clots in the microvasculature resulting in tissue hypoxia. In the past, the accepted treatment for frostbite has been minimizing damage, re-warming, and managing compromised tissue with wound care, permissive auto-amputation, or amputation surgeries. The University of Colorado Health Burn Center has been aggressively treating frostbite injuries since 2011 with thrombolytic therapy using Tissue Plasminogen Activator (t-PA) to address microvascular clots in an effort to save digits that might otherwise be amputated. The t-PA treatment of frostbite has significantly decreased our rates of amputation in patients who received treatment within forty-eight hours of injury. The data collected over the past five years by our program, in addition to other medical centers across the country and internationally, is showing that there may be a viable treatment options to offer victims of frostbite to preserve frostbitten digits and minimize complications in addition to traditional therapies. Introduction Frostbite is an injury that occurs from the freezing of body tissues and results in physiologic changes. It may vary in depth from superficial tissue extending down to muscle or bone. The primary factors that influence the onset and depth of frostbite are: length of exposure, temperature, wind speed, and amount of exposed body surface area. Individual factors that contribute are altitude, clothing (too tight, wet, or inadequate), drug or alcohol use, concurrent injuries, dehydration, poor nutrition, hypothermia, immersion, and dementia. Additionally, any medical condition that compromises circulation or sensation can predispose to frostbite, such as diabetes, atherosclerosis, or neuropathies according to McLeron in the State of Alaska Cold Injury Guidelines (2003). A strong correlation between not having a guide and contracting frostbite in high risk alpine expeditions is also noted in a descriptive study by Harirchi, Arvin, Vash, and Zararmand (2005). Distal extremities such as hands and feet are mostly likely areas to be effected (around 90% of reported injuries), however the face, neck, or perineum may also be injured (Handford et al., 2014). The pathophysiology of frostbite is divided into distinct stages according McIntosh, et al., in the Wilderness Medical Society (WMS) Practice Guidelines for the Prevention and Treatment of Frostbite. The pre-freeze stage consists of cooling of tissues with accompanying constriction of blood vessels resulting in decreased sensation or numbness, but does not involve ice crystal formation. The freezethaw stage, ice crystals may form inside (rapid freeze) or outside cells (more slow freezing injury) causing damage to cell membranes, disruption of electrolytes across the cell membranes, cellular dehydration, cell rupture and eventual cell death. As the freezing process continues the body responds

with cycles of vasoconstriction and dilation of blood vessels resulting in blood leakage from vessels and clot formation within the vessels. The resulting late ischemic phase results from progressive tissue ischemia and death from vasoconstriction, showers of clots in the microvasculature, clot formation in larger vessels, and the inflammatory process caused by release of chemical mediators. The initial cellular damage caused by ice crystals and post-thawing processes is worsened if refreezing occurs (2011). Depth of injury is determined using a system similar to that used to describe burns. Traditionally, language such as first degree through fourth degree has been used to describe wounds. The WMS Guidelines (2011) and State of Alaska Cold Injury Guidelines (2003) suggest a more simple classification system may be preferred where wounds are described as superficial or deep tissue injuries. The superficial injury (first and second degree injuries) involves only the top layers of epidermis or dermis with no to minimal expected tissue loss. Injuries may appear pale, swollen, have blisters filled with clear fluid after thawing, and have some redness surrounding blisters. Skin feels firm, but not hard prior to re-warming. Deep tissue injuries (previously third and fourth degree injuries) extend through the dermis (second layer of skin) into subcutaneous tissues and may be as deep as bone. Skin feels hard and cold, and may appear white or grey. Pulses may not be present. These wounds may have blood filled blisters after thawing. It is anticipated there will be tissue damage and loss with an injury of this depth. Prevention is the first and most important treatment of frostbite. Frostbite is an injury that is generally preventable and may not be improved by medical therapy after the initial injury occurs, especially if treatment is delayed or multiple freeze-thaw cycles occur. Prevention strategies include proper clothing, optimizing nutrition and hydration, maintaining adequate core body temperature, minimizing effects of medical conditions or substances/medications that may cause decreased perfusion, use of hand and foot warmers, frequent cold checks, avoiding substances that may decrease awareness of cold (drugs or alcohol), team awareness of potential for cold injury, use of a guide on high risk expeditions, and use of supplemental oxygen in hypoxic conditions (such as above 7,500 meters) (McIntosh, et al., 2011; Handford, et al., 2014; Harirchi, et al., 2005; Hashmi, Rashid, Haleem, Bokhari, & Hussain, 1998). Field treatment of frostbite recommendations are depend on accessibility to a controlled environment, patient protection, transportation time to medical facilities, and concurrent other injuries such as trauma or hypothermia. According to the State of Alaska Cold Injury Guidelines “the decision to thaw the frostbitten tissue in the field commits the provider to a course of action that may involve pain control, maintaining warm water baths at a constant temperature, and protecting the tissue from further injury during re-warming and eventual transport. Victims should not walk on feet that have been re-warmed (McLeron, 2003).” Additionally, in a study looking at frostbite prevalence by Hashmi et al. in extreme environments such as the Karakoram Range, only two percent of subjects were able to evacuate in 6 hours and nearly half could not be rescued before 48 hours (1998). It should also be noted that if transport is prolonged (greater than 2 hours) frequently frostbite will often thaw spontaneously as a consequence of keeping the patient warm (McLeron, 2003). Therefore, the decision to actively rewarm in the field may be appropriate or passive re-warming may occur unintentionally with protecting the patient from cold or during transportation. However, if it is reasonable warming should occur in a

medical facility. Additionally, any traumatic injuries, hypothermia, or other serious medical conditions should be addressed before any attempt is made to re-warm frostbitten areas. According to Handford, et al., McIntosh, et al., and McLeron, if the decision is made to rewarm, ensure that a detailed history is taken noting when the injury occurred, history of conditions (temperature, wind chill, wet/dry exposure, duration of any thermal protection), and any prior treatment. Do NOT: rub the frozen part, allow the patient to have alcohol or tobacco, apply ice or snow, attempt to thaw in cold water, or thaw using high temperatures generated by stoves, fires, or exhaust. Obtain a full set of vital signs. Remove any jewelry as swelling is expected as thawing occurs. Perform rehydration with oral or intravenous fluids, as most patients with frostbite will be dehydrated. This will be exacerbated by high altitude. Use a warm water bath between 37-39 degrees C (99-102 degrees F) and a container large enough to accommodate the affected area without touching the sides or bottom. Additional warm water must be available to maintain water temperature and water should be circulated around the extremity. Re-warming should continue until tissue becomes red/purple in color and tissue is pliable. Expect the need for pain medication including a possible need for narcotics, as rewarming may result in pain. Ibuprofen or Aspirin may be used for pain control and may also block production or inflammatory mediators. After re-warming is complete, allow area to air dry, do not towel off. Blisters should be left intact if possible, if necessary may be drained by sterile needle aspiration. Topical aloe Vera gel has been shown to inhibit prostaglandins and may be applied prior to dressing. Dress the affected part with loose protective dressing with padding between affected digits. Keep the extremity elevated above the level of heart if possible. Most importantly, protect the now thawed tissue from possibly re-freezing or other trauma (2014; 2011; 2003) Traditionally, after re-warming injured areas were monitored for the wound to eventually demarcate identifying the areas of tissue that would not heal and then permissive auto-amputation or delayed surgical amputation was performed. Ideally this process is monitored by a provider familiar with the treatment of frostbite. Both the WMS Society Practice Guidelines (2011) and the States of Alaska Cold Injuries Guidelines (2003) discuss that many medications have been used as adjunctive treatments for frostbite after injury, but data to support their use is limited or some medications are not available. The use of nonsteroidal antiinflammatory drugs, such as Ibuprofen or Aspirin, to block prostaglandins and thromboxanes lacks evidence in research to support their use. Vasodilator therapy, such as the “Alaska Method,” has shown no benefit in frostbite in research. Low molecular weight dextran to improve hydration is no longer available on the market. Vasodilator/anti-inflammatory therapies using various combinations of Aspirin, Iloprost, and t-PA have shown significant benefit in deep frostbite in a small study by Cauchy, Cheguillaume, and Chetaille in 2011. However, there are currently no centers in North America with published experience using prostacyclin and Iloprost intravenously is not available in the United States. Since 2005, the use of Tissue Plasminogen Activator (t-PA) to “bust clots” in the microvasculature to treat frostbite has been reported in medical literature in small studies. In 2009, the University of Colorado Hospital Burn Center implemented a quality improvement project to explore the use of t-PA in the treatment of severe frostbite in our region. Through standardization of and use of intravenous t-PA

in the treatment of severe frostbite, we anticipated an immediate improvement in patient outcomes and reduction in digit amputations. Methods In 2009, an interdisciplinary team at the University of Colorado Hospital reviewed the current evidence on the use of t-PA as a thrombolytic for the treatment of frostbite, which has been documented in two small single center studies at the University of Utah (Bruen et al., 2007) and Hennepin County Medical Center (Twomey, Peltier, & Zera, 2005). A standard protocol was developed including indications and contraindications to t-PA therapy, nursing assessments, and weight-based t-PA dosing based on previous research. This protocol was put into practice in 2011. Retrospective comprehensive chart reviews were completed on patients admitted with frostbite. These reviews evaluated the number of digits affected and ultimately amputated due to severe frostbite (this determined based on documentation of compromised circulation or bone-scan results). The charts were also reviewed for the administration of intravenous t-PA. Patients were eligible for t-PA therapy for severe frostbite in distal limbs and digits if they met the following criteria: absent or weak Doppler signals in limbs and/or digits with no improvement on active rewarming and presented within 24-48 hours of frostbite injury. Relative contraindications to therapy include concurrent or recent trauma, stroke, or bleeding, recent surgery, multiple freeze-thaw cycles, more than 48 hours of cold exposure, severe uncontrolled high blood pressure, pregnancy, current anticoagulation therapy, thrombocytopenia, or history of gastrointestinal bleeding. Results In 2013 and 2014, 42 patients were admitted to the Burn Center for frostbite injury and 11 of those patients were treated with t-PA after evaluation by the attending burn surgeon. Of those patients not eligible for therapy: 10 had injuries not severe enough to quality for therapy, 17 were outside the 48 hour window, 1 had a history of GI bleed, 1 had a history of cerebral aneurysm, and 2 unknown. •

2013 –

18 patients admitted related to frostbite injury

14 male, 4 female

4 patients received t-PA •

Contraindications- 5 not severe to meet indications, 8 outside of 48 hour window; 1 unknown

Mean age 44; median age 43

Total of 135 digits affected (105 non t-PA, 30 t-PA administered)

23/105 non t-PA digits amputated (22% amputation rate)

0/30% t-Pa administered digits amputated (0% amputation rate)

2014 –

24 patients admitted related to frostbite injury

21 male, 3 female

7 patients received t-PA •

Contraindications- 5 not severe to meet indications, 9 outside of 48 hour window; 1 unknown; 1 history of GI bleed, 1 history of cerebral aneurysm

Mean age 40; median age 39

Total of 197 digits affected (148 non t-PA, 49 t-PA administered)

46/148 non-t-PA digits amputated (31% amputation rate)

1/49 t-PA administered digits amputated (2% amputation rate)

Complications: No significant bleeding complications since the implementation of this protocol. -

1 patient had bilateral thigh hematomas and 1 patient had a hematoma on her forehead without a bleed on CT. No transfusion required. T-PA did not have to be stopped after initiating administration.

Conclusion Treatment of severe frostbite injury using thrombolytic therapy is described in both the WMS Practice Guidelines and States of Alaska Cold Injuries Guidelines as potentially beneficial therapy for severe frostbite in patients who can be treated within 24 hours of thawing and who do not have any contraindications to the use of t-PA. Thrombolytic therapy should be conducted in a center with experience in the use of t-PA for frostbite and intensive care monitoring capabilities. It also comes with the risk of systemic bleeding (McIntosh, et al., 2011; McLeron, 2003). The small scale study from the University of Utah Medical Center provides data showing a digital amputation rate in patients not treated with t-PA of 41% (97/234) and after treatment using intravenous or intra-arterial t-PA, the rate shows a significant decrease (p=