Acute asthma in pregnancy Nicola A. Hanania, MD; Michael A. Belfort, MD, PhD
Objectives: To provide an overview on the interrelationship between asthma and pregnancy, focusing on management of pregnant women presenting with an acute severe exacerbation. Design: A review of the current English-language published clinical trials was performed based on MEDLINE search using the Medical Subject Headings pregnancy and asthma. Current reviews on the topic and practice guidelines were also reviewed. Results: Asthma is the most common medical condition to complicate pregnancy, and episodes of acute asthma requiring emergency department visits or hospitalization have been reported in 9 –11% of pregnant women managed by asthma specialists. Pregnancy can affect the course of asthma, and the risk of asthma exacerbations requiring intervention in pregnant women is higher than in nonpregnant women. Similarly, asthma can affect pregnancy outcomes. Maternal inflammatory pathways may contribute to the poor pregnancy outcomes, especially in
sthma is one of the most common medical conditions that can complicate pregnancy. Pregnancy can affect the course of asthma (1, 2), and asthma can affect pregnancy outcomes (3). Management of asthma during pregnancy has been recently reviewed (4 –10). Although most pregnant women with asthma have an uneventful course during their pregnancy, a few may experience severe lifethreatening exacerbations that require hospitalization and intensive care management. Although management of acute exacerbation in this situation is similar to that in a nonpregnant patient with the same illness, one should be mindful of the physiologic changes that occur during pregnancy to ensure maternal and fetal safety. In addition, fetal considerations will affect certain management strategies such as permissive hypercapnia
From the Section of Pulmonary and Critical Care Medicine, Department of Medicine, Baylor College of Medicine, Houston, TX (NAH); the Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, UT (MAB); and the Department of Perinatal Research, HCA Healthcare, Nashville, TN (MAB). Copyright © 2005 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins DOI: 10.1097/01.CCM.0000182789.14710.A1
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women with uncontrolled asthma. Although data on the effects of maternal asthma on pregnancy have been conflicting, mainly because many published studies have not corrected for asthma severity, it has generally been observed that poorly managed asthma during pregnancy is associated with a higher risk of preterm delivery, low birth weight, and complications such as preeclampsia. Optimal therapy of asthma has been shown to contribute to improved maternal and fetal outcomes. Conclusions: Asthma can complicate the course of pregnancy, and pregnancy can worsen asthma control in some women. Optimal management of asthma during pregnancy is key in ensuring the safety of the mother and the fetus. (Crit Care Med 2005; 33[Suppl.]:S319 –S324) KEY WORDS: pregnancy; asthma; medications; corticosteroids; beta-agonists; exacerbation
and hypemia. Early identification and appropriate pharmacologic therapy of acute asthma are key in achieving a successful outcome.
reported in 9 –11% of pregnant women managed by asthma specialists (15–17).
Prevalence of Asthma in Pregnancy
Maternal and Fetal Physiologic Considerations During Pregnancy
Many of the earlier reports addressing the prevalence of asthma during pregnancy were inaccurate because they were predominantly based on retrospective data. More recently, Kwon et al. (11) reviewed United States national health surveys between 1997 and 2001and determined that asthma affected between 3.7% and 8.4% of pregnant women in the United States. A rising trend in the prevalence of asthma was also observed (11). Racial differences in asthma morbidity during pregnancy have recently been described (12). As it is has been described in nonpregnant women, black women tend to have significantly more morbidity during pregnancy than white women. Insurance status was the most significant factor to account for the racial/ethnic disparity in asthma (13). It is estimated that asthma complicates the course of 200,000 –376,000 pregnancies every year (14). Furthermore, episodes of acute asthma requiring emergency department (ED) visits or hospitalization have been
Pregnancy is associated with numerous mechanical, immunologic, biochemical and hemodynamic, and respiratory physiologic changes (18 –25). Adequate knowledge of these changes is essential to ensure optimal maternal and fetal health outcomes. Hormonally mediated functional changes produce a 50% increase in minute ventilation in late pregnancy secondary to progesterone-mediated stimulation of the respiratory center. This hyperventilation usually results from an increase in tidal volume, with minimal changes in respiratory rate. Arterial blood gases often reveal a compensated respiratory alkalosis (pH of 7.40 –7.45, PCO2 of 28 –32 mm Hg) with a mild increase in PO2 (106 –110 mm Hg). The increase in pH secondary to respiratory alkalosis is usually blunted by an increase in renal excretion of bicarbonate (explaining the polyuria of early pregnancy). Structural changes to the chest wall affect lung volumes, the most notable being a reduction of functional residual capacity. Although S319
the functional residual capacity is decreased by as much as 18% in late pregnancy, physiologic tests of large airway function such as forced expiratory volume in 1 sec, forced vital capacity, forced expiratory volume in 1 sec/forced vital capacity ratio, and peak expiratory flow rate remain unchanged. The mean forced expiratory flow during the middle half of forced vital capacity is also unaffected by pregnancy. Therefore, these physiologic measures remain useful indicators of asthma control and are helpful tools in the diagnosis and follow-up of asthma in pregnant women. Cardiac function changes dramatically as pregnancy progresses, with an increase in total blood volume by approximately 40% (2 L) over the prepregnant state by the third trimester of pregnancy. Plasma volume increases more than red cell mass, resulting in the so-called physiologic hemodilution or anemia of pregnancy. Left ventricular compliance and end-diastolic volume increase to accommodate this expanded intravascular volume. Central venous pressure, however, remains unchanged, although cardiac output increases by 30 –50% by the end of the second trimester. Associated with these are structural cardiac changes, including a marked increase in left ventricular mass. During the third trimester, a decrease in the cardiac output may be appreciated in the supine position as a result of aortic and venacaval compression and subsequent decrease in venous return. However, cardiac output increases by 15% during labor. This is associated with an increase in oxygen consumption during uterine contractions. Oxygen delivery to the growing fetus and removal of volatile (carbonic acid) and nonvolatile (lactic acid and keto acids) acids produced by the fetus depend on proper functioning of the uteroplacental unit. Transfer of oxygen and CO2 across the fetoplacental barrier involves doubleBohr and double-Haldane effects in the placenta and is dependent on maternal venous equilibration (26). The PO2 in the umbilical veins is lower than that in maternal placental venous channels and is in the order of 30 –37 mm Hg. The fetus is able to grow in this low-oxygen environment as a result of multiple compensatory mechanisms. These include a higher hemoglobin content, increased oxygen affinity of fetal hemoglobin, preferential blood flow to vital organs in the fetus, high cardiac output, and leftward shift of the oxygen dissociation curve (26). S320
Chronic hypoxia can lead to intrauterine growth restriction and low birth weight. Maternal oxygen therapy can, under some circumstances, significantly improve oxygenation of vital organs and the fetal brain (26). A low maternal PCO2 is, by the same token, essential to normal fetal acid-base balance. A gradient must be maintained between the fetus and the placenta, and any increase in maternal PCO2 will affect the ability of the fetus to shed its acid complement and will inevitably result in progressive fetal acidosis, even in the face of adequate oxygenation.
Effect of Asthma on Pregnancy Studies on the effects of asthma on maternal and fetal outcomes are nonconclusive. A few studies found no significant difference in birth outcomes between asthmatic and nonasthmatic women (17). Several other studies have demonstrated increased adverse outcomes, including intrauterine growth restriction (14, 27– 31), preterm labor and delivery (14, 28, 29, 32, 33), and preeclampsia (28, 29, 34). Other adverse outcomes reported include increased prevalence of transient tachypnea of the newborn (35, 36), meconium staining (37), oligohydramnios (37), development of pneumonia during pregnancy (38), and increased risk of cesarean delivery (28, 29, 39). In a nested casecontrol study involving 3,253 pregnant women and aimed at determining the extent to which maternal asthma is associated with preterm delivery, Sorensen et al. (33) demonstrated a two-fold increased risk of preterm delivery in women with asthma compared with women who had no history of asthma (odds ratio, 2.03; 95% confidence interval, 1.01– 4.09). It is not clear whether these adverse outcomes are a result of asthma, secondary to asthma therapy, or related to other factors that share common mechanisms with asthma. In general, most studies have shown that fetal outcome is improved in severe asthmatics who are treated with appropriate medications and when acute asthma is avoided (40, 41). Schatz et al. (15) reported that women whose asthma was actively managed had maternal and fetal outcomes that were not different from a control group without asthma. The same group described a direct correlation between maternal forced expiratory volume in 1 sec during pregnancy and infant birth weight (42). In another study, Murphy et al. (30) ob-
served that the birth weight of female neonates of mothers not using inhaled corticosteroids for asthma was significantly reduced compared with women whose asthma was controlled on inhaled corticosteroids. They hypothesized that this is caused by a reduced level of placental 11 ␤-hydroxysteroid dehydrogenase type 2 activity in pregnant asthmatics not using inhaled corticosteroids, which leads to increased levels of fetal cortisol. These studies lend strong support to the current notion that pregnancy outcomes in asthmatic women are affected positively by treatment directed at controlling symptoms and preventing asthma-related complications. Other potential explanations for increased prenatal risks include the hypoxia/acidosis injury from poorly controlled asthma, medications used to treat asthma, and demographic factors associated with asthma but not related to the disease itself or its treatment.
Effect of Pregnancy on Asthma The effect of pregnancy on the course of asthma is unpredictable (43), and asthma has been reported to worsen, improve, or remain unchanged during pregnancy (1, 3, 14, 44). The mechanisms responsible for this are not well understood, although the multiple physiologic and biochemical changes during pregnancy may potentially ameliorate or potentiate the course of asthma (1, 44). Turner et al. (45), summarizing some large retrospective studies, reported that 22% of patients experienced improvement in their asthma, 40% remained unchanged, and 20% noted worsening disease. In a prospective study of 568 pregnant asthmatic women, Kircher et al. (44) noted improvement of control in 34%, worsening in 36%, and unchanged status in 26%. In another study, which reviewed the outcome of 198 pregnancies in 181 patients, Stenius-Aarniala et al. (46) reported improvement of asthma control in 18%, worsening in 42%, and no change in 40%. There is some evidence to suggest that worsening of asthma during pregnancy is related to the baseline asthma severity. Schatz et al. (47) followed 1,739 pregnant asthmatics before 26 wks of gestation and classified them into mild, moderate, and severe disease. They noted a correlation between severity of disease and asthma morbidity during pregnancy, including exacerbation, unscheduled visits, hospiCrit Care Med 2005 Vol. 33, No. 10 (Suppl.)
talization, and requirement for corticosteroids. Interestingly one third of the subjects whose asthma was classified as mild at entry switched categories during pregnancy to either the moderate or severe group. This observation emphasizes the need for close follow-up of these patients during pregnancy. Asthma exacerbation is more likely to occur during the second and third trimesters, with significantly fewer asthma attacks occurring in the last 4 wks and during labor (48). With successive pregnancies, the course of asthma has been found to be similar to that experienced in previous pregnancies (48). There is also a significant correlation between the course of rhinitis and the course of asthma during pregnancy, suggesting that the same mechanisms may influence both disorders and that gestational rhinitis may predict the course of asthma during pregnancy (44).
Management of Asthma During Pregnancy The principles of management of chronic asthma during pregnancy are not different from those recommended for nonpregnant women (8, 9, 49). The goals of asthma management during pregnancy include: a) optimal control of asthma symptoms, b) attainment of normal pulmonary function, c) prevention and reversal of asthma exacerbation, and d) prevention of maternal and fetal complications. There is limited information on the long-term efficacy and safety of currently approved asthma medications in pregnant women, largely because traditional, double-blind, placebo-controlled research has not been traditionally performed in pregnant women. Unfortunately, concerns about potential adverse or teratogenic effects of asthma medications may occasionally lead to poor compliance with recommended treatment or to inadequate treatment with subsequent adverse consequences (50, 51). Cydulka et al. (51) reported that pregnant asthmatics presenting to the ED were less likely to be prescribed controller medications (corticosteroids) and more likely to have symptoms of ongoing exacerbation at 2-wk follow-up. Concerns about the safety of asthma medications on pregnancy outcomes have been recently addressed in several studies. Schatz et al. (52) evaluated the relation between asthma medications and adverse perinatal outcomes in ⬎2,000 subjects. No sigCrit Care Med 2005 Vol. 33, No. 10 (Suppl.)
nificant relationship between adverse outcomes and the use of inhaled ␤-agonists, inhaled corticosteroids, theophylline, or cromolyn/nedocromil was identified. There was an observed increased risk of preterm and low birth weights with the use of oral corticosteroids. It is still unknown whether this effect is secondary to the medication itself or to level of severity of asthma. The safety of inhaled corticosteroids in pregnancy has also been demonstrated in several recent studies (53– 55). These data suggest that inhaled corticosteroids should be used when indicated in the management of asthma during pregnancy.
Management of Acute Asthma During Pregnancy It is estimated that approximately 18% of all pregnant asthmatics have at least one ED visit, and as many as 62% of the pregnant women with acute severe asthma require hospitalization (56). As previously mentioned, poorly controlled severe asthma may result in a variety of maternal and fetal complications, including increased risk of preeclampsia, intrauterine growth restriction, preterm infants, and perinatal mortality. On the other hand, when optimally managed with appropriate medications and monitoring, pregnant asthmatics manifest a very low likelihood of complications. Pregnant women with asthma should be considered to be high-risk patients, and their management requires a close partnership and coordination between primary care physicians, obstetricians, asthma-care specialists, and pediatricians. Emergency Department Evaluation. ED evaluation and treatment of the pregnant asthmatic is the same as in the nonpregnant state, with some modifications. Peak flows should be compared with usual predicted values or personal best if available. If arterial blood gases are obtained, it should be remembered that a pregnant woman usually has a baseline compensated respiratory alkalosis. Therefore, worsening of the alkalosis as a result of asthma exacerbation may lead to fetal hypoxia. Conversely, acute respiratory acidosis may be present when PaCO2 is above the normal 28 –32 mm Hg. Maternal acidosis can lead to inability of the fetus to unload CO2 if the maternal venous and fetal umbilical artery CO2 gradient is diminished. The hemodynamic effects of the enlarging uterus on maternal circulation in the supine position
should always be kept in mind during the assessment of a pregnant woman in the third trimester of pregnancy (49), and the patient should be examined in a sitting position, if possible, or in a supine position with a left or right tilt and the uterus displaced to avoid the supine hypotensive syndrome. Differential diagnosis of acute asthma during pregnancy should include other conditions that may complicate pregnancy, such as pulmonary edema, cardiomyopathy, pulmonary embolism, and amniotic fluid embolism (57). It is of paramount importance to initiate treatment for acute asthma exacerbation as early as possible. All patients with moderate to severe exacerbation should be treated in a monitored setting. An obstetrician or perinatologist should also be involved to monitor the well-being of the fetus. It is very important to identify potential patients who may be at risk for fatal asthma, such as those with history of intubation and those with frequent ED visits, hospitalization, or previous intensive care unit (ICU) admission for asthma. Prevention of maternal hypoxia or hypercarbia, reversal of bronchospasm, and prevention of exhaustion are overarching concerns during the management of acute asthma in a pregnant woman. Oxygen supplementation should be given to maintain oxygen saturation at ⬎95% (49). Fluid status should be carefully assessed, and intravenous fluid hydration should be administered if necessary. The initial treatment should include the administration of inhaled albuterol every 20 mins, up to three doses in the first hour. Ipratropium bromide (500 g) may be concomitantly administered in severe cases. Systemic corticosteroids, either intravenously or orally, should be given to patients who show no improvement with the initial bronchodilator therapy and to those with moderate to severe exacerbation. Intravenous aminophylline has not been shown to have additional bronchodilator effects in the ED setting. If a patient is already taking oral theophylline, a stat theophylline blood level should be obtained (49). Patients should be reassessed closely to monitor response to therapy. This includes continuous fetal heart rate monitoring in those women at a gestational age of ⬎23 wks. The decision to hospitalize the patient or discharge home is based on the response achieved in the first 4 hrs in the ED. Hospital Management of Acute Asthma. Hospitalized patients with acute S321
asthma must be carefully evaluated and appropriately transferred to the ICU, especially at the onset of maternal fatigue, evidence of fetal distress, or signs of impending maternal respiratory failure as evidenced by worsening PaCO2 (⬎35 mm Hg). A progressive increase in maternal PCO2, regardless of maintained oxygenation, is an indication for intubation and ventilation to prevent hypercarbia, maternal respiratory failure, and fetal acidosis. As mentioned above, acute asthma can result in dangerously low fetal oxygenation, and thus, the basic management of acute, life-threatening asthma exacerbation during pregnancy has the immediate goals of preventing and correcting hypoxemia (PaO2 ⬍ 60) with supplemental oxygen or mechanical ventilation (58), reducing hypercarbia (PaCO2 ⬎ 40), reversing bronchospasm with inhaled ␤-agonists and systemic steroids, and avoiding maternal exhaustion. Although inhaled ␤2-agonists remain the most important bronchodilators in this setting, intravenous or subcutaneous administration of ␤2-agonists such as terbutaline may be considered in some cases (49). Systemic administration of epinephrine should be avoided (if possible) during pregnancy because of its vasoconstrictive effect on the uteroplacental vasculature. When used in this setting, close ICU monitoring is needed to avoid fetal and maternal complications. Although the role of intravenous infusion of magnesium sulfate on the course of acute asthma has not been extensively studied, data from nonpregnant women with asthma suggest that it may have an added bronchodilator effect in patients with acute severe asthma (59). Blood levels of MgSO4 can be safely maintained at 4 – 6 mmol/L in pregnant women (infusion of 2 g/hr), but there is the potential for respiratory depression, and the patient should be monitored for this complication. Mechanical Ventilation in Acute Asthma. Intubation and mechanical ventilation are often needed in pregnant women with life-threatening asthma, especially in those who develop severe hypercapnia (PaCO2 ⬎ 40 – 45 mm Hg), respiratory acidosis, altered consciousness, maternal exhaustion, and fetal distress (49). Because of airway narrowing due to hyperemia, intubation should be performed via an oral rather than a nasal route. The decreased functional residual capacity and increased oxygen consumption in pregnancy may lower oxygen reS322
serve such that a short period of apnea at the time of intubation may be associated with a precipitous drop in PaO2. Preoxygenation of pregnant asthma patients with 100% oxygen is helpful before intubation, and cricoid pressure must be maintained to prevent gastric insufflation and subsequent aspiration before and during intubation. The principles of mechanical ventilation in patients with severe acute asthma have been previously described (60, 61). In general, minute ventilation should be adjusted to avoid hyperventilation, which may lead to respiratory alkalosis (PCO2 ⬍ 28 mm Hg), which can lead to the reduction of uterine blood flow and impaired fetal oxygenation. In addition, every effort should be undertaken to avoid increasing the dynamic hyperinflation, which may lead to volutrauma and barotrauma. This can usually be accomplished by small tidal volumes (6 – 8 mL/kg), high peak inspiratory flow rates (100 –120 L/min), low respiratory rates (8 –12 breaths/min), and use of square-wave inspiratory flow pattern. Every effort should be taken to avoid hypotension during mechanical ventilation to prevent inadequate fetalplacental blood flow. The risks and benefits of controlled hypoventilation or permissive hypercapnia in the pregnant patient are more complex compared with the nonpregnant patient. The transfer of CO2 across the placenta is dependent on the PCO2 difference of approximately 10 mm Hg between fetal and maternal circulation (26). This difference seems to be fairly constant over a wide range of CO2 tensions. Maternal hypercapnia could result in fetal respiratory acidosis and a shift of the fetal hemoglobin dissociation curve to the right, further limiting the ability of fetal hemoglobin to bind oxygen. These theoretical concerns about permissive hypercapnia emphasize the need for further research before justifying its routine clinical application. Other Management Strategies. For patients responding poorly despite mechanical ventilation, a favorable outcome may be obtained with the use of heliumoxygen mixture (58). Bronchoalveolar lavage using saline (62) or metaproterenol (63) has also been attempted, with successful outcome in a few case reports. On rare occasions, uncontrollable lifethreatening asthma may be refractory, despite mechanical ventilation and intensive medical therapy. In such cases, termination of pregnancy may be considered as an option and has been successfully
managed with termination of pregnancy by cesarean section (64, 65). In cases in which patients are admitted to an ICU at ⬎23 wks and ⬍34 wks of gestation, steroid therapy with two doses of intramuscular (12 mg) betamethasone administrated 24 hrs apart should be considered. If necessary, the dosing interval can be shortened to 12 hrs. This therapy has been shown to significantly reduce neonatal brain bleeds and the prevalence of hyaline membrane disease and respiratory distress syndrome. Cesarean section should always be considered as a therapeutic option in refractory cases, and the authors have anecdotally seen remarkable improvement in respiratory function after delivery. The reasons for this are unclear but may involve reduced pressure on the diaphragm from the uterus, decreased oxygen consumption (20 –30% reduction after delivery of the fetus), improved oxygen delivery (removal of the placental shunt), and the ability to employ previously restricted therapeutic strategies such as permissive hypercarbia and hypoxia. The nursing staff and anesthesia personnel should be aware of the potential for a caesarean section in the ICU, and appropriate preparations are advised. Unless there are telemetry facilities between the labor and delivery unit and the ICU, a pregnant patient with a viable fetus beyond 23 wks of gestation will require the presence of a labor nurse to continuously assess the fetal condition and be available to assist at a caesarean section. Although there may conceivably be objections by the ICU staff to having surgery performed in the ICU, there are good reasons not to transport the patient to an operating room for the surgery. Almost always, the patient has a precarious respiratory condition and is being supported with a sophisticated machine and ventilation profile. Disconnecting her from that machine and changing all of her ventilatory variables may significantly set her back and result in worsening of the maternal condition. Second, transport may result in inability to monitor the fetus at a time when maternal ventilation status is changing, resulting in fetal compromise or the need to emergently deliver the baby. This converts a relatively planned surgery in a critically ill but stable patient into an emergency operation with all of its attendant increase in risk. If properly planned for, adequate lighting can be arranged, anesthesia administered in a controlled circumstance, and the surgery completed Crit Care Med 2005 Vol. 33, No. 10 (Suppl.)
very satisfactorily. Most of these patients will be receiving broad-spectrum antibiotic therapy well before surgery, and the potential for increased infectious risk is clearly outweighed by the risks of transporting the patient to an operating room.
Management of Acute Asthma During Labor and Delivery Acute asthma exacerbation during labor and delivery is uncommon, but if it occurs, it may cause substantial maternal and fetal distress. Current asthma guidelines recommend that all regularly scheduled asthma medications should be continued during labor and delivery (49). Patients experiencing an acute asthma exacerbation should be treated promptly as outlined above. Intensive fetal and maternal monitoring is recommended. In patients who were treated with systemic corticosteroids before the onset of labor, “stress” doses of intravenous corticosteroids every 8 hrs until 24 hrs postpartum should be administered (49). In the event that a cesarean section is needed, preanesthetic atropine and glycopyrrolate may provide bronchodilation, and ketamine is one of the preferred anesthetic agents. Halothane in small doses may also provide a mild bronchodilator effect (66). The use of halogenated compounds does increase the risk of uterine atony, and in cases in which postpartum hemorrhage is encountered, anesthetic gases with uterine relaxant activity should be discontinued until the uterus has contracted and the bleeding has stopped.
Obstetrical Management of Pregnant Patients with Asthma Lumbar epidural analgesia reduces oxygen consumption and minute ventilation and is considered an excellent choice during labor. Because morphine and meperidine may cause histamine release, their use should be avoided, and the use of fentanyl as a narcotic analgesic is preferred. If preterm labor occurs during pregnancy, tocolytic therapy may be considered. Because most of the patients with asthma are already receiving inhaled ␤2agonists, administration of systemic ␤2agonists as tocolytic agents may cause significant adverse effects and thus should be avoided. Other agents such as magnesium sulfate may be considered in this situation. Indomethacin may induce bronchospasm, especially in aspirinCrit Care Med 2005 Vol. 33, No. 10 (Suppl.)
sensitive asthmatics, and thus should be avoided. Calcium antagonists such as nifedipine are believed to be safe, but data are few in asthmatic patients. For labor induction, oxytocin and prostaglandin E2 suppositories can be used safely; however, 15-methylprostaglandin F2-␣ can induce bronchospasm, and its use should be avoided in pregnant women with asthma (49). In those women who experience postpartum hemorrhage after delivery and who are asthmatic, methylergonovine, Pitocin, and misoprostol are believed to be safe, whereas 15-methylprostaglandin F2-␣ should probably be avoided.
Summary Management of asthma during pregnancy should involve consideration of the effects of the illness and its treatment on the developing fetus. The key to success for managing acute asthma during pregnancy includes early identification and treatment, stabilizing the hemodynamics and oxydynamics of the patient, and close monitoring of both mother and the fetus. Knowledge of normal maternal and fetal physiology and the implementation of steps to maintain fetal oxygen delivery while avoiding fetal acidosis are important in managing patients with acute severe asthma. A multidisciplinary team approach is required to ensure a successful outcome for the mother and fetus. Acute asthma should be promptly treated with intensive bronchodilator therapy, systemic corticosteroids, and oxygen therapy. In patients with life-threatening acute asthma, mechanical ventilation should be initiated early and in a controlled setting, and careful ventilator management strategies should be implemented to avoid complications such as barotrauma and volutrauma. In very rare circumstances, termination of pregnancy may be lifesaving.
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