ASTHMA IN PREGNANCY Puneet Khanna www.anaesthesia.co.in anaesthesia.co.in@gmail.com

Introduction Asthma is one of the most common medical conditions that can complicate pregnancy. Pregnancy can affect the course of asthma and asthma can affect pregnancy outcomes It is estimated that asthma complicates the course of 200,000 –376,000 pregnancies every year Early identification and appropriate pharmacologic therapy of acute asthma are key in achieving a successful outcome.

Can changes in asthma be expected in pregnancy 1/3 worsening, 1/3 improvement Changes unpredictable Symptoms of wheeze and sleep and activity limitation due to asthma were significantly increased between 25 and 32 weeks’ gestation. Increase in progesterone with advancing gestation contributes to (cAMP)-induced bronchodilation, thereby improving asthma and peak flow.

Global Initiative for Asthma (GINA) guidelines. Severity before pregnancy and in each month of pregnancy was described as intermittent, mild persistent, or moderate/severe Mild persistent group, severity was reduced in months 6 and 9 compared with the second month. fractional exhaled nitric oxide (FENO) Tamasi and colleagues found that FENO was not altered by pregnancy itself, but among pregnant women with asthma FENO was correlated with the level of asthma control

Physiologic considerations 50%ˆ in MV late pregnancy secondary to progesterone- mediated stimulation of the respiratory center. Hyperventilation usually results from an increase in TV, with minimal changes in RR. ABG - 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) FRC is decreased by as much as 18% in late pregnancy Physiologic tests of large airway function such as FEV1, FVC, FEV1/FVC ratio, and PEFR unchanged

Risk factors for asthma exacerbations during pregnancy more common in the late second trimester Women with severe asthma are most likely to experience exacerbations in pregnancy. Atopy, sinusitis, and gastro esophageal reflux Other risk inadequate prenatal care, obesity, lack of appropriate treatment with inhaled corticosteroids . Viral infection was the most common self-reported cause of severe asthma exacerbations Inhaled corticosteroid (ICS) the risk of having an exacerbation was reduced by more than 75% among women who were regular users of ICS

Effects of asthma on pregnancy Effects of asthma on maternal and fetal outcomes are nonconclusive. Increased adverse outcomes including IUGR ,preterm labor and delivery and preeclampsia TTN, meconium staining, oligohydramnios, development of pneumonia during pregnancy, and increased risk of cesarean delivery. Sorensen et al. demonstrated a two-fold increased risk of preterm delivery in women with asthma compared with women who had no history of asthma

Effects of asthma on pregnancy (contd…) Adverse outcomes are a result of asthma, secondary to asthma therapy ,factors that share common mechanisms with asthma. Murphy et al. 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 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

Effects of pregnancy on asthma The effect of pregnancy on the course of asthma is unpredictable Kircher et al. noted improvement of control in 34%, worsening in 36%, and unchanged status in 26%. Stenius-Aarniala et al. reported improvement of asthma control in 18%, worsening in 42%, and no change in 40%. A correlation between severity of disease and asthma morbidity during pregnancy, including exacerbation, unscheduled visits, hospitilization

Effects of pregnancy on asthma (contd…) Successive pregnancies, the course of asthma has been found to be similar to that experienced in previous pregnancies. Correlation between the course of rhinitis and the course of asthma during pregnancy

Management of asthma during pregnancy Optimal control of asthma symptoms, Attainment of normal pulmonary function, Prevention and reversal of asthma exacerbation, Prevention of maternal and fetal complications. Information on the long-term efficacy and safety of currently approved asthma medications in pregnant women

Is asthma associated with congenital malformations Pregnant women with asthma have a 30% increased risk of any Congenital malformation Malformations - moderate-dose ICS compared with non users 63% increased risk of malformations among users of high doses of ICS in the first trimester, Nervous system (not including spinabifida),respiratory system and digestive system,cardiac defects, and orofacialclefts. A case-control study demonstrated thatthe risk of gastroschisis was increased among women using bronchodilators in themonth before conception and during the first trimester, compared with nonusers of medication

Schatz et al. evaluated the relation between asthma medications and adverse perinatal outcomes in 2,000 subjects . The use of inhaled –agonists, inhaled corticosteroids, theophylline, or cromolyn/nedocromil was identified. An observed increased risk of preterm and low birth weights with the use of oral corticosteroids. no increased risk of malformations among users of budesonide.

Management of acute asthma during pregnancy 18% of all pregnant asthmatics have at least one ED visit Pregnant women with asthma should be considered to be high-risk patients, Management requires a close partnership and coordination between primary care physicians, obstetricians, asthma-care specialists, and pediatricians.

Structured clinical assessment of asthma during pregnancy

Differential diagnosis of acute asthma pulmonary edema cardiomyopathy pulmonary embolism amniotic fluid embolism 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.

Oxygen supplementation oxygen saturation at 95% Fluid status , intravenous fluid Initial treatment 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, Intravenous aminophylline Oral theophylline, a stat theophylline blood level should be obtained Patients should be reassessed closely to monitor response to therapy. Decision to hospitalize the patient or discharge home is basedon the response achieved in the first 4 hrs in the ED.

Hospital management of acute asthma ICU, - onset of maternal fatigue, evidence of fetal distress, or signs of impending maternal respiratory failure A progressive increase in maternal PCO2, regardless of maintained oxygenation, is an indication for intubation and ventilation Immediate goals of preventing and correcting hypoxemia (PaO2 60) with supplemental oxygen or mechanical ventilation), reducing hypercarbia (PaCO2 reversing bronchospasm with inhaled-agonists and systemic steroids,and avoiding maternal exhaustion

Mechanical ventilation in acute asthma Life-threatening asthma, severe Hypercapnia (PaCO2 40–45 mm Hg), respiratory acidosis, altered consciousness ,maternal exhaustion, and fetal distress MV should be adjusted to avoid hyperventilation, which may lead to respiratory alkalosis (PCO2 28 mm Hg) Reduction of uterine blood flow and impaired fetal oxygenation Avoid hypotension during mechanical ventilation to prevent inadequate fetal placental blood flow. The risks and benefits of controlled hypoventilation or permissive hypercapnia in the pregnant patient are more complex compared with the non pregnant patient.

Management of acute asthma during labor and delivery Asthma guidelines recommend that all regularly scheduled asthma medications should be continued during labor and delivery. 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. In cesarean section , preanesthetic atropine and glycopyrrolate may provide bronchodilation Ketamine is one of the preferred anesthetic agents.

Management of acute asthma during labor and delivery (contd…) Halothane in small doses may also provide a mild bronchodilator effect. The use of halogenated compounds does increase the risk of uterine atony 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 patient with asthma Lumbar epidural analgesia reduces oxygen consumption and minute ventilation - excellent choice during labor. Morphine and meperidine may cause histamine release, Fentanyl as a narcotic analgesic is preferred. If preterm labor occurs during pregnancy, tocolytic therapy may be considered. Patients with asthma are already receiving inhaled 2- agonists, administration of systemic 2- agonists as tocolytic agents may cause significant adverse effects and thus should be avoided.

Labor induction, oxytocin and prostaglandin E2 suppositories can be used safely 15-methylprostaglandin F2- can induce broncho spasm, and its use should be avoided in pregnant women with asthma. Postpartum hemorrhage after delivery IN asthmatic, methyl ergonovine, Pitocin, and misoprostol are believed to be safe, whereas 15-methylprostaglandin F2- should probably be avoided

Obstetrical management of pregnant patient with asthma (contd…) Indomethacin may induce bronchospasm, especially in aspirin sensitive aspirin sensitive asthmatics, and thus should be avoided. Magnesium sulfate may be considered in this situation. Calcium antagonists such as nifedipine are believed to be safe, but data are few in asthmatic patients.

Summary The key to success for managing acute asthma during pregnancy includes- early identification and treatment stabilizing the hemodynamics oxydynamics of the patient close monitoring of both mother and the fetus.

Summary (contd…) 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.

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