Asthma in Pregnancy

1. See Also
   1. Asthma
2. Pathophysiology
   1. Oxygen consumption increases 25% in pregnancy
   2. Arterial pCO2 falls in pregnancy
      1. Non-pregnant pCO2 levels are red flags in pregnancy
   3. Uncontrolled Severe Asthma results in IUGR
      1. Asthma control in pregnancy is critical
      2. Bracken (2003) Obstet Gynecol 102:739-52
3. Admission Criteria
   1. Arterial pH <7.35 (normal pH 7.40)
   2. Arterial pCO2 >40 mmHg (normal pCO2 28-32 mmHg)
   3. Arterial pO2 <70 mmHg
   4. Pulse >120 beats per minute
   5. Respiratory Rate >30 breaths per minute
4. Management: Anti-inflammatory agents
   1. Outpatient
      1. Budesonide (Pulmicort) 1-4 puffs bid
         1. Preferred Inhaled Corticosteroid in pregnancy
         2. Best studied agent in pregnancy
      2. Beclomethasone MDI (Vanceril) 2-5 sprays bid-qid
      3. Flunisolide (AeroBid) 2-4 puffs bid
      4. Fluticasone (Flovent) 2 puffs bid
      5. Cromolyn Sodium 2 sprays qid
         1. Inhaled Corticosteroids are preferred over cromolyn
   2. Outpatient exacerbation management
      1. Prednisone 40 mg bursts 7-14 days
   3. Inpatient
      1. Methylprednisolone 1 mg/kg IV bolus every 6-8 hours
   4. Precautions: Prednisone and Methylprednisolone
      1. Use systemic steroids sparingly in first trimester
      2. Risk of Cleft Palate, IUGR, and Preterm Labor
5. Management: Bronchodilator agents
   1. Outpatient
      1. Albuterol 2 puffs every 4 hours prn
      2. Montelukast (Singulair)
      3. Zafirlukast (Accolate)
   2. Inpatient
      1. Albuterol Nebulizer 2.5 mg in 3 cc Normal Saline
      2. Theophylline (rarely used now)
   3. Emergent Management
      1. Epinephrine (1:1000)
         1. Dose: 0.01 ml/kg to 0.2-0.5 ml SC every 30 min prn