II. 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 [PubMed]

III. 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

IV. 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

V. 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

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