What is the best next step in managing a 30-year-old pregnant woman with asthma exacerbation, currently on albuterol (salbutamol) with mild improvement, and oxygen saturation of 92% on room air?

Management of Asthma Exacerbation in a Pregnant Woman

Begin oxygen therapy immediately, aiming for oxygen saturation greater than 95%, which is the best next step for this pregnant woman with asthma exacerbation and current oxygen saturation of 92% on room air. 1

Assessment of Current Status

This 30-year-old pregnant woman (2 weeks gestation) presents with:

• Shortness of breath for 2 days
• No improvement with home medications (albuterol and budesonide)
• No fever, cough, or chest pain
• History of well-controlled asthma with one prior hospitalization
• Current vital signs: RR 24, BP 140/80, O2 saturation 92% on room air
• Diffuse wheezing on examination
• Some improvement with albuterol and ipratropium in ED

Management Algorithm

Step 1: Immediate Oxygen Therapy

• Administer high-flow oxygen via face mask
• Target oxygen saturation >95% (especially important in pregnancy) 1
• This prevents maternal and fetal hypoxia, which is particularly dangerous in pregnancy

Step 2: Continue Bronchodilator Therapy

• Continue albuterol treatments every 20-30 minutes initially 1
• Add ipratropium bromide to nebulizer treatments 1
• Consider continuous nebulization if response is inadequate 1

Step 3: Systemic Corticosteroids

• Administer oral prednisolone or IV hydrocortisone 1
• Corticosteroids are safe in pregnancy when benefits outweigh risks
• Do not delay administration as they take hours to begin working

Step 4: Monitoring

• Repeat peak flow measurements 15-30 minutes after each treatment 1
• Continuous pulse oximetry to ensure saturation remains >95% 1
• Monitor fetal status in coordination with obstetrics (already initiated)

Rationale for Oxygen as First Priority

1. Current hypoxemia: The patient's oxygen saturation of 92% is below the recommended target of >95% for pregnant women 1

2. Pregnancy considerations: Maintaining adequate oxygenation is critical for both maternal and fetal well-being. Even mild hypoxemia can compromise fetal oxygen delivery 2

3. Guidelines recommendation: British Thoracic Society guidelines specifically recommend maintaining SaO2 >92% in all patients and >95% in pregnant women 1

4. Sequential approach: While all treatments are important, oxygen should be initiated first, followed by bronchodilators and corticosteroids 1

Why Other Options Are Not Appropriate First Steps

• Having patient supine: This would worsen respiratory mechanics and potentially increase hypoxemia
• Chest radiograph: While useful in some cases, not indicated as first step when clinical presentation is consistent with asthma exacerbation 1
• Long-acting beta agonist: Not appropriate during acute exacerbation; short-acting agents are preferred 3
• Theophylline: Not first-line therapy and has significant potential for toxicity 1

Important Considerations in Pregnancy

• Asthma exacerbations during pregnancy can lead to adverse maternal and fetal outcomes
• Oxygen therapy is particularly important as fetal development is sensitive to hypoxemia
• Continue fetal monitoring throughout treatment
• Avoid medications with known teratogenic effects, but do not withhold essential asthma treatments
• Most standard asthma medications (including beta-agonists and corticosteroids) are considered acceptable during pregnancy when clinically indicated

Monitoring for Improvement

• Assess response to oxygen therapy within minutes
• Expect improvement in respiratory rate and work of breathing
• Target oxygen saturation >95% throughout treatment
• Continue to monitor peak flow measurements after each bronchodilator treatment
• Reassess need for hospitalization based on response to initial therapy

The management of asthma exacerbation in pregnancy requires prompt intervention with oxygen being the immediate priority to ensure adequate oxygenation for both mother and fetus.