Asthma

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Asthma is a common disorder of the lung where inflammation causes the bronchi to swell and narrow the airways (ie. bronchospasm) . This leads to reversible, recurrent airway obstruction. Symptoms include wheezing, shortness of breath, or difficulty breathing, which are often associated with “triggers” → at night, during exercise, with allergens (ie. infection, animals, mold, smoking, pollen, etc).

Let’s talk through asthma and how to treat it!

  • How do I diagnose asthma? 

    • History - wheezing, cough, shortness of breath, chest tightness; temporal relationships and triggers 

    • Physical - wheezes on auscultation 

      • Should be confirmed by demonstrating airway obstruction on spirometry that is at least partially reversible 

      • Pulmonary function tests!

  • FEV1 forced expiratory volume in 1 second

    • >12% increase in FEV1 after bronchodilator = asthma

  • FVC forced vital capacity (basically all the air that you can breathe out) 

  • Normal FEV1/FVC ratio is around 75%, but predicted normal values can be calculated based on age, sex, and height

    • Asthma is an obstructive process, so FEV1/FVC ratio will be reduced

      • This is opposed to a restrictive process, where the FEV1/FVC ratio is not reduced, but both FEV1 and FVC ARE reduced about equally)

  • How does asthma change in pregnancy / why do we care about it in pregnancy? 

    • Oxygen is good for everyone!

      • Goal is adequate oxygenation of the fetus and prevent hypoxic episodes in pregnant person 

    • Poorly controlled asthma may be associated with increased prematurity, need for C/S, preeclampsia, growth restriction, other perinatal complications, and maternal morbidity/mortality 

  • How do I classify asthma?

ACOG PB 90

  • How do I treat asthma? 

    • In general: 

      • Avoid factors that precipitate attacks (ie. allergens, smoke, pollen) 

      • Get consultants on board if complex or difficult! (i.e., medicine/pulmonary)

    • Mild intermittent asthma - albuterol as needed, no daily meds 

    • Mild persistent asthma - add low dose inhaled corticosteroids 

      • Additional alternatives that could be considered are things like Cromolyn, leukotriene receptor antagonist, or theophylline 

    • Moderate persistent asthma - add long-acting beta agonist (i.e., salmeterol) alongside low dose inhaled corticosteroid / increase to medium-dose inhaled corticosteroid (if needed) / medium-dose inhaled steroid and salmeterol 

    • Severe persistent asthma - High-dose inhaled corticosteroid and salmeterol, and if needed, oral corticosteroid 

@AmbCareRx

  • Assessment of acute asthma

    • Medical history and exam (as always) 

    • Examine airway function and fetal well-being if after 24 weeks 

    • Patients with FEV1 measurements >70% for >60 minutes can usually be discharged if not in distress

    • Can order VBG if you want to get a gas, and can likely keep in ED for treatment if FEV1 <70% but >50%  

    • However, if FEV1 <50%, may need admission 

    • If patient becomes more drowsy, poor response, severe symptoms, confusion or PCO2>42mmHg, this may be a reason to admit to ICU 


  • Treatment of acute asthma (in ED or in OB triage) 

    • Oxygen for saturation >95%; measure spirometry at bedside with respiratory therapy.

    • Inhaled short-acting beta2 agonist by nebulizer or metered dose inhaler 

    • Oral systemic corticosteroid if no immediate response.

      • If patients have FEV1 that is <40%, may need high dose inhaled short-acting beta2 agonist + ipratropium by nebulizer every 20 minutes or continuously for 1 hour and oral corticosteroids 

    • If impending respiratory arrest - intubation and mechanical ventilation — get critical care, pulmonary, and/or anesthesia on board!

    • If improved / discharging: short-acting inhaler (i.e., albuterol) 2 puffs every 3-4 hours as needed and oral corticosteroids 40-60mg for 3-10 days. No need for tapering the steroid!

      • Ensure post-discharge follow up within 1 week!