acute asthma; asthma exacerbation

Introduction

also see asthma &/or status asthmaticus

Etiology

• allergic bronchopulmonary aspergillosis (recurrent asthma exacerbations)

Clinical manifestations

• inability to speak in full sentences, diaphoresis, flaring of the nares, & use of accessory muscles during inspiration are signs of impending respiratory failure

Laboratory

• arterial blood gas (hospitalized patients)
  • pCO2 is often low
  • a normal or mildly elevated pCO2 in severe asthma may be a sign of respiratory muscle fatigue & impending respiratory failure

Diagnostic procedures

• peak flow meter (useful at home, emergency department)

Complications

• pneumomediastinum

• disease interaction(s) of acute asthma with myocardial ischemia

Management

• also see status asthmaticus & specific etiology
• admission to intensive care for:
  • pCO2 >= 42 mm Hg
  • persistent FEV1 or peak flow < 40% of predicted despite 1 hour of aggressive treatment with bronchodilators
  • endotracheal intubation for respiratory failure
    • consider vocal cord dysfunction for acute asthma that improves immediately with intubation
  • noninvasive positive pressure ventilation (NPPV) benefit unclear
• pharmaceuticals
  • see individual therapeutic classes
  • systemic glucococorticoids
    • home treatment with prednisone 40 mg QD for 5 days
    • dexamethasone 0.3 to 0.6 mg/kg, up to 15 mg/day PO QD, or as one IM injection
      • use longer courses for kids who continue to have symptoms
    • single 12-mg dose of oral dexamethasone equivalent to 5 days of 60-mg prednisone daily
  • beta-2 adrenergic receptor agonists
    • MDI as effective as nebulizer
    • continuous therapy with nebulizer more effective than intermittent therapy with MDI
      • NNT = 10 to prevent 1 hospitalization
    • addition of nebulized albuterol of no benefit*
  • albuterol-ipratropium nebulizer + intravenous methyl prednisolone
    • first line for hospitalized patients
    • avoid beta-blocker if patient presents with concurrent NSTEMI
  • epinephrine SQ 0.3-0.5 mL of a 1:1000 solution
    • rescue medication for life-threatening asthma
  • intravenous magnesium sulfate may be beneficial in patients presenting with severe asthma
  • antibiotics of no benefit & may be harmful
    • azithromycin of no benefit
  • vitamin D of no benefit in preventing severe asthma exacerbations
• heliox may be of benefit vs endotracheal intubation for severe asthma
  • of no benefit
• cardioselective beta-blockers may appropriate in patients with stable asthma & clear indications
  • nonselective beta-blockers should be avoided
  • worsening of asthma symptoms & declines in pulmonary function may occur with the first few doses of a cardioselective beta-blocker
    • cardioselective agents can reduce FEV1 & interfere with treatment of asthma
  • avoid all beta-blockers in patients with unstable asthma
• oral glucocorticoids upon discharge from the emergency department
  • no added benefit or harm of inhaled glucocorticoids in combination with oral glucocorticoids
• in patients with diabetes mellitus type-2 & asthma, metformin cuts odds of asthma attacks by 30%; adding a GLP-1 receptor agonist reduces odds by another 40%

* The NNT lists NNT for nebulized ipratropium = 11 to prevent hospitalization due to asthma attack; however, the 2 most recent references find no benefit.

More general terms

• asthma
• exacerbation

More specific terms

• status asthmaticus
• thunderstorm asthma