Managing acute, severe asthma: Part 2

Hospitalization for acute, severe asthma is warranted if significant improvement does not occur within 1 to 2 hours of treatment. Patients with significant work of breathing, including some who are acutely hypercapnic, may be candidates for noninvasive positive pressure ventilation. Patients who are severely distressed, obtunded, or on the verge of respiratory collapse should be intubated and mechanically ventilated. Initial ventilator settings should include a respiratory rate of 12 to 14 breaths per minute, a tidal volume between 7 and 8 mL/kg, and an inspiratory flow rate of 80 L/min with a constant flow pattern. Attempt to keep initial minute ventilation less than 115 mL/kg/min, to avoid dangerous levels of dynamic hyperinflation (DHI). The severity of DHI is crucial to risk assessment and subsequent adjustment of ventilator settings. Once patients begin breathing spontaneously, they may benefit from small amounts of ventilator-applied positive end-expiratory pressure. Before discharge, patients should be given adequate asthma education as well as oral and inhaled corticosteroids.