TY - CHAP M1 - Book, Section TI - Status Asthmaticus A1 - Corbridge, Thomas A1 - Hall, Jesse B. A2 - Hall, Jesse B. A2 - Schmidt, Gregory A. A2 - Kress, John P. PY - 2015 T2 - Principles of Critical Care, 4e AB - While some data suggest a decrease in the number of asthmatics requiring intubation and mechanical ventilation in recent years, all aspects of the management of severe asthma should be mastered by the intensivist, including optimizing mechanical ventilation in the face of large increases in airway resistance and propensity for dynamic hyperinflation.Severe asthma exacerbation is defined by several, but not necessarily all, of the following features: dyspnea at rest, upright positioning, inability to speak in phrases or sentences, respiratory rate >30 breaths per minute, use of accessory muscles of respiration, pulse >120 beats/min, pulsus paradoxus >25 mm Hg, peak expiratory flow rate <50% predicted or personal best, hypoxemia, and eucapnia or hypercapnia.Altered mental status, paradoxical respirations, bradycardia, a quiet chest, and absence of pulsus paradoxus from respiratory muscle fatigue identify imminent respiratory arrest.Airway wall inflammation, bronchospasm, and intraluminal mucus cause progressive airflow obstruction. Fewer patients develop sudden-onset asthma from a more pure form of bronchospasm.Airflow obstruction causes ventilation-perfusion inequality, lung hyperinflation, and increased work of breathing.Oxygen, β-agonists, and systemic corticosteroids are first-line treatments. Second-line treatments include ipratropium bromide, magnesium sulfate, leukotriene modifiers, theophylline, inhaled steroids, and heliox.Noninvasive ventilation is potentially useful in hypercapnic patients not requiring intubation.Postintubation hyperinflation decreases right heart preload and results in tamponade physiology. This may present as tachycardia, hypotension, and even cardiac arrest. A ventilator strategy that lowers lung volume decreases these potential complications.Treating airflow obstruction and prolonging the expiratory time during mechanical ventilation decreases lung hyperinflation. Expiratory time is prolonged by lowering minute ventilation and increasing inspiratory flow rate.Deep sedation allows for safe and effective mechanical ventilation in most intubated patients. Paralysis increases the risk of complications.Patient education, environmental control measures, and use of controller agents help prevent future exacerbations. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1107719189 ER -