Status asthmaticus: an overview.

Status asthmaticus (SA) is a life-threatening exacerbation of asthma that is refractory to usual therapeutic interventions. The etiologic factors leading to SA and pathophysiologic alterations in airway caliber, respiratory muscle function, and respiratory gas exchange are reviewed. Important parameters in the assessment of patients presenting with SA are highlighted, including the necessity to document the severity of airflow obstruction with measurement of peak expiratory flow rate or one-second vital capacity. The indications for measurement of arterial blood gases, characteristic alterations in oxygen and carbon dioxide tension, and the appropriate therapeutic measures are emphasized. In addition, the roles of beta-adrenergic agonist and anticholinergic bronchodilators, methylxanthines, and glucocorticoids are discussed in the context of the rational management of patients with SA. Airway management and assisted mechanical ventilation are reviewed, with helpful guidelines for respirator adjustment based on patient responses to the physiologic alterations that develop during assisted ventilation.