pulmonary disorders
Treatment of Acute Asthma Exacerbations
Hospitalization
Hospitalization generally is required if patients have not returned to their baseline within 4 hours of aggressive emergency department treatment. Criteria for hospitalization vary, but definite indications are Failure to improve Worsening fatigue Relapse after repeated beta-2 agonist therapy Significant decrease in PaO2 (to<50 mm Hg) Significant increase in PaCO2 (to>40 mm Hg) A significant increase in PaCO2 indicates progression to Overview of Respiratory Failure . (NIPPV) may be needed in patients whose condition continues to deteriorate despite aggressive treatment, to alleviate the work of breathing. Tracheal Intubation and invasive PaCO2 > 60 mm Hg Decreased level of consciousness Excessive respiratory secretions Facial abnormalities (ie, surgical, traumatic) that could impede noninvasive ventilation Overview of Mechanical Ventilation should be strongly considered if there is no convincing improvement after 1 hour of NIPPV. Intubationand mechanical ventilation allow the provision of sedation to further alleviate the work of breathing, but the routine use of neuromuscular blocking agents should be avoided because of possible interactions with corticosteroids that can cause prolonged neuromuscular weakness.Ketaminemay be used for awake intubation if the user has familiarity with its use and adverse effects (eg, laryngospasm, rigidity, and bronchorrhea). 80 L/minute) to prolong exhalation time, minimizing auto positive end-expiratory pressure (auto-PEEP). Initial tidal volumes can be set to 6 to 8 mL/kg of ideal body weight, and extrinsic PEEP should be used to facilitate patient-initiated triggering and minimize ventilator dyssynchrony from auto-PEEP. High peak airway pressures will generally be present because they result from high airway resistance and inspiratory flow rates. In these patients, peak airway pressure does not reflect the degree of lung distention caused by alveolar pressure. However, if plateau pressures exceed 30 to 35 cm water, then tidal volume should be reduced to limit the risk of Pneumothorax . When reduced tidal volumes are necessary, a moderate degree of hypercapnia is acceptable ("permissive hypercapnia"), but if arterial pH falls below 7.10, a slow 