Noninvasive Ventilation in Acute Lung Injury/Acute Respiratory Distress Syndrome

Abstract

The acute respiratory distress syndrome (ARDS) is a clinical syndrome of lung injury characterized by severe dyspnea, refractory hypoxemia, and bilateral radiographic opacities. It is clinically defined by the following criteria: acute onset (less than 7 days), bilateral alveolar opacities consistent with pulmonary edema, Pao2/Fio2 < 200, pulmonary artery occlusion pressure less than 18 mmHg, or no clinical evidence of left atrial hypertension [1]. It is now recognized that there is a gradation of the severity of clinical lung injury: patients with less-severe hypoxemia (defined by a Pao2/Fio2 ratio of 300 or less) are considered to have acute lung injury (ALI), and those with more severe hypoxemia (defined by a Pao2/Fio2 ratio of 200 or less) are considered to have ARDS [1]. The mainstay of treatment for patients with ALI/ARDS is intubation and mechanical ventilation. However, endotracheal intubation is associated with significant morbidity, including upper airway trauma, barotrauma, and pneumonia [2–4]. As a result, any intervention that obviates the need for endotracheal intubation in ALI/ARDS is welcome.