Obesity and acute lung injury

Acute lung injury (ALI) is a clinical syndrome defined by the acute onset of hypoxemic respiratory failure and bilateral pulmonary infiltrates not primarily due to left atrial hypertension (1;2). When hypoxemia is more severe, the condition is termed acute respiratory distress syndrome (ARDS). ALI/ARDS is a common cause of respiratory failure with a crude incidence of 78.9 per 100,000 person-years and an age-adjusted incidence of 86.2 per 100,000 person-years (3). In-hospital mortality remains unacceptably high between 38% and 60% (2;3). It is estimated that there are almost 191,000 cases of ALI annually, accounting for 3.6 million hospital days and almost 75,000 deaths (3). Because of physiologic and biochemical changes associated with obesity, it is possible that excess weight affects the incidence and/or outcome of ALI. Alterations in thoraco-abdominal compliance and gas exchange might predispose obese patients to respiratory failure and ALI and could affect the response to therapeutic measures. The inflammation of obesity might also incline obese patients to lung injury when they suffer a secondary insult (e.g. sepsis). However, provider bias and disparities in provided care could be as influential in the outcome of obese patients with ALI and require consideration in the assessment of any such association (4;5).