acute lung injury
adult respiratory distress syndrome
A condition due to a diffuse infiltrative process in the lungs, which affects ±150,000/year (US), and is characterised by acute pulmonary oedema and respiratory failure, poor oxygenation, increased functional residual capacity and decreased compliance; ARDS may accompany various medical and surgical conditions, and may be associated with interstitial pneumonitis—usual, desquamative and lymphoid types.Aetiology
Gram-negative sepsis, pneumonia, shock, gastric acid aspiration, trauma, drug overdose, toxic gas (chlorine, NO2, smoke) exposure, severe metabolic derangement, pancreatitis.
Clinical findings
A 6–24-hour latency period is followed by hypoxia, decreased aeration, dyspnoea, severe SOB and “stiff” lungs—i.e., decreased pulmonary compliance.
Imaging
Extensive, diffuse bilateral fluffy infiltrates.
Management
Nitric oxide (NO), 18 ppm, may reduce mean pulmonary artery pressure; 37 to 30 mm Hg, may reduce intrapulmonary shunting (36% to 31%), increase ratio of partial pressure of arterial O2 to inspired O2 (PaO2/FiO2), an index of arterial oxygenation efficiency (±152 to ±199); other management strategies include PEEP.
Prognosis
The outcome of ARDS is a function of underlying cause.
Mortality
± 60%, the cause of death has shifted from hypoxia to multiple organ failure.