PRONE POSITIONING IN ACUTE LUNG INJURY

More than 20 years ago, critical care workers first observed that oxyg enation improved when patients with acute respiratory distress syndrom e were ventilated in the prone position. In recent reports, on turning prone, from 50 to 100% of patients improve oxygenation to a degree su fficient to allow a reduction in the level of positive end-expiratory pressure or fraction of inspired oxygen. It appears that vascular cond uctance in lung regions previously in the dorsal position is augmented by an increase in air space volume, with the effect that prone positi on ventilation will reduce shunt and improve ventilation-perfusion mis match, Factors determining which patients will respond have not yet be en elucidated. Although many questions regarding the role of prone ven tilation are unanswered, of greatest importance is whether this techni que reduces morbidity and mortality of patients with acute respiratory failure. Only carefully conducted, randomized trials can answer this question.