Effect of mechanical ventilation and positive end-expiratory pressure (PEEP) on chest radiograph.

The effect of differing ventilator settings and positive end-expiratory pressure (PEEP) on the chest radiograph was studied in 12 patients with acute respiratory failure. Changing ventilator settings produced dramatic variations in the appearance of pulmonary infiltrates in technically identical radiographs exposed over a 10-15 min period. PEEP had the greatest effect on radiographic appearance. In seven patients, the diagnosis or estimation of severity of pulmonary infiltrates would have been altered if only the film during PEEP had been available. Knowledge of ventilator settings is vital in evaluating the severity of infiltration and radiographic diagnosis in patients with acute respiratory failure.