Prone position in mechanically ventilated patients with severe acute respiratory failure.

The purpose of this study was to characterize changes in oxygenation, expressed as Pa02/F'02, when patients with ,severe acute respiratory failure (Pa02/FI02 < 150), unrelated to left ventricular failure to atelectasis, were turned to and from a supine to prone position at 1- and 4-h intervals. Ventilator settings were unchanged. Thirty-two consecutive patients were studied 1 h before, 1 and 4 h during and 1 h after placing in a prone position with Pa02/F102 of 103 ± 28, 158 ± 62, 159 ± 59, and 128 ± 52, respectively (ANOVA, p < 0.001). After 1 h in a prone position, improvement of Pa02/Flo2 by 20 mm Hg or more was considered a positive response. Seven patients studied had no response (22%), hereafter referred to as nonresponders, and 25 had a positive response (78%), hereafter referred to as responders. Among the seven nonresponders, two did not tolerate the prone position and were returned supine before the end of the 4-h trial. With the remaining five, Pa02/F102 evolution was 83 ± 29, 77 ± 19, 83 ± 33, and 81 ± 47, respectively. For two of the 25 responders, measurements are missing after returning to the supine position. In 10 of the 23 responders (43%) who completed the 4 h prone trial, the Pa02/F102 returned to its starting value when patients were repositioned supine: 117 ± 24, 164 ± 44, 156 ± 55, and 110 ± 34, respectively (ANOVA, p < 0.01). In 13 of the 23 (57%) improvement persisted: 105 ± 27, 187 ± 58, 189 ± 49, and 157 ± 49, respectively (ANOVA, p < 0.001). Repeated improvements after turning to a prone position were frequently observed. Side effects in the 32 patients after a total of 294 periods in a prone position included minor skin injury and edema, two instances of apical atelectasis, one catheter removal, one catheter compression, one extubation, and one transient supraventricular tachycardia. C"atte G, Sab J-M, DuBois J-M, Sirodot M, Gaussor­ gues P, Robert D. Prone position in mechanically ventilated patients with severe acute respira­ tory failure. AM J RESPIR CRIT CARl MED 1997;155:47)-478. The purpose of this study was to determine the effect of the prone position in a large consecutive series of 32 patients presenting severe acute respiratory failure characterized by Pa02/PI02~ 150 and to determine the persistence and recurrence of any positive effect. Patients with acute respiratory failure characterized by rapid impairment of oxygenation unrelated to left ventricular failure or atelectasis require mechanical ventilation with high lev­ els of the fractional concentration of inspired oxygen (PIo2) and positive end-expiratory pressure (PEEP) to maintain adequate oxygenation. These ventilator settings may themselves be toxic and dangerous; therefore, any intervention that allows reduction of the PIo2 and/or PEEP may be beneficial. Previous studies have demonstrated that patients with adult respiratory distress syn­ drome (ARDS) have lung condensations that are preferentially located in the dorsal regions (1). Several smaller studies have reported in selected cases that turning patients with ARDS to a prone position might substantially improve oxygenation (2-6). Our results show that use of the prone position is frequently help­ ful in clinical practice.