Early enteral nutrition in mechanically ventilated patients in the prone position

Objective: To assess the tolerance of early enteral nutrition in critically ill patients receiving invasive mechanical ventilation in the prone position. Design: Prospective, comparative study. Setting: General intensive care unit in a university-affiliated hospital. Patients: A total of 71 consecutive patients receiving invasive mechanical ventilation with early nasogastric enteral nutrition were studied for 5 days while being treated continuously in the supine position (supine position group, n = 37) or with intermittent prone positioning for severe hypoxemia (prone position group, n = 34). Interventions: Inclusion occurred within 24 hrs of mechanical ventilation initiation. Daily 18-hr enteral nutrition via a 14F gastric tube was initiated. Prone position, patients were turned every 6 hrs as long as Pao(2)/FIo(2) remained at <150, with a FIo(2) of 0.6 and positive end-expiratory pressure of 10; the head was slightly elevated. When supine, patients in both groups were semirecumbent. Residual gastric volume was measured every 6 hrs, and enteral nutrition was discontinued if it exceeded 250 mL or vomiting occurred. Measurements and Main Results: The groups were similar for age, sex, Simplified Acute Physiology Score 11, mortality, and risk factors for enteral nutrition intolerance. At baseline, Pao(2)/FIo(2), was lower in prone position patients than in supine position patients (127 +/- 55 vs. 228 +/- 102; p < .001). As compared with supine position patients, prone position patients had significantly greater residual gastric volumes on days 1, 2, and 4 and experienced more vomiting episodes (median, 1 [interquartile range, 0-2] vs. 0 [interquartile range, 0-1]; p < .05). Enteral nutrition was stopped in 82% of prone position patients and 49% of supine position patients (p < .01) so that daily enteral nutrition volumes were lower with prone position patients. In the prone position group, vomiting occurred more frequently in the prone than in the supine position (relative risk, 2.5; 95% confidence interval, 1.5-4.0; p < .001). Conclusion: In critically ill patients receiving invasive mechanical ventilation in the prone position, early enteral nutrition is poorly tolerated. Prokinetic agents or transpyloric feeding and semirecumbency should be considered to enhance gastric emptying and to prevent vomiting in patients receiving mechanical ventilation in the prone position.