. Enteral nutrition during prone positioning in mechanically ventilated patients.The Enteral Nutrition (EN) tends to be stopped during prone positioning to prevent the risk of acid reflux and vomiting.To compare the gastric residual volume during continuous enteral nutrition in patients in prone and supine position.Observational restrospective study on Acute Respiratory Distress Syndrome patients, mechanically ventilated, with continuous enteral nutrition implemented according to the same protocol, in prone and supine position.The 25 patients included had a mean age of 51.13±15.93 (range: 16-80) years. Gastic residual volume was checked on 656 occasions (408 in supine and 248 in prone position). Mean infusion rate was 63.3±18.5 ml/h: 62.1±18.9 ml/h in supine and 66.2±16.5 ml/h in prone position. The mean overall gastric residual volume was 24.4±54.2 ml: 20.6±18.9 ml in supime and 23.6±50.0 ml in prone posizion. In 4 occasions (2 in prone and 2 in supine position9, the gastric residual volume was > 300ml; EN was interrupted on 1 occasion with a gastric residual volume >500ml.No clinically relevant differences of gastric residual volume were observed in prone and supine position. A protocol for the management of gastric residual volume allows a safe and effective administration of EN also in patients positioned for several hours in prone position.