Gastric Ultrasound to Monitor Gastric Residual Volume

"A first gastric ultrasound will be performed in the supine and the right lateral (RLD) decubitus position, allowing a qualitative analysis of the gastric contents (empty, liquid, solid, solid-liquid). The antral area will also be measured in both positions. The volume of gastric fluid content will be calculated according to the following formula: volume (ml) = -7,8 + (0,035 x antral area in RLD (mm²)) + 0,127 x age (month).~This examination will be immediately followed by the aspiration of gastric contents through the nasogastric tube used for enteral feeding, into 50-ml syringes, by a nurse blinded to the result of the first ultrasound examination. A second antral ultrasound examination will then be performed, by the same investigator blinded to the volume aspirated.~The occurrence of regurgitation and / or vomiting occurring within the 12 hours before and after the examination will be recorded."