Tolerance of enteral feeding : from quantity to quality of gastric residual volume?

Nutritional support is essential in the management of critically ill patients; enteral nutrition is preferred to parenteral[1], as the latter may favour immune compromise, infections, higher costs and adverse outcome in some patients subsets. Moreover, many studies showed that this evidence is even more pronounced with the use of early enteral nutrition[2]. The major concerns with its use are the potential development of Upper Digestive Intolerance (UDI, i.e. presence of Gastric Residual Volumes, GRV, of 150-500 mL on two consecutive measurements, or >500 mL, or vomiting)[3] and the risk of aspiration of gastric content and pneumonia. Recently, some authors demonstrated that GRVs are poor markers of gastric aspiration in enterally fed critically ill patients[4], downsizing their role in the development of aspiration pneumonia. To our knowledge there are no reports on the role that the presence of air in the stomach may play in the development of aspiration. The aim of our study was to test the association between UDI, presence of air and the development of pneumonia in enterally fed, critically ill patients.