Use of gastric residual volume to guide enteral nutrition in critically ill patients: a brief systematic review of clinical studies.

Abstract Objective In critically ill patients, the optimal procedure to monitor upper gastrointestinal function is controversial. Several authors have proposed gastric residual volume (GRV) as a tool to guide enteral nutrition. The aim of this contribution is to briefly discuss corresponding studies. Methods We electronically searched MEDLINE, EMBASE, and CINAHL for studies relevant to the subject. Results Six randomized controlled trials (RCTs) and six prospective observational studies were identified. Each analyzed different thresholds of GRV to guide enteral nutrition and to avoid complications (e.g., vomiting, aspiration, nosocomial pneumonia) in artificially ventilated patients. Due to heterogeneity in outcome measures, patient populations, type and diameter of feeding tubes, and randomization procedures, combination of the results of the six RCTs into a meta-analysis was not appropriate. High-quality RCTs studying medical patients could not demonstrate an association between complication rate and the magnitude of GRV. The only observational study that adjusted results to potential confounders and that studied surgical patients found, however, that the frequency of aspiration increased significantly if a GRV > 200 mL was registered more than once. Conclusion For mechanically ventilated patients with a medical diagnosis at admission to the intensive care unit, monitoring of GRV appears unnecessary to guide nutrition. Surgical patients might profit, however, from a low GRV threshold (200 mL).