Enteral (tube) feeding delivers nutrition directly into the stomach or small intestine for patients unable to eat safely by mouth. Clinicians monitor the Gastric Residual Volume (GRV) as a safety practice to assess how well the stomach is tolerating the nutrition. GRV represents the contents remaining in the stomach from the previous feeding and digestive secretions. Monitoring this volume helps clinicians assess the risk of complications, particularly aspiration, where stomach contents enter the lungs. The decision to hold a tube feed due to a high GRV balances patient safety against the goal of providing adequate nutrition.
Understanding Gastric Residual Volume
The Gastric Residual Volume (GRV) is the liquid aspirated from the stomach following enteral nutrition administration, including the formula and digestive juices. GRV serves as a marker for gastric emptying, indicating how quickly the stomach moves contents into the small intestine. A high residual volume suggests the stomach is not processing the feed fast enough, causing a buildup. Delayed emptying can be caused by underlying illness, certain medications (like sedatives), or the stress of being unwell. The procedure involves temporarily stopping the feed and gently aspirating the stomach contents using a syringe attached to the feeding tube.
Current Thresholds for Stopping Feeds
The specific volume that triggers stopping a feed has evolved significantly in clinical guidelines. Historically, low thresholds (e.g., 100 mL or 150 mL) were used, but this often caused unnecessary interruptions and did not reduce the incidence of aspiration. Modern clinical consensus, supported by organizations like the American Society for Parenteral and Enteral Nutrition (ASPEN), favors much higher thresholds. In critical care settings, guidelines suggest feeding should generally not be stopped for residuals less than 500 mL, measured over a four- to six-hour period. This shift prioritizes continuous nutrition, focusing instead on holistic assessment, including signs like abdominal distension, nausea, and vomiting, which are better indicators of true feeding intolerance.
Troubleshooting High Residual Volumes
When GRV exceeds the accepted threshold, clinicians implement interventions to safely continue nutritional support. The immediate action is to temporarily pause the enteral feeding to allow the stomach time to empty. The patient’s position is reassessed, ensuring the head of the bed is elevated to at least 30 to 45 degrees to minimize reflux and aspiration risk. A common strategy involves administering pro-motility agents, or prokinetics, such as metoclopramide, to enhance gastric emptying. If the feed is continuous, the infusion rate may be slowed down and then gradually advanced as tolerance improves.
Special Considerations for Residual Checks
The relevance of checking Gastric Residual Volume is influenced by the type of feeding tube and the feeding schedule. GRV checks are only applicable to tubes that terminate in the stomach, such as nasogastric or gastrostomy tubes. They are irrelevant for small bowel feeding tubes (e.g., nasojejunal tubes) because the small intestine is not a reservoir and contents are rapidly absorbed. GRV is monitored more closely with continuous infusion feeds, often checked every four to six hours, compared to bolus or intermittent feeding. Critically ill patients have a higher risk of delayed gastric emptying, leading to an increased emphasis on clinical assessment and often a move toward post-pyloric feeding if high residuals persist.