A gastrostomy tube, commonly called a G-tube, is a flexible tube inserted through the abdominal wall directly into the stomach to provide nutrition, fluids, or medication. Checking the gastric residual volume (GRV) is a procedure performed to monitor the stomach’s ability to empty its contents. This check is a standard safety practice that helps caregivers and healthcare providers assess how well the patient is tolerating the feeding regimen. Understanding the proper technique for measuring and interpreting this volume is crucial for preventing potential complications.
Understanding Gastric Residual Volume
The term “residual” refers to the volume of liquid remaining in the stomach, consisting of undigested formula, water, and gastrointestinal juices. Measuring GRV monitors the rate of gastric emptying—how quickly the stomach moves contents into the small intestine. A consistently high volume indicates delayed gastric emptying and feeding intolerance. When the stomach is overly full, the risk of regurgitation, vomiting, and subsequent aspiration of contents into the lungs increases, making GRV monitoring a standard safety practice.
Necessary Preparation Before Checking
Before beginning the measurement process, ensure all necessary supplies are gathered and the patient is positioned correctly. Meticulous hand hygiene is required to minimize the risk of introducing bacteria. Equipment typically includes a 60-milliliter catheter-tip or ENFit syringe and a clean container for measuring the fluid. Position the patient with their head and upper body elevated to at least a 30- to 45-degree angle; this upright position reduces the risk of reflux. If the patient is receiving continuous tube feeding, the pump must be paused immediately before connecting the syringe to the G-tube.
Step-by-Step Guide to Measuring Residuals
The process begins by preparing the G-tube access port, often by removing the cap or plug and connecting the 60-milliliter syringe directly to the tube. Before withdrawing contents, gently instill a small amount of air or water into the tube to ensure patency and clear any blockages. Once connected, unclamp the G-tube if it was clamped, allowing access to the stomach.
To aspirate the contents, pull the plunger of the syringe back slowly and gently. Rapid or forceful aspiration should be avoided, as this can cause the tube to collapse or irritate the stomach lining. The goal is to withdraw all stomach contents until resistance is felt, or no more fluid can be easily pulled back into the syringe barrel.
After collecting the fluid, accurately measure the total volume. If the volume exceeds the capacity of the 60-milliliter syringe, empty the contents into the clean container and repeat the aspiration process until the stomach is empty. The total amount in milliliters must be immediately noted and recorded on the patient’s intake and output sheet. The frequency of checking residuals is determined by the specific care plan, such as before each intermittent feed or every four hours during continuous feeding.
Interpreting Results and Next Steps
Once the volume is measured, the next steps depend on the specific protocol set by the patient’s healthcare provider. While historical thresholds were often 200 to 250 milliliters, many current guidelines suggest a higher threshold, such as 500 milliliters, for non-critically ill adults. The patient’s personalized care plan specifies the acceptable maximum volume and is the most reliable guide for the caregiver.
If the measured GRV is below the established limit, the aspirated contents should be carefully returned to the stomach through the G-tube. Returning the residual volume is important because it contains necessary electrolytes, digestive enzymes, and nutrients. After re-instilling the fluid, flush the tube with a prescribed amount of water to prevent clogging before resuming the feeding.
If the measured volume exceeds the limit or appears abnormal (e.g., bile-stained or dark brown), immediate action is required. The excess volume should be discarded, and the tube feeding must be temporarily held or slowed to allow the stomach time to empty. Report this finding to a healthcare professional, as it may necessitate a change in the feeding rate, formula, or medications to improve gastric motility.