A Percutaneous Endoscopic Gastrostomy (PEG) tube is a feeding tube placed through the abdominal wall directly into the stomach, providing a path for nutrition, fluids, and medications when a person cannot safely eat or drink by mouth. Gastric Residual Volume (GRV) is the amount of fluid remaining in the stomach, representing the contents from previous feedings and natural digestive secretions. Measuring this volume is a procedure performed through the PEG tube to assess how well the stomach is emptying its contents before introducing more formula. This check helps monitor the person’s digestive tolerance to the prescribed feeding regimen.
Rationale and Timing for Residual Volume Checks
The primary reason for performing a gastric residual check is to monitor for delayed gastric emptying. An excessive buildup of fluid and formula in the stomach can increase the risk of regurgitation and pulmonary aspiration, where stomach contents are accidentally inhaled into the lungs, potentially causing pneumonia. Checking the residual volume is a common method used to assess a patient’s tolerance to the enteral feeding process.
The frequency of checking residuals is often determined by the feeding schedule and institutional protocol, as clinical guidelines can vary widely. For those receiving intermittent or bolus feedings, the residual volume is typically measured immediately before administering the next bolus of formula. For individuals on continuous feedings, the check is usually performed every four to eight hours. Consistent monitoring helps identify early signs of feeding intolerance, allowing for timely adjustments to the feeding rate or formula type.
Step-by-Step Procedure for Measuring Gastric Residual Volume
The procedure begins with proper preparation, ensuring hand hygiene is performed and clean gloves are worn to maintain safety and prevent infection. Necessary supplies include a large-volume syringe, typically 60 cubic centimeters (cc), which is needed to aspirate the stomach contents, and a clean container for temporary collection if required. Before starting, the person should be positioned with the head of the bed elevated to at least 30 to 45 degrees, which helps reduce the risk of reflux during the procedure.
If the individual is on a continuous feed, the pump must be paused momentarily before accessing the tube. The syringe is then connected to the port of the PEG tube, which may first require opening a clamp or turning a stopcock valve to allow access. Gently and slowly pull back on the plunger of the syringe to withdraw the stomach contents until resistance is felt or no more fluid can be easily aspirated.
Once the stomach contents are withdrawn, hold the syringe upright to read the volume of the aspirated fluid accurately in milliliters (mL). Unless the volume is excessively high or the contents appear abnormal, the aspirate must be carefully returned to the stomach.
Returning the fluid prevents the loss of valuable electrolytes, digestive enzymes, and nutrients. After re-instilling the residual volume, the tube should be flushed with a small amount of warm water, typically 30 mL, to clear the line and prevent formula from clogging the tube. The feeding can then be resumed, and the time, volume, and characteristics of the residual should be documented.
Interpreting Results and Necessary Actions
The interpretation of the measured Gastric Residual Volume is based on facility-specific protocols and the patient’s individual tolerance. While thresholds vary, holding a feed for volumes less than 500 mL is generally discouraged in non-critically ill patients, as this can unnecessarily interrupt nutrition delivery. Some facilities may still use lower thresholds, such as 200 mL, to indicate a need for further evaluation, though the trend is toward higher volumes.
If the measured GRV exceeds the established threshold, the initial action is to temporarily hold the feeding for a short period, often one hour, and then recheck the residual volume. If the subsequent check shows a reduction in volume, the feeding can often be resumed, potentially at a slightly slower rate, while monitoring for further signs of intolerance. If the high volume persists after the recheck, the healthcare provider should be notified for an in-depth clinical assessment.
Beyond the numerical volume, the physical characteristics of the aspirate are important. The presence of:
- A thick consistency,
- Foul odor,
- Fresh blood, or
- Dark, coffee-ground material
warrants immediate notification of the healthcare provider, regardless of the measured volume. High residuals may prompt the medical team to consider interventions such as administering prokinetic medications to improve gastric motility or changing the feeding tube to a post-pyloric location to bypass the stomach.