From the Research
The amount of residual that determines passing a nasogastric tube (NGT) clamping trial is typically less than 200-250 mL over 4-6 hours. To conduct a clamping trial, the NGT is clamped for a set period, after which the tube is unclamped and gastric residual volume (GRV) is measured. If the residual volume is below this threshold, it suggests adequate gastric emptying and the patient may be ready for tube removal. However, this should be considered alongside other clinical factors such as absence of vomiting, presence of bowel sounds, passage of flatus or stool, and the patient's ability to tolerate oral intake. The rationale behind this threshold is that normal gastric emptying should prevent significant accumulation of secretions, even when the tube is clamped. Higher residual volumes may indicate delayed gastric emptying or obstruction, suggesting the patient is not yet ready for NGT removal.
Some studies suggest that the threshold for residual volume can be higher, with one study indicating that GRVs of less than 500 mL should not result in termination of enteral feeding 1. However, the most relevant study for determining the threshold for passing an NGT clamping trial is not explicitly stated in the provided evidence.
Key factors to consider when evaluating the patient's readiness for NGT removal include:
- Absence of vomiting
- Presence of bowel sounds
- Passage of flatus or stool
- Ability to tolerate oral intake
- Overall clinical condition of the patient
It's essential to note that protocols may vary between institutions, and the decision to remove an NGT should always be made by considering the patient's overall clinical condition, not solely based on residual volume. The use of prokinetic agents, such as erythromycin or metoclopramide, may also be considered to facilitate gastric emptying and tolerance to intragastric nutrition 2, 3.