The stomach is a reservoir, allowing slow emptying of 5 to 15 mL at a time, into the small bowel for continued digestion and absorption.
During meal ingestion, the stomach can expand to approximately 1,000 mL before pressure in the stomach’s lumen starts to increase.
Normal gastric emptying occurs within three hours and after a lag time of approximately one hour for a meal.
Gastric emptying is slower for high fat meal.
The stomach empties liquids more quickly, within one hour for a glucose solution and two hours for a protein solution drink.
During fasting, the stomach secretes approximately 500 to 1,500 mL, in the feeding state, it secretes approximately 2,500 mL per day.
Gastric residual volume refers to fluid remaining in the stomach at a point in time during enteral nutrition feeding.
The literature suggests a high GRV, ranges from 100 to 500 mL.
There is no correlation between GRVs and either objective physical exam or radiographic scores.
Enteral feedings should not be stopped for a single high GRV if there are no other physical examination or radiography findings to show actual gastrointestinal dysfunction.
Recommendations are that GRV should be checked every four hours during the first 48 hours of gastric feeding and, after that, every six to eight hours for patients who are not critically ill.
Enteral nutrition should not be stopped for a GRV of less than 500 mL unless there are other signs of feeding intolerance.
Signs of feeding intolerance include emesis, abdominal distention, constipation, fullness, abdominal pain, or nausea.
GRV measurements vary with the type and diameter of feeding tubes, the position of the feeding tubes in the stomach, and the position of the patient’s body.
No data to prove that GRV measurements are clinically meaningful anyway.
Delayed gastric emptying occurs with those with gastroparesis, diabetes mellitus, gastric outlet obstruction, ileus, recent surgery, trauma, or sepsis and narcotic pain medication.
Efforts to prevent aspiration of gastric contents are important in these patients.
Methods to prevent aspiration in patients who are fed enterally: raising the head of the bed by 30 to 45 degrees, minimizing the slowing effect of narcotics on bowel motility, use of prokinetic medications such as metoclopramide and erythromycin can be used when appropriate to stimulate gastric motility, and optimal blood glucose control.
No studies have established that residual gastric volume monitoring decreases the risk of ventilation associated pneumonia.
No specific relationship has been demonstrated between increased gastric volume, regurgitation, gastric content aspiration and ventilator associated pneumonia.
Among adult patients requiring mechanical ventilation and receiving enteral nutrition, the absence of gastric volume monitoring was not inferior to routine residual gastric volume monitoring in terms of the development of ventilated associated pneumonia (Reignier J et al).
Postpyloric or jejunal feeding tubes are recommended when delayed gastric emptying or gastric outlet obstruction.
Continuous rather than bolus enteral infusions are recommended for high-risk patients, as
are the use of laxatives or stool softeners to promote bowel regularity and antiemetic medications.
Gastric dysmotility is common in the critically ill due to underlying illness, use of narcotics, decreased blood flow from hypotension, and vasopressor use.
Gastric dysmotility increases gastric emptying time with increased risk of vomiting, aspiration, and ventilator associated pneumonia.