How long should nasogastric (NG) feeds be held before an operation in adult patients, including those with complex medical histories or critical illness?

Preoperative Fasting for Nasogastric Tube Feeds

Gastric tube feeds (nasogastric or gastrostomy) should be stopped 6 hours before anesthesia, treating them the same as solid food, while jejunal feeds can safely continue until transport to the operating room for non-abdominal procedures. 1

Standard Fasting Guidelines by Route

Gastric Feeding Routes (NG tubes, PEG tubes)

• Stop feeds 6 hours before anesthesia 2, 1
• Gastric tube feeds are considered equivalent to solid food intake for aspiration risk 1
• This applies to all patients without specific high-risk features for aspiration 2

Jejunal Feeding Routes (NJ tubes, J-tubes)

• Can continue until transport to the operating room for non-abdominal procedures 1
• Post-pyloric feeding bypasses the stomach, reducing aspiration risk 3
• For abdominal surgery, follow institutional protocols as surgical manipulation may require earlier cessation

Clear Liquids

• Permitted until 2 hours before anesthesia 2, 1
• This includes water, clear juices, and other transparent fluids 2
• The traditional "nil by mouth from midnight" approach is unnecessary and causes patient discomfort 2, 4

Clinical Rationale

The 6-hour cutoff for gastric feeds mirrors solid food guidelines because:

• Gastric emptying time for enteral formulas approximates that of solid food 2
• Multiple randomized trials show no increased aspiration risk with shortened clear fluid fasts, but gastric feeds require longer clearance 4
• Jejunal feeds bypass the stomach entirely, eliminating the gastric reservoir concern for non-abdominal cases 1, 3

Common Pitfalls to Avoid

Do not apply the 2-hour clear liquid rule to gastric tube feeds - this is a frequent error. Enteral formulas delivered to the stomach must follow the 6-hour solid food guideline 1. The 2-hour rule applies only to clear liquids taken orally or via tube 2.

Do not unnecessarily prolong fasting beyond these timeframes - holding feeds from midnight or for excessive periods increases caloric deficits without improving safety 5. One study showed patients kept NPO sustained 1,983 kcal deficits versus 762 kcal in appropriately managed patients 5.

Verify tube position before resuming feeds - post-pyloric tubes (jejunal) versus gastric tubes determine the fasting protocol 1, 3. Radiographic confirmation is essential as bedside methods are unreliable 6.

High-Risk Populations

For patients with increased aspiration risk (decreased consciousness, gastroesophageal reflux, emergency surgery, difficult airway), consider:

• Extending the fasting period beyond 6 hours for gastric feeds 7, 8
• Using post-pyloric (jejunal) feeding routes when possible 3
• Maintaining head-of-bed elevation ≥30 degrees during feeding and for 30 minutes after 2

The decreased level of consciousness and supine positioning are the most significant aspiration risk factors, more so than the presence of the feeding tube itself 8.

Postoperative Resumption

Restart tube feeds within 24 hours after surgery in patients unable to meet >50-60% of caloric needs orally 1, 2:

• Begin at low flow rates (10-20 mL/hour) 2, 1
• Advance gradually over 5-7 days as tolerated 2
• Early enteral nutrition reduces postoperative complications 1