Should a patient be kept Nil Per Os (NPO) for days before surgery or only on the day of surgery?

Preoperative Fasting: NPO Only on Surgery Day, Not Days Before

Patients should be kept NPO only on the day of surgery, not for days before surgery, with clear fluids allowed until 2 hours before anesthesia and solid food until 6 hours before anesthesia. 1

Evidence-Based Preoperative Fasting Guidelines

Recommended Fasting Times

• Clear fluids: Allow until 2 hours before anesthesia
• Light meal: Allow until 6 hours before anesthesia
• Full meal (including meat, fatty and fried foods): Require 8+ hours fasting 1

Traditional practice of keeping patients NPO from midnight is unnecessary and potentially harmful. The 2022 ERAS Society guidelines explicitly state that "preoperative fasting from midnight is unnecessary in most patients" and that prolonged fasting results in extended periods without fluids or nutrition, which can negatively impact surgical outcomes 1.

Benefits of Shorter Fasting Periods

• Reduced perioperative discomfort and anxiety
• Improved patient hydration status
• Decreased insulin resistance
• Potentially shorter hospital length of stay 1

Special Considerations

Nutritional Risk Patients

For patients with severe nutritional risk (defined as weight loss >10-15% within 6 months, BMI <18.5 kg/m², or serum albumin <30 g/L), nutritional therapy should be provided for 7-14 days prior to major surgery, even if surgery must be delayed 1. During this period:

• Oral intake should be encouraged
• Oral nutritional supplements (ONS) should be provided when energy needs cannot be met through normal food 1
• Clear fluids can still be consumed up to 2 hours before surgery

Carbohydrate Loading

Preoperative carbohydrate treatment (instead of overnight fasting) should be administered to reduce perioperative discomfort and may impact postoperative insulin resistance 1.

Implementation Algorithm

1. Assess patient's nutritional status:

   • If severely malnourished: Provide 7-14 days of nutritional therapy before surgery
   • If not malnourished: Proceed with standard fasting protocol

2. Day before surgery:

   • Normal diet until bedtime
   • Consider carbohydrate loading the night before surgery

3. Day of surgery:

   • Clear fluids allowed until 2 hours before anesthesia
   • No solid food within 6 hours of anesthesia
   • For high-fat meals, extend fasting to 8+ hours

Common Pitfalls to Avoid

1. Excessive fasting: Many institutions still practice "NPO after midnight" despite evidence showing it's unnecessary and potentially harmful 2, 3. This often results in patients fasting much longer than required due to surgical delays.

2. Confusion between clear liquids and solid food: Clear distinction must be made between the two, with different fasting times for each.

3. One-size-fits-all approach: Failing to consider patient-specific factors like nutritional status or type of surgery.

4. Overlooking nutritional needs: Especially in malnourished patients who require preoperative nutritional optimization.

Quality Improvement Considerations

Recent quality improvement initiatives have demonstrated that reducing NPO past midnight requirements is feasible and safe 4. One initiative showed a 50% reduction in NPO past midnight usage by implementing evidence-based fasting protocols and pre-procedure clear liquid diets, with no increase in aspiration events or procedural delays.

The traditional practice of prolonged preoperative fasting is increasingly being questioned, with multiple studies showing that it provides no additional safety benefit while potentially causing patient discomfort and physiological stress 5, 2, 3.