Preoperative Fasting Guidelines: Evidence-Based Recommendations

Current Fasting Rules Before Anesthesia (ASA/ESPEN/ERAS)

Historical "NPO after midnight" is outdated. Modern guidelines minimize dehydration, insulin resistance, and patient discomfort.

Minimum Fasting Intervals

Intake	Minimum Fast	Examples
Clear liquids	2 hours	Water, clear juice (no pulp), black coffee/tea, sports drinks, carbohydrate-rich pre-op drinks
Breast milk	4 hours
Infant formula, light meal (toast, cereal)	6 hours
Fried/fatty foods, meat	8 hours

Special Considerations

• ERAS protocols: Encourage clear fluids until 2 hrs; carbohydrate loading (50 g maltodextrin) night before + 2 hrs pre-op → ↓ insulin resistance, ↓ LOS.
• Difficult airway / GERD / obesity / pregnancy: May warrant longer fasting or pharmacologic prophylaxis (metoclopramide, H2 blocker, PPI, sodium citrate).
• Pediatrics: Same intervals; avoid prolonged fasting → hypoglycemia, distress.
• Medications: Most chronic meds (except oral hypoglycemics, SGLT2i, anticoagulants per protocol) taken with sip of water <2 hrs.

Communication

Provide written instructions at pre-op visit; confirm understanding. Document last intake time on arrival.