NPO Guidelines

NPO Guidelines - Empty Tummy Tactics

• Purpose: Prevent pulmonary aspiration of gastric contents during anesthesia, reducing risk of complications (e.g., aspiration pneumonitis).

• Pathophysiology of Aspiration:

  • Aspiration occurs when gastric contents enter the lungs.
  • Severity depends on volume and acidity of aspirate.
  • Critical thresholds: Gastric volume > 0.4 ml/kg (or > 25 ml) and pH < 2.5.

  ⭐ Mendelson's syndrome is defined by aspiration of gastric contents with pH < 2.5 and volume > 0.4 ml/kg (typically > 25 ml).

• Factors ↑ Aspiration Risk:

  • Full stomach (e.g., recent meal, gastroparesis).
  • Impaired protective airway reflexes.
  • GERD, hiatal hernia.
  • Obesity.
  • Pregnancy.
  • Emergency surgery.
  • Diabetes, opioid use.
  • Difficult airway or intubation.

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NPO Guidelines - Clocking Clear & Solids

Nil Per Oral (NPO) guidelines are crucial to reduce aspiration risk during anesthesia. American Society of Anesthesiologists (ASA) recommendations are standard:

• 2h for clear liquids.

• 4h for breast milk.

• 6h for infant formula, non-human milk, or a light meal.

• 8h (or more) for a heavy, fried, or fatty meal (includes meat).

• Chewing Gum/Hard Candy: Often allowed until just before induction if not swallowed. Gum should be removed pre-induction. Always confirm institutional policy.

⭐ Clear liquids include water, fruit juices without pulp, carbonated beverages, clear tea, and black coffee. Importantly, milk (even in tea/coffee) is NOT considered a clear liquid and requires a longer fasting duration.

NPO Guidelines - Special Patient Plays

• Pediatrics: Age-specific fasting crucial to prevent aspiration.
  • Clear liquids (water, pulp-free juice): 2h
  • Breast milk: 4h
  • Infant formula: 6h
  • Non-human milk / Light meal (e.g., toast): 6h
  • Solids (fried/fatty food, meat): 8h
• Pregnancy: Hormonal changes & mechanical pressure ↑ aspiration risk.
  • Labor: Clear liquids often permitted; assess individually.
  • Elective C-section: Solids 6-8h, clear liquids up to 2h pre-induction.

  ⭐ For elective cesarean delivery, solids should be withheld for 6-8 hours; clear liquids up to 2 hours pre-induction are generally safe in uncomplicated pregnancies.

  • Emergency C-section: Treat as full stomach; RSI essential.
• Diabetes Mellitus: Potential for gastroparesis. Consider longer NPO; assess gastric emptying if concerned. Individualize based on severity and glycemic control.
• GERD / Obesity / Hiatal Hernia: Higher risk of regurgitation/aspiration. Individualize NPO; often extended fasting. Pharmacological aids (e.g., H2 blockers, PPIs) beneficial.
• Emergency Surgery: Always assume full stomach, irrespective of last meal. Rapid Sequence Intubation (RSI) is standard to secure airway.
• Pharmacological Aids (Aspiration Prophylaxis):
  • Antacids (e.g., sodium citrate): Neutralize existing gastric acid.
  • H2 Blockers (e.g., ranitidine): ↓ Acid volume & production.
  • PPIs (e.g., omeprazole): ↓ Acid production (less effective for acute use).
  • Prokinetics (e.g., metoclopramide): ↑ Gastric emptying; use cautiously (contraindications, side effects).

High‑Yield Points - ⚡ Biggest Takeaways

• Clear liquids (water, black coffee/tea, pulp-free juices) require a 2-hour fast.
• Breast milk digestion is faster; requires a 4-hour fasting period.
• Infant formula and non-human milk necessitate a 6-hour fast.
• A light meal (e.g., toast and clear liquid) also requires 6 hours of fasting.
• Heavy or fatty meals significantly delay gastric emptying, mandating an 8-hour fast.
• NPO aims to reduce pulmonary aspiration risk; oral meds often allowed with water sips 1-2 hours pre-op.