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Fasting from midnight--the history behind the dogma
1University of Calgary, 12 Aspen Ridge Court SW, Calgary AB, Canada. maltby@ucalgary.ca
Fasting guidelines have evolved. Historically, patients fasted overnight, but research shows clear liquids are safe until 2 hours before elective surgery, improving patient comfort and evidence-based care.
Area of Science:
- Anesthesiology
- Surgical Care
Background:
- Historical medical texts and journals from the 19th and 20th centuries established overnight fasting dogma.
- This practice stemmed from extrapolating risks from emergency 'full-stomach' cases to elective surgery patients.
Observation:
- A 25 mL gastric fluid volume, found in half of healthy fasting patients, was incorrectly used as a high-risk aspiration marker.
- Subsequent large-scale studies revealed the actual aspiration risk to be minimal in elective settings.
Findings:
- Meta-analysis of randomized clinical trials confirms the safety of allowing clear oral liquids up to 2 hours preoperatively for healthy patients.
- This evidence challenges the traditional prolonged preoperative fasting recommendations.
Implications:
- Modern evidence supports updating preoperative fasting guidelines for elective surgery.
- Adopting evidence-based practices can enhance patient safety and comfort, moving away from outdated dogma.
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