Prolonged preoperative fasting is still routine on many lists, yet it causes thirst, hunger, dehydration and irritability without improving aspiration safety. The established limits are shorter than the overnight nil-by-mouth that often happens in practice.
Apply the 2-4-6 rule: clear fluids up to 2 hours before anaesthesia, breast milk up to 4 hours, and a light meal or non-human milk up to 6 hours. Many guidelines now actively encourage sipping clear fluids up to shortly before transfer in most patients, rather than imposing a long fluid fast.
The common failure is the list order changing and a patient being kept starved for many extra hours by default. Write clear fluid timings on the list, encourage clear fluids until the 2-hour point, and reserve longer fasting for genuine aspiration-risk situations such as significant reflux, gastroparesis, bowel obstruction or recent GLP-1 use per local policy.
- Allow clear fluids up to 2 hours, breast milk up to 4 hours, and a light meal up to 6 hours before anaesthesia.
- Encourage sipping clear fluids up to shortly before transfer in most patients.
- Avoid defaulting to prolonged overnight fasting when the list order changes.
- Reserve longer fasting for genuine aspiration risk such as obstruction, gastroparesis or per local GLP-1 policy.
Why it matters
Over-long fasting is common and harms patient comfort and hydration without improving aspiration safety.
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