Preoperative Care Guidelines

General Guidelines

For healthy patients undergoing elective procedures, the American Society of Anesthesiologists recommends clear liquids up to 2 hours before anesthesia, light meals up to 6 hours, and fatty/fried foods up to 8 hours before anesthesia to minimize dehydration, irritability, and hypoglycemia 1, 2
Prolonged fasting can lead to dehydration, irritability, and hypoglycemia, according to the Anaesthesia journal guidelines 2
The 6-2 rule is recommended: no solid foods for 6 hours and clear fluids allowed until 2 hours before the procedure, with volume being less important than the absence of particulate matter, as stated in the World Journal of Emergency Surgery and Clinical Nutrition 3, 4
Up to 400ml of clear fluid is considered safe within the 2-hour window before surgery 5, 6

The International Committee for the Advancement of Procedural Sedation recommends a risk-stratification approach for special populations, considering a one-size-fits-all approach may not be suitable 2
Patients with high-risk features, such as severe heart failure or left main disease, should be monitored more closely but follow the same NPO guidelines, as recommended by the Journal of the American College of Cardiology 7
Additional precautions may be needed for patients with morbid obesity, diabetes mellitus, known delayed gastric emptying, gastroesophageal reflux, or emergency procedures, as recommended by the American Society of Anesthesiology (ASA) and the European Society for Clinical Nutrition and Metabolism (ESPEN) 4, 8

Breast milk should be fasted for at least 4 hours, and infant formula should be fasted for at least 6 hours, following the same basic NPO guidelines as adults 1
For otherwise healthy patients, fasting from clear liquids should be maintained for at least 2 hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia, as recommended by the American Society of Anesthesiologists 1, 9
Permitted clear liquids up to 2 hours before procedures include water, fruit juices without pulp, carbonated beverages, clear tea, black coffee without milk, clear sports drinks, and carbohydrate-rich nutritional drinks, according to the American Society of Anesthesiologists 1, 9

Meta-analyses of randomized controlled trials report smaller gastric volumes in adults given clear liquids 2-4 hours before procedures, with Category A1 evidence, as reported by the American Society of Anesthesiologists 1
Meta-analyses also report higher gastric pH values in both adults and children, with Category A1 evidence, according to the American Society of Anesthesiologists 1
Evidence shows that clear fluid intake up to 2 hours before anesthesia does not increase aspiration risk, supporting the 6-2 rule, as found in the World Journal of Emergency Surgery and Clinical Nutrition 3, 4
The 6-2 rule is supported by multiple professional societies, including the American Society of Anesthesiology and European Society for Clinical Nutrition and Metabolism, with a Grade A recommendation (97% agreement) for allowing clear fluids up to 2 hours before anesthesia in patients without specific aspiration risk 4
Allowing clear fluids up to 2 hours before surgery reduces patient discomfort, including thirst and headaches, and helps maintain proper hydration status, as recommended by the European Society for Clinical Nutrition and Metabolism (ESPEN) 4, 6

Patients should drink clear fluids freely until 2 hours before the scheduled procedure time and avoid solid foods after midnight for scheduled morning surgery, or have a light breakfast at least 6 hours before the procedure for scheduled afternoon surgery 10
Patients can safely have sips of water with medications up to 2 hours before surgery, without increasing aspiration risk, as recommended by the American Society of Anesthesiology (ASA) and supported by evidence-based guidelines 4, 6, 8