"Nulla per os [NPO] after midnight" reassessed.

The concept that fasting produces an "empty stomach" has been shown to be incorrect. Numerous studies demonstrate that fasting neither diminishes gastric volume nor decreases gastric acidity and the risk of pulmonary aspiration is not increased by the preoperative intake of clear liquids. Nevertheless, most surgeons and anesthesiologists continue to adhere to the traditional NPO after midnight tradition, a tradition which should be abandoned. Withholding fluids preoperatively is not only of no benefit to patients but may even be harmful. Based on current knowledge and experience, the following guidelines, which represent a beneficial and humane advance for all surgical patients, are recommended. 1) Adults and children undergoing elective surgery under general anesthesia as inpatients or outpatients in good health (ASA Class I or II) and without specific contra-indications (such as morbid obesity, gastrointestinal disease, etc.) should be allowed and encouraged to drink clear fluids up to two hours before surgery. 2) Patients undergoing elective surgery under general anesthesia and major regional blocks that might require conversion to general anesthesia should remain NPO for solids and non-clear liquids for a minimum of six hours before scheduled surgery. 3) Patients undergoing elective surgery under regional local anesthesia in good health and without specific contra-indication should be allowed and encouraged to have their normal breakfast and fluids as desired on the day of surgery.