Gastric Emptying Conclusion Clinical Studies References Introduction Clinically significant pulmonary aspiration during general anaesthesia is rare in healthy patients having elective surgery. The largest study reports an incidence of 1 in approximately 10,000 patients, with no deaths in more than 200,000. The majority of serious cases of pulmonary aspiration occur in emergency cases, particularly trauma, obstetrics and abdominal surgery in which delayed gastric emptying may be further prolonged by administration of opioid narcotic analgesics. The purpose of fasting guidelines for healthy patients undergoing elective surgery is to minimize the volume of gastric contents while avoiding unnecessary thirst and dehydration.
Dehydration is particularly important in hot countries.
Guidelines should be based on clinical studies in surgical patients or, when this evidence is not available, on the physiology of digestion and gastric emptying. During the 1960s in North America the preoperative order 'nothing by mouth after midnight' was applied to solids as well as liquids. The change was widely accepted although the reasons for it have been lost in the mists of time. Pulmonary aspiration was known to be one of the leading causes of anaesthetic related mortality. However, Roberts and Shirley did not establish a relationship between volume in the stomach and volume aspirated into the lungs.