Pre‐operative starvation – have we changed our views since Emerson, Wrigley and Newton?
Authors: Bliss A. 
Published: March 2003

Introduction  The aims of fasting guidelines are to prevent regurgitation and pulmonary aspiration whilst limiting potential problems from thirst, dehydration and hypoglycaemia. In 1998, Emerson et al. undertook a postal survey of APA members in order to establish a standard for pre‐operative fasting times for children undergoing elective surgery (1). In 1999, the American Society of Anesthesiologists (ASA) published a substantial, evidence‐based document (2), which included recommendations that differ from UK practice in 1998. The ASA guidelines have now been adopted by the AAGBI (3). I was interested to see if the opinions and practices of UK paediatric anaesthetists had changed in the light of such recent publications.

Method  Delegates attending the 28th Annual Scientific Meeting of the APA were given the opportunity to complete a single shot, tick‐box questionnaire. The questionnaire asked delegates to indicate their own practice on the elective starvation time (hours) of neonates, infants and children for a range of oral intake: clear fluids, breast milk, formula feed, non‐human milk and solids. The results were summarised and reported using simple descriptive statistics.

Results  Two‐hundered and thirty‐one forms were available to delegates and 149 completed forms were collected, giving a response rate of 64.5%. Of these, 1.3% offered no response on neonatal starvation. The vast majority of respondents (∼ 90%) agreed on a 2 hour fast for clear fluids in infants and children. Two thirds of respondents indicated fasting times for breast milk of 4 hours, with almost a third advocating a 3 hour fast. For neonates on formula feeds, 51% of respondents indicated a 4 hour fast, whilst 37% indicated a 6 hour fast. For infants on formula feeds, respondents were more evenly divided between 4 hours and 6 hours. Just over half would starve infants and children 6 hour after non‐human milk with approximately a third reporting a 4 hour fast. Approximately four fifths marked a 6 hour fast from solids for infants and children whilst one sixth marked only a 4 hour fast.

Discussion In 2001, there is little variation in practice from recommended UK and US guidelines for a 2 hour clear fluid fast. Some anaesthetise small babies after a 3 hour breast milk fast. Although guidelines suggest a 4 hour fast physiological data would support the stomach being empty 3 hours after a breast milk feed (4). The variability in UK practice and guidelines and the US guidelines relates mainly to formula feed and non‐human milk. The predominance of casein or whey in the milk determines the rate of gastric emptying. A review of physiological studies (5) suggests casein based milk requires at least 5 hours to leave the stomach, whilst whey based milk mimics breast milk with more rapid emptying. Strict adherence to a 6 hour fast for small babies normally taking 4 hour bottle feeds may lend to problems with thirst and irritability.

Conclusion The results of this survey suggest that the practice of these paediatric anaesthetists on the whole follows the guidelines recommended in 1998. There is a sizeable minority whose practice of pre‐operative starvation is less cautious. Although the limited physiological studies available do not appear to support such liberal fasting regimes other than in neonates, there is little data to relate the potential risks of short starvation periods to the incidence of clinically significant pulmonary aspiration. A significant national audit may provide the answer.