Perioperative fasting and feeding in adults, obstetric, paediatric and bariatric population: Practice Guidelines from the Indian Society of Anaesthesiologists

PREAMBLE Preoperative fasting involves being nil by mouth before surgical procedures requiring sedation or anaesthesia.[1] In the postoperative period, complete avoidance of oral dietary intake is practiced, till recovery of bowel function for abdominal surgeries.[2] Impairment or abolition of airway reflexes following deep sedation or anaesthesia can lead to pulmonary aspiration of gastric contents.[3] The ideal condition for minimising the risk of regurgitation and aspiration is an empty stomach before deep sedation or anaesthesia, which may be impossible to achieve due to the continuous gastric secretory activity along with impaired physiology due to various aetiologies encountered in the preoperative period. Traditional cut off points of gastric aspirate volumes of >25 mL with pH <2.5 have long been quoted to correlate with significant pulmonary aspiration leading to respiratory failure.[45] This critical pH and volume was obtained by Roberts and Shirley on a Rhesus monkey and were extrapolated to humans.[6] Although pH and gastric volume have been traditionally measured using aspiration techniques, the modern research modalities utilising pharmacokinetic properties of orally administered water-soluble substances such as paracetamol, magnetic resonance imaging (MRI) and scintigraphy have provided better insights into the physiology of gastric emptying. Newer modalities such as gastric ultrasonography (GUS) have been increasingly used to study the gastric volumes and emptying. What is the need for the Indian Society of Anaesthesiologists (ISA) guidelines? A large number of surgical procedures are conducted daily in India, with diverse health care settings and differing practice standards. The patient population varies in terms of food items consumed, with a variable fat content, caloric content and nutrient composition in different regions and states. The socio-cultural, geographic and economic factors also play a role in the food habits. The overall culture and eating habits of the population is largely similar in countries of South Asia that includes India, Bhutan, Nepal, Bangladesh, Sri Lanka, Maldives, Afghanistan and Pakistan, but the available guidelines do not apply uniformly across these countries and very few evidences address the problems peculiar to this region. These issues have been taken into consideration during the formulation of 'Practice guidelines on perioperative fasting and feeding' by the ISA. This document emphasises the concerns related to the safe duration of fasting before and after administration of sedation or anaesthesia for elective, diagnostic or surgical procedures. 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