Pre‐Operative Fasting for Breast Milk, Formula Milks, and Cow's Milk: A Narrative Review of the Literature and Implications for Fasting Guidelines for Children Undergoing Elective Surgery

ABSTRACT There exists, across the world, significant variation in pre‐operative pediatric fasting guidance for breast, formula, and cow's milk. Alongside recent shifts toward liberal clear liquid intake in response to prolonged fasts, there is also a trend emerging toward more liberal milk fasts. This narrative review aims to shed light on the following questions on the topic of pre‐operative fasting of milks in children: What current published guidelines exist, what do they recommend and why? What benefits might reduced fasting times provide? Is there evidence that shorter fasting rules are as safe as longer fasting rules? What is the physiology of gastric emptying for milks? What is the evidence that gastric emptying differs for cow's, formula, or breast milk, and does age have an influence? The extent to which we are currently able to answer these questions aims to both better inform those formulating perioperative fasting guidelines and to stimulate standardized research into gastric emptying and pre‐operative fasting of milk in children.