Review of Preoperative Carbohydrate Loading

Preoperative carbohydrate-containing clear liquids (usually composed of approximately 12% carbohydrate predominantly in maltodextrin form) have provided benefits for the surgical population and further have been included in the Enhanced Recovery After Surgery (ERAS) Society's recommendations as part of a multimodal approach to reduce surgical patients' length of stay and complication rates. Carbohydrate metabolism is greatly affected by the fed state, which is activated by preoperative carbohydrate fluids given up to 2 hours prior to surgery in contrast to the traditional midnight preoperative fast. Carbohydrate-rich fluids have been proven to enhance patient comfort prior to surgery and have been theorized to reduce insulin resistance, reducing patient catabolism, with a positive impact on perioperative glucose control and muscle preservation. This practice is further hypothesized to support the ERAS goals of reducing both complication rate and length of stay. Preoperative carbohydrate fluid loading is difficult to prove, as the degree of surgical procedure and postoperative pathways are likely more reflective of patient outcome. The use of carbohydrate-loading protocols warrants further adequately blinded, placebo-controlled studies, including the use of variable surgical techniques, reproduction of the hyperinsulinemic euglycemic technique measurements, investigation of ideal carbohydrate fluid composition, and the use of similar surgeries in comparison. Preoperative carbohydrate loading is just one of the many strategies linked to the success of ERAS protocols.