Randomized Controlled Study of Preoperative Oral Carbohydrate Loading Versus Fasting in Patients Undergoing Major Abdominal Surgery

The surgical patients are influenced by many stressors during operation such as the prolonged fasting hours. Importantly, these stressors are iatrogenic and have been shown to disturb homeostasis with little benefit. Surgery itself, induces an endocrine and inflammatory stress response and contributes to postoperative insulin resistance (PIR) which increased also by Preoperative fasting.

Postoperative insulin resistance is a state of reduced insulin-mediated glucose uptake in skeletal muscles and adipose tissue, with an increased glucose release due to hepatic gluconeogenesis and hyperglycemia.

Strategies to reduce the postoperative stress response and postoperative insulin resistance include shortening the preoperative fasting time via preoperative carbohydrate oral drink administration (carbohydrate load). Preoperative fasting is the first step in postoperative insulin resistance development. The traditional fasting time of 6-8 h before elective surgery to prevent pulmonary aspiration usually extends up to 12 h in anesthetic practice. Overnight fasting is a physiological state of reduced insulin sensitivity due to the normal hormonal diurnal rhythm. If patients undergo surgery in the prolonged fasted state, insulin resistance may begin even before surgery.

A preoperative carbohydrate drink acts as a morning meal, may improve insulin sensitivity and propel the patient's metabolic state towards anabolism. The rationale of this study is to compare the differences between preoperative CHO loading and a conventional fasting protocol on the postoperative insulin resistance, Glasgow prognostic score (GPS), subjective patient well-being and surgical clinical outcome.