Effects of preoperative oral carbohydrate on postoperative discomfort in patients undergoing elective surgery: a meta-analysis of randomized controlled trials.

PURPOSE Fasting is a standard preoperative procedure performed to prevent vomiting and pulmonary aspiration during anaesthesia and surgery. However, fasting can cause postoperative physical and psychological discomfort. Intake of oral carbohydrate (CHO) may mimic the intake of food, which prevents postoperative discomfort. We conducted a meta-analysis to evaluate the effect and safety of preoperative oral CHO in adult surgical patients. METHODS Randomized controlled trials (RCTs) were searched for in the PubMed, EMBASE, and Cochrane Library databases. A meta-analysis was performed to calculate a pooled effect size by using random-effects models. The satisfaction outcomes were mouth dryness, hunger, thirst, pain severity, duration of hospitalization, homeostatic model assessment for insulin resistance (HOMA-IR), and the incidence of postoperative nausea and vomiting. The safety outcomes were the incidence of aspiration and infection. RESULTS In total, 57 RCTs involving 5606 patients were included. The outcomes of mouth dryness, thirst, hunger, and pain were assessed by a 10-point visual analogue scale (0 = best, 10 = worst). The severity of mouth dryness (weighted mean difference [WMD]: -1.26, 95% CI: -2.36 to -0.15), thirst (WMD: -1.36, 95% CI: -2.05 to -0.67), hunger (WMD: -1.66, 95% CI: -2.53 to -0.80), pain (WMD: -0.68, 95% CI: -1.01 to -0.35), duration of hospitalization (WMD: -0.39 day, 95% CI: -0.66 to -0.12), and HOMA-IR (WMD: -1.80, 95% CI: -2.84 to -0.76) were significantly lower in the CHO group than in the control group. The incidence of postoperative nausea and vomiting did not differ between the CHO and control groups. No aspiration was recorded in any of the groups. CONCLUSIONS Preoperative CHO can alleviate patient's discomfort without safety concerns. Surgeons and anaesthesiologists should strongly promote preoperative CHO as a strategy to enhance recovery after surgery protocols.