Evidence Based Practice and Quality Assurance
Background and Goal of Study: Preoperative oral intake of carbohydraterich clear fluids in elective surgery patients (ASA I-II) is safe (1), improves preoperative well-being (2) and reduces postoperative insulin resistance (PIR) (3). This has not been tested in patients with higher ASA physical status.
Materials and Methods: Ethically approved 160 patients admitted for open heart surgery after giving written informed consent were randomly allocated to intake of a 12.5% carbohydrate drink (CHO, n = 56), flavoured water (Placebo, n = 60), or overnight fasting (Control, n = 44). CHO and Placebo were double-blinded and given to drink 800 ml during the evening before and 400 ml on the morning of surgery. Patients were monitored from induction of general anaesthesia (GA) until 24 hours postoperatively. Gastric fluid volume (GFV) was estimated according to intraoperative passive gastric reflux and subjective variables of preoperative discomfort were measured by 100 mm visual analogue scales. Blood glucose levels were equally controlled to ≤10.0 mmol/l by standardised insulin treatment. Exogenous insulin dosage was suggested a surrogate marker for PIR. Statistics: Kruskal-Wallis-Mann-Whitney-U-Test, Brunner's Analysis (ANOVA-type statistic).
Results: Thirst was significantly reduced in CHO [7 (0-75)mm] vs Control [30 (0-90)mm, p < 0.01] and in tendency compared to Placebo [8 (0-76)mm p = 0.06]. The groups did not differ in GFV [CHO 0 (0-80)ml vs Placebo 0 (0-150)ml vs Control 0 (0-200)ml, p = 0.39]. Regurgitation or aspiration were not observed in any of the cases. Blood glucose levels and insulin dosages did not differ between groups (p = 0.49 and p = 0.65). Subgroup analysis of non insulin dependent diabetes mellitus (NIDDM) patients (CHO n = 10, Placebo n = 14, Control n = 8) did not show differences in blood glucose levels and insulin dosages (p = 0.28 and p = 0.47).
Conclusions: Oral intake of carbohydrate rich fluids in ASA III-IV patients up to 2 hours before induction of GA does not seem to influence PIR; and particularly not in patients with NIDDM. Preoperative CHO can be recommended for patients up to ASA physical status IV.
1 Spies CD, Breuer JP et al. Anaesthesist
2 Hausel J et al. Anesth Analg
3 Soop M et al. Am Physiol J Endocrinol Metab