Glucose Disposal in Morbidly Obese Patients in the Early Post-operative Period

Background: In surgical patients, operative stress causes protein catabolism, muscle mass loss, and impaired glucose tolerance. We investigated fuel metabolism and glucose and protein turnover in 15 obese subjects who underwent biliopancreatic diversion (BPD) by using stable labelled isotopes. Methods: 6 males and 9 females (age 45.11±8.9 years, BMI of 48.85±4.43 kg/m2) who underwent BPD were studied, and the APACHE II score was calculated. Patients were studied 3 times (before BPD, 1st and 3rd postoperative day). Glycemia was stable - maintained by continuously infusing Rapid Insulin. Each day of the study, the patients received a primed, constant infusion [15N2]of urea, and, 180 min after, a [6.6-2H] glucose infusion started and continued for 3 hours. Indirect calorimetry was performed during the study, under TPN (30 kcal/kg). Results: The APACHE score was lower on the 3rd postoperative day than on the 1st postoperative day (7.4±2.7 vs 6.3±2.6, p<0.05). The npRQ was different throughout the post-operative period (0.82±0.03 vs 0.9±0.06, p< 0.05), while urinary nitrogen excretion, energy expenditure and glycemia did not change. The insulin amount infused was lower during the 3rd post-operative day (44.25±12.3 vs 64.12±11 UI on the 1st one, p<0.05). Insulinemia was lower during the 3rd than during the 1st postoperative day (66.4±9.49 vs 117.44±8.49 µU/ml, p<0.05). Non-essential fatty acid levels were higher on the 3rd post-operative day than on the 1st one (0.98±0.6 vs 0.45 ±0.34 mmol/L, p<0.01). No differences were observed in glucose and urea turn-over. Conclusion: The metabolic pattern of morbidly obese patients operated by BPD was similar to that of other critically ill patients previously studied in the literature. Furthermore, the increased glucose oxidation rate observed on the 3rd post-operative day was coupled with an improved clinical condition.