Insulin resistance after cardiopulmonary bypass in the elderly patient.

OBJECTIVES: Preoperative carbohydrate administration attenuates insulin resistance. We studied effects of preoperative oral carbohydrate loading in elderly patients undergoing coronary artery bypass grafting. DESIGN: Eighteen patients were assigned either to get a carbohydrate drink or to be controls. Perioperatively, glucose was administered. A gastric emptying test was performed. Glucose and insulin concentrations were measured. Levels of glucose, insulin and stress hormones were studied pre-, per- and postoperatively. RESULTS AND DISCUSSION: Preoperative carbohydrate loading did not affect stress hormones. Gastric residual after the carbohydrate drink was 11+/-3% (mean+/-SEM). Glucose concentration was lower before anaesthesia induction in the carbohydrate group, possibly due to increased insulin release. Insulin levels differed at baseline, induction and day six. All patients returned to baseline on day six. CONCLUSIONS: The study group was insulin resistant on postoperative day one and two. The effects were explainable by the traumatic stress response. No adverse effect was noted from the carbohydrate drink. If glucose is administered intravenously during surgery, there is no obvious advantage of preoperative carbohydrate loading on insulin resistance or stress hormone response.

Body mass index and albumin in the preoperative evaluation of cardiac surgery patients.

BACKGROUND AND AIMS: An increasing proportion of cardiac surgery is performed in the elderly where nutritional status is an important predictor of outcome. Our aim was to evaluate serum albumin concentration (S-albumin) and body mass index (BMI) as markers of malnutrition in relation to outcome measured as mortality and frequency of infections. PATIENTS AND METHODS: We studied 886 consecutive patients who underwent cardiac surgery with extra-corporeal circulation for valve procedures, coronary artery bypass grafting or a combination of those. Preoperative assessment included age, gender, BMI, smoking habits, diabetes, left-ventricular function, S-albumin and C-reactive protein. Postoperative data was type of surgery, in-hospital stay, signs of infections and mortality. Risk factors for mortality were identified using the Cox proportional hazard model and risk factors for infections by using the logistic-regression model. RESULTS: The patients (age 67+/-9.5 years) were followed for 22+/-6 months. In an univariate analysis low BMI and low S-albumin increased relative hazard for death and risk for infection. In a multivariate analysis low BMI, but not S-albumin, increased relative hazard for death and low S-albumin, but not BMI, increased risk for infection. Age, diabetes and longer bypass time increased the risk for infection. CONCLUSION: In cardiac surgery patients a low BMI increased the relative hazard for death and low S-albumin increased the risk for infection. We suggest that these parameters provide useful information in the preoperative evaluation.