The anticatabolic effect of neuraxial blockade after hip surgery

Although the protein-sparing effect of neuraxial blockade after abdominal surgery is well established, its metabolic effect after operations on the lower extremities remains unclear. In this study, we tested the hypothesis that combined spinal and epidural blockade (CSE) inhibits amino acid oxidation after hip surgery. Sixteen patients undergoing hip replacement surgery received either general anesthesia followed by IV patient-controlled analgesia with piritramide (control; n = 8) or CSE using bupivacaine 0.5% for spinal anesthesia and ropivacaine 0.2% with 0.5 mu g/mL of sufentanil for postoperative epidural analgesia (CSE; n = 8). Glucose and protein kinetics were assessed by stable isotope tracer technique ([6,6-H-2(2)]glucose, L-[1-C-13]leucine) on the day before and one day after surgery. Plasma concentrations of glucose, lactate, free fatty acids, cortisol, glucagon, and insulin were also determined. CSE prevented the increase in plasma glucose concentration during and immediately after the operation (60 min after skin incision: CSE 4.9 +/- 0.7 versus control 6.2 +/- 0.7 mmol/L; P < 0.05; postanesthesia care unit: CSE 5.0 +/- 0.9 versus control 7.3 +/- 1.1 mmol/L; P < 0.05). Intraoperative cortisol plasma concentrations were smaller in the CSE group than in the control group. One day after the operation, however, glucose plasma concentration, glucose production, and glucose clearance were comparable in both groups. CSE inhibited the postoperative increase in leucine oxidation rate (CSE 30 +/- 12 versus control 43 +/- 8 mu mol.kg(-1)-h(-1); P < 0.05). There were no differences between the groups in protein breakdown, whole body protein synthesis, and plasma concentrations of lactate, free fatty acids, insulin, and glucagon. In conclusion, CSE prevents hyperglycemia during hip surgery and inhibits protein catabolism thereafter.