Epidural anesthesia and analgesia decrease the postoperative incidence of insulin resistance in preoperative insulin-resistant subjects only.
BACKGROUND
Insulin resistance (IR) is a feature of the endocrine stress response to surgery. It is not known whether a preoperative state of IR would affect the postoperative endocrine response. We sought to characterize the preoperative state of IR in a group of patients undergoing elective hip and knee arthroplasty, and to determine to what extent perioperative epidural analgesia modifies the postoperative state of IR in those who are and are not insulin-resistant before surgery.


METHODS
Sixty patients undergoing either hip or knee arthroplasty were screened by using the homeostatic model assessment (HOMA) in two populations: insulin-resistant patients and noninsulin-resistant patients, whereas HOMA is fasting insulin (microU/mL) x fasting glucose (mmol/L)/22.5. The patients belonging to each population were then randomly assigned to receive either intraoperative epidural blockade followed by postoperative epidural analgesia (epidural group) or general anesthesia followed by patient-controlled analgesia (control group). Analgesia was assessed with visual analog scale up to 48 h after surgery and HOMA was repeated at the end of surgery and 48 h after surgery to determine the postoperative state of IR.


RESULTS
Epidural anesthesia and analgesia significantly influenced the postoperative HOMA score (smaller proportion of IR) in the postoperative period only in those patients who were insulin-resistant before surgery (P < 0.01). In contrast, noninsulin-resistant patients had a similar postoperative proportion of IR between the epidural and control groups (P > 0.05). At rest and during movement, visual analog scale scores were not different between groups at the end of surgery and in the first and second days after surgery.


CONCLUSIONS
Epidural anesthesia and analgesia compared to general anesthesia followed by patient-controlled analgesia decreased the incidence of IR soon after surgery and 48 h after surgery only in patients who were insulin-resistant before surgery.