[Effect of continuous epidural infusion of morphine on postoperative glucose metabolism]

Abstract

Plasma growth hormone (GH), insulin, prolactin and blood glucose levels were measured to evaluate postoperative pain relief either with epidural morphine or systemic analgesics in 16 patients who underwent gastrectomy. Continuous epidural morphine with a pump (CADD-PCA, Model 5200P, Pharmacia) was given to eight (epidural morphine group) patients. A bolus of epidural morphine was administered through an indwelling thoracic (Th8.9) catheter at 3 hrs prior to the expected end of surgery, which was followed with continuous epidural infusion of morphine at a rate of 0.167-0.042 mg.hr-1 with the pump during and after anesthesia and surgery with gradually decreasing dose until the third postoperative day. The remaining eight patients (systemic analgesics group) repeatedly received intravenous or intramuscular pentazocine and buprenorphine when needed. Plasma GH levels increased significantly only on the first postoperative day in both groups. Plasma insulin levels increased significantly on the first postoperative day in both groups. Blood glucose levels increased significantly at the end of surgery and during the following three postoperative days in both groups. There are no statistical differences in plasma GH, insulin and blood glucose levels between the two groups. Plasma prolactin concentrations increased significantly at the end of surgery and they were significantly higher in the systemic analgesic group than in the epidural morphine group. They, however, returned to the previous day's levels on the first postoperative day in both groups. Our study suggests that continuous epidural infusion of morphine has no suppressing effect on postoperative changes in plasma GH, insulin, prolactin and blood glucose levels as compared with systemic analgesic regimen.