Low dose clonidine premedication accentuates the hyperglycemic response tosurgery

Purpose: To investigate the influence of low dose clonidine premedication o n perioperative glucose homeostasis. Methods: Sixteen patients undergoing abdominal hysterectomy for benign uter ine myoma were randomly assigned to receive either iv clonidine (1 mug.kg(- 1)) 30 min before induction of general anesthesia (clonidine, n=8) or salin e (control, n=8). Plasma concentrations of glucose, insulin, cortisol, epin ephrine and norepinephrine were measured before, during and two hours after surgery. At the same time heart rate, mean arterial pressure and cardiac o utput were recorded. Results: In both groups, glucose concentrations significantly increased dur ing and after surgery. Intraoperative glucose plasma concentration in the c lonidine group was higher than in the control group (clonidine: 6.8 +/- 0.6 mmol.L-1 vs control: 5.7 +/- 0.8 mmol.L-1, P < 0.05). This was accompanied by a lower insulin plasma concentration (clonidine: 3.9 +/- 1.9 muU.mL(-1) vs control: 6.5 +/- 2.8 muU.mL(-1), P < 0.05). Heart rate, mean arterial p ressure and cardiac output remained unchanged throughout the study period w ithout any differences between the groups. While norepinephrine plasma conc entrations increased in the control group only (P < 0.05), the plasma conce ntrations of epinephrine and cortisol increased in both groups (P < 0.05). Clonidine significantly attenuated the cortisol response as reflected by lo wer intra- and postoperative cortisol plasma concentrations than in the con trol group (P < 0.05). Conclusion: Premedication with clonidine 1 mug.kg(-1) accentuates the hyper glycemic response to lower abdominal surgery caused by the decrease in insu lin plasma concentrations.