Hemodynamics, intramucosal pH and regulators of circulation during perioperative epidural analgesia.

Purpose: To evaluate the effects of perioperative epidural analgesia on hemodynamics, splanchnic perfusion and regulators of circulation.
Methods: Twenty patients undergoing aortic surgery were randomised into two groups: epidural analgesia group (EAG): epidural analgesia with bupivacaine (15 ml, 0.125%) was started before surgery. Eight and 16 hr postoperatively 10 ml bupivacaine 0.125% and 1 mg morphine were given. Control group (COG): patients received no epidural catheter. Monitoring included pulmonary artery catheter and gastric tonometer. Norepinephrine, epinephrine, renin, ADH, ANP and endothelin were measured: before epidural analgesia (T0), before aortic clamping (T1), 20 min after aortic clamping (T2), after declamping the first leg (T3), at end of surgery (T4), one hour (T5) and 24 hr postoperatively (T6).
Results: At T5 mean arterial blood pressure decreased in EAG compared with baseline (86 +/- 16 to 75 +/- 8 mmHg) and compared with COG (75 +/- 8 vs 84 +/- 11 mmHg). At T2 pulmonary capillary wedge pressure and cardiac index increased and at T6 decreased in both groups. Systemic vascular resistance decreased at T I and at T3-T5 in EAG compared with COG and at T1 and T3-T6 to baseline (1472 +/- 448 to 1027 +/- 184 dyn x sec x cm(-5) x m(-2)). In EAG and in COG, pHi decreased compared with baseline but without group differences. In both groups, epinephrine, norepinephrine, renin, and ADH levels increased from baseline. Endothelin and ANP levels showed no changes.
Conclusions: Perioperatively administrated epidural bupivacaine has no beneficially effects on hemodynamics, pHi or release of regulators of circulation.