THE EFFECT OF LUMBAR EPIDURAL AND GENERAL-ANESTHESIA ON PLASMA-CATECHOLAMINES AND HEMODYNAMICS DURING ABDOMINAL AORTIC-ANEURYSM REPAIR

Twenty-four patients undergoing abdominal aortic aneurysm (AAA) repair were studied to compare the effects of lumbar epidural anesthesia (LE A) and general anesthesia (GA) on plasma catecholamine levels and hemo dynamics before and during infrarenal aortic cross-clamping. Patients received either a high dose of opioid anesthetic (GA group, n = 12), o r lumbar epidural anesthesia to T4 sensory level with a light general anesthetic (LEA group, n = 12). Systemic vascular resistance (SVR) and norepinephrine (NE) and epinephrine (E) levels were measured before a nesthetic induction (before epidural activation in the LEA group, and before general anesthesia induction in the GA group), 15 min before cr oss-clamping, and 1, 5, and 10 min after cross-clamping. There was a l arge (P < 0.05) increase in NE and E in the GA group by 15 min before aortic cross-clamping, but NE and E levels in the LEA group did not in crease. The GA group had significantly higher levels of NE and E than the LEA group 15 min before cross-clamping and also after clamping. NE levels in the LEA group increased after cross-clamping, and NE levels in the GA group remained constant. E levels remained stable in both g roups after cross-clamping. After clamping, SVR increased in both grou ps, but the increase occurred after 1 min in the GA group and took 5 m in to become significant in the LEA group. There was no significant co rrelation between changes in NE or E and changes in SVR in either grou p. This study shows that epidural anesthesia to T4 prevents NE and E i ncreases in response to abdominal surgery. E does not increase in resp onse to clamping, and NE increases only in the LEA group. Catecholamin e level changes were not reflected in SVR differences between groups. SVR seems to be more dependent on mechanical changes from the cross-cl amping than to changes in catecholamine levels.