Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
Cardiopulmonary bypass (CPB) is associated with a release of catecholamines and inflammatory cytokines. We tested the hypothesis that both, high thoracic epidural anesthesia (TEA) and iv clonidine as supplement for general anesthesia attenuate postoperative stress and modulate the inflammatory response of CPB.
Method: Following IRBA informed consent was obtained from 70 patients scheduled for elective CABG. All patients underwent general anesthesia with sufentanil and propofol. TEA was randomly induced prior to general anesthesia and continued during the study period in 25 patients in order to block the cardiac sympathetic activity (anesthetized dermatomes: C6-Th10). Another 24 patients received iv clonidine in doses being effective to attenuate the adrenergic stress response in surgery (Clon) . After a bolus of 4 [micro sign]g/kg before induction of general anesthesia, clonidine was infused at a rate of 1 [micro sign]g/kg/hr during surgery and of 0.5 [micro sign]g/kg/hr postoperatively. The remaining 21 patients underwent general anesthesia as routinely performed (contr). Plasma epinephrine was determined before drug/TEA intervention (baseline), 30 minutes afterwards (interv), and at ICU admission. Interleukin-6 and -10 (IL 6, IL 10), tumor necrosis factor alpha (TNF alpha) and hemodynamics were measured pre- and postoperatively. Data are means +/- SEM and analyzed by two way Anova.
RESULTS: Both, TEA and iv clonidine supplement reduced the required rate of narcotics. While the perioperative catecholamine support was comparable between the groups, TEA and clonidine reduced postoperative heart rate, compared to control. This reduction was more pronounced in the TEA-group without impairing cardiac output or mean arterial pressure. Plasma epinephrine increased in all groups, however to a significantly lower level in the TEA group. TNF alpha-release following CPB was significantly lowered in the TEA group. IL-10 and IL-6 rose in all groups without any inter-group difference. IL-10 peaked at ICU admission, IL-6 six hrs afterwards. TEA treatment resulted in earlier extubation, compared to clonidine supplement and to the control group. (Figure 1)
Conclusion: General anesthesia supplemented by TEA or iv clonidine attenuates postoperative tachycardia following CABG in humans. In the TEA group this effect is associated with a reduction of perioperative epinephrine release and an modulating effect of TEA on the immune response. This evidence of decreased stress response and release of proinflammatory TNF alpha may have favorable impact on postoperative course and morbidity.
1. Acta Anaesthesiol Scand, 1990; 34:132