SUBARACHNOID NEOSTIGMINE DOES NOT AFFECT BLOOD-PRESSURE OR HEART-RATEDURING BUPIVACAINE SPINAL-ANESTHESIA

Background and Objectives. Intraspinal administration of neostigmine h as been shown to prevent induction of hypotension in rats by bupivacai ne spinal block, and thus to provide greater hemodynamic stability. Th is study was undertaken to determine whether subarachnoid neostigmine would prevent bupivacaine spinal anesthesia from causing hypotension o r bradycardia in patients undergoing abdominal hysterectomy. Methods. Of 40 patients scheduled for abdominal hysterectomy under spinal anest hesia, 20 were randomly assigned to each of two groups. The control gr oup (CG) received 1.5 mL subarachnoid saline followed by 15 mg (3 mL) of hyperbaric bupivacaine 0.5%. The neostigmine group (NG) received 75 mu g (1.5 mt) of subarachnoid neostigmine followed by 15 mg (3 mL) of hyperbaric bupivacaine 0.5%. No preload was given. Hypotension was cr eated with 4-mg intravenous boluses of ephedrine to keep blood pressur e above 75% of the baseline value. The skin body temperature was measu red with probes at the suprascapular region and at the foot. Results. Spinal neostigmine (75 mu g) failed to prevent bupivacaine-induced hyp otension. There was no statistical difference in the incidence of brad ycardia between the groups (NG, 2/20; CG 1/20), although the bradycard ia appeared to be qualitatively different, being somewhat delayed in t he NG. Spinal neostigmine did not alter the onset or duration of senso ry block and did not affect skin body temperature in either anesthetiz ed or unanesthetized sites. The incidence of intraoperative nausea was 20% in the NG and 5% in the CG. Conclusion. A 75-mu g subarachnoid ne ostigmine dose does not affect blood pressure or heart rate during bup ivacaine spinal anesthesia.