Control of blood pressure and heart rate in patients randomized to epidural or general anesthesia for lower extremity vascular surgery

Abstract

Study Objective: To examine the degree of success at maintaining patients randomized to epidural or general anesthesia for peripheral vascular surgery within predetermined blood pressure (BP) and heart rate (HR) limits. To investigate associations between such hemodynamic control and intraoperative myocardial ischemia and postoperative major cardiac morbidity. Design: Prospective randomized clinical trial. Setting: University-affiliated hospital. Patients: 100 patients undergoing elective lower extremity revascularization for atherosclerotic peripheral vascular disease. Interventions: Patients were randomized to receive either epidural anesthesia or general anesthesia. Blood pressure and HR limits were determined prior to randomization. Hemodynamic monitoring and management of anesthesia was standardized. Myocardial ischemia and major cardiac morbidity were diagnosed by a blinded cardiologist, based on continuous ambulatory ECG monitoring, cardiac enzymes, and 12 lead ECGs. Intraoperative BP and HR data were analyzed by investigators masked to the type of anesthesia given. Measurements and Main Results: A greater percentage of patients randomized to general anesthesia had intraoperative BPs more above their limit (95% vs. 72%, p = 0.002) and/or more rapid changes in HR (75% vs. 48%, p = 0.008) or BP (100% vs. 93%, p = 0.04) than those randomized to epidural anesthesia. Intraoperative ischemia and major cardiac morbidity were similar in the two anesthesia groups. Patients experiencing intraoperative ischemia, regardless of anesthetic type, more frequently had BPs greater than 10% above their upper limit (90% vs. 60%, p = 0.04) and/or more rapid HR changes (90% vs. 58%, p = 0.03) compared with patients without ischemia. These vital sign abnormalities, however, were not necessarily temporally related to the ischemic episodes. Patients experiencing subsequent major cardiac morbidity were not different from other patients with respect to excursions out of BP or HR limits. Conclusions: Prevention of elevated intraoperative BP and/or rapid changes in BP or HR may be more successful with epidural than with general anesthesia. Such vital sign abnormalities may occur more frequently in patients who have had intraoperative ischemia or are at risk for having it later in the procedure.