CONTINUOUS SPINAL-ANESTHESIA WITH A MICROCATHETER AND LOW-DOSE BUPIVACAINE DECREASES THE HEMODYNAMIC-EFFECTS OF CENTRONEURAXIS BLOCKS IN ELDERLY PATIENTS

This prospective randomized study was designed to investigate the hemodynamic effects and quality of continuous spinal anesthesia (CSA) after rapid injection of a low dose of 0.5% bupivacaine through a 32-gauge microcatheter. The method was compared with continuous epidural (CEA) and single-dose spinal anesthesia (SSA). Seventy-seven elderly patients (ASA II-III) ranging from 57 to 94 yr old and undergoing lower limb surgery were assigned to CSA (n = 26), CEA (n = 26), and SSA groups (n = 25). In all three groups, mean arterial pressure (MAP) and heart rate (HR) were assessed continuously for 30 min after initial injection, as well as after every reinjection of local anesthetic in the CSA and CEA groups. Bupivacaine (0.5%) was used as a local anesthetic. The initial doses were 1 mL of CSA, 10 mL of CEA, and 3 mL of SSA. The reinjection doses were 1 mL of CSA and 5 mL of CEA. In the CSA group, MAP did not decrease, whereas in the CEA group, the maximum decrease was 15% +/- 3% (mean +/- SEM) for the initial injection, 12% +/- 2% for the first repetition, and 13% +/- 2% for the second repetition. In the SSA group, the largest decrease of MAP was 19% +/- 2%. All changes of MAP in the CEA and SSA groups were significantly larger compared with CSA group (P < 0.05). A total of seven patients in these two groups needed vasopressors due to a decrease of MAP of more than 30% from baseline values. Heart rate did not change. Although of minor clinical importance, the segmental level of analgesia was significantly lower in the CSA group [T10 (T8-T11)] (median + range) than in the CEA [T9 (T7-T10)] and SSA groups [T9 (T6-T10)]. The duration of analgesia was significantly shorter in CSA (90 +/- 5 min) than in CEA (137 +/- 11 min) or SSA (158 +/- 6 min). CSA with a low anesthetic dose produces satisfactory quality of anesthesia, but with fewer hemodynamic effects than CEA or SSA in elderly patients.