INCREMENTAL DOSING VERSUS SINGLE-DOSE SPINAL-ANESTHESIA AND HEMODYNAMIC STABILITY

We compared the hemodynamic stability after spinal anesthesia with two different dosing regimens in the elderly. Fifty patients, all older t han 60 yr and scheduled for elective knee or hip surgery were assigned to two groups. After administration of 10 mL/kg of lactated Ringer's solution (RL) intravenously (IV) in the first group, we performed a co ntinuous spinal anesthesia (CSA) by means of a 28-gauge catheter throu gh which repetitive injections of 2.5-5 mg of plain bupivacaine 0.5% w ere given. In the other group, a single-dose spinal anesthesia (SS) wi th 20 mg of the same local anesthetic (LA) was carried out. Noninvasiv e mean arterial pressure (MAP), heart rate, and levels of analgesia we re measured. To maintain MAP within 25% of initial value, the patients received additional IV fluids (RL) as first measure. When MAP could n ot be maintained despite hydration, incremental doses of ephedrine wer e given IV. Six patients in the CSA group and 17 in the SS group devel oped a level of anesthesia higher than T6 (P < 0.01). In the SS group more fluid was needed (792 vs 388 ml) than in the CSA group (P < 0.01) . Moreover, more patients of the SS group (11 vs 4) required ephedrine (P < 0.05). We conclude that CSA produces reliable and predictable an algesia for lower limb surgery with less need for correction of hemody namic changes compared to SS.