[Spinal anesthesia with pethidine as the sole agent].

Twenty-two patients of ASA physical status 1 or 2 undergoing surgery of the perineal region received intrathecal pethidine as the sole agent. The anesthetic effect of 0.5 mg.kg-1 (group 1) or 0.7 mg.kg-1 (group 2) of pethidine was evaluated and compared. Patients were randomly assigned to one of the two groups (12 in group 1 and 10 in group 2). Subarachnoid puncture was performed with the patient in the sitting position, using a 25 gauge spinal needle at the lumbar vertebral level of L4/5 or L5/S. The patients remained sitting for 5 min before being placed in the supine position. Two patients in the group 1 had inadequate sensory blockade and they were excluded from further study. The average segmental level of analgesia was S1 in group 1 and L2 in group 2. Motor blockade of the anal sphincter was seen in all patients. During the operation, the patients were stable hemodynamically and no respiratory depression was noticed. Prolonged postoperative analgesia was obtained and some patients did not require additional analgesics during postoperative period. Four patients complained of itching, two patients of nausea and two developed arrhythmias.