Spinal anesthesia with meperidine. Effects of added α-adrenergic agonists : Epinephrine versus clonidine

We determined the effects of intrathecally administered epinephrine and clonidine on the duration and quality of a meperidine spinal block. Forty-five patients scheduled for orthopedic surgery, divided into three groups, received spinal anesthesia with 1 mg/kg 5% meperidine, alone or with 200 microg epinephrine or 2 microg/kg clonidine. Using a double-blind method, the onset, extension, and duration of sensory block (to pinprick) and the duration and degree of motor block (Bromage scale) were assessed. Hemodynamic responses, duration of postoperative analgesia, degree of sedation, and occurrence of side effects were also recorded. The addition of epinephrine to the meperidine solution prolonged the sensory block (P