Background and Objectives. This study examines the effect of epinephrine on the time to achieve a T4 sensory level when added to a hyperbaric bupivacaine-fentanyl mixture for spinal anesthesia.

Methods. Sixty-nine healthy parturients scheduled for elective cesarean delivery were randomly assigned to three groups. All patients were given 9 mg hyperbaric 0.75% bupivacaine with 25 μg fentanyl. Group 1 received no epinephrine while Groups 2 and 3 received 100 μg and 200 μg epinephrine, respectively. Injection of the spinal anesthetic solutions was performed with the patient in the sitting position. Immediately after drug administration, patients were placed supine with their heads elevated on a pillow and 15° of left uterine displacement was maintained. Vital signs and sensory levels were obtained every minute for 10 minutes.

Results. In Groups 2 and 3, the mean time to T4 sensory level was significantly longer (6.9 minutes and 6.6 minutes, respectively) than in Group 1 (4.6 minutes). As a subset, patients weighing more than 90.8 kg achieved a T4 sensory level faster than did those weighing less than 90.8 kg (3 minutes and 5.1 minutes, respectively), but in both groups epinephrine prolonged the onset time to T4 (5.8 minutes and 7.3 minutes, respectively). Three patients were excluded because of failure to obtain a T4 sensory level.

Conclusions. The onset time to T4 is related inversely to patient weight, and epinephrine (100 μg and 200 μg) delays the onset of sensory block to T4 when administered with subarachnoid hyperbaric bupivacaine-fentanyl.