Background and objectives The potential risks of spinal lidocaine have generated interest in an alternative local anesthetic solution. Features of anesthetic block were therefore assessed in a double-blind randomized prospective study following administration of spinal bupivacaine in small doses.

Methods Ninety patients scheduled for lower limb saphenous vein stripping were randomized to receive a 4-mL hyperbaric solution containing 4, 6, or 8 mg bupivacaine in the subarachnoid space. Sensory and motor block and hemodynamic changes were assessed at regular intervals. Patients were also questioned regarding transient radicular irritation symptoms.

Results The mean duration of sensory block increased with increasing dose (duration at L2: 56 ± 27, 71 ± 29, 79 ± 25 minutes in groups 4, 6, and 8 mg, respectively, P < .05). Motor block was also dose dependent. The incidence of grade 3 motor block increased from 0%, to 21%, and to 53%. No patient had symptoms of transient radicular irritation. Arterial pressure and heart rate were stable throughout the study.

Conclusion Hyperbaric bupivacaine 6-8 mg provides a suitable alternative to spinal lidocaine for surgical procedures of short duration.