Comparison of hyperbaric ropivacaine and hyperbaric bupivacaine in unilateral spinal anaesthesia

To evaluate the clinical efficacy and safety of unilateral spinal anaesthesia with 0.66% hyperbaric ropivacaine compared with 0.5% hyperbaric bupivacaine for arthroscopic knee surgery.

Forty patients with American Society of Anesthesiology physical status grade I-II were randomly and double blindly allocated to one of two groups. Spinal anaesthesia was performed from the L3-4 or L4-5 interspace with the patient in the lateral decubitus position and with the operative side below. Group B (n = 20) received 7.5 mg of 0.5% hyperbaric bupivacaine and group R (n = 20) received 10 mg of 0.66% hyperbaric ropivacaine. Patients stayed in the lateral decubitus position for 10 minutes and were then turned to the supine position. The characteristics of spinal block, intraoperative quality of spinal anaesthesia, adverse effects and recovery times were recorded.

The onset of sensory block and motor block were significantly earlier in group B compared with group R (p < 0.05). The duration of sensory block and motor block were significantly shorter for group R compared with group B (p < 0.05). Bilateral sensory block occurred in 85% of patients in group B and in 40% of patients in group R (p < 0.05). Bilateral motor block occurred in 70% of patients in group B and in 25% of patients in group R (p < 0.05).

For outpatient knee arthroscopy, 10 mg of 0.66% hyperbaric ropivacaine is preferred to 7.5 mg of 0.5% hyperbaric bupivacaine because it provides a more selective unilateral block and a faster recovery.