The effects of intravenous granisetron on the sensory and motor blockade produced by intrathecal bupivacaine.

Background: We hypothesized that pretreatment with i.v. granisetron would affect the sensory and motor components of spinal blockade through 5-HT(3) receptor blockade.

Methods: Forty unpremedicated patients scheduled for elective knee arthroscopy under spinal anesthesia were randomly allocated to receive either i.v. granisetron 1 mg (granisetron group) or saline (control group) on arrival to the operating room. Two and half milliliters (12.5 mg) of hyperbaric bupivacaine 0.5% was injected intrathecally. Regression of the sensory level and motor blockade, and the hemodynamic changes were evaluated.

Results: There were no significant differences between the two groups in the maximum cephalad spread of sensory block or the time to maximum sensory level. Compared with the control group, patients who received granisetron had significantly faster sensory regression times by two segments (69.8 +/- 25.5 min vs 88.0 +/- 27.8 min, P = 0.036), to segment T12 (105.5 +/- 25.1 min vs 127.0 +/- 30.5 min, P = 0.019) and to segment S1 (162.8 +/- 41.1 min vs 189.8 +/- 39.8 min, P = 0.041), respectively. In contrast, motor block did not differ between the two groups at any study time. No significant differences were detected between the two study groups in the hemodynamic data.

Conclusion: We concluded that i.v. granisetron facilitated a faster recovery of sensory block after bupivacaine subarachnoid anesthesia.