INTRATHECAL FENTANYL PROLONGS SENSORY BUPIVACAINE SPINAL-BLOCK

The purpose of investigation was to study the effect of intrathecal fe ntanyl on the onset and duration of hyperbaric bupivacaine-induced spi nal block in adult male patients. Forty-three patients undergoing lowe r extremity or genitourinary surgery were enrolled to receive either 1 3.5 mg hyperbaric bupivacaine 0.75% + 0.5 ml CSF it, (Group I) or 13.5 mg hyperbaric bupivacaine 0.75% + 25 mu g fentanyl it (Group II) acco rding to a randomized assessor-blind protocol. The onset and duration of sensory block were assessed by pinching the skin with forceps in th e midclavicular line bilaterally every two minuter for first twenty mi nuter and then every five to ten minuter. Similarly, the onset and dur ation of motor block were assessed and graded at the same time interva ls using the criteria described by Bromage. The time required for two sensory segment regression and sensory regression to L(1) dermatome wa s 74 +/- 18 and 110 +/- 33 min vs 93 +/- 22 and 141 +/- 37 min in Grou ps I and II, respectively (P < 0.05). Intrathecal fentanyl did not enh ance the onset of sensory or motor block, or prolong the duration of b upivacaine-induced motor spinal block. Fewer patients demanded pain re lief in the fentanyl-treated group than in the control group in the ea rly postoperative period (19% vs 59%; P < 0.05). Episodes of hypotensi on were more frequent in the fentanyl-treated group than in the contro l group (43% vs 14%; P < 0.05). We conclude that fentanyl, 25 mu g it, prolonged the duration of bupivacaine-induced sensory block (sensory regression to L(1) dermatone) by 28% and reduced the analgesic require ment in the early postoperative period following bupivacaine spinal bl ock.