effect of fentanyl in spinal anesthesia with bupivacaine in opium abusers

background spinal anesthesia is a common procedure in the anesthesia. in some studies it has been shown that chronic use of opioids is associated with shorter duration of spinal anesthesia when local anesthetics are applied. objectives this trial was conducted in order to determine effect of fentanyl on the duration of spinal block by bupivacaine in chronic opium abusers who undergo spinal anesthesia and have lower thresholds for pain. patients and methods this study was a randomized clinical trial in which 50 opium abusers (25 patients in each group) undergoing lower extremity orthopedic surgeries with spinal anesthesia were selected. the patients were randomly divided into two groups. the study group received 15 mg hyperbaric bupivacaine 0.5% plus 25 µg fentanyl, while the control group received 15mg hyperbaric bupivacaine 0.5% plus 0.25 ml normal saline. results all randomly selected cases were male (44.7 ± 13.6 year). the mean duration of sensory block was much longer in the study group (87.8 ± 7.22 minutes) in comparison with the control group (70.47 ± 5.45 minutes) (p < 0.001). there was no statistically significant difference between the two groups regarding their age and duration of surgery. conclusions bupivacaine administration in spinal anesthesia for spinal block has a shortened duration in comparison to the combination of bupivacaine and fentanyl in chronic opium abusers.