the effect of remifentanil– propofol compared with fentanyl– propofol on urine output in patients undergoing lumbar posterior spinal fusion

background: remifentanil is a narcotic drug used in anaesthesia for establishment of hemodynamic stability. the purpose of this study was to compare the effects of remifentanil and fentanyl on urine excretion. methods: in a randomized clinical trial, 60 patients, who were candidates for elective surgery for lumbar posterior spinal fusion, were divided randomly into two groups of 30 as remifentanil – propofol (r) and fentanyl- propofol (f). maintenance of anaesthesia drugs in group r included 100 mcg/kg/min propofol and 0.5- 0.25 mcg/kg/min remifentanil. it included 100 mcg/kg/min propofol and 5- 0.5 mcg/kg/min fentanyl in group f. vital signs and urine output were recorded every half an hour. results: the mean age of patients was 49.5± 12.7 years. urine output in group r showed significantly greater reduction than in group f (p< 0.001). increase of urine output was seen in both groups over the time. conclusion: urine output in patients undergoing lumbar posterior spinal fusion who received remifentanil was less compared to the fentanyl group.