Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 2 2 2016 06 13 175 178 EN Valiollah Hassani Minimally Invasive Surgery Research Center, Iran University of Medical Sciences. Pars Advanced and Minimally Invasive Manners Research Center, Pars hospital, Tehran, Iran. Abolfazl Rahimzadeh Pars Advanced and Minimally Invasive Manners Research Center,Pars hospital, Iran University of Medical Sciences, Tehran, Iran. Nasim Nikoubakht Department of Anesthesiology and Pain Medicine, Iran University of Medical Sciences, Tehran, Iran Azadeh Sayarifard Preventive and Community Medicine Specialist, Center for Academic and Health Policy, Tehran University of Medical Sciences, Tehran, Iran. Kayvan Latifi Department of Anesthesiology and Pain Medicine, Iran University of Medical Sciences, Tehran, Iran. 2016 04 23 2016 06 13 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. https://aacc.tums.ac.ir/index.php/aacc/article/view/70 https://aacc.tums.ac.ir/index.php/aacc/article/download/70/163