Comparison of analgesic effect of pregabalin-fentanyl and midazolam-fentanyl combinations on the severity of pain in the patients undergoing extracorporeal shock wave lithotripsy: a double-blind clinical trial

Background and Objective: Kidney stone disease goes back to thousands of years ago. Extracorporeal Shock Wave Lithotripsy (ESWL) is currently the first line treatment for this disease. Different analgesics were already used to relieve pain in the patients but they still complain about their pain. Therefore, the effect of two combinations of pregabalin-fentanyl and midazolam-fentanyl was investigated in controlling pain in the patients undergoing ESWL in this study.Materials and Methods: This was double-blind clinical trial on 141 patients visiting Lithotripsy Unit in Peymaniyeh Hospital in Jahrom Town. The participants were selected using a simple sampling method. Inclusion criterion was 8mm < kidney stone < 20mm. Exclusion criteria were 20 kg/m2 < body mass index (BMI) < 30 kg/m2, a history of mental disorders, namely addiction to analgesics and opiates. Finally, the patients were randomly assigned to two groups. One microgram per kilogram fentanyl was administered intravenously and 300mg pregabalin was given orally to the patients ten minutes before surgery in the first group (pregabalin-fentanyl and n = 47). One microgram per kilogram fentanyl and one microgram per kilogram midazolam were injected intravenously to the patients ten minutes prior to operation in the second group (fentanyl-midazolam and n = 46). Then, standard shock wave lithotripsy was carried out in both groups. The severity of pain was measured every 20 minutes during the operation and two hours after the operation using the Visual Analog Scale for Pain (VAS Pain). The collected data was analyzed using SPSS version 21. Descriptive statistics (mean, standard deviation and percent) and analytical statistical tests (Mann-Whitney and Chi-square) were used to analyze the data.Results: The mean age of participants was 43.80±13.71 in the first group (pregabalin + fentanyl) and 39.0±11.19 in the second group (midazolam + fentanyl). Chi-square test results were matched in both groups in terms of age, gender, number of shocks and size of the stone. The Mann-Whitney test results showed a significant difference between the first and second groups in terms of pain score from the first 20 minutes up to 2 hours after drug administration (p-value<0.05). The results also showed that the number of patients experiencing higher than average severity of pain in the second group was significantly less than the first group (pvalue< 0.05).Conclusion: The results of this study showed that the number of patients experiencing higher than average severity of pain in the group receiving midazolam-fentanyl combination was less than the group receiving pregabalin-fentanyl combination. Therefore, it can be deduced that fentanyl in combination with midazolam has a greater analgesic effect on pain relief in the patients undergoing ESWL.Keywords: pregabalin-fentanyl, midazolam-fentanyl, pain, extracorporeal shockwave lithotrips