Short-term perfusion and respiratory effects of dexketoprofen, tramadol, and their combination in renal colic: A prospective randomized capnography study

Objective: Intravenous non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, including dexketoprofen trometamol and tramadol, remain the primary analgesic options for treating acute renal colic in emergency departments. However, concerns about respiratory depression associated with opioids can limit the use of tramadol with confidence, and there are limited data on the short-term respiratory and perfusion effects of these agents. The present study aimed to evaluate the short-term effects of intravenous dexketoprofen trometamol, tramadol, and their combination on tissue perfusion and respiratory function. The study assessed these effects using EtCO₂ and related physiological parameters. The study population comprised hemodynamically stable emergency department patients presenting with acute renal colic.Methods: In this prospective, randomized, controlled trial conducted in an academic emergency department, adults aged 18–55 with acute renal colic received one of three intravenous regimens: dexketoprofen trometamol (50 mg), tramadol (100 mg), or their 50 mg/50 mg combination. Vital signs, SpO₂, and EtCO₂ were recorded at baseline, 30, and 60 minutes; arterial blood gases, including lactate, were drawn at baseline and 60 minutes. The primary endpoint of the study was the EtCO₂ trajectory over time.Results: In a study of 102 patients (with 34 patients in each group), EtCO₂, heart rate, and blood pressure were found to be similar between the groups at all measured time points. Furthermore, analysis using mixed-effects models revealed no significant group-by-time interactions. SpO₂ levels were found to be lower in the combination group compared to the dexketoprofen group at the 60-minute mark (93.8% vs. 95.4%; ANOVA p = 0.018; post hoc p = 0.016). In the present study, seven patients, all in tramadol-containing arms, exhibited transient SpO₂ levels below 90%, though none of these patients required oxygen supplementation. The blood-gas parameters demonstrated stability, while lactate levels exhibited a significant decrease across all groups, without any observed between-group variation.Conclusion: In patients with renal colic who were hemodynamically stable, the three treatment plans resulted in similar short-term effects on EtCO2, hemodynamics, and blood-gas parameters. The findings of this study demonstrate that modest SpO₂ declines, accompanied by transient desaturations in the tramadol-containing arms, provide substantiated support for the implementation of pulse oximetry and capnography monitoring when tramadol is administered. It should be noted that the study was not designed to assess comparative safety, and thus the findings should be considered physiological observations only. The lactate reduction may be indicative of a resolution of pain-related stress; however, this remains a hypothesis that requires further investigation.Trial Registration: The study was registered at ClinicalTrials.gov (ID: NCT07386288). Registration was retrospective.