Aim and backgroundIn most emergency departments (ED), opioids are the primary analgesic agents for trauma patients. However, safe alternative drugs are required because of possible adverse effects. Ketamine, an anesthetic agent, provides satisfactory analgesia at low doses and is an alternative drug that has begun to be used in numerous areas with fewer side effects. This study aimed to compare low-dose ketamine and fentanyl infusions in terms of their pain-relieving effects and observed adverse effects in patients presenting to the ED with isolated long bone fractures.Materials and methodsThis single-center observational study was conducted in the ED of the Marmara University Pendik Training and Research Hospital between August 2018 and December 2019. Patients diagnosed with isolated long bone fractures who were administered low-dose ketamine or fentanyl rapid infusions for pain relief were included in the study. Patient pain scores were evaluated using the visual analog scale (VAS) with a standard horizontal 10-centimeter line. The primary outcome of the study was to compare the changes in pain at 30 and 60 min after medication administration for each group.Resultsp=0.319), 30 min (p=0.631), and 60 min (p=0.347) after treatment were similar in both groups. In terms of the observed adverse effects, dizziness was more common in the ketamine group (p=0.010).A total of 100 patients were included in the study. Ketamine infusion was administered to 48% (n=48) of the patients as a pain reliever. After 60 min of observation, pain was significantly reduced in both study groups. However, the pain scores at baseline (ConclusionThe results of this study showed that low-dose ketamine infusion (0.3 mg/kg/h) had a similar effect to fentanyl infusion (1 mcg/kg/h) as a pain reliever in patients with isolated long bone fractures in the ED. Post-traumatic long bone fractures constitute 3.5-4% of emergency department (ED) admissions annually in the United States of America . AccordiIn the article published by Hornik et al. in 2023, 2.32 million emergency visits with long bone fractures were examined . While tKetamine is a dissociative anesthetic agent that blocks N-methyl-d-aspartate (NMDA) receptors . This drThis study aimed to compare the analgesic efficacy of the initial dose of low-dose ketamine and fentanyl (a synthetic opioid) in patients who presented to the ED with isolated post-traumatic long-bone fractures.Study designThis single-center, prospective, observational clinical study was conducted between August 2018 and December 2019 at the ED of the Marmara University Pendik Training and Research Hospital. The hospital is an urban, medical school-affiliated, Level I trauma center and tertiary care referral center with over 200,000 adult ED presentations annually. This study was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines . MarmaraStudy setting and protocolMarmara University Pendik Training and Research Hospital is a Level I trauma center. When a trauma patient presents to our hospital, a detailed examination is performed by the primary physician, and if necessary, his/her first resuscitation and stabilization are provided. Patient pain is evaluated using the visual analog scale (VAS) score and noted in the patient file. The primary physician selects an appropriate analgesic agent in line with the current pain management guidelines, considering parameters such as pain intensity, age, and known diseases -19. In pStudy populationTrauma patients over the age of 16 years who presented to the ED were evaluated by their primary physician, diagnosed with isolated long bone fracture, and treated with a sub-dissociative dose of ketamine (0.3 mg/kg) or fentanyl (1 mcg/kg) to relieve pain were included the study. Other inclusion criteria were having a VAS evaluation before the analgesic agent administration, acceptance of participation in the study, stable hemodynamics, no unconsciousness, and no known allergy to any of these agents. Patients who withdrew consent or required sedation during follow-up were excluded from the study.Variables and data measurementThe patients were divided into two groups, ketamine and fentanyl, according to the analgesic agent they received. Demographic data such as age, sex, comorbidity, mechanism of injury, anatomical location of the fracture, pain intensity score, vital signs at 0, 30, and 60 min, observed adverse effects during treatment, and need for rescue analgesics were recorded for both groups.The pain intensity of the patients was evaluated using a VAS score. A 10-cm horizontal line was used for VAS measurements. The left side of the line described “no pain,” while the right side described the “most severe pain in life.” There were no other markings on the line, and the patients marked this line based on the pain they felt. Pain was measured in centimeters from the left end of the scale to the point marked by the patient. This measurement was performed three times .The primary outcome of our study was to compare the changes in VAS scores at the 30th and 60th minutes from baseline in both groups. Secondary outcomes included a comparison of changes in vital signs at 30 and 60 min, the need for rescue analgesics, and side effects between the two groups. According to studies in the literature, a clinically significant change is defined as a change of 1.1 to 1.37 points in the VAS score. We accepted the value of 1.37 as significant in our study .Statistical analysisThe Statistical Package for Social Sciences (SPSS) for Mac 25.0  program was used for statistical analysis. The distribution normality of the data was evaluated using Kolmogorov-Smirnov test. Categorical variables are presented as numbers and percentages, whereas numerical variables are presented as medians and interquartile ranges. For comparisons between groups, we used the chi-squared test for categorical data and the Mann-Whitney U test for numerical data. Statistical significance was set at p<0.05.During the study period, 139 patients with isolated long bone fractures presented at the ED. Thirty-nine patients were excluded based on these exclusion criteria. One hundred patients were included in this study. It was observed that 52% of patients (n=52) received fentanyl, whereas 48% (n=48) received ketamine as an analgesic agent  years, and that of the ketamine group was 44.0 (30.0-60.0) years (p=0.548). Thirty percent (n=30) of the patients were female. A comparison of the demographic and fracture characteristics of the study groups is shown in Table The baseline (t0), 30th-, and 60th-minute VAS scores of both groups are shown in Table The adverse effects observed throughout the study and the need for rescue agents are summarized in Table In the ketamine group, VAS scores decreased by 2.0 units at 30 min and 3.0 units at 60 min, whereas it decreased by 2.0 units at 30 min and 3.5 units at 60 min in the fentanyl group. The VAS scores decreased clinically significant  in both Jahanian et al. investigated the efficacy and safety of low-dose ketamine and morphine . In theiBeaudoin et al. conducted a double-blind randomized placebo-controlled trial in patients with severe acute pain . PatientBronsky et al. compared ketamine and fentanyl in trauma patients with severe pain in the pre-hospital setting and found that ketamine provided adequate analgesia in more patients . In addiWidespread use of opioids has increased the incidence of opioid-related illnesses and deaths. This problem was defined as a public health crisis in 2017 by the United States Department of Health & Human Services and continues to be updated every year . Again iThis was an observational study with certain limitations. The primary physician determined the drugs administered to the patients and the infusion rate. Therefore, undesirable differences in drug distribution were observed at some fracture sites (the femur and tibia). Although no difference was detected between the initial VAS scores in both groups, the effect of this distribution on the study results remains unclear. Moreover, in this study, the infusion rates of the drugs were not evaluated. Previous studies have reported that with rapid applications of ketamine, adverse effects occur more frequently because serum concentrations reach higher levels in a short time . By condLow-dose ketamine appears to be an alternative to fentanyl for pain treatment in patients with long bone fractures in the ED. Although no serious adverse effects were observed in our study, dizziness was more frequent in patients treated with ketamine. Therefore, ED physicians should be aware of these adverse effects. We believe that ketamine will be used more frequently as an alternative to opioids with future randomized controlled studies.