The present double-blinded, randomized, clinical trial aimed at comparing the sedative and side effects of a combination of dexmedetomidine and ketamine (DK) with propofol and fentanyl (PF) to induce analgesia in patients undergoing colonoscopy. The study population consisted of candidates for colonoscopy referring to Colonoscopy Unit in Shahid Beheshti Hospital in Qom, Iran. The sample size was determined maximum eight subjects in each group using two population means, according to the findings of the study by Goyal et al. (5), and considering different outcomes including hypotension, hypoxemia, and apnea; however, the sample size was increased to 32 subjects in each group in order to normalize distribution and better observe complications.
Inclusion criteria were: being eligible for colonoscopy, age above 18 years, the American Society of Anesthesiologists physical status (ASA-PS) class 1 and 2, and willingness to participate in the study. Exclusion criteria were: a history of allergy to the drug, drug addiction, and use of psychiatric drugs, ASA class ≥ 3, known psychological problems, emergency cases, and unwillingness to participate in the study.
Subjects were selected through consecutive sampling. The patients were divided into two groups of A and B using permuted block randomization. The size of blocks was 4 and were selected by casting dice. Allocation to the treatment groups A and B was performed by simple randomization (coin toss). The study was a double-blinded trial and both the patient and physician assessing the outcomes were unaware of the treatment type.
After assigning patients to treatment groups and obtaining the written informed consent from them, the demographic information including gender, age, height, and weight as well as primary vital signs including systolic blood pressure, mean arterial pressure, blood oxygen saturation (SpO2), and heart rate were recorded in the checklist of each patient.
Sedation was induced in group A (PF) using midazolam (0.02 mg/kg), fentanyl (1 µg/kg), and propofol (1 mg/kg) and in group B (DK) using midazolam (0.02 mg/kg), dexmedetomidine (0.3 µg/kg), and ketamine (0.25 mg/kg).
Sedation score was assessed using Ramsey sedation scale at 2, 5, 10 and 15 minutes. Sedation score and vital signs of each patient at predetermined time points, total dose administered, duration of colonoscopy, intraoperative complications including nausea, vomiting, bradycardia, hypotension, chills, delusions, hallucinations, apnea, and the degree of gastroenterologist satisfaction with the procedure as totally satisfactory (easy to perform), satisfactory (difficult to perform), and unsatisfactory (impractical) were recorded in the checklist of each patient. Besides, recovery assessments including time the patient entered to the recovery room, interval between colonoscopy completion and discharge, pain score at discharge using the Wong Baker faces pain assessment scale, patient satisfaction at discharge (i.e., totally satisfactory, satisfactory, and unsatisfactory), and recovery complications including nausea, vomiting, bradycardia, hypotension, shivering, delusions, hallucinations, and apnea were recorded in each patient's checklist.
Data were analyzed by SPSS version 18 software using descriptive statistics including mean and standard deviation and analytical statistics including chi-square and independent t-test, as well as repeated measure analysis. P-value < 0.05 was considered significant.
Ethical considerations: The study process and possible complications were explained to patients and they were asked to sign the informed consent forms in case of willingness to participate in the study. The study protocol designed on the basis of Helsinki declaration for ethical consideration and was approved by the Ethics Committee of Qom University of Medical Sciences (ethics code: IR.MUQ.REC.1397.149); the study was also registered at the Iranian Center for Clinical Trials (No. IRCT20161205031252N11).