Ketamine as the Main Analgesic Agent During Analgesia-based Sedation for Elective Colonoscopy- a Randomised, Double-blind, Control Study

This prospective, randomized control study was conducted after obtaining the approval of the Ethics Committee and the written consent of the patients, in the Department of Anesthesia and Intensive care unit between 2020 and 2021. Ninety ASA physical statuses I and II, patients who were older than 18 years were included in this study. Exclusion criteria were: all colonoscopies lasting longer than 30 minutes, patients with previous abdominal surgery, patients treated for neuropathic pain, malignant and respiratory diseases, pregnant women, gastrointestinal obstruction, patients using antihypertensive and antiarrhythmic drugs, psychiatric patients, patients with ASA physical status III and higher, and patients who refused to participate in the study.

All patients had fasted for the previous 8 hours prior to the procedure and had undergone a digestive tract preparation procedure. Patients were randomly (computer generated) divided into three groups: patients whom were administrated fentanyl and propofol (Group FP), patients whom were administrated ketamine and propofol (Group KP) and patients whom were administrated propofol (Group C-control group). The syringes were coded before the procedure by an anesthetist who was not involved in the sedation process. Syringes were also selected in terms of volume in a similar manner, while patients, anesthesiologists, colonoscopists, and anesthetists were blinded to the medication regimen.

After the patient admission to the endoscopy room and identification, an intravenous line was placed and intravenous fluid administration (saline) was started. All patients were placed in the lateral position and placed on non-invasive blood pressure monitoring, three-channel ECG and peripheral oxygen saturation. Oxygen support is provided via a facial mask at a flow rate of 5 L/min.

Sedation protocol. All three groups of patients were premedicated with 0.05 mg kg-1 of midazolam (PanPharma), 5 minutes before the starting of the procedure. Afterwards, sedation induction was performed with 1 mcg kg-1 of fentanyl (Panpharma; SanMed) and 0.5 mg kg-1 of propofol (Fresenius Kabi; Amicus Pharma) for Group FP. Ketamine (Inresa Arzneimittel) 0.5 mg kg-1 and 0.5 mg kg-1 of propofol for Group KP, and 1 mg kg-1 of propofol for Group C. During the procedure, the patients RSS scores was maintained at 5 with an additional 0.5 mg kg-1 bolus dose of propofol when required.

Data collection and measurements Assessment of hemodynamic and respiratory stability. MAP and HR were noted upon entry of the patient into the endoscopic cabinet, immediately after the administration of propofol, and then every 5 minutes during the procedure. A number of episodes of hypertension, hypotension, tachycardia, and bradycardia were noted. Hypertension is defined as an increase in blood pressure greater than 20%, and hypotension for a decrease in blood pressure greater than 20% from baseline. Tachycardia is defined as an increase in heart rate> 100 beats per minute. Bradycardia as a drop in heart rate <50 beats per minute. Respiratory stability was assessed at the same time intervals using a peripheral pulse oximeter. A number of desaturation episodes were recorded for each group. Desaturation was defined as a decrease in peripheral oxygen saturation <95% measured with a pulse oximeter.