Objective: The objective of this study was to improve the patient comfort and safety during procedures done under anaesthesia and sedation. The analgesia nociception index (ANI) noninvasively provides information on the nociception-antinociception balance, and it can beused to assess analgesia objectively. We aimed to compare the effects of analgesia management with conventional methods and with ANImonitoring on total opioid consumption, sedation and analgesia levels in patients who underwent colonoscopy using sedo-analgesia.Methods: Adult patients (n=102), scheduled for procedural sedation, were prospectively analysed. After the induction with propofol andketamine, infusions of propofol (2 mg kg−1 h−1) and remifentanil (0.05 mcg kg−1 min−1) were started. In Group A, remifentanil infusions weretitrated to maintain the ANI value between 50 and 70, whereas in Group C, analgesic requirements were met according to the attendinganaesthetist’s intention. The heart rate, blood pressure, respiratory rate, SpO2, BIS, Numeric Rating Scale (NRS) and Ramsay SedationScale were monitored. Complications, analgesics consumption, duration of the procedure, demographic information, NRS and the ModifiedAldrete Score were evaluated.Results: A total remifentanil amount used in Group A was 66.51±47.87 mcg and 90.15±58.17 mcg in Group C (p=0.011); there was nodifference in total amounts of ketamine and propofol given. There was a negative correlation between ANI and NRS scores of Group Apatients at Minute 0 at the level of 0.402, which was significant statistically (p=0.003).Conclusion: Opioid consumption was diminished when ANI monitoring was used, and thus the patient safety was improved. Further studieswith longer procedure times and with a greater number of patients are required to demonstrate whether there is a difference in side effectsand recovery times.