A randomized controlled trial for measuring effects on cognitive functions of adding ketamine to propofol during sedation for colonoscopy

February 3, 2021

Authors: Liang Tian, Hengfei Luan, Pin Zhu, Zhiyuan Zhang, Hongguang Bao

Journal: Medicine

DOI: 10.1097/MD.0000000000021859

Year Published: 2020


The purpose of this study was to evaluate the effects of adding ketamine to propofol on cognitive functions in patients undergoing sedation for colonoscopy.


In this randomized, double-blinded, and controlled study, 200 patients were randomly allocated to ketamine/propofol admixture group (Group KP, n = 100), and propofol group (Group P, n = 100). Patients in Group KP received 0.25 mg/kg of ketamine and 0.5 mg/kg of propofol. Patients in Group P received 0.5 mg/kg propofol. Cognitive functions were measured using CogState battery before and after the colonoscopy procedure. Ninety five patients in Group KP and 92 patients in Group P had completed the CogStates tests and were included in the data analysis.


Compared with before procedure baseline, the performance on detection and identification tasks were significantly impaired after the procedure in both Group KP (P = .004, P = .001) and Group P patients (P = .005, P < .001). However, one-card learning accuracy and One-back memory was only impaired in Group KP patients (P = .006, P = .040) after the endoscopy but left intact in Group P patients. Group KP patients showed more severe impairment in one-card learning accuracy compared with Group P patients (P = .044). Group KP patients have better 5 minutes MAP (P = .005) and were also less likely to suffer from complications such as respiratory depression (P = .023) and hypotension (P = .015). OAA/S scores, BIS, MAP, complications, recovery times, and endoscopist and patient satisfaction were similar between the 2 groups.


Although adding ketamine to propofol for sedation in colonoscopy provided fewer complications such as respiratory depression and hypotension, it also causes more impairment in cognitive functions.

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