Introduction
Gastrointestinal endoscopy is an essential screening and therapeutic tool for gastrointestinal diseases. It is important to perform endoscopic procedures under sedation for higher patient comfort and acceptance [1,2]. Propofol, a good hypnotic with rapid onset, rapid recovery, and minimal side effects, is the most widely used in anesthesia induction and maintenance during endoscopic procedures [3-7]. However, propofol may result in hypotension, bradycardia, respiratory depression, and loss of protective reflexes [8], especially in elderly patients. Adjuvants are usually needed in many cases because co-administration can improve anaesthetic efficacy and reduce the incidences of adverse events caused by a single drug [9].
Esketamine, a noncompetitive, N-methyl-D-aspartate receptor antagonists [10], has analgesic, anaesthetic and sympathomimetic properties and is known to cause less cardiorespiratory depression [11,12]. Therefore, it could be an ideal adjunct to propofol for endoscopic procedures [12,13]. However, very few studies have been reported the effectiveness and safety of esketamine adjunct to propofol sedation during endoscopic procedures in elderly patients.
We therefore designed this randomized, double-blinded and controlled study to assess the effectiveness and safety of esketamine as an adjunct to propofol target-controlled infusion (TCI) and determine the effect of different doses of esketamine on the median effective concentration (EC50) of propofol for gastrointestinal endoscopy in elderly patients.