Comparison of the effects of esketamine, sufentanil, or lidocaine combined with propofol on tussis reflection during upper gastrointestinal endoscopy: study protocol for a randomised, two centre, three-blind, controlled trial

Background: Tussis, which increases the incidence of airway spasm, aspiration, nausea, and vomiting, is a common complication faced during upper gastrointestinal (GI) endoscopy. However, sedatives and analgesics exhibit inhibitory actions against airway reflexes to different degrees. Our assumption is a combination of propofol and small doses of sufentanil, esketamine, or lidocaine, especially the combination of propofol and esketamine, might reduce tussis incidence.

Method: The study will be performed as a randomised controlled three-blind, two-centre trial. Patients undergoing upper GI endoscopy, ≥ 18 years old, with American Society of Anesthesiologists (ASA) classification I-III will be randomised to four groups: P group (single administration of propofol), P + S group (administration of propofol and sufentanil in combination), P + K group (administration of propofol and esketamine in combination), and P + L group (administration of propofol and lidocaine in combination) (N = 100 per group). The primary endpoints include the frequency of tussis, nausea and vomiting, and/or body movements observed at the insertion of the endoscope into the pharyngeal cavity or within 5 min of endoscope insertion. Secondary outcomes are recovery assessment, patients' and endoscopists' satisfaction with the procedure, MMSE scores, MET scores, sleep condition, and the number of sedation-related events. Data on sedation-related events are collected by recording of vital signs. Satisfaction parameters and mental states are collected by means of questionnaires and evaluation scales before and after the procedure and on different following days.

Discussion: Esketamine can reduce tussis occurrence with good tolerability and relax the bronchus and also provides high clearance rates and low possibility of adverse reactions. We aim to demonstrate that the combination of esketamine with propofol for sedation in patients subjected to upper GI procedure is nevertheless superior to only administration of propofol or a combination of propofol with other anaesthetics, such as opioids or lidocaine.

Trial registration: ClinicalTrials.gov. NCT05497492 , Registered 09 August 2022.