A prospective, randomized clinical trial according to the CONsolidated Standards Of Reporting Trials (CONSORT) statement was performed on patients undergoing elective outpatient gastrointestinal endoscopy requiring sedation. This study was approved by the Research Ethical Committee of the First Affiliated Hospital of Wenzhou Medical University, and written informed consent was obtained from all patients participating in the trial. The trial was registered before patients’ enrollment at Chinese Clinical Trial Registry (http://www.chictr.org.cn, ChiCTR1900022639; principal investigator: L. C.; date of registration: April 19, 2019).
Patients
The study population comprised of 202 patients receiving elective outpatient gastrointestinal endoscopy between May and September 2019.Eligible patients were aged 30–65, and they were of ASA physical status I-II and were presenting for elective gastrointestinal endoscopy. Patients with any one of the following conditions were excluded from the study: inadequate Chinese comprehension; Montreal Cognitive Assessment (MoCA) score<26 (A final total score of 26 and above is considered normal) [6]; body mass index >25 kg/m2; renal insufficiency, liver dysfunction; atrioventricular block; significant cardio-respiratory instability; neurological disease; mental disorder; or dexmedetomidine allergy.
All patients received oral bowel preparation the night before endoscopy. Patients were randomly divided into groups by computer. Randomization results were concealed in opaque envelopes until after consent was obtained and the anesthesiologists, patients, endoscopists and postoperative observers were blind to the results.
Procedure
After consent was obtained, demographic and medical data were recorded. Patients completed the MoCA before gastrointestinal endoscopy(at least three weeks earlier). IV access was established and patients were not given IV fluids. Oxygen was administered at 5 L/min via a nasal tube when patients arrived at the endoscopy room. Routine patient monitoring included electro-cardiography, pulse oximetry, and noninvasive arterial blood pressure measurement in keeping the stability of hemodynamics.
Patients were randomized allocated into the control (C) or the Dexmedetomidine (D) group, and sedative drugs were administered IV. Patients were given 5μg sufentanil and 0.5 mg atropine in both groups. The group D was a continuous intravenous pumping of dexmedetomidine at a dose of 0.3μg/kg (this procedure was completed within 10 minutes) before the anaesthesia; the group C was given an equal volume of normal saline instead. The method of propofol administration was determined by the anesthesiologist. Anesthesiologists were advised to aim for a depth of sedation in modified observer’s assessment of alertness/sedation (OAA/S) score = 0 (Does not respond to painful trapezius squeeze) [5] for the whole procedure (Table 1). Predefined complications (hypotension, bradycardia, hypoventilation, etc.) were managed by anesthesiologists. After the endoscopy, patients were transferred to the postanesthesia care unit (PACU). MoCA were evaluated at 30min or 60min after patients reached an OAA/S score = 5 (responds readily to name spoken in normal tone) in group C (groupC30 or groupC60), and 30min in group D.
Measurements
Gender, age, amount of propofol, Sedation time (defined as the time from administration of the first drug and until removal of the endoscope), endoscopist and patient satisfaction, MoCA score (range, 0–30).
Cognitive test
The MoCA was a rapid assessment scale for mild cognitive dysfunction [6]. It includes attention and concentration, executive functions, memory, language, visuoconstructional skills, conceptual thinking, calculations, and orientation. The total possible score is 30 points; a score of 26 and above is considered normal (https://www.mocatest.org/). In order to reduce errors caused by learning benefits from short-term repetitive testing, patients did not test the MoCA on the same day.
Sample size calculation and randomization
The sample size was planned and calculated according to comparison of the MoCA among group C30, group C60 and group D. In a one-way ANOVA study, sample sizes of 16, 16, and 16 are obtained from the 3 groups whose means are to be compared. The total sample of 48 subjects achieves 96% power to detect differences among the means versus the alternative of equal means using an F test with a 0.05 significance level. The size of the variation in the means is represented by their standard deviation which is 0.60. The common standard deviation within a group is assumed to be 1.00. With a 10% dropout rate, 102 patients were studied to allow for minimize statistical errors. 202 patients were collected in our study, randomized to group C30 (76 cases), group C60 (62 cases) and group D (64 cases).
Statistical analysis
Data were tested for normal distribution using the Kolmogorov–Smirnov test. Continuous data were expressed as the mean ± standard deviation (SD) and categorical data were expressed as number (percentage). For comparison of demographic and operative data, quantitative data were compared with the one-way ANOVA, Bonferroni method and categorical data were compared with the χ2 test. For repeated-measurement data, data were analyzed by repeated-measures analysis of variance using the Bonferroni method. All analyses were conducted using SPSS software, version 17.0 for Windows. A P value < 0.05 were considered to indicate statistical significance.