Remifentanil enhances the sedative effect of remimazolam during anesthesia induction in patients undergoing hysteroscopy: a randomized controlled trial

Remimazolam is a novel, short-acting benzodiazepine. This study aimed to investigate whether remifentanil enhances the sedative effect of remimazolam during anesthesia induction in patients undergoing hysteroscopy. We included 258 adult patients who underwent hysteroscopy. Patients were randomly allocated to three groups (<i>n</i> = 86) in a 1:1:1 ratio. Patients in the saline group received no remifentanil but normal saline during anesthesia induction. Patients in the remifentanil-1 group received low-dose remifentanil (plasma concentration 1 ng/ml), and those in the remifentanil-2 group received higher doses of remifentanil (plasma concentration 2 ng/ml) during anesthesia induction. After reaching the preset plasma concentration of remifentanil, remimazolam was administered (5 mg/kg/h) until loss of consciousness (LOC). During anesthesia maintenance, remimazolam and remifentanil were changed to ensure that the MOAA/S score reached 0. The primary outcome was the time from remimazolam administration to LOC. The secondary outcomes included the doses of remimazolam until LOC, characteristics of the operation and anesthesia, vital signs, and adverse events. The time from remimazolam administration to LOC was 154 (139, 180), 120 (104, 139), and 117 (105, 135) s in the saline group, remifentanil-1group, and remifentanil-2 groups, respectively (<i>p</i> &lt; 0.05). The doses of remimazolam until LOC were 12(11, 13), 9.6(8.7, 11), and 8.9(7.9, 10) mg in the saline group, remifentanil-1group, and remifentanil-2 groups, respectively (<i>p</i> &lt; 0.05). There was no significant difference in the characteristic of surgery and anesthesia between groups. Remifentanil enhances the sedative effect of remimazolam during anesthesia induction in patients undergoing hysteroscopy. The trial was registered at http://www.chictr.org.cn (ChiCTR2200062983). Remimazolam is a novel, short-acting benzodiazepine. Combinations of sedatives, including propofol and benzodiazepines, with opioids are commonly used for anesthesia.Remifentanil enhances the sedative effect of remimazolam during anesthesia induction in patients undergoing hysteroscopy.Combinations of opioids, such as remifentanil, with benzodiazepines, such as remimazolam, enhance the sedative effect of remimazolam during anesthesia induction. Remimazolam is a novel, short-acting benzodiazepine. Combinations of sedatives, including propofol and benzodiazepines, with opioids are commonly used for anesthesia. Remifentanil enhances the sedative effect of remimazolam during anesthesia induction in patients undergoing hysteroscopy. Combinations of opioids, such as remifentanil, with benzodiazepines, such as remimazolam, enhance the sedative effect of remimazolam during anesthesia induction.