[Effective dose of remimazolam combined with oxycodone for inhibition of modified nasopharyngeal airway insertion reaction in female patients of different ages during hysteroscopic surgery].

To investigate the 50% effective dose (ED50) and the 95% effective dose (ED95) of remimazolam combined with oxycodone to inhibit the response of modified nasopharyngeal airway insertion for hysteroscopic surgery in female patients of different ages. Female patients aged 25-75 years who underwent hysteroscopic surgery with American Society of Anesthesiologists (ASA) grade Ⅰ-Ⅲ were prospectively enrolled from Beijing Tongren Hospital Affiliated to Capital Medical University from December 2023 to February 2024. All patients were divided into young and middle-aged group (25-<60 years old) and elderly group (≥60 years old). During the induction of anesthesia, atropine 0.2 mg, dexamethasone 5 mg, and oxycodone 0.1 mg/kg were injected intravenously in sequence. Three minutes later, remimazolam was injected intravenously. Once the eyelash reflex disappeared and Patient State Index (PSI)<50, a well-lubricated modified nasopharyngeal airway was inserted through the nasal cavity. The modified Dixon sequential method was applied. When inserting the modified nasopharyngeal airway, the presence of coughing, shaking the head, swallowing, and body movement was considered positive, while the absence of these symptoms was considered negative. The initial doses of remimazolam in both groups were 0.3 mg/kg with a dose increase and decrease gradient of 0.01 mg/kg. The first dose for the young and middle-aged group and the elderly group was determined to be 0.28 mg/kg and 0.26 mg/kg respectively based on the insertion reactions. The ED50, ED95 and 95% confidence intervals (CI) for inhibiting the reaction of modified nasopharyngeal airway insertion when using remimazolam combined with oxycodone of the two groups were compared. The adverse events after the induction of anesthesia were recorded. A total of 28 cases in young and middle-aged group, aged (40.2±6.1) years, and 29 cases in the elderly group, aged (66.3±3.2) years, were included. The ED50 of the young and middle-aged group was 0.284 (95%CI:0.274-0.293) mg/kg, which was higher than that of the elderly group at 0.260 (95%CI:0.244-0.273) mg/kg (P=0.002). The ED95 of the young and middle-aged group was 0.303 (95%CI: 0.293-0.365) mg/kg, which was higher than that of the elderly group at 0.286 (95%CI: 0.273-0.430) mg/kg (P=0.003). There were no adverse events such as nasopharyngeal pain, dizziness, lethargy, nausea and respiratory depression. One patient in the elderly group had transient hypoxemia after induction of anesthesia, which improved after mandibular support. In this study, when remimazolam was combined with oxycodone, the ED50 for inhibiting the response to the modified nasopharyngeal airway insertion for hysteroscopic surgery in young and middle-aged and elderly female patients was 0.284 and 0.260 mg/kg, respectively, and the ED95 was 0.303 and 0.286 mg/kg, respectively. The difference should be noted in the clinical use of drugs.