To evaluate the dose-effect relationship of ciprofol combined with remifentanil to inhibit responses to gastroscope insertion.

Patients who planned to undergo gastroscopy from January 2024 to April 2024 were included. Inclusion criteria: age 18-65 years old, American Society of Anesthesiologists (ASA) grade Ⅰ to Ⅱ, body mass index (BMI) 18.5-27.9 kg/m². Ciprofol was injected intravenously for 30 s, remifentanil was injected intravenously for 1.0 μg/kg for 60 s. The patients' ciprofol dose was adjusted by Dixon sequential method. The initial dose was set at 0.30 mg/kg and the adjustment range was ±0.02 mg/kg. Probit regression was used to calculate the ED50 and ED95 of ciprofol combined with 1.0 μg/kg remifentanil to inhibit gastroscope insertion. The heart rate, noninvasive mean arterial pressure (MAP) and oxyhemoglobin saturation (SpO₂) of patients were recorded immediately after entering the endoscopy room (T0), 1 min after ciprofol injection (T1), immediately after gastroscope insertion (T2), immediately after gastroscope withdrawal (T3), and at the time of recovery (T4). Recovery time, length of postanesthesia care unit (PACU) stay and perioperative complications were recorded.

According to the Dixon sequential method, the study was terminated after 28 patients were enrolled. Probit regression results showed that the ED50 of cipofol combined with 1.0 μg/kg remifentanil inhibited responses to gastroscope insertion was 0.254 mg/kg (95% CI: 0.242-0.266 mg/kg). The ED95 was 0.290 mg/kg (95% CI: 0.260-0.320 mg/kg). The MAP of T1, T2 and T3 was significantly lower than that of T0, with statistically significant differences (P<0.05). The recovery time of patients was (5.3±1.8) min and the length of PACU stay was (46.4±11.1) min. Bradycardia, hypoxemia and hypotension occurred in 2, 2 and 3 patients, respectively.

The ED50 and ED95 of cipofol combined with 1.0 μg/kg remifentanil to inhibit responses to gastroscope insertion are 0.254 mg/kg and 0.290 mg/kg, respectively. This anesthesia program has a low incidence of perioperative complications and has high efficacy and safety.