Abstract:Objective To investigate the 90% effective dose (ED90) of ciprofol combined with alfentanil in inhibiting gastroscopy insertion response in elderly patients.Methods 110 patients were selected to undergo painless gastroscopy examination on a scheduled basis. 110 patients were randomly divided into ciprofol group alone (group H, n = 57) and ciprofol group combined with alfentanil 5 μg/kg (group A, n = 53). The trial was conducted according to the Biased coin design up-and-down (BCD-UDM) sequential. Patients in group H were given only intravenous infusion of ciprofol and patients in group A were pre-infused with intravenous alfentanil at 5 μg/kg, followed by intravenous infusion of ciprofol, and gastroscopy was initiated when the modified observer's assessment of alertness/sedation scale (MOAA/S) was ≤ 1 point. The initial dose of ciprofol was 0.200 mg/kg in all cases, and the adjacent isotropic dose was 0.030 mg/kg. If the patient's MOAA/S was still > 1 or the patient had a response that interfered with the operative examination, such as choking or body movement, during gastroscopy placement, 2.0 min after the intravenous infusion of ciprofol, was regarded as an ineffective response, then the next patient was elevated by one dose gradient. If the anesthetic effect of the previous patient was judged to be a valid response, the next patient was randomized to a dose according to the BCD-UDM, with an 11% (b = 0.11) probability of decreasing the dose gradient by one dose, and an 89% (1-b = 0.89) probability of remaining unchanged, and the experiment was terminated at the 45th effective response in each group. Probabilistic unit regression analysis was used to calculate the ED90, 95% effective dose (ED95), and 95% confidence intervals (CI) for the inhibition of gastroscopy placement response with ciprofol alone and the combination of 5 μg/kg alfentanil in elderly patients.Results The ED90 of ciprofol in group A was 0.296 mg/kg (95%CI: 0.275 ~ 0.338 ), and ED95 was 0.310 mg/kg (95%CI: 0.291 ~ 0.383); The ED90 of ciprofol in group H was 0.407 mg/kg (95%CI: 0.390 ~ 0.447), and ED95 was 0.420 mg/kg (95%CI: 0.402 ~ 0.483). Compared with group H, the total amount of ciprofol was significantly reduced in group A, the time of awakening and time of leaving the hospital were significantly shorter, and the incidence of intraoperative hypotension and hypoxemia was significantly lower, the differences were statistically significant (P < 0.05).Conclusion The ED90 of ciprofol combined with 5 μg/kg of alfentanil and ciprofol alone in inhibiting gastroscopy implantation in elderly patients are 0.296 mg/kg and 0.407 mg/kg respectively.