The 95% effective dose of ciprofol-assisted sedation for knee arthroplasty in elderly patients: a prospective cohort study

Background: Sedation is an important component of regional anesthesia. The pharmacokinetics and pharmacodynamics of elderly patients undergo changes with increasing age, resulting in heightened sensitivity to a multitude of drugs. There is a paucity of data regarding the 95% effective dose of ciprofol-assisted sedation for knee arthroplasty under intrathecal anesthesia in elderly patients. Materials and methods: A prospective cohort study was conducted on elderly patients aged 65 years and above who were undergoing knee arthroplasty. The initial maintenance dose of ciprofol for sedation was 0.2 mg · kg −1 · h −1 . The degree of sedation was evaluated using the Modified Observer’s Assessment of Alertness and Sedation (MOAA/S) scale, while bispectral index (BIS) values were monitored. The maintenance dose of ciprofol for each subsequent patient was adjusted by the biased coin design up-and-down sequential method. The ED 95 for ciprofol-assisted sedation was calculated by isotonic regression, and 95% confidence interval was obtained by bootstrapping algorithm on the results of 2000 replicates. At the same time, the changes of vital signs and the occurrence of adverse events during and after operation were recorded. Results: A total of 66 patients participated in the study. 1 patient was excluded due to insufficient observation time; 4 patients who had hypotension were relieved and excluded after giving ephedrine; 2 patients were relieved and excluded after atropine was given due to bradycardia and 3 patients were excluded due to abnormal limb movements. Among the 56 patients who completed the experiment, no sedation-related adverse events occurred. The ED 95 for ciprofol-assisted sedation was calculated to be 0.363 mg · kg −1 · h −1 [95% CI, 0.352 ~ 0.375 mg · kg −1 · h −1 ]. Conclusion: At intrathecal anesthesia block planes of T10 to T11, the ED 95 of ciprofol-assisted sedation for knee replacement in elderly patients is 0.363 mg · kg −1 · h −1 [95% CI, 0.352 ~ 0.375 mg · kg −1 · h −1 ].