Effect of vaginal delivery history on oliceridine ED₅₀ combined with propofol during painless hysteroscopy: a modified Dixon sequential study

Objective To determine the median effective dose (ED 50 ) of oliceridine combined with propofol for inhibiting movement response during hysteroscopy in patients with versus without a history of vaginal delivery. Methods Patients scheduled for hysteroscopy who met the inclusion criteria were stratified into two cohorts: those with no history of vaginal delivery (NVD cohort, including nulliparous women and those with prior cesarean section only) and those with a history of vaginal delivery (VD cohort). Based on the Dixon sequential outcomes, patients were further classified as negative subcohort (successful hysteroscopy, indicating no body movement) or positive subcohort (failed hysteroscopy, indicating body movement). An initial intravenous oliceridine dose of 20 μg/kg was administered, followed by propofol 1.5 mg/kg after 2 min. Successful induction was defined as a Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) score of 0 (no response to trapezius squeeze) and a bispectral index (BIS) < 60. Intraoperative propofol boluses (0.5 mg/kg) maintained BIS between 40 and 60. Oliceridine dosing was adjusted using a modified Dixon up-and-down sequential method (dose ratio 1:1.2 between adjacent levels) until at least seven crossover points were recorded. The primary outcome was the ED 50 of oliceridine for suppressing body movement, calculated by probit regression with 95% confidence interval (CI). Cohort comparison of ED 50 was performed using a Z -test. Results The ED 50 of oliceridine for suppressing movement response during hysteroscopy was 21.603 μg/kg (95% CI: 19.922–23.752) in the NVD cohort and 17.816 μg/kg (95% CI: 15.880–19.981) in the VD cohort. A formal Z -test confirmed that the NVD cohort required a 21% higher ED 50 than the VD cohort, and this difference was significant ( Z = 2.646, p = 0.008). No significant baseline differences were observed between the negative and positive subcohorts (all p > 0.05). The NVD negative subcohort required higher oliceridine ( Z = 3.19, p < 0.001); the VD negative subcohort consumed more propofol ( t = 2.11, p = 0.038) and oliceridine ( Z = 3.05, p = 0.002). No severe adverse events occurred. Conclusion During painless hysteroscopy, the ED 50 of oliceridine combined with propofol for suppressing movement response was 21% higher in patients without a history of vaginal delivery than in those with such a history. This finding suggests that a history of vaginal delivery may be a useful factor to consider when individualizing initial oliceridine dosing in this setting. Clinical trial registration ChiCTR2500095126 ( https://www.chictr.org.cn )