Yu Wei,1– 3,* Jianwei Wang,1– 3,* Zifeng Xu,1– 3 Rui Ma1– 3 

1Department of Anesthesiology, the International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China; 2Shanghai Key Laboratory of Embryo Original Diseases, Shanghai, Peoples Republic of China; 3Shanghai Municipal Key Clinical Specialty, Shanghai, Peoples Republic of China

*These authors contributed equally to this work

Correspondence: Rui Ma; Zifeng Xu, Department of Anesthesiology, the International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Key Laboratory of Embryo Original Diseases, Shanghai Municipal Key Clinical Specialty, Huashan Road 1961, Shanghai, 200030, People’s Republic of China, Tel +86-021-64070434, Email marui_merrygood@163.com; xuzf@shsmu.edu.cn

Aim: This study aimed to assess the correlation of plasma concentration (Cp) and effect-site concentration (Ce) of propofol and remifentanil with level of consciousness and evaluate their reference values during extubation in patients scheduled day-case operative hysteroscopy under propofol-remifentanil anesthesia.
Methods: Propofol (Marsh model) and remifentanil (Minto model) were simultaneously administered using a target-controlled infusion (TCI) pump for the induction and maintenance of anesthesia. The Cp and Ce of propofol (PCp and PCe) and remifentanil (RCp and RCe) before anesthesia induction, at the end of surgery, and at the time of extubation were respectively recorded. Predictive performance was assessed using the jackknife method.
Results: At the time of extubation, PCp was 1.17 ± 0.168 (95% CI: 1.14– 1.20 μg/mL), PCe was 1.7 ± 0.212 (95% CI: 1.65– 1.74 μg/mL), RCp was 0.769 ± 0.12 (95% CI: 0.75– 0.79μg/mL), and RCe was 0.972 ± 0.179 (95% CI: 0.94 − 1.01 μg/mL). The Pk values of PCp, PCe, RCp and RCe were 0.999, 0.993, 1.00 and 0.995, separately. Postoperative decreases in PCp (r = 0.089, p < 0.001), PCe (r = 0.087, p= 0.001), RCp (r = 0.072, p < 0.000) and RCe (r = 0.077, p < 0.001) were significantly correlated with the recovery time.
Conclusion: PCp, PCe, RCp and RCe, together with OAA/S Scale and the recovery of spontaneous respiration might be potential reference indicators for extubation in day-surgery hysteroscopy following general anesthesia using TCI.

Keywords: day surgery, effect-site concentration, plasma concentration, prediction probability, target-controlled infusion