The active ingredient in ciprofol, HSK3486, an isopropylphenol derivative, gives it a significantly higher affinity for the GABAA receptor compared to propofol. Ciprofol is 4–5 times stronger than traditional propofol [7–9]. Ciprofol has showed advantages comparing to propofol such as stable hemodynamics and reduced injection pain incidence [10–11]. Along with the increasing use of ciprofol, a deeper understanding of its role in sedation is needed.
Effective anesthesia depth monitoring is essential for evaluating the effection of anesthetics, and could inform dosage adjustments of anaesthetic drugs [12]. There have a range of methods for monitoring anesthesia depth, including BIS, E-Entropy, Narcotrend, AEP, PSI, IoC, and so on[13]. BIS, endorsed by the U.S. FDA, has emerged as the "gold standard" for its prevalence in clinical practice. While BIS demonstrates efficacy in monitoring ciprofol-induced sedation, the reporting of alternative methods in assessing sedation levels of ciprofol is very rare. A more comprehensive assessment of ciprofol using a wider variety of monitoring methods is essential.
IoC is an emerging monitoring approach, includes IoC1 and IoC2. IoC1 is adept at monitoring sedative effects, while IoC2 inflecting painful stimuli mainly with sedative effects simultaneous [14]. The target range for IoC1 during deep sedation is 40–60, and for IoC2, 30–50, signifying optimal sedation and analgesia levels [15–16]. Induction of general anaesthesia may trigger dramatic haemodynamic fluctuations, thereby increasing the risk of cardiovascular and cerebrovascular accidents [17]. Utilizing IoC1 and IoC2 in tandem facilitates a more holistic monitoring of sedation and analgesia during ciprofol induction.
This study's findings indicated significant alterations in both BIS and IoC1 values at T2(after sufentanil injection but before ciprofol injection) and T3 (after ciprofol injection when the patient loses consciousness), demonstrating IoC1 could track sedation changes timely. The Fig. 1A clearly shows that IoC1 and BIS values fluctuate within 40–60 from T4 to T8, suggesting comparable efficacy of IoC1 in monitoring sedation levels during ciprofol-induced general anesthesia.
To objectively evaluate the consistency between IoC1 and BIS during ciprofol induction, this study utilized Bland-Altman for statistical analysis. Bland-Altman analysis graphically represents the agreement between two measurement methods, indicating good consistency when the majority of data points reside within the 95% confidence interval and the maximum difference is deemed clinically acceptable. In this study, Bland-Altman plots revealed that the majority of data points were within this interval and the maximum difference, which is deemed clinically acceptable, with no significant difference between the two measurements. Those confirmed the strong consistency between IoC1 and BIS in monitoring sedation levels during induction of general anaesthesia by ciprofol.
ROC curve analysis demonstrated that the AUC for IoC1 and BIS in monitoring at the time of lossing consciousness exceeded 0.98, signifying high predictive accuracy for IoC1 during the loss of consciousness.
The study findings also demonstrate that IoC2 is sensitive to track variations in the level of analgesia combined with sedation across various time points during induction. And the mean values of IoC2 were ranging with 30–50 from T4-T8. Previous studies have shown that IoC2 can be successfully used to monitor the level of compound anaesthesia induced by propofol [18]. This study demonstrated that IoC2 responded to changes in compound anaesthesia levels at various time points during ciprofol induction rapidly, and IoC2 reflected the level of analgesia combined with sedation during deep anaesthesia induce by ciprofol. Tl Wang et al have reported that the integrated application of IoC1 and IoC2 for elderly patients undergoing laparoscopic surgery could decrease propofol and opioid dosage, minimize stress responses which including increased blood glucose and lactic acid levels, thereby reducing complications and accelerating patient recovery [19]. Another research indicates that in elderly patients undergoing thoracoscopic lobectomy, the dual monitoring of IoC1 and IoC2 can curtail remifentanil and vasoactive drug usage, thereby stabilizing hemodynamics[20]. Collectively, the significance of the combined IoC1 and IoC2 monitoring in clinical anesthesia is obvious. This study confirmed the accuracy of IoC monitoring of ciprofol, provides additional monitoring methods for the clinical use of ciprofol, and lay a stronger foundation for better clinical use of ciprofol.
There are still some shortcomings in this study. Firstly, the study was limited to the induction phase of general anesthesia. The accuracy of IoC for monitoring the maintenance and awakening phases of ciprofol anaesthesia has not been studied. Secondly, the sample size for this study is not very large. These need to be confirmed by more studies in the future.
Overall, this study demonstrated that IoC1 exhibiting a strong consistency with BIS in monitoring sedation levels during ciprofol-induced general anesthesia, affirmed the effectiveness of IoC1 on the sedative monitoring effects of ciprofol when consciousness disappears. IoC is an effective monitoring tool for sedative effects of ciprofol-induced general anesthesia.