A Study On The Application Of Surgical Pleth Index And Index Of Consciousness 2 In Patients Undergoing Total Intravenous Anesthesia

Background and objectives:Adequacy of anesthesia requires the anesthetist to adjust the dose of anesthetic according to the patient’s response to sedation,analgesia and myorelaxation.This approach is crucial to enhancing the quality of intraoperative anesthesia management and postoperative recovery.Precise intraoperative monitoring serves as the foundation and central element of adequacy of anesthesia.Although conventional monitoring indicators exist for monitoring sedation and myorelaxation,there are no globally accepted,objective and valid indicators for monitoring noxious stimulation.Surgical pleth index（SPI）and index of consciousness 2（IoC2）are two indicators for monitoring noxious stimulation during surgery.SPI is determined by integrating photoplethysmography pulse wave amplitude and heart beat interval,and quantifying peripheral sympathetic nervous system activity.IoC2 is based on index of consciousness 1 and derived from the electroencephalographic anesthesia depth monitor of Shenzhen Weihaokang Company.The electroencephalogram signal is segmented into several regions and the electroencephalogram amplitude is calculated using specific frequency bands to indicate the patient’s level of noxious stimulation.Studies have shown that intraoperative monitoring of noxious stimulation using SPI or IoC2 can decrease opioid consumption and improve postoperative recovery quality.However,there are few comparative studies on the application of the two indicators in monitoring the effectiveness of noxious stimulation and predicting early postoperative pain.Therefore,this study aims to collect 120 patients undergoing thyroid surgery under total intravenous anesthesia to investigate the effectiveness of SPI and IoC2 in monitoring intraoperative noxious stimulation and predicting early postoperative pain,so as to achieve rational application of intraoperative analgesic drugs and optimize postoperative analgesic protocols,improve the intrinsic quality of anesthesia,and provide data to support the clinical application of noxious stimulation monitoring instruments.Part Ⅰ:A study on the application of surgical pleth index and index of consciousness2 in monitoring noxious stimulation in patients undergoing total intravenous anesthesiaMethods:We selected 120 patients aged 18-65 years with a BMI of 18.5-30 kg/m² and ASA class Ⅰ or Ⅱ undergoing elective thyroid surgery under total intravenous anesthesia.Each patient was induced with propofol-remifentanil and maintained with target-controlled infusion of propofol and remifentanil.Patients were monitored for depth of sedation using bispectral index（BIS）and for noxious stimulation using SPI and IoC2.The data recorded included:SPI,IoC2,HR and MAP values 2 min before noxious stimulation,mean values of SPI,IoC2,HR and MAP within 2 min before noxious stimulation,the maximum values of SPI,IoC2,HR and MAP within 2 min after noxious stimulation,SPI,IoC2,BIS,HR,MAP values at the time of loss of consciousness,at the time of tracheal intubation,at 5 min of tracheal intubation,at the start of surgery,at 5 min of the start of surgery,at the time of skin suture,and at the end of surgery.The effectiveness of SPI,IoC2,HR and MAP in monitoring intraoperative noxious stimulation and the effectiveness of SPI and IoC2 in predicting cardiovascular response to noxious stimulation were analyzed by receiver operator characteristic（ROC）curve.ROC curve pairwise comparisons were analyzed using the Z test.Spearman rank correlation method was used to analyze the correlation between SPI,IoC2 and BIS,HR,MAP.Results:1.According to ROC curve analysis,SPI,IoC2,HR and MAP all had monitoring value for noxious stimulation（P<0.05）,and the differences in area under curve（AUC）between SPI and HR,MAP,IoC2 and HR,MAP were statistically significant（P<0.05）,but there was no statistically significant difference in AUC between SPI and IoC2（P>0.05）.ΔSPI,ΔIoC2,ΔHR andΔMAP also had monitoring value for noxious stimulation（P<0.05）,and the differences of AUC betweenΔSPI andΔHR,ΔMAP,ΔIoC2 andΔHR,ΔMAP were statistically significant（P<0.05）,but the difference of AUC betweenΔSPI andΔIoC2 was not statistically significant（P>0.05）.There were statistically significant differences in AUC between SPI andΔSPI,IoC2andΔIoC2,HR andΔHR,MAP andΔMAP for monitoring the noxious stimulation（P<0.05）.2.According to ROC curve analysis,SPI and IoC2 had predictive value for cardiovascular response to tracheal intubation stimulation（P<0.05）,and there was no statistically significant difference in AUC between SPI and IoC2（P>0.05）.SPI and IoC2 had no predictive value for cardiovascular response to skin incision stimulation（P>0.05）.3.According to Spearman rank correlation analysis,the correlation coefficients of SPI and IoC2 with BIS,HR,MAP were r _SPI-BIS=0.060,r _SPI-HR=0.301,r _SPI-MAP=0.347,r _IoC2-BIS=0.371,r _IoC2-HR=0.131,r _IoC2-MAP=0.260,respectively.SPI and HR,MAP,IoC2 and BIS,HR,MAP were positively correlated,the correlations were significant（P<0.05）,SPI and BIS correlation was not significant（P>0.05）.Conclusions:SPI and IoC2 have monitoring value for noxious stimulation,and their effectiveness is comparable,both of which are better than the traditional evaluation indicators HR and MAP which are based on hemodynamics;SPI and IoC2 have predictive value for cardiovascular response to tracheal intubation stimulation and both are of equal validity;SPI is significantly and positively correlated with HR and MAP,IoC2 is significantly and positively correlated with BIS,HR and MAP.Part Ⅱ:A study on the application of surgical pleth index and index of consciousness2 in predicting early postoperative pain in patients undergoing total intravenous anesthesiaMethods:We selected 120 patients aged 18-65 years with a BMI of 18.5-30 kg/m² and ASA class Ⅰ or Ⅱ undergoing elective thyroid surgery under total intravenous anesthesia.Each patient was induced with propofol-remifentanil and maintained with target-controlled infusion of propofol and remifentanil.Patients were monitored for depth of sedation using BIS and for noxious stimulation using SPI and IoC2.The mean values of SPI,IoC2,HR and MAP within 5 min before the end of surgery were recorded.Numerical rating scale was used to evaluate the pain scores of patients 5,10 and 15 minutes after extubation,and the maximum pain score was recorded as N_max.The effectiveness of SPI,IoC2,HR and MAP in predicting early postoperative pain was analyzed by ROC curve.ROC curve pairwise comparisons were analyzed using the Z test.Spearman rank correlation method was used to analyze the correlation between SPI,IoC2and Nmax.Results:1.According to ROC curve analysis,SPI and IoC2 had predictive value for early moderate to severe postoperative pain（P<0.05）,while HR and MAP had no predictive value for early moderate to severe postoperative pain（P>0.05）.The differences of AUC between SPI and HR,MAP,IoC2 and HR,MAP were statistically significant（P<0.05）,but the difference of AUC between SPI and IoC2 was not statistically significant（P>0.05）.2.According to Spearman rank correlation analysis,the correlation coefficients of SPI and IoC2 with N_max were r _SPI-Nmax=0.649、r_IoC2-Nmax=0.442,respectively,showing a significant positive correlation（P<0.05）.Conclusions:SPI and IoC2 have predictive value for early moderate to severe postoperative pain,and their effectiveness is comparable,both of which are better than the traditional evaluation indicators HR and MAP which are based on hemodynamics;both SPI and IoC2 are significantly and positively correlated with early postoperative pain intensity.