The Accuracy Of Surgical Pleth Index For Predicting Postoperative Pain In Cancer Patients

Objective:To analyze the accuracy of surgical volume measurement index in predicting postoperative pain in tumor patients by recording the changes of SPI value and VAS scores in the last 10min before the end of surgery for patients under general anesthesia,and to provide reference for clinical postoperative pain management.Methods:Seventy-two patients with abdominal tumor resection under selective sevoflurane-remifentanil general anesthesia were selected,aged 18～75 years,ASA grade I or II,NYHA grade I to II,BMI 18～30kg/m².After the patient entered the room,a warm blanket was routinely laid for insulation,upper limb venous access was established,oxygen flow was 4～5L/min for oxygen inhalation,and GE B850 patient monitor was connected.Electrocardiogram（ECG）,Non-invasive Blood Pressure（NIBP）,Saturation of Pulse Oxygenation（Sp O₂）,End-tidal Partial Pressure of Carbon Dioxide(P_ETCO₂),Bispectral index（BIS）,Surgical Pleth Index（SPI）and Body Temperature（T）were regularly monitored.The left radial artery was catheterized under local anesthesia with lidocaine and the invasive arterial blood pressure（IBP）was monitored.Anesthesia induction:intravenous injection of propofol 1.5mg/kg,sufentanil 0.3μg/kg,cisatacurium 0.2mg/kg,endotrachea intubation after auxiliary ventilation,followed by mechanical ventilation,the ventilation mode is Volume Controlled Ventilation（VCV）,Tidal Volume（VT）6～8ml/kg,Inspiratory to Expiratory Ratio（I:E）1:2,Respiratory Rate（RR）12～14 times/min,maintain P_ETCO₂ at 35～45mm Hg.Anesthesia maintenance:inhalation of 1%～3%sevoflurane,remifentanil0.1～0.2μg/（kg·min）,BIS value maintained between 45～60,intermittent injection of cisatracurium to maintain muscle relaxation.All patients were treated with PCIA electronic pump after surgery.PCIA regimen:Butorphanol tartrate 0.15mg/kg+Sufentanil 1μg/kg+Palonosetron 0.25mg,diluted to100ml with 0.9%Sodium chloride injection,Bolus 0.5ml,locking time 15min.After operation,connect and run the PCIA electronic pump.Baseline values of MAP,HR,and BIS were recorded after admission,and baseline values of SPI were recorded during anesthesia induction.MAP,HR,BIS and SPI values were recorded immediately after endotracheal intubation,immediately after skin cutting,and immediately after surgery.SPI values were recorded every10s and MAP and HR every minute in the last 10min before the end of surgery.All patients were admitted to the Postanesthesia Care Unit（PACU）for evaluation.When the Ramsay score was 2 points,the VAS pain score was performed every 3 minutes（digital score was 0～10 points,0～3 points for mild pain,4～6 points for moderate pain,7～10 was classified as severe pain）lasted for 15min（time points were recorded as T₁,T₂,T₃,T₄,T₅）,VAS pain scores at 1h,6h,12h,24h,and 48h after recovery(time points were recorded as T₆,T₇,T₈,T₉,and T₁₀),and the number of pressing of PCA after surgery was recorded.Draw the Receiver Operating Characteristic Curve（ROC）of SPI、MAP、HR and postoperative VAS pain score in the last 10 minutes before the end of the operation,and calculate the Area Under ROC Curve（AUC）,P value,threshold,sensitivity,specificity and Youden index were calculated.The ROC curves of△SPI（△SPI being the difference between maximum SPI and baseline）,△MAP（the difference between MAP and baseline）,△HR（the difference between HR and baseline）and postoperative VAS pain scores were drawn,and the Area Under ROC Curve（AUC）),P value,threshold,sensitivity,specificity,and Youden index were calculated.Results:1.The AUC of ROC curve of SPI in T₁～T₁₀ for predicting postoperative pain degree was 0.858,0.851,0.817,0.817,0.782,0.773,0.670,0.628,0.763,0.925,respectively.The threshold value of SPI for predicting mild and moderate severe pain 1h after surgery was 38.The AUC of ROC curve of△SPI at T₁～T₁₀ for predicting postoperative pain was 0.818,0.823,0.861,0.861,0.802,0.803,0.680,0.738,0.660,0.797,respectively.The threshold value of△SPI for predicting mild and moderate severe pain at 1h after surgery was 22.Its predictive power is higher than SPI.Conclusion:1.SPI and△SPI 10min before the end of surgery can predict the degree of acute pain within 1h after surgery,and their thresholds for predicting mild and moderate pain within 1h after surgery are 38 and 22,respectively.2.The ability of△SPI to predict postoperative pain at 1h was better than that of SPI.