The Correlation Between Preoperative Pain Sensitivity And Intraoperative Stress Response Intensity Of Female Patients Under General Anesthesia And Provide Basis For Personalized Medication Of General Anesthesia

Objective:To investigate the correlation between preoperative pain sensitivity and intraoperative stress response intensity of female patients under general anesthesia and provide basis for personalized medication of general anesthesia.Methods:30 female cases (ASA physical status Ⅰ～Ⅱ)aged 35～65, undergoing open radical resection of rectal carcinoma (operative incision≥15cm) under general anesthesia by intubation were random enrolled. On the afternoon of the day before operation, a pain threshold tester was employed to determine the skin pain sensitivity indexes of these patients (pain threshold and threshold of pain tolerance) by their beds by point electrical stimulation. Channels for intravenous infusion were established in left lateral elbows for the induction with anesthetics. The bispectral index (BIS), electrocardiogram (ECG), heart rate (HR), respiratory rate (RR), SpO2, systolic pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were monitored. All patients received total intravenous anesthesia (TIVA). During the induction, propofol (initial concentration:3μg/ml; then adjust the concentration until BIS reaches 40～50) was first given by target controlled infusion, Cis-atracurium (0.2mg/kg) was administrated intravenously, remifentanil (6ng/ml) was given by target controlled infusion, and trachea cannula was placed 3 minutes later. The target controlled concentration of remifentanil was lowered to 4ng/ml after the placement of trachea cannula, while the plasma propofol concentration was adjusted to keep BIS at 40～50. When BP and HR were resumed to the baseline values, the target controlled concentration of propofol was adjusted to 2μg/ml, and then was increased to 3μg/ml before skin incision, and fentanyl citrate injection (4μg/kg) was also administrated by intravenous drip. The target controlled plasma concentration of propofol was maintained at 4-6ng/ml, with 0.1mg/kg of cis-Atracurium being added every 45 minutes. During the experiment, SBP, DBP, MAP, HR, SpO2, EtCO2 and BIS were recorded at the following 11 time points:before anesthesia (stay calm for 10 minutes after entering operation room), upon intubation,2 minute after intubation,10 minutes after intubation, upon skin incision,2minute after skin incision, at 30min, at lh, at 2h, upon abdomen closure, and at the end of operation. Also, blood specimens were collected and detained for determining norepinephrine (NE), cortisol (Cor), superoxide dismutase (SOD) and malondialdehyde (MDA) in plasma. The statistical results of the measurement data were analyzed using SPSS 19.0 statistical software. The differences of MAP, HR, and concentrations of NE, Cor, SOD and MDA in plasma before and after corresponding time points were calculated. Pearson correlation analysis was employed to identify the correlations of preoperative pain threshold and threshold of pain tolerance with the differences of MAP, HR, and concentrations of NE, Cor, SOD and MDA in plasma before and after corresponding time points.Results: ① Pain threshold was negatively correlated with the differences in MAP, HR and NE concentrations before and after tracheal intubation, before and after skin incision, and before and after abdominal closure (P<0.05), while threshold of pain tolerance had no correlations with the above differences (P>0.05).② Threshold of pain tolerance was negatively correlated with the differences between the cortisol concentration before anesthesia and those half an hour, one hour and two hours after incision respectively (P<0.05), while pain threshold has no correlations with the above differences (P> 0.05). ③Threshold of pain tolerance was negatively correlated with the differences between the SOD and MDA concentration before anesthesia and those one hour and two hours after incision respectively (P<0.05), while pain threshold showed no correlations with the above differences (P>0.05).Conclusions:For female patients undergoing open radical resection of rectal carcinoma under general anesthesia with the same anesthesia depth and the same pain relieving degree, tracheal intubation and operative stimulation cause stress responses of varying intensities that are negatively correlated with the preoperative threshold of pain tolerance. In other words, the lower the preoperative threshold of pain tolerance, the stronger the intraoperative stress response is, while these responses have no correlations with pain threshold.