Preoperative Pain Sensitivity Predict Patients' Stress Responses During Intubation And Skin Incision

Objective: To investigate whether preoperative pain sensitivity predict patients, stress response and opioids consumption during anesthetic intubation and skin incision.Methods: Fifty women(ASA physical statusⅠ～Ⅱ)aged 20～55, undergoing elective abdominal surgery requiring at least a 10-cm-long skin incision, needed general anesthesia were studied. We used the electricity dolorimeter to meaure patients, pain sensitivity, inlcuding pain threshold and pain tolarance, a State Trait Anxiety Inventory (STAI) was also used to examine the mental state the day before surgery. During anesthesia, total intravenous anesthesia, we used propofol with target controlled infusion(TCI), the target concentration was 4μg/ml, vecuronium 0.1mg/kg and fentanyl 3μg/kg for intubation. After intubation, propofol was maintained at 2μg/ml with TCI. 3min before incision, the propofol target concentration was up to 3μg/ml, fentanyl 1.5μg/kg was used for intravenous injection. Mean arterial blood pressure(MAP), heart rate(HR) electrocardiogram(ECG) and pulse oximentry(Spo2) were measured, and arterial blood sample for plasma concentrations of norepinephrine(NE) was drawed at 10min after entering operationroom(T1), immediately before intubation(T2), 2min after intubation(T3), immediately before incision(T4), 2min after incision(T5). We use the SPSS statistics software to analyze the correlation between STAI, pain threshold, pain tolanrance and the changes of MAP, HR , NE before and after intubation and incision.Results: Fifty women were enrolled. Their preoperative pain threshold and pain tolerance were 0.90±0.40mA and 2.53±0.77mA, respectively. The mean raw STAI score for state anxiety was 47.22±7.98, trait anxiety was 41.14±6.21. The STAI score was not correlated with pain threshold and pain tolerance(P>0.05), and was not correlated with the changes of MAP, HR and NE(P>0.05). Pain tolerance not pain threshlod had significant inverse correlation with the changes of MAP, HR, NE before and after intubation (r =-0.766, P<0.05. r =-0.703, P<0.05. r =-0.781, P<0.05) and skin incision(r =-0.688, P<0.05. r =-0.638, P<0.05. r =-0.710, P<0.05).Conclusion: Pain tolarance had significant inverse correlation with stress response during anesthetic intubation and skin incision.