Correlation of preoperative pain threshold and pain tolerance threshold with the intensity of stress reaction induced by endotracheal intubation and skin incision / 中华麻醉学杂志

ABSTRACT

Objective To investigate the correlation of preoperative pain threshold and pain tolerance threshold with the intensity of stress reaction induced by endotracheal intubation and skin incision. Methods Fifty ASA Ⅰ or Ⅱ women, aged 20-55 yr, undergoing elective abdominal surgery requiring at least a 10-cm-long skin incision under general anesthesia, were studied. The electricity dolorimeter was used to measure the patients' pain sensitivity, including pain threshold and pain tolerance, and a State Trait Anxiety Inventory (STAI) was also used to examine the mental state the day before surgery. Total intravenous anesthesia was performed in all the patients.Anesthesia was induced with TCI of propofol 4 μg/ml (effect-site concentration). After patients lost consciousness,fentanyl 3 μg/kg and vecuronium 0.1 mg/kg were injected intravenously. Tracheal intubation was performed 3 min later and the patients were mechanically ventilated. MAP and HR were recorded and arterial blood samples were taken for determination of plasma concentrations of norepinephrine (NE) at 10 min after entering operation room (T1), immediately before intubation (T2), 2 min after intubation (T3), immediately before incision (T4) and 2 min after incision (T5). The differences in MAP, HR and plasma concentrations of NE before and after intubation and skin incision were calculated. SPSS 13.0 statistical software was used to analyze the correlation of STAI,pain threshold, and pain tolerance threshold with the differences in MAP, HR and NE before and after intubation and skin incision. Results Pain threshold was not correlated with the differences in MAP, HR and NE (P ＞0.05). Pain tolerance threshold was negatively correlated with the differences in MAP (r= - 0.766, r =-0.688,P＜0.05), HR (r=-0.703, r=-0.638, P ＜ 0.05) and NE (r=-0.781, r=-0.781, P＜0.05). The STAI score was not correlated with pain threshold and pain tolerance threshold (P ＞ 0.05) .Conclusion Preoperative pain tolerance threshold is negatively correlated with the intensity of stress reaction induced by endotracheal intubation and skin incision, but there is no correlation between pain threshold and the intensity of stress reaction.