Prediction of Postoperative Pain From Electrical Pain Thresholds After Laparoscopic Cholecystectomy

Early postoperative pain correlates to persisting pain, psychosocial distress, and delayed mobilization with thromboembolic and infectious complications. Electrical pain thresholds (EPT) have shown promising results in being able to predict postoperative pain, but the results are conflicting. The aim of this study was to test whether EPT levels can be used to predict the postoperative pain in patients of both sexes.

One hundred eighty patients scheduled for laparoscopic cholecystectomy were included in this prospective clinical study. Individual levels of EPT were measured before surgery, and the pain intensity was evaluated in the early postoperative period.

There were significant correlations between EPT and the maximum postoperative pain intensity (rs=-0.21, P=0.009), time to the first rescue opioid (rs=0.26, P=0.006), and the total dose of rescue opioid (rs=-0.22, P=0.001). The interaction test showed significant influence of the sex on the ability of EPT to predict the postoperative pain intensity. Female patients with low EPT (<15) had a 4.5 times higher risk of postoperative pain (P=0.003).

Levels of EPT are reproducible, and the technique is well tolerated. However, it can be used to predict postoperative pain only in women. A weak correlation with the postoperative pain intensity, found here as well as previously, and the high sex dependency of the EPT levels obtained considerably limit the predictive value of this technique for routine use in perioperative clinical practice.