Evaluation of a Preoperative Pain Score in Response to Pressure as a Marker of Postoperative Pain and Drugs Consumption in Surgical Thyroidectomy

Abstract

The success and effectiveness of a day surgery model are essentially related to a good postoperative course with a rapid recovery. Adequate management of analgesia during the hospital stay and after discharge becomes mandatory in reducing postoperative patient discomfort, and in facilitating discharge to home. The aim of this study was to identify the efficacy of preoperative visual analog scale (VAS) score in predicting postoperative pain and analgesic drugs consumption. The hypothesis of a significant relation between preoperative pain and postoperative pain tolerance thresholds was tested using Spearman rank-order correlations, applied to patients scheduled for thyroidectomy in a Day Surgery Unit. Patients scheduled for total thyroidectomy underwent a preoperative pain test to assess the VAS value after a fixed stimulus (inflation of a sphygmomanometer with a pressure of 250 mm Hg). To estimate the power of the VAS in prediction of the postoperative analgesic requests, we divided the patients into 3 groups according to the preoperative VAS values (A group, including all patients with preoperative VAS≤3; B group including patients with preoperative VAS>3≤6; C group with preoperative VAS>6).Then we correlated preoperative results with postoperative VAS values and postoperative analgesic drug consumption, analyzing the correlation between the sensitivity and the specificity of the VAS test for a range of different cutoff values. Thirty-two patients were included. A group (10 patients) showed a medium postoperative VAS<4, and required less analgesics than other groups (ketorolac, 51 mg). B group (10 patients) and C group (12 patients) showed higher postoperative VAS value and required more analgesic drug (B, 80 mg; C, 90 mg+1 g acetaminophen). Using the receiver operating characteristic or relative operating characteristic examination and calculating the underlying area , we could measure the discriminating ability of the test and found that the best VAS score cutoff was 3. The use of a preoperative test to assess individual pain threshold may be predictive for postoperative pain and analgesic request. The mathematical and statistical model used in this study confirms that a difference in the value of VAS of 3 shall be mathematically eligible for analgesia treatment.