Prediction of Acute Postoperative Pain from Assessment of Pain Associated With Venous Cannulation.

BACKGROUND: It has previously been reported that venous cannulation-induced pain (VCP) can be used to predict acute postoperative pain after laparoscopic cholecystectomy. Patients rating VCP at ≥2.0 VAS units had 3.4 times higher risk for moderate or severe pain. The purpose of this study was to evaluate if VCP scores of ≥2.0 VAS units are associated with higher risk for acute postoperative pain after various common surgical procedures. METHODS: In a prospective clinical observational study, 600 male and female 18- to 80-year-old patients scheduled for elective surgery were included. The primary outcome measure was the difference in maximum postoperative pain intensity between low responders (VCP < 2.0) and high responders (VCP ≥ 2.0) to VCP. Secondary outcome measures were the difference in proportion of patients with moderate or severe postoperative pain between low and high responders, and potential influence of age, gender, and preoperative habitual pain. RESULTS: Patients scoring VCP ≥2.0 VAS units reported higher acute postoperative pain intensity levels than those scoring VCP <2.0 VAS units (median 3.0 [interquartile range 0.0 to 5.0] vs. 0.2 [interquartile range 0.0 to 4.0], P = 0.001), and also had 1.7 times higher risk for moderate or severe postoperative pain (P = 0.005). Moderate or severe postoperative pain was reported by 38% of patients with VCP scores of ≥2.0 VAS units and by 26% with VCP scores of <2.0 VAS units (P = 0.005). CONCLUSION: Scoring of VCP intensity before surgery, requiring no specific equipment or training, is useful to predict individual risks for moderate or severe postoperative pain, regardless of patient age or gender, in a setting involving different kinds of surgery.

Single Nucleotide Polymorphisms Associated with Pain Sensitivity After Laparoscopic Cholecystectomy.

Objective: To systematically evaluate variations in single-nucleotide polymorphisms within 13 candidate pain genes in patients differing in phenotype characteristics based on a composite measure of pain sensitivity. Methods: In a case-control study, 149 patients scheduled for laparoscopic cholecystectomy were individually categorized according to preoperative pain sensitivity and postoperative pain intensity. Cases (pain group) reported cannulation-induced pain intensity higher than 2.0, together with postoperative pain intensity of 7.0 or higher (visual analog scale [VAS] units), and controls (low-pain group) reported cannulation-induced pain intensity of 2.0 or lower, together with postoperative pain intensity lower than 4.0 (VAS units). Genotyping of exomes was performed in 32 case and 25 control patients compared with respect to variations within 13 candidate pain genes. Results: There were no statistically significant differences in single nucleotide polymorphisms (SNPs) within the candidate genes between the case and control groups, but minor allele SNPs in the ABCB1 and COMT genes were more common in patients with higher levels of pain sensitivity and intensity. Conclusion: In this candidate gene study, based on a composite measure of pain sensitivity, no variations reached statistical significance after correction for multiple testing, most likely due to the large number of markers analyzed and few patients. Nevertheless, the results suggest a possible genetic contribution of single-nucleotide polymorphisms within the ABCB1 and COMT genes in individuals with higher levels of pain sensitivity.

Prediction of Postoperative Pain From Electrical Pain Thresholds After Laparoscopic Cholecystectomy.

OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). DISCUSSION: 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.