Accuracy of analgesia/nociception index in assessing severity of postoperative pain

Abstract

Objective To investigate the accuracy of analgesia/nociception index (ANI) in assessing the severity of postoperative pain in patients. Methods Eighty patients, aged 21-77 yr, of American Society of Anesthesiologists physical status Ⅰ-Ⅲ, scheduled for elective operation, were admitted to the postanesthesia care unit after the patients were extubated at the end of operation, and ANI was monitored.Immediately after admission to the postanesthesia care unit (T0), numerical rating scale (NRS) score was recorded.If NRS score was 0-3, the patients received no treatment, and NRS score was recorded again 10 min later (T1). If NRS score was 4-10, fentanyl 50 μg was injected intravenously, and NRS score was recorded again 5 min later (T2). ANI value was recorded at T0, T1 and T2.NRS score was considered as the criterion for assessment of the severity of pain.The receiver operating characteristic curve was used to analyze the sensitivity and specificity of ANI in determining NRS scores, the cut-off value was determined, and the area under the curve and 95% confidence interval were calculated.Pearson correlation was used to analyze the correlation between ANI and NRS score. Results The area under the curve (95% confidence interval) of ANI in determining NRS scores was 0.873 (0.816-0.929), and the cut-off value was 45 with a sensitivity of 74.8% and a specificity of 87.5%.ANI was negatively correlated with NRS score, and the correlation coefficient was -0.705 (P<0.05). Conclusion ANI provides high accuracy in assessing the severity of postoperative pain with a cut-off value of 45 in the patients. Key words: Pain, postoperative; Pain measurement