Pain assessment using the Analgesia Nociception Index in patients undergoing sedation: a systematic review and meta-analysis.

Background: This systematic review and meta-analysis analyzed the utility of the Analgesia Nociception Index (ANI) in detecting intraoperative and procedural pain in sedated patients.

Methods: A comprehensive search of the Cochrane Central Register of Controlled Trials, Ovid-MEDLINE, Ovid-Embase, and Google Scholar databases was performed to identify relevant studies. The primary outcome was the diagnostic accuracy of ANI, assessed by pooled sensitivity, specificity, likelihood ratios, and diagnostic odds ratio (DOR). Secondary outcomes were the correlation between ANI and pain assessment scales, the effect of norepinephrine (NE) on ANI, and differences in opioid consumption between the ANI-guided and control groups.

Results: Eleven studies were included in the systematic review, with ten studies incorporated into the meta-analysis. ANI demonstrated moderate sensitivity (0.746, 95% confidence interval [CI] = 0.683-0.803) and specificity (0.776, 95% CI = 0.741-0.808) for detecting intraoperative and procedural pain, with a pooled DOR of 10.491. ANI was lower in the pain state than that in the no-pain state (standardized mean difference [SMD] = -1.140, 95% CI = -1.239 to -1.041, I² = 93.63%). ANI-guided analgesia was associated with a significant reduction in opioid consumption (SMD = -0.410, 95% CI = -0.643 to -0.178, I² = 0.0%). There were no significant differences in ANI between the NE and control groups. ANI showed a negative correlation with pain scales (r = -0.110 to -0.470).

Conclusions: ANI effectively differentiated between the pain and non-pain states in sedated patients with moderate diagnostic accuracy and helped reduce opioid consumption. However, the high heterogeneity suggests the need for cautious interpretation.