Background: The Analgesia/Nociception Index (ANI), a 0-100 non-invasive index calculated from heart rate variability, reflects the analgesia/nociception balance during general anesthesia. The principal objective of this study was to evaluate the performance of ANI to predict hemodynamic reactivity during suspension laryngoscopy. The secondary objectives were to investigate the performances of ANI and bispectral index (BIS) to assess sedation and of BIS to predict hemodynamic reactivity during the procedure.
Methods: Fifty patients undergoing suspension laryngoscopy with total intravenous anesthesia using propofol and remifentanil were analysed in this prospective observational study. The ANI, BIS and Observer's Assessment of Alertness/Sedation (OAA/S) scale were measured at predefined time-points during the procedure. Receiver-operating characteristic (ROC) curves were built to evaluate the performance of ANI and BIS to predict hemodynamic reactivity (increase by more than 20% of heart rate and/or systolic blood pressure within 5 min) and assess sedation (OAA/S ≤ 2) during the procedure.
Results: For the prediction of hemodynamic reactivity, better performance was observed with ANI in comparison to BIS (ROC curve AUC [95% CI] = 0.88 [0.83-0.92] vs. 0.73 [0.66-0.79], P < 0.05). The sensitivity and specificity of ANI ≤ 55 to predict hemodynamic reactivity within 5 min were 88% and 83%, respectively. For the assessment of sedation, a better performance was observed with BIS in comparison to ANI (ROC curve AUC [95% CI] = 0.91 [0.86-0.94] vs. 0.68 [0.61-0.74], respectively, P < 0.05).
Conclusion: ANI exhibits good performance for the prediction of hemodynamic reactivity and BIS exhibits good performance for the assessment of sedation during suspension laryngoscopy with propofol/remifentanil total intravenous anesthesia.