Analgesia Nociception Index (ANI) to predict intraoperative haemodynamic changes: results of a pilot investigation

The Analgesia Nociception Index has been described to reflect different levels of intraoperative nociceptive stimulation during total intravenous anaesthesia. The association between this index and haemodynamic changes during sevoflurane-based anaesthesia was investigated in 30 patients with the hypothesis that changes in the Analgesia Nociception Index may coincide with or even predict haemodynamic changes.

The Analgesia Nociception Index as well as blood pressure and heart rate were observed during induction, at skin incision, at times of an Analgesia Noceception Index decrease > 20% ('event') and pre-/post-fentanyl administration.

The Analgesia Nociception Index decreased with airway manipulation [mean: 52 (before) vs. 33 (after); P < 0.005] and after skin incision [mean: 63 (before) vs. 38 (after); P < 0.001], and it increased after fentanyl administration [53 (before) vs. 59 (after); P < 0.05]. However, its predictive probability to indicate heart rate and blood pressure increases of >10% was low (heart rate 0.61; blood pressure 0.59).

The Analgesia Nociception Index appears to reflect different levels of stimulation during sevoflurane-based general anaesthesia. However, it was of little predictive value to pre-empt significant haemodynamic changes.