Effect of landiolol on bispectral index and spectral entropy responses to tracheal intubation during propofol anaesthesia.

BACKGROUND beta1-Adrenoceptor antagonists suppress the haemodynamic and arousal responses to tracheal intubation. The Entropy Module shows two spectral entropy-based indices, response entropy (RE) and state entropy (SE). The difference between RE and SE (RE-SE) may reflect nociception during general anaesthesia. In the present study, we investigated the effect of landiolol on entropy indices in response to tracheal intubation. METHODS A total of 60 patients were randomly assigned to receive saline (Group S), remifentanil (Group R), or landiolol (Group L). Anaesthesia was induced by propofol target-controlled infusion. Two minutes after the induction of anaesthesia, infusion with vecuronium bromide and remifentanil, landiolol, or saline was initiated. Tracheal intubation was performed 7 min after anaesthesia induction. Arterial pressure, heart rate (HR), bispectral index (BIS), and entropy indices were recorded. RESULTS In Group S, RE increased significantly after tracheal intubation, but there was no significant increase in BIS or SE. These increases in RE were abolished in Groups R and L. RE-SE increased significantly after tracheal intubation in Group S, whereas no increase in RE-SE was observed in Groups R and L. Increases in mean arterial pressure and HR after tracheal intubation were suppressed in Groups R and L compared with Group S. CONCLUSIONS RE increased in response to tracheal intubation, whereas BIS and SE did not. Landiolol and remifentanil suppressed the increase in RE after tracheal intubation with significant inhibition of RE-SE difference.