Effect of remifentanil or esmolol on bispectral index and entropy to tracheal intubation during propofol anesthesia

ABSTRACT

BACKGROUND: The bispectral index (BIS) and entropy (response entropy, state entropy; RE, SE) have been used to monitor the anesthetic depth, and the difference between RE and SE (RE-SE difference) may represent the nociceptive stimuli during general anesthesia. This study was designed to determine whether BIS or entropy (RE, SE, and RE-SE difference) represent the response to tracheal intubation with iv bolus of remifentanil or esmolol forstable hemodynamic control during propofol anesthesia. METHODS: Eighty-nine patients were randomly divided into three groups (the control, esmolol, and remifentanil groups). Patient received propofol by target controlled infusion with air 2 L/min and O2 2 L/min. After the maintenance with target effect site concentration of propofol 5 microgram/ml for 5 min, patients received normal saline or esmolol 1.0 mg/kg or remifentanil 1.0 microgram/kg iv bolus according to group. And rocuronium 0.6 mg/kg iv bolus was administered and tracheal intubation was done. We measured mean arterial pressure (MAP), heart rate (HR), BIS, and entropy (RE, SE, RE-SE difference) during tracheal intubation. RESULTS: Changes in MAP or HR after tracheal intubation were greater in the control and esmolol groups than those in the remifentanil group. Although BIS, RE, and SE did not increase after intubation in all groups, but RE-SE difference significantly increased at 1 min after tracheal intubation in the control and esmolol group, but was unchanged in the remifentanil group. CONCLUSIONS: Among BIS, RE, SE and RE-SE difference, RE-SE difference is the good indicator for estimate of nociception during tracheal intubation.