BACKGROUND:Esmolol, a short-acting beta 1-antagonist, can reduce anaesthetic requirements and decrease seizure activity during electroconvulsive therapy even after a single dose of 80 mg. We studied the effect of esmolol on the bispectral index scale (BIS), which is a processed EEG recently introduced to monitor depth of anaesthesia. METHODS: We gave esmolol 80 mg to 30 healthy male patients after induction of anaesthesia usingpropofol, with either fentanyl (group 1) or placebo (group 2). Patients were ventilated mechanically through a laryngeal mask airway and anaesthesia was maintained using propofol to keep the BIS value between 55 and 60. RESULTS:Esmolol did not affect the BIS index value in either group. In group 1, the areas (mean (SD)) under the BIS vs time curve 3 min before and 3 min after esmolol administration were 145 (9) and 146 (8) respectively (P = 0.116). In group 2 values were 147 (8) and 146 (7) respectively (P = 0.344). In contrast, in group 1 the area under the systolic arterial pressure (SAP) curve was 299 (31) before and 270 (29) after esmolol (P < 0.001), and 156 (17) and 141 (17) respectively for heart rate (P < 0.001). In group 2 values were 326 (36) and 302 (41) for SAP (P < 0.001) and 182 (25) and 155 (22) for heart rate (P < 0.001). CONCLUSIONS: The results suggest that a single dose of esmolol affects the SAP and heart rate but does not affect BIS values.
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BACKGROUND:Esmolol, a short-acting beta 1-antagonist, can reduce anaesthetic requirements and decrease seizure activity during electroconvulsive therapy even after a single dose of 80 mg. We studied the effect of esmolol on the bispectral index scale (BIS), which is a processed EEG recently introduced to monitor depth of anaesthesia. METHODS: We gave esmolol 80 mg to 30 healthy male patients after induction of anaesthesia using propofol, with either fentanyl (group 1) or placebo (group 2). Patients were ventilated mechanically through a laryngeal mask airway and anaesthesia was maintained using propofol to keep the BIS value between 55 and 60. RESULTS:Esmolol did not affect the BIS index value in either group. In group 1, the areas (mean (SD)) under the BIS vs time curve 3 min before and 3 min after esmolol administration were 145 (9) and 146 (8) respectively (P = 0.116). In group 2 values were 147 (8) and 146 (7) respectively (P = 0.344). In contrast, in group 1 the area under the systolic arterial pressure (SAP) curve was 299 (31) before and 270 (29) after esmolol (P < 0.001), and 156 (17) and 141 (17) respectively for heart rate (P < 0.001). In group 2 values were 326 (36) and 302 (41) for SAP (P < 0.001) and 182 (25) and 155 (22) for heart rate (P < 0.001). CONCLUSIONS: The results suggest that a single dose of esmolol affects the SAP and heart rate but does not affect BIS values.