Positive-pressure ventilation-induced variations in arterial pressure have been related to cardiac sympathetic activity in animals. However, the effect of β-adrenoceptor blockade on these variations in anaesthetized humans under positive-pressure ventilation has not yet been investigated. In the present study, RAPV (respiratory-related arterial pressure variability) and %SPV (percentile systolic pressure variation) were determined before and after esmolol treatment in ten mechanically ventilated patients. RAPV and %SPV decreased significantly after intravenous esmolol (I mg/kg of body weight) treatment (maximal decrease of RAPV, 50% and %SPV, 35%). Linear regression analysis of RAPV and %SPV before and after esmolol treatment both revealed high correlation (r = 0.93 and 0.91 respectively). The amplitudes of RAPV and %SPV also significantly increased in a graded way with higher tidal volumes. Thus we propose that esmolol suppresses the variations in arterial pressure induced by positive-pressure mechanical ventilation, and we suggest that RAPV and %SPV may be alternative choices for monitoring cardiac sympathetic regulation in anaesthetized patients under positive-pressure ventilation.
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