Why the study?
Does elevation of inhaled halothane or isoflurane alter electrocardiographic and hemodynamic variables in intact beagle dogs?
Does elevation of inhaled halothane or isoflurane alter electrocardiographic and hemodynamic variables in intact beagle dogs?
In beagle dogs, increasing concentrations of halothane or isoflurane causes reversible hypotension and QRS prolongation without altering heart rate or other ECG intervals, likely due to compensatory sympathetic reflexes.
Should not change human anesthetic practice; leaves open translation of QRS effects to clinical settings.
We assessed concentration-dependent effects of halothane or isoflurane inhalation on the electrocardiographic and hemodynamic variables using a cross-over design in intact beagle dogs (n = 4). Elevation of inhaled halothane from 1.0% to 2.0% or isoflurane from 1.5% to 2.5% decreased the mean blood pressure and prolonged the QRS width without significantly altering the heart rate, PR interval or QT interval. However, the observed changes disappeared after regressions of both anesthetic conditions to their initial settings. These results indicate that hypotension-induced, reflex-mediated increase of sympathetic tone may have counterbalanced the direct negative chronotropic, dromotropic and repolarization slowing effects of the anesthetics.
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Saito et al. (2021) studied this question.
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