What are the cardiovascular effects of halothane anesthesia over time in unmedicated volunteers?
Halothane anesthesia induces initial, concentration-dependent cardiovascular depression that partially attenuates after prolonged (5 hours) administration.
The author examined the cardiovascular effect of halothane in 15 unmedicated volunteers under moditions of constant arterial carbon dioxide tension and body temperature. Compared with awake measurements, the effects during the first hour of anesthesia included depression of enrdiac output, stmke volume, arterial pressure, left ventricular minute and stroke work, and myocardial contractility (as evidenced by the ballistocardiogram IJ-wave amplitude), muscle blood flow, and total body oxygen consumption. Mean right atrial pressure incrensed. These efeect were directly related to halothane concentration. Total peripheral resistance and heart rate were unchnnged and, at lighter anesthetic levels, skin blood flow increased. After five hours of anesthesia saveral values returned to towards or above awake values. These were: cardiac output, stroke volume, left ventricular work or stroke work, IJ-wave amplitude, muscle blood flow, and mean right atrial pressure. Told peripheral resistance fell and heart rate increased with progressive duration of anesthesia.
Eger et al. (1970) studied this question.
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