Many studies have been performing to attenuate hemodynamic responses in related to anesthesia of hypertensive patients because increased blood pressure and heart rate may be even fatal.
The author performed this experimental study to evaluate the hemodynamic effect of labetalol which has dual site of action(non-specific beta and postsynaptic alpha 1 receptor blockade) and SNP on cardiovascular system under the 1％ isoflurane anesthesia in 14 mongrel dogs.
Heart rate(HR), systolic arterial blood pressure(SAP), diastolic arterial blood pressure(DAP), mean arterial blood pressure(MAP), central venous pressure(CVP), pulmonary arterial pressure (PAP), pulmonary capillary wedge pressure(PCWP), and cardiac output(CO) were measured after labetalol 0.08mg/kg, 0.24mg/kg, and 0.72mg/kg intravenous bolus injection and SNP 0.7mg/kg/min, 2.1mg/kg/min, and 6.3mg/kg/min intravenous dripping. Besides stroke volume(SV), cardicac index(CI), left ventricular stroke work index(LVSWI), systemic vascular resistance (SVR) and pulmonary vascular resistance(PVR) were calculated.
The results were summerized as follows
1. SAP, DAP and MAP were decreaed significantly in both groups. HR were decreased significantly in labetalol group but there was no change in SNP group.
2. PCWP showed a tendency to increase in labetalol group but to decrease in SNP group, PAP showed no change in both groups.
3. CO and CI were decreased significantly but SV was not changed in labetalol group. There were no changes in SNP group. LVSWI showed a tendency to decrease in both groups.
4. CVP, SVR and PVR were not changed in both groups.
The author conclude both labetalol and SNP are effective to attenuate hemodynamic responses in hypertensive patients. But labetalol is preferable for .hypertensive patient with coronary heart disease because it has dual blocking action.
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