The Effect of Nitroglycerine-Induced Hypotension on the Hemodynamics During Isoflurane-N2O-O2 Anesthesia in Dogs

Nitroglycerin(NTG) can be used intravenously to induced hypotension. NTG has a short plasma half-life, is easy to control, and has no direct toxic effect or toxic metabolites.

The purpose of this study was to evaluate the effects of nitroglycerine-induced hypotension on the hemodynamics during isoflurane-N₂O-O₂ anesthesia in dogs.

Hemodynamic measurement(left ventricular pressure, aortic pressure, pulmonary wedge pressure, pulmonary artery pressure. heart rate, cardiac output, maximal and minimal dP/dT) were determined in 8 dogs at 30min after induction(baseline values), 15min after isoflurane-N₂O-O₂ inhalation(1 MAC, FIO₂ 0.5), 15min after intravenous NTG adminstration and 15min after the termination of isoflurane-NTG.

1) At 15min after isoflurane-N₂O-O₂ inhalation, left ventricular pressure, aortic pressure, maximal dP/dT values were decreased, and heart rate was increased significantly compared to baseline values. but pulmonary wedge pressure, pulmonary artery pressure, cardiac output and minimal dP/dT did not changes significantly.

2) At 15min after IV NTG administration, left ventricular pressure, aortic pressure, pulmonary wedge pressure, pulmonary artery pressure, cardiac output and miximal dP/dT were decreased, minimal dP/dT was increased significantly compared to the previous values.

3) At the termination of isoflurane-NTG, left ventricular pressure, aortic pressure, pulmonary wedge pressure, cardiac output and maximal dP/dT were increased, minimal dP/dT was decreased significantly compared to the previous values, but left ventricular pressure, aortic pressure and pulmonary wedge pressure were lower than the the baseline valus.