Hemodynamic effects of inhaled nitroglycerin in patients with pulmonary hypertension undergoing mitral valve replacement surgery

ABSTRACT

There has been a renewed interest in nitric oxide donor drugs such as nitroglycerin, delivered by the inhalational route for treatment of pulmonary arterial hypertension [PHT], since the presence of [PHT] affects the prognosis of the patients. Aim of this study was to investigate the postoperative hemodynamic effects of nitroglycerin inhalation on patients with [PHT] undergoing mitral valve replacement surgery. Twenty-two patients who diagnosed as having pulmonary hypertension [mean pulmonary artery pressures >25 mmHg] and underwent mitral valve replacement surgery were included in the study. Basal systemic and pulmonary hemodynamics were recorded in postoperative period at [T0] before inhalation of nitroglycerin. Then 2.5 microg/kg/min nitroglycerin liquid nebulized by 2 l/min gas flow of 40% oxygen and air mixture were given to the patients. Thereafter, the same parameters were measured at the first [T1], second [T2], and fourth [T3] hours after the beginning of nitroglycerin inhalation and one hour after the end of treatment [T4]. With respect to heart rate, mean arterial pressure, systemic vascular resistance, cardiac index, mixed venous oxygen saturation and arterial carbon dioxide tension, there were no statistically significant differences at T0, T1, T2, T3, or T4. On the other hand, the mean pulmonary artery pressure, pulmonary vascular resistance and intrapulmonary shunt fraction decreased significantly, whenever the PaO2/FiO2 ratio increased significantly at T1, T2 and T3 when compared to that of T0 and T4. The results of the present study suggest that nitroglycerin inhalation causes a significant decrease in both mean pulmonary artery pressure and pulmonary vascular resistance in patients with pulmonary hypertension undergoing mitral valve replacement surgery without decreasing mean arterial pressure and systemic vascular resistance thus can be used as a therapeutic modality during postoperative course