Right Ventricular Residual Blood Volume in Chronic Pulmonary Diseases.

Abstract

It is well known that various pulmonary diseases result in circulatory failure, particulary in right heart overload or failure. Since the concept of cor pulmonale was proposed by MeGinn and White in 1935 from a monogenetic standpoint of cardiopulmonary physiology, there have been many works on the right heart function in the disturbance of the pulmonary circulation resulted from decrease in pulmonary vascular bed. As a part of our serial works on the genesis of chronic cor pulmonale, the measurement of the right ventricular residual blood volume was done in chronic pulmonary diseases, since it was our understanding that to know the right heart function the residual blood volume and end-diastolic volume of the right ventricle and the residual fraction or the ration of the residual blood volume to end-diastolic volume are as important as cardiac output, pulse rate, circulation time, circulating plasma volume and intra-cardiac and intra-vascular pressure.Method The dye dilution method of Bing and the formula of Holt were utilized. Two cardiac catheters were inserted, the one into the main pulmonary artery and the another into the right ventricle. The evans blue was instantly injected into the right ventricle, and the blood was continuously aspirated from the main pulmonay artery by the specially made apparatus which is, under the negative pressure of more than 500 mmHg, capable of aspirating four or more fractional blood samples a minute. The concentration of the evans blue in the plasma of each blood sample was measured and plotted against time. From the thus obtained dye dilution curve, the residual volume was calculated according to the formula of Holt.Results and Discussion a) The right ventricular end-diastolic volume showed a direct linear correlation with the residual volume and the stroke volume. That is, the residual volume was increased as the right ventricular end-diastolic volume was increased.b) The residual fraction was increased and the mean pulmonary circulation time was prolonged in chronic pulmonary diseases. An increase in the residual fraction was marked in cor pulmonale. The residual fraction was 53.5% in chronic pulmonary emphysema, 52.8% in bronchiectasis, 55.5% in bronchial asthma and 51.1% in pulmonary tuberculosis. When compared with means of healthy subjects (48 to 55%), these values were within normal limits or around the upper border of the normal. In 6 cases of cor pulmonale, however, which had elavated pulmonary artery pressure and was in right heart failure, the residual fraction was markedly increased showing the mean of 64.5%.c) There was a significant difference between a group with the electrocardiographic finding of right ventricular hypertrophy and a group without right ventricular hypertrophy. In the former group, the residual volume and the residual fraction were increased.d) Both the residual volume and the residual fraction were directly correlated with the mean pulmonary artery pressure. The residual fraction was increased in those with the total pulmonary vascular resistance above 400 dyne·sec·cm-5.e) The residual volume and the residual fraction were not correlated with the finding of cardiac enlargement by chest roentgenogram.f) The residual fraction was increased in many cases of tachycardia which showed the resting pulse rate of more than 100 per minute.g) The mean pulmonary circulation time was not at all correlated with the residual fraction.h) Inhalation of air of low O2 or high CO2 content and exercise were done in 13 cases. From the change in circulatory hemodynamics in these cases, it is clear that the cardiac output was increased to maintain the enough blood flow to meet the increased demand of each living tissue. An decrease in the residual blood volume and a marked decrease in the residual fraction were observed at the same time and with an increase in pulse rate the cardiac output was increased as well. [the rest omitted]