A MEASUREMENT OF PULMONARY BLOOD-VOLUME INCREASE DURING SYSTOLE IN HUMANS

Pulmonary blood volume increase during systole was measured in patient s by analysing chest images obtained during ECG gated radionuclide ang iography examination. The difference in the total radiation counts bet ween systole and diastole in regions of interest, which included the l ungs and the left ventricle, was measured and the relative pulmonary s ystolic blood volume increase (SBVI)-the ratio between the pulmonary S BVI and the cardiac stroke volume-was calculated. The relative pulmona ry SBVI, which is a measure for the compliance of the pulmonary blood vessels, was found to be 0.26-0.85, and the average Value was 0.57 +/- 0.15. The relative pulmonary SBVI was inversely correlated with the p atient age (r = 0.27, p < 0.05) and with the left ventricular ejection fraction and stroke volume (r = 0.36, p < 0.01) due to decreased arte rial compliance for older patients and for increased pulmonary blood v olume respectively. The correlation coefficients were not high, indica ting that the compliance of the patients is determined mainly by other individual factors. Radionuclide plethysmography enables qualitative assessment of pulmonary arterial compliance.