Pulmonary blood volume in patients with interstitial pneumopathy and pulmonary heart disease. Its study at rest and during exercise
Pulmonary Heart Disease
Pulmonary blood volume (PBV) measurements have been reported in chronic lung disease that do not include diffuse interstitial lung disease (ILD) and cor pulmonale (CP). In this study, PBV was measured using the double injection single sampling method, at rest and at exercise in ten patients with ILD due to extrinsic allergic alveolitis (n = 6) or usual interstitial pneumonia (n = 4). Lung biopsies were obtained in 8 patients, and in none of them the stage of fibrosis was predominant over inflammation. The degree of vascular lesions was in four patients grade I and in four grade II (Heath-Edwards classification). At rest, most of the patients had elevated mean pulmonary artery pressure (PAP) and vascular resistance (PVR), (mean PAP 30 +/- 4 mmHg and 336 +/- 171 d.s. cm.-5, respectively), hypoxemia (paO2 = 48 +/- 2 mmHg) and a severely reduced PBV (53.6 +/- 11 ml.s.qm.). At exercise, pulmonary arterial hypertension worsened and, although PBV value increased significantly (rest = 53.6 +/- 11.6 ml.m2, s.qm. exercise 132 +/- 28 ml.s.qm.p less than 0.01) it remained abnormally low with respect to normal value. Comparison of the mean intravascular pressure-PBV measurements relationship in different lung diseases showed that ILD patients with CP have the greatest abnormality. Possible explanations for the severe reduction in PBV include restriction of extra-alveolar vessels as a consequence of lung volume loss, restriction of intra-alveolar vessels due to structural and functional changes imposed by the inflammation-fibrosis process and vascular restriction due to vasoactive factors (alveolar hipoxia).