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Alveolar‐capillary membrane conductance is the best pulmonary function correlate of exercise ventilation efficiency in heart failure patients
Author(s) -
Guazzi Marco,
Reina Giuseppe,
Tumminello Gabriele,
Guazzi Maurizio D.
Publication year - 2005
Publication title -
european journal of heart failure
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.149
H-Index - 133
eISSN - 1879-0844
pISSN - 1388-9842
DOI - 10.1016/j.ejheart.2004.10.009
Subject(s) - medicine , cardiology , diffusing capacity , ventilation (architecture) , heart failure , pulmonary function testing , lung volumes , respiratory minute volume , vital capacity , pulmonary diffusing capacity , lung , respiratory system , lung function , mechanical engineering , engineering
Background In heart failure (HF), changes in lung mechanics and gas diffusion are limiting factors to exercise. Their contribution to an increased exercise ventilation to CO 2 production (VE/VCO 2 ) slope is undefined. Methods A total of 67 stable HF patients underwent cardiopulmonary exercise and pulmonary function tests, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV 1 ), maximal voluntary ventilation (MVV), total lung capacity (TLC) and alveolar diffusing capacity with its subcomponents (alveolar‐capillary membrane conductance ( D m ) and capillary blood volume ( V c )). Results: Patients showed a mild restrictive pattern (FEV 1 =85±15% and FVC=75±13% of normal predicted) and a moderate D m reduction (32±12 ml min −1 mm Hg −1 ). Average peak VO 2 was 15.6±4.0 ml min −1 kg −1 and the VE/VCO 2 slope was 39.6±11.0. At simple Spearman correlation analysis, all variables, but V c , correlated with peak VO 2 ; only D m correlated with VE/VCO 2 slope. At partial Spearman correlation, all variables lost the peak VO 2 correlation, and D m still inversely correlated with VE/VCO 2 slope ( r =−0.35; p =0.005). In patients with a high VE/VCO 2 slope (cutoff value 34), despite comparable lung volumes, D m was significantly more depressed (30±13 vs. 35±10 ml min −1 mm Hg −1 ; p <0.01). Conclusions: Pulmonary function tests and alveolar gas diffusing capacity poorly correlate with peak VO 2 . D m impairment rather than lung volumes correlates with exercise ventilation efficiency. This finding further adds to the pathophysiological relevance of an abnormal gas exchange in HF patients.