Influence of bronchial blood flow and conductance on pulmonary function in stable systolic heart failure

BackgroundThe aim of this study was to determine the relationship between airway blood flow (Q˙aw), airway conductance (Gf-aw) and pulmonary function in patients with stable HF.Methods12 controls (CTRL: age = 63 ± 9 years, FVC = 98 ± 15%pred, LVEF = 61 ± 6%) (all data presented as mean ± SD), 16 patients with mild HF (HF-A, NYHA I–II: age = 64 ± 9 years, FVC = 90 ± 17%pred, LVEF = 28 ± 6%), and 14 patients with moderate/severe HF (HF-B, NYHA III–IV: age = 65 ± 6 years, FVC = 84 ± 12%pred, LVEF = 26 ± 6%) were studied. Q˙aw was assessed using soluble gas measurements; perfusion pressure across airway bed (ΔPaw) was estimated from systemic and pulmonary pressure measurements; Gf-aw was calculated as Q˙aw/ΔPaw; PF was assessed by spirometry.ResultsWhile Q˙aw was not significantly different between CTRL (61.3 ± 17.9 μL min−1 mL−1), HF-A (70.1 ± 26.9 μL min−1 mL−1) and HF-B (56.2 ± 14.9 μL min−1 mL−1) groups, Gf-aw, was elevated in HF-A (1.1 ± 0.4 μL min−1 mL−1 mmHg−1, p < 0.03) and tended to be elevated in HF-B (1.2 ± 0.6 μL min−1 mL−1 mmHg−1, p = 0.07) when compared to CTRL (0.8 ± 0.3 μL min−1 mL−1 mmHg−1). Significant positive correlations were found between Gf-aw and RV/TLC for HF-A (r = 0.63, p < 0.02) and HF-B (r = 0.58, p < 0.05).ConclusionsThese results support the hypothesis that increased bronchial conductance and bronchial congestion may be related to greater small airway obstruction and as such may play a role in the PF abnormalities and symptoms of congestion commonly observed in HF patients.