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

The aim of this study was to determine the relationship between airway blood flow (Q(aw)), airway conductance (G(f-aw)) and pulmonary function in patients with stable HF.

12 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 (ΔP(aw)) was estimated from systemic and pulmonary pressure measurements; G(f-aw) was calculated as Q(aw)/ΔP(aw); PF was assessed by spirometry.

While Q˙(aw) was not significantly different between CTRL (61.3±17.9 microL min(-1)mL(-1)), HF-A (70.1±26.9 microL min(-1)mL(-1)) and HF-B (56.2±14.9 microL min(-1)mL(-1)) groups, G(f-aw), was elevated in HF-A (1.1±0.4 microL min(-1)mL(-1)mm Hg(-1), p<0.03) and tended to be elevated in HF-B (1.2±0.6 microL min(-1)mL(-1)mm Hg(-1), p=0.07) when compared to CTRL (0.8±0.3 microL min(-1)mL(-1)mm Hg(-1)). Significant positive correlations were found between G(f-aw) and RV/TLC for HF-A (r=0.63, p<0.02) and HF-B (r=0.58, p<0.05).

These 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.