Alveolar-capillary gas exchange and exercise performance in heart failure

Infusion of saline in congestive heart failure (CHF) acutely impedes the alveolar-capillary gas transfer (Dm) due to an upregulated sodium ion movement across the lung microvessels. This method was used for investigating the debated issue of a link between D-M impairment and exercise performance in CHF. In 15 patients, but not in 10 controls, infusions of 150 and 750 ml of 0.9% saline were associated with decreases in D-M (-9.8% and -17.5%) that significantly correlated with changes in peak exercise oxygen uptake (-9.4% and -11.5%) and in the slope of ventilation-to-carbon dioxide production ratio (+9.8% and +14.6%), demonstrating that alveolar-capillary gas transfer may be implicated in exercise intolerance in CHF.