Impaired Pulmonary Diffusion During Exercise in Patients With Chronic Heart Failure

Abstract

Background-Pulmonary diffusion is impaired at rest in patients with chronic heart failure (CHF) and has been implicated in the generation of symptoms and exercise intolerance. The aim of this study was to determine whether pulmonary diffusion is impaired during exercise in CHF, to examine its relationship to pulmonary blood flow, and to consider its functional significance in relation to metabolic gas exchange. Methods and Results-Carbon monoxide transfer factor (TLCO) and pulmonary blood flow (Q C ) were measured by a rebreathe technique at rest and during steady-state cycling at 30 W in 24 CHF patients and 10 control subjects. Both patients and control subjects were able to raise TLCO and Q C during exercise. However, the patient group had a lower diffusion for a given blood flow (TLCO/Q C ) both at rest (3.6Ϯ0.16 and 4.8Ϯ0.23 mL ⅐ L Ϫ1 ⅐ mm Hg Ϫ1 ; PϽ0.001) and during exercise (2.8Ϯ0.16 and 3.4Ϯ0.13 mL ⅐ L Ϫ1 ⅐ mm Hg Ϫ1 for CHF patients and control subjects, respectively; PϽ0.05). TLCO/Q C was related to the ventilatory equivalent for carbon dioxide (VEVCO 2 ) production at 30 W (TLCO/Q c versus VEVCO 2 , rϭϪ0.58, PϽ0.01) and to peak exercise oxygen consumption measured during a progressive test (TLCO/Qc versus VO 2peak , rϭ0.57, PϽ0.01) in these patients. Conclusions-Patients with CHF are able to recruit reserves of TLCO and Q C during exercise. However, the TLCO/Q C ratio is consistently impaired in these patients and relates to both exercise hyperpnea and peak exercise oxygen consumption. Whether this impairment in alveolar gas exchange is reversible in CHF and therefore is a potential target for therapy has yet to be determined.

Endothelial Dysfunction and Lung Capillary Injury in Cardiovascular Diseases

“…Dm at rest and relative changes on exertion correlate with O2 uptake at peak exercise 51 . The correlation, however, is even greater between Dm and the excessive ventilatory requirement to carbon dioxide (CO2) output, which is typical in these patients 52 .…”

Indoor Air Quality in Two University Sports Facilities

“…However, athletes and ordinary practitioners of sports can be at risk when they are exercising or training in polluted environments due the fact that: i) the amounts of pollutants inhaled increase proportionally with increasing ventilation rates, ii) most of the air is inhaled through the mouth, bypassing the normal nasal mechanisms for filtration of large particles and soluble vapours, and iii) the increased airflow velocity carries pollutants deeper into the respiratory tract (Carlisle and Sharp, 2001). Moreover, pulmonary diffusion capacity has been shown to increase with exercise (Smith et al, 1999;Zavorsky and Lands, 2005), and therefore it may be postulated that the diffusion of pollutant gases boosts with exercise (Carlisle and Sharp, 2001). Indoor air pollution may increase the risk of irritation phenomena, allergic sensitisation, acute and chronic respiratory disorders and lung function impairment (Viegi et al, 2004;AnnesiMaesano and Dab, 2006).…”

An open-circuit method for determining lung diffusing capacity during exercise: comparison to rebreathe

“…In addition, the rise in DL CO with exercise [typically paralleling the rise in cardiac output (Q ) in health] may be reduced in these same patient groups, suggesting a limited expansion of the alveolar-capillary bed (15,17,27).…”