Alveolar Air and O 2 Uptake During Exercise in Patients With Heart Failure

• Published in: Journal of cardiac failure Vol. 24; no. 10; p. 695
• Main Authors: Van Iterson, Erik H, Smith, Joshua R, Olson, Thomas P
• Format: Journal Article
• Language: English
• Published: United States 01.10.2018
• Subjects: Exercise Test; Exercise Tolerance - physiology; Female; Heart Failure - metabolism; Heart Failure - physiopathology; Humans; Male; Middle Aged; Oxygen Consumption - physiology; Pulmonary Alveoli - metabolism; Pulmonary Diffusing Capacity - physiology; Stroke Volume; Aerobic exercise capacity; Oxidative capacity; Metabolic demand; HFpEF; O transport; HFrEF; Exercise intolerance
• ISSN: 1532-8414
• DOI: 10.1016/j.cardfail.2018.08.001

Peak exercise pulmonary oxygen uptake (V̇O ) is a primary marker of prognosis in heart failure (HF). The pathophysiology of impaired peak V̇O is unclear in patients. To what extent alveolar airway function affects V̇O during cardiopulmonary exercise testing (CPET) has not been fully elucidated. This study aimed to describe how changes in alveolar ventilation (V̇ ), volume (V ), and related parameters couple with exercise V̇O in HF. A total of 35 patients with HF (left ventricular ejection fraction 20 ± 6%, age 53 ± 7 y) participated in CPET with breath-to-breath measurements of ventilation and gas exchange. At rest, 20 W, and peak exercise, arterial CO tension was measured via radial arterial catheterization and used in alveolar equations to derive V̇ and V . Resting lung diffusion capacity for carbon monoxide (DL ) was assessed and indexed to V for each time point. Resting R between V̇O and V̇ , V , DL , and DL /V was 0.68, 0.18, 0.20, and 0.07, respectively (all P < .05 except DL /V ). 20 W R between V̇O and V̇ , V , DL , and DL /V was 0.64, 0.32, 0.07, and 0.18 (all P < .05 except DL ). Peak exercise R between V̇O and V̇ , V , DL , and DL /V was 0.55, 0.31, 0.34, and 0.06 (all P < .05 except DL /V ). These data suggest that alveolar airway function that is not exclusively related to effects caused by localized lung diffusivity affects exercise V̇O in moderate-to-severe HF.