Physiological and clinical relevance of exercise ventilatory efficiency in COPD

[摘要] Exercise ventilation (Vxe2x80xb2E) relative to carbon dioxide output (Vxe2x80xb2CO2) is particularly relevant to patients limited by the respiratory system; e.g. those with chronic obstructive pulmonary disease (COPD). High Vxe2x80xb2Exe2x88x92Vxe2x80xb2CO2 (poor ventilatory efficiency) has been found to be a key physiological abnormality in symptomatic patients with largely preserved forced expiratory volume in 1xe2x80x85s (FEV1). Establishing an association between high Vxe2x80xb2Exe2x88x92Vxe2x80xb2CO2 and exertional dyspnoea in mild COPD provides evidence that exercise intolerance is not a mere consequence of detraining. As the disease evolves; poor ventilatory efficiency might help explaining xe2x80x9cout-of-proportionxe2x80x9d breathlessness (to FEV1 impairment). Regardless; disease severity; cardiocirculatory co-morbidities such as heart failure and pulmonary hypertension have been found to increase Vxe2x80xb2Exe2x88x92Vxe2x80xb2CO2. In fact; a high Vxe2x80xb2Exe2x88x92Vxe2x80xb2CO2 has been found to be a powerful predictor of poor outcome in lung resection surgery. Moreover; a high Vxe2x80xb2Exe2x88x92Vxe2x80xb2CO2 has added value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of COPD severity. Documenting improved ventilatory efficiency after lung transplantation and lung volume reduction surgery provides objective evidence of treatment efficacy. Considering the usefulness of exercise ventilatory efficiency in different clinical scenarios; the Vxe2x80xb2Exe2x88x92Vxe2x80xb2CO2 relationship should be valued in the interpretation of cardiopulmonary exercise tests in patients with mild-to-end-stage COPD.

[学科分类] 呼吸医学