Prognostic Value of Alveolar Volume in Systolic Heart Failure
Heart failure (HF) is a common clinical disorder carrying significant morbidity and mortality. Ventilatory impairment is known to occur in patients with HF, and is ascribed to factors such as heart enlargement, pulmonary stiffness due to chronic interstitial edema, and respiratory muscle dysfunction. The coexistence of chronic airflow obstruction may add to ventilatory dysfunction, and is believed to have a negative prognostic impact in patients with chronic HF.
As of now, most of the studies on the prognostic impact of respiratory dysfunction in HF focused on simple spirometry, with only a few exploring the exchange of gases across the alveolar-capillary membrane.
Alveolar volume (VA) is the volume of air in the lung available for gas exchange, and is currently measured by the dilution of an inert gas during a single breath-hold maneuver. Due to the single-breath approach, such measurement is sensitive to ventilatory disturbances. In healthy subjects, VA equals total lung capacity (TLC) measured by multiple-breath helium dilution. In subjects with ventilatory impairment, VA is often much lower than TLC because of the insufficient mixing of gas in alveolar spaces.
We conducted a prospective, observational study aimed at establishing the prognostic value of VA, as % of the predicted value, in 260 consecutive patients with systolic HF. The outcome measure was all-cause mortality over a median follow-up time of about three years.
Background
Heart failure (HF) is a common clinical disorder carrying significant morbidity and mortality. Ventilatory impairment is known to occur in patients with HF, and is ascribed to factors such as heart enlargement, pulmonary stiffness due to chronic interstitial edema, and respiratory muscle dysfunction. The coexistence of chronic airflow obstruction may add to ventilatory dysfunction, and is believed to have a negative prognostic impact in patients with chronic HF.
As of now, most of the studies on the prognostic impact of respiratory dysfunction in HF focused on simple spirometry, with only a few exploring the exchange of gases across the alveolar-capillary membrane.
Alveolar volume (VA) is the volume of air in the lung available for gas exchange, and is currently measured by the dilution of an inert gas during a single breath-hold maneuver. Due to the single-breath approach, such measurement is sensitive to ventilatory disturbances. In healthy subjects, VA equals total lung capacity (TLC) measured by multiple-breath helium dilution. In subjects with ventilatory impairment, VA is often much lower than TLC because of the insufficient mixing of gas in alveolar spaces.
We conducted a prospective, observational study aimed at establishing the prognostic value of VA, as % of the predicted value, in 260 consecutive patients with systolic HF. The outcome measure was all-cause mortality over a median follow-up time of about three years.
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