Breathing With Heart Failure: How Hard Can It Be?

Abstract

The syndrome of heart failure (HF) is often accompanied by numerous derangements in ventilatory function. These pathophysiological changes in ventilatory function are believed to augment the mechanical work required to breathe during exercise (Wb). However, the precise contributions of resistive and elastic work to this overall higher Wb in HF remain unclear.

PURPOSE: To quantify the resistive and elastic components of Wb during exercise in HF patients and age-matched, healthy controls at standardized levels of minute ventilation ( ).

METHODS: The elastic and resistive Wb were assessed in 9 male HF patients (NYHA class I-III) and 9 age-matched, healthy male controls at minute ventilations of 20, 40, 60 and 80 L[BULLET OPERATOR]min-1 during graded exercise. The components of Wb were quantified using oesophageal manometry and modified Campbell diagrams.

RESULTS: Dynamic lung compliance was lower across all minute ventilations in HF patients (P<0.05). Moreover, the inspiratory and expiratory resistive Wb was higher in HF patients compared with controls at any given (P<0.05). The inspiratory elastic Wb was higher at minute ventilations of 40-60 L[BULLET OPERATOR]min-1 during exercise in HF patients. (P<0.05).

CONCLUSIONS: The findings of this study indicate that the overall higher Wb in HF patients may be more so related to greater amounts of resistive than elastic Wb during exercise.