Respiratory drive and breathing pattern abnormalities are related to exercise intolerance in chronic heart failure patients

Abstract

BackgroundPatients with chronic heart failure (CHF) are characterized by exercise intolerance and ventilatory abnormalities that are related to poor prognosis. We hypothesized that CHF patients have increased respiratory drive and abnormal breathing pattern during exercise in relation to disease severity. Materials and methodsThe study population consisted of 219 stable CHF patients and 30 healthy control subjects. All subjects underwent a symptom-limited cardiopulmonary exercise testing (CPET), pulmonary function tests, measurement of the maximal inspiratory pressure (PImax) and respiratory drive (P0.1).Measurements included peak oxygen uptake (VO2 peak, ml/kg/min). Respiratory drive was measured by mouth occlusion pressure P0.1 and P0.1/PImax ratio at rest, and by mean inspiratory flow (VT/TI) at rest and during exercise. CHF patients were divided into 3 groups according to VO2 peak (Group A: >20, Group B: 20–16 and Group C: <16ml/kg/min). ResultsCHF patients presented higher P0.1/PImax (4.1±3.6 vs 3.0±1.5, p=0.007) and VT/TI at rest (0.48±0.14 vs 0.41±0.10, L/s respectively, p=0.004) and lower VT/TI at peak exercise (2.17±0.66 vs 2.56±0.73, L/s, p=0.009) compared to controls. P0.1/PImax was higher in CHF Group C vs B vs A (4.9±2.9 vs 3.6±1.8 vs 3.1±1.8, respectively, p<0.001), while VT/TI at peak exercise was lower (1.71±0.43 vs 2.15±0.52 vs 2.65±0.64, L/s, respectively, p<0.001). ConclusionsCHF patients present increased respiratory drive at rest and abnormal breathing pattern during exercise in relation to CHF severity.