Augmented peripheral chemoreflex in patients with heart failure and inspiratory muscle weakness

https://doi.org/10.1016/j.resp.2010.01.009Get rights and content
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Abstract

We hypothesized that heart failure patients with inspiratory muscle weakness (IMW) present greater peripheral chemoreflex responsiveness and augmented exercise ventilatory oscillation compared to patients with preserved inspiratory muscle strength. We studied 19 heart failure patients: 9 with IMW (maximal inspiratory pressure [PImax] < 70% of predicted) and 10 with preserved inspiratory muscle strength. Inspiratory muscle strength was measured via pressure transducer. Peripheral chemoreflex was evaluated by the single-breath CO2 test. Exercise ventilatory oscillation was determined as the ratio between amplitude and mean of each oscillation during incremental exercise. Patients with IMW had greater peripheral chemoreflex response (0.11 ± 0.03 l min−1 Torr−1) than those with preserved inspiratory muscle strength (0.07 ± 0.03 l min−1 Torr−1, p = 0.02). Moreover, there was a significant and inverse correlation between PImax and peripheral chemoreflex response (r = −0.57, p = 0.01). Likewise, there was a significant and inverse correlation between PImax and ventilatory oscillations (r = −0.46, p = 0.04). Our findings indicate that IMW is linked to increased peripheral chemoreflex and augmented exercise ventilatory oscillation in patients with chronic heart failure.

Keywords

Single-breath CO2 test
Exercise oscillatory ventilation
Inspiratory muscle training

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Sources of support: C.C. Callegaro was supported by scholarship from the National Council for Scientific and Technological Development (CNPq), Brasilia, Brazil. This study was supported by a grant from the Research Incentive Fund of the Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.