Neural processing of respiratory sensations during resistive load-induced dyspnea in patients with COPD

Abstract

Introduction and background: COPD is characterized by dyspnea, which can further be influenced by dyspnea-specific fear (DSF). Pulmonary rehabilitation (PR) improves both dyspnea and DSF, but it remains untested whether these improvements are also reflected in the neural processing of respiratory sensations.

Aims and objectives; We tested whether reductions in DSF over the course of PR would be paralleled by reduced neural processing of respiratory sensations during a dyspnea challenge.

Methods: Before and after a 6-month PR program, 15 patients with COPD (FEV1%pred=48.4±27.4, 6MWD=466.5±92.1) underwent two blocks of inspiratory resistive loaded breathing. During blocks, brief inspiratory occlusions were presented to evoke respiratory-related evoked potentials (RREPs) in the electroencephalogram. Intensity and unpleasantness of dyspnea and occlusions were rated on a Borg scale. DSF was assessed with the Breathlessness Beliefs Questionnaire (BBQ).

Results: While paired sample t-tests showed pre-post PR improvements in BBQ somatic focus (BBQ-SF) subscores (∆2.5±4.9, p<.05), no significant changes were found in Borg scores or peak amplitudes of the RREP components. Higher pre-PR BBQ-SF subscores were related to higher ratings of intensity (r=.65, p<.01) and unpleasantness (r=.74, p<.01) of the occlusions, and also to higher peak amplitudes of the RREP P3 component pre-PR (r=.58, p<.05).

Conclusions: High baseline DSF seemed associated with the perception and the neural processing of respiratory sensations. Improvements in DSF during PR were not reflected in the perception or the neural processing of respiratory sensations during resistive load-induced dyspnea.