Evolution of symptoms, quality of life, and objective breathing markers in a prospective case series of patients with post-COVID-19 dysfunctional breathing

Abstract Dysfunctional breathing (DB) was described after coronavirus disease 2019 (COVID-19) and can contribute to persistent dyspnoea and other associated symptoms but the evolution of DB after COVID-19 is poorly described. Individuals with persistent symptoms after COVID-19 were evaluated and those diagnosed with DB were included. DB was diagnosed by identifying an abnormal breathing pattern during cardiopulmonary exercise testing (CPET) associated with compatible symptoms after ruling out cardiopulmonary conditions that could account for the symptoms. All included patients were prospectively followed and systematically assessed 6–9 months after their diagnosis. Given the multiplicity of analyses and the absence of a pre-specified primary analysis, all findings should be considered exploratory and hypothesis-generating. Forty-eight patients were included and 45 patients were successfully reassessed at 6–9 months. Forty-two received specific respiratory physiotherapy targeting DB. The proportion of individuals with a Nijmegen score ≥ 23 decreased from 30 (68%) at baseline to 19 (43%) at follow-up ( p = 0.02). Dyspnea improved at 6–9 months, with 0%, 11%, 44%, 35%, and 11% of patients presenting mMRC grades 0, 1, 2, 3, and 4 at baseline, compared with 20%, 39%, 37%, 4%, and 0% at follow-up ( p < 0.001). Improvements in quality of life and functional status were observed. However, 21 patients (47%) continued to experience significant functional limitations, defined as a post-COVID-19 functional status (PCFS) scale score ≥ 2. Objective markers of DB during CPET improved, with reductions in hyperventilation, dispersion of breathing parameters, and the number of sighs. In most patients diagnosed with DB after COVID-19, improvements in symptoms, QoL, functional status and objective markers of DB were observed at 6–9 months. A substantial proportion of patients remained disabled.