Exercise responses and mental health symptoms in COVID-19 survivors with dyspnoea.

Objectives: Dyspnoea is a common persistent symptom post-coronavirus disease 2019 (COVID-19) illness. However, the mechanisms underlying dyspnoea in the post-COVID-19 syndrome remain unclear. The aim of our study was to examine dyspnoea quality and intensity, burden of mental health symptoms, and differences in exercise responses in people with and without persistent dyspnoea following COVID-19.

Methods: 49 participants with mild-to-critical COVID-19 were included in this cross-sectional study 4 months after acute illness. Between-group comparisons were made in those with and without persistent dyspnoea (defined as modified Medical Research Council dyspnoea score ≥1). Participants completed standardised dyspnoea and mental health symptom questionnaires, pulmonary function tests, and incremental cardiopulmonary exercise testing.

Results: Exertional dyspnoea intensity and unpleasantness were increased in the dyspnoea group. The dyspnoea group described dyspnoea qualities of suffocating and tightness at peak exercise (p<0.05). Ventilatory equivalent for carbon dioxide ('/') nadir was higher (32±5 28±3, p<0.001) and anaerobic threshold was lower (41±12 49±11% predicted maximum oxygen uptake, p=0.04) in the dyspnoea group, indicating ventilatory inefficiency and deconditioning in this group. The dyspnoea group experienced greater symptoms of anxiety, depression and post-traumatic stress (all p<0.05). A subset of participants demonstrated gas-exchange and breathing pattern abnormalities suggestive of dysfunctional breathing.

Conclusions: People with persistent dyspnoea following COVID-19 experience a specific dyspnoea quality phenotype. Dyspnoea post-COVID-19 is related to abnormal pulmonary gas exchange and deconditioning and is linked to increased symptoms of anxiety, depression and post-traumatic stress.