A new phenotype of patients with post-COVID-19 condition is characterised by a pattern of complex ventilatory dysfunction, neuromuscular disturbance and fatigue symptoms.

BACKGROUND

Patients with post-COVID-19 condition frequently suffer from chronic dyspnoea. The causes and mechanism for dyspnoea in these patients without evidence of structural lung disease are unclear.

METHODS

Patients treated for COVID-19 at Charité University Hospital in Berlin received pulmonary function testing including respiratory muscle strength tests and completed health-related quality-of-life questionnaires during follow-up. Patients with post-COVID-19 condition during outpatient follow-up with fatigue and exertional intolerance (PCF) were compared to patients with post-COVID-19 condition with evidence of chronic pulmonary sequelae (post-COVID-19 restriction (PCR)) as well as to patients without post-COVID-19 condition (NCF).

RESULTS

A total of 170 patients presented for follow-up. 36 participants met criteria for PCF, 28 for PCR and 24 for NCF. PCF patients reported dyspnoea in 63.8%. % predicted value of respiratory muscle strength (median (IQR)) was reduced in PCF (55.8 (41.5-75.9)) compared to NCF and PCR (70.6 (66.3-88.9) and 76.8 (63.6-102.2), respectively; p=0.011). A pattern of reduced forced vital capacity (FVC), but normal total lung capacity (TLC), termed complex ventilatory dysfunction defined as TLC - FVC >10% predicted was observed and occurred more frequently in PCF (88.9%) compared to NCF and PCR (29.1% and 25.0%, respectively; p<0.001).

CONCLUSION

Dyspnoea in PCF is characterised by reduced respiratory muscle strength and complex ventilatory dysfunction indicating neuromuscular disturbance as a distinct phenotype among patients with post-COVID-19 condition. These observations could be a starting point for developing personalised rehabilitation concepts.