CPET ventilatory characteristics of dysfunctional breathing in long COVID patients with persistent dyspnea

ABSTRACT

Background: Cardio-pulmonary exercise test (CPET) can differentiate causes of persistent dyspnea beyond cardiopulmonary limitation. Dysfunctional breathing (DB) has been increasingly identified in long COVID in two main forms, hyperventilation [HV] or periodic deep sighing [PDS]. Aims and objectives: We aimed to contrast the CPET ventilatory parameters in post COVID patients without cardiopulmonary limitations. Four groups were compared a) normal CPET, b) PDS, c) HV and d) mixed pattern (PDS & HV). Method(s) CPET patterns (N, HV, PDS and mixed) were determined in 76 SARS-CoV2 patients [Mean age 48.2 (SD15.0), women (n=49, 64%)]. We compared breath by breath ventilatory parameters using raw data and coefficients of variation focusing on breathing frequency, tidal volume, VE/VCO2 and ins- and expiratory time. Result(s) Normal CPET were found in 26 (30%), HV in 12 (16%), PDS in 25 (33%) and mixed in 16 (21%)., dyspnea level and timing of evaluation between COVID and CPET (mean 230 days) were similar between groups. See figure for ventilatory parameters at rest and exercise. Conclusion(s) In long COVID patients with normal lung function and normal oxygen consumption but persistent dyspnea, assessment of the variability of ventilation at rest and exercise using CPET can reliably identify DB and differentiate its main forms (PDS or HV), thus offering a physiological explanation for dyspnea and allowing targeted therapy.