CPET evidence of dysfunctional breathing after SARS-CoV2 in patients with persistent dyspnea

Abstract

<b>Background:</b> Post SARS-CoV2 dyspnea might persist for months after infection. Among the various causes of persistent dyspnea, dysfunctional breathing (DB) as defined as an erratic ventilation during cardiopulmonary exercise test (CPET) has been anecdotally described. <b>Aims and objectives:</b> We aimed to examine the prevalence of DB among patients with resolved SARS-CoV2. <b>Methods:</b> CPET was performed in 31 SARS-CoV2 patients (median age 62 [IQR 20], female sex 41.9%) with persistent dyspnea ≥ 12 weeks after acute infection. CPET patterns including DB were determined by 2 pulmonologists. Non parametric and Χ square tests were applied to analyze the association between CPET patterns and pulmonary functions tests and severity of SARS-CoV2. <b>Results:</b> Three dominant patterns were identified (respiratory limitation [RL] with gas exchange abnormalities, normal CPET/deconditioning [D] and DB). Isolated DB was found in 9 patients (29%), while RL was found in 19 (59%) and D in 3 (9.7%). DB patients had significantly less severe initial infection (55.6%), better TLCO (median [IQR] 73% [22%]), higher VO2 (21.3 ml/min/kg [5.2]) lower VE/VCO2 slope (29.4 [5.3]) and higher SpO2 (94%[3]) than RL patients. <b>Conclusions:</b> At ≥ 3 months after infection, one third of patients with persistent dyspnea exhibit dysfunctional breathing, which appears to be a feature of COVID-19 not described in other viral infections. We hypothesize that DB is an important physio-pathological mechanism of disabling dyspnea in younger outpatients with SARS-CoV2.