Ventilatory efficiency in long-term dyspnoeic patients following COVID-19 pneumonia.

Piamonti D; Department of Public Health and Infectious Diseases, Sapienza University of Rome, Italy.
Panza L; Flore R;Baccolini V;Pellegrino D; Sanna A;Lecci A;Lo Muzio G; Angelone D; Mirabelli FM; Morviducci M;Onorati P; Messina E;Panebianco V; Catalano C; Bonini M; Palange P

Respiratory physiology & neurobiology [Respir Physiol Neurobiol] 2024 May 31; Vol. 327, pp. 104285.
Date of Electronic Publication: 2024 May 31.

Background: Long COVID is defined as persistency of symptoms, such as exertional dyspnea, twelve weeks after recovery from SARS-CoV-2 infection.
Objectives: To investigate ventilatory efficiency by the use of cardiopulmonary exercise testing (CPET) in patients with exertional dyspnea despite normal basal spirometry after 18 (T 18 ) and 36 months (T 36 ) from COVID-19 pneumonia.
Methods: One hundred patients with moderate-critical COVID-19 were prospectively enrolled in our Long COVID program. Medical history, physical examination and lung high-resolution computed tomography (HRCT) were obtained at hospitalization (T 0 ), 3 (T 3 ) and 15 months (T 15 ). All HRCTs were revised using a semi-quantitative CT severity score (CSS). Pulmonary function tests were obtained at T 3 and T 15 . CPET was performed in a subset of patients with residual dyspnea (mMRC ≥ 1), at T 18 and at T 36 .
Results: Remarkably, at CPET, ventilatory efficiency was reduced both at T 18 (V’ E /V’CO 2 slope = 31.4±3.9 SD) and T 36 (V’ E /V’CO 2 slope = 31.28±3.70 SD). Furthermore, we identified positive correlations between V’ E /V’CO 2 slope at T 18 and T 36 and both percentage of involvement and CSS at HRCT at T 0 , T 3 and T 15 . Also, negative linear correlations were found between V’ E /V’CO 2 slope at T 18 and T 36 and DL CO at T 3 and T 15 .
Conclusions: At eighteen months from COVID-19 pneumonia, 20 % of subjects still complains of exertional dyspnea. At CPET this may be explained by persistently reduced ventilatory efficiency, possibly related to the degree of lung parenchymal involvement in the acute phase of infection, likely reflecting a damage in the pulmonary circulation.