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

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) and 36 months (T) 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), 3 (T) and 15 months (T). All HRCTs were revised using a semi-quantitative CT severity score (CSS). Pulmonary function tests were obtained at T and T. CPET was performed in a subset of patients with residual dyspnea (mMRC ≥ 1), at T and at T.

RESULTS

Remarkably, at CPET, ventilatory efficiency was reduced both at T (V'/V'CO slope = 31.4±3.9 SD) and T (V'/V'CO slope = 31.28±3.70 SD). Furthermore, we identified positive correlations between V'/V'CO slope at T and T and both percentage of involvement and CSS at HRCT at T, T and T. Also, negative linear correlations were found between V'/V'CO slope at T and T and DL at T and T.

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.