Correlation between lung ultrasonography and pulmonary function tests in the post-COVID-19 follow-up: a prospective study.

<bold>Introduction:</bold> While lung ultrasonography (LUS) has been widely used in the acute phase of COVID-19 pneumonia, there is not enough information available to assess the diagnostic value of LUS in post-COVID-19 and its relation to pulmonary function tests (PFTs). <bold>Methods:</bold> Sixty-seven patients (female-24; male-43; mean age of 57.5±13 years) with persistent clinical symptoms after COVID-19 pneumonia were prospectively enrolled and underwent PFTs and LUS. The LUS examination was performed with a linear transducer to score various artifacts on a pleural line and a 12-zone scoring system was implemented (total score ranged between 0 and 36 points). <bold>Results:</bold> In total 101 pairs of both LUS examinations and PFTs were performed (67 patients underwent one assessment, 32- a second and 2- a third follow-up assessment). The mean time from the onset of COVID-19 until enrolment was 277± 189 days. Alterations in DLCO and FVC (<80% of the lower limit of normal) were detected in 55 cases (54.5%) and 20 cases (19.8%), respectively. The mean LUS score was 11.7±7.14 and exhibited a moderate negative correlation with DLCO (r= -0.56), FVC (r= -0.42), FEV1 (r= -0,43), and a weak negative correlation with TLC (r= -0.39), p<0,05 respectively. Patients with confirmed fibrotic-like lesions showed significantly lower DLCO scores (p=0. 000001). <bold>Conclusions:</bold> The LUS severity score was inversely related to PFTs results. A higher degree of lung involvement in LUS was associated with poorer lung function; thus, LUS might be considered as a screening tool for follow-up examinations in post-COVID-19 survivors.