Lung ultrasound as a tool for monitoring the interstitial changes in recently hospitalised patients with COVID-19 pneumonia - The COVIDLUS study.

Background Long-term respiratory effects can occur after COVID-19 pneumonia (CP). The COVID Lung Ultrasound Study (COVIDLUS) aimed to investigate the utility of serial lung ultrasound (LUS) to track functional and physiological recovery after hospitalisation in patients with CP. Methods Between April 2021 and April 2022, 21 patients were recruited at discharge (D0). LUS was performed on D0, day 41 (D41) and day 83 (D83). CT Thorax was performed on D83. Lymphocyte count, Ferritin, Lactate Dehydrogenase, Troponin, CRP, and D-dimers were measured at D0, D41 and D83. 6 minute walking test (6MWT) was performed on D83 and quality of life questionnaires and spirometry completed on D41 and D83. Results 19 subjects completed the study (10 males [52%]; mean age: 52 years [range:37-74]). 1 patient died. LUS scores were significantly higher at D0, compared to D41 and D83 (Mean score:10.9 [D0]/2.8 [D41]/1.5 [D83]; p < 0.0001). LUS scores correlated poorly with CT at D83 (Pearson r2  = 0.28). Mean lymphocyte counts were lower at D0 but increased at D41 and D83. Mean serum Ferritin was significantly lower at D41 and D83, as compared to D0. The mean 6MWT distance was 385 m (130-540 m). Quality of life measures did not differ at D41 and D83. Lung function increased between D41 and D83 with mean increase in FEV1 and FVC of 160 ml and 190 ml respectively. Conclusion LUS can monitor the early recovery of lung interstitial changes from CP. The utility of LUS to predict development of subsequent lung fibrosis post-COVID deserves further study.