Evolution of Techniques and New Protocols for Lung Ultrasound Examination in COVID-19 Pneumonia Patients

Abstract

Competent triage of patients with COVID-19 pneumonia is not only about efficient allocation of hospital resources, but also about making timely decisions that can ultimately save the patient's life. When healthcare facility is overloaded, computed tomography to assess the severity of COVID-19-associated pneumonia in each individual case is not always possible. Alternative solutions, however, are opted.The aim of the study was to develop Lung UltraSound (LUS) protocols with high diagnostic potential for assessing the severity of pneumonia caused by COVID-19, which can be reliably used instead of CT during triage in an emergency setting.Materials and methods. We conducted a retrospective analysis of data on 161 hospitalized patients with confirmed pneumonia caused by COVID-19, subjected to both CT and LUS within 24 hours after hospitalization. Three consecutive LUS protocols, including two LUS developed by the NMHC (National Medical Surgical Center) authors, were tested to choose the most reliable protocol for assessing the severity of lung damage in pneumonia caused by COVID-19 (based on correlation with chest CT results). We also checked the applicability of LUS for the prognosis of the disease.Results. Moderate (50% CT) and severe (50% CT) lung damage can be distinguished when using both - the 16-zone and 12-zone LUS NMHC scanning protocols. The AUC for the ROC curves was almost identical: 0.83 (95% CI: 0.75–0.90 and 0.81 (95% CI: 0.73–0.88) for the 16-zone and 12-zone LUS NMHC protocols, respectively. The 16-zone LUS NMHC had an optimal threshold of 20 scores with a sensitivity of 67% and a specificity of 82%, while the 12-zone LUS NMHC provided an optimal threshold of 15 scores with the same sensitivity but lower specificity — only 73%. Neither the 16-zone nor the 12-zone NMHC LUS protocols could predict the outcome.Conclusion. The newly developed 16- and 12-zone LUS NMHC scanning protocols for patients with pneumonia caused by COVID-19 proved to be easy to implement, demonstrating a strong correlation with CT results. The 16-zone LUS NMHC protocol is probably more relevant for triage of patients with more than 50% of pulmonary tissue involvement based on CT data. Both protocols can be useful in emergency settings and in medical institutions with limited or no access to CT.