Point of care lung ultrasound is a useful tool to diagnose Covid-19 pneumonia, according to a retrospective multicenter observational study of patients admitted to the Emergency Department (ED).¹

This study included 479 patients, who presented to four different EDs in Italy, Portugal and Spain with symptoms suggestive of Covid-19. Many of these patients also had comorbid conditions including COPD, congestive heart failure and diabetes increasing their risk for Covid-19. Along with physical examination, a lung ultrasound in the ED was performed by the trained emergency physician before a conventional chest x-ray was done or while waiting for the report. The chest x-ray was reported by the ED radiologist. The data was collected retrospectively.

Out of the 479 patients included in the study, 87% were diagnosed with Covid-19.

In Covid-positive patients, the most common findings on lung ultrasound were B-lines seen in 80.1% patients, irregular pleural lines in 59.2% patients and small sub-pleural consolidations in 55.3% patients. When the lung US findings were analyzed in relation to the molecular test results for Covid, only B lines and small sub-pleural consolidation were found to be associated with positive test results, while effusions and irregular pleural lines showed no such association. Irregular pleural lines are common in patients with COVID-19 pneumonia, but they are not a pathognomonic finding. However, only 59% of Covid-positive patients had sub-pleural consolidations. Hence, absence of sub-pleural consolidations alone cannot be used to rule out COVID-19 infection with pulmonary involvement, according to the researchers.

Chest x-ray was normal in nearly 18% of patients, while ground glass, interstitial pattern and small consolidations were reported in 31.6%, 59.7% and 18.6% patients, respectively. Ground glass appearance, pleural effusions and small consolidations were found to be significantly correlated with positive Covid-19 test, while the presence of interstitial pattern and normal chest x-ray did not.

High-resolution computed tomography (HRCT) chest is routinely done to diagnose Covid-19 pneumonia and also to monitor its progression or resolution. It has often been used as a screening test for Covid-19. But it is an expensive test and is also associated with risk of exposure to radiation when used indiscriminately. Moreover, it often cannot be relied upon when there is a surge in cases, when rapid examination and triaging is crucial.

The present study has demonstrated the comparable accuracy of lung ultrasound and chest x-ray in diagnosing Covid-19 pneumonia. The presence of B lines and small subpleural consolidation on lung ultrasound and ground glass appearance, small consolidations, and pleural effusion on chest x-ray had a significant correlation with positive test for COVID-19.

Based on their observations, the study authors suggest point of care lung ultrasound as a low-cost alternative to the more expensive HRCT with added advantages of accuracy and no radiation exposure. Its disinfection is also easy. Besides serving as a diagnostic tool, it is also useful in prognostication of patients.

Reference

1. Costantino Caroselli, et al. Early lung ultrasound findings in patients with COVID-19 pneumonia: a retrospective multicenter study of 479 patients. J Ultrasound Med. 2022 Jan 18. doi: 10.1002/jum.15944. Online ahead of print.