Discussion
In this study, we prospectively addressed the role of LUS in a cohort of
children with proven SARS-CoV-2 infection, evaluated in a tertiary level
referral center for pediatric COVID-19. Vertical artifacts are the most
common signs on LUS, while subpleural consolidations, white lung and
pleural effusions are relatively rare, compared to described reports
from adult with COVID-19. LUS had a 90.9% sensitivity in detecting
signs of lung involvement by COVID-19. Importantly, the LUS allowed to
differentiate between those with mild or moderate disease.
In this study, we evaluated the role of LUS in the follow-up of children
with COVID-19, a data not yet addressed in current literature. LUS
control was performed of day 4 of disease and showed in most cases a
resolution or improvement of LUS findings. The improvement in LUS was
concordant with the improvement of clinical conditions and laboratory
tests, suggesting that LUS can also be used in the monitoring of the
disease in children with COVID-19, as also previously suggested in
adults with COVID-19 (11,12) and children with other lung
infections.19
A recent multicentric, European study described 582 children and
adolescents with PCR-confirmed SARS-CoV-2 infection, with a median age
of 5 years.20 Majority of children had mild disease,
including infants, and 52% of evaluated children had radiologic
findings of pneumonia (47%) or acute respiratory distress syndrome
(5%). Considering the widely accepted ability of LUS in detecting both
pneumonia and ARDS, and the fact that majority of children have a mild
disease, our study highlights the possibility of using LUS as a routine
and primary level diagnostic in children with stable clinical
conditions, reserving secondary level imaging (including CT) to those
with diffuse lung disease or with unstable clinical conditions, as
previously hypothesized.2
This approach would have several benefits: first of all, would reduce
radiation exposure related to the routine use of CT scan, suggested by
the Chinese Study group on children with COVID-19; secondly, this
approach would allow the same physicians to perform both clinical
examination, blood sampling and nasopharyngeal swab, and LUS, during the
first clinical examination in the emergency department, reducing the
risk of exposure to SARS-CoV-2 of other operators. Third, LUS can be
used multiple time and can allow close follow-up of children,
potentially directly at home, reducing the pressure on critically
overloaded emergency department during the peak of the pandemic.
In this study, only a limited number of children performed chest X-ray
or CT scan, therefore we have not been able to compare the different
technics. For ethical reasons, the routine use of CT scan for research
purposes was not allowed in our Institution, and only those children
with more severe disease, or in case of clinical decision of the
evaluating doctor, underwent CT scan. Importantly, the use of LUS as the
first examination performed in children COVID-19 has allowed to reserve
the CT only in selected cases, that is, to those who presented at the
first LUS a greater interstitial involvement. In addition, these
patients were subjected to closer multiparametric and ultrasound
monitoring during the hospitalization, performing ultrasound controls in
addition to those defined by the study protocol (T0-T1). In 75% of
children enrolled we performed a LUS after 10 days from the
negativization of swab for SARS-CoV-2and we found in all a normalization
of the lung parenchyma.
Although not showed in the results section, it is important to mention
that none of the pediatricians responsible of performing LUS resulted
positive to SAR-CoV-2 infection on multiple screening procedures
performed within the Institution, confirming that if appropriately
performed, LUS is safe also in the context of SARS-CoV-2.