4 | DISCUSSION
There has been limited data
regarding the usefulness of LUS in children with COVID‑19. Given the
paucity of children-related articles in scientific literature, Norbedo
et al. reviewed only 2 studies on ultrasound use for COVID-19 suspected
pediatric patients and compared them with the published findings in
adult patients. They demonstrated that in the context of pediatric
patient evaluation use of LUS could aid in detecting COVID-19 pneumonia,
even if a small case series reported encouraging
results8. Caroselli et al. identified only seven
studies using LUS to diagnose SARS-CoV-2 infection in newborns and
children and compared it with published findings, including 117 studies
describing the use of chest X-ray or chest computed tomography in
pediatric patients with COVID-19, and the review indicates that the use
of LUS should be encouraged in pediatric patients, who are at highest
risk of complications from medical ionizing
radiation28. To the best of our knowledge, this is the
first systematic review study of the pediatric age group to evaluate the
use of LUS versus CXR and chest CT in children with COVID‐19. In the
present study, we identified 33 patients (14.11%) with lung
abnormalities on LUS who had a normal chest radiograph, but no patients
with normal lung US had abnormalities on the CXR. Therefore, we conclude
that lung ultrasound is more accurate than CXR in identifying patients
with COVID-19 pneumonia. Moreover, we identified 3 patients(6%) with
lung abnormalities on chest LUS who had a normal CT in this review. Feng
et al. reported two cases (out of 5 children) and Hizal et al. reported
only one case (out of 28 children) of discordance of LUS and chest CT
results, respectively, an increased B‐line in the lower lobe and normal
chest CT findings17,.21. All three patients underwent
LUS and CT at the time of admission to the hospital with mild to
moderate symptoms. Musolino et al. report that more B lines were
presented in children in the early stage of the COVID-19
children20. Furthermore, the cause of this
inconsistency could be that CT scan was suggested as a screening method
due to rapid identification of pulmonary images typical of COVID-19 such
as the ground-glass opacity; however, it is also demonstrated that the
pathological findings are pathological are often found
later29. Meanwhile, the fact that COVID‐19 lung
involvement begins predominantly from peripheral regions of the lung
creates an advantage in detecting these lesions via LUS. Consequently,
the abnormal LUS findings detected in patients with normal CT made us
believe that LUS is a sensitive diagnostic tool of child COVID‐19
pneumonia, especially in the early
stage of the disease and mild cases.
To avoid excessive radiation exposure and contamination of suites,
personnel and equipment, the British Paediatric Respiratory Society
recommended that chest CT should be reserved for unstable cases with
increasingly clinical deterioration or if surgery cannot be
postponed30. However, as is widely known, the clinical
COVID-19 manifestations in children are mild or moderate compared to the
adult population; therefore, there is an urgent need to understand the
correlation between lung US findings and clinical severity in this
desease31. In our review, only 3 relevant studies were
included. The study of Giorno et al. was the first in the pediatric
COVID-19 population to analyze lung US aeration scores and demonstrated
that patients that classified as moderate and severe/critical had major
abnormalities on lung US and consequently higher lung US aeration
scores15. They do not have statistical power to
confirm the lung US aeration score as a disease severity predictor given
the small sample size. Li et al. retrospectively evaluated neonates with
confirmed COVID‐19 as well as 11 age‐ and gender‐matched controls
(control group) simultaneously and the LUSS was significantly higher in
the COVID‐19 group(P <0.05), suggesting that might be an
additional tool to help clinicians in risk
stratification18. However, this was a retrospective
study, and few positive cases were not enrolled due to a lack of timely
LUS examination. Musolino et al. conducted a prospective observational
study, including 30 patients with swab‐confirmed COVID‐19 infection and
the patients were subjected to an LUS within 6 h from admission and
after 96 h. The results showed that LUS had a 90.9% sensitivity in
detecting signs of lung involvement by COVID‐19. Importantly, the LUS
allowed differentiating between those with mild or moderate
disease20. Since the ultrasound aspects described in
the study are not pathognomonic of SARS-CoV‐2 infection and also found
in the course of other lung diseases, the result is still encouraging.
In view of this, LUS can be useful
to identify patients with lung involvement and in staging their severity
in this new disease.
As residual lung fibrosis may develop after viral infections also in
children with COVID‐19, a longitudinal follow‐up study with invasive or
less invasive imaging techniques would be of remarkable value.
Interestingly, only one study about the application of LUS in
longitudinal follow-up on COVID-19 children was founded. This limited
use of LUS in children, if reflective of daily clinical practice,
contradicts available scientific evidence. Denina et al., using LUS done
a follow-up for 28 patients to study the sequelae of COVID-19 in
children and lung ultrasound findings correlated with the clinical
improvement, showing a complete normalization within 5 weeks from
hospital discharge in the majority of patients14.
Therefore, we believe it is urgent
to prompt further investigation into longitudinal follow‐up study with
LUS and an extended time follow-up is also necessary.
Finally, research on COVID-19 pneumonia diagnosis is hampered by the
difficulties in obtaining a systematic comparison with a CT scan.
Despite, we believe that it provides valuable information, as there is
limited data regarding pediatric patients with this condition. In
addition, all the sonographers from the literatures were not blinded to
clinical information because lung US assessment is performed regularly
as an extension of the physical examination. Therefore, we recommended
that LUS findings always should be interpreted in light of the clinical
context.
Consequently, we suggest that LUS
is a useful tool in diagnosing children with COVID‐19 during the
pandemic. When LUS is used in the initial diagnostic steps in early
diagnosis and follow-up monitoring of COVID-19 pneumonia in children,
reduction in chest CT assessments may be possible.