During this global respiratory pandemic, LUS has been referred as a key tool in the clinical management of patients with COVID-19-related lung injury [26].
Even though we describe a small sample of pediatric patients, it might be a representative picture of what we could expect to find on the lung ultrasound of children with a COVID-19 infection. In adults, it has been described that LUS findings in COVID-19 patients are similar to those extensively described in patients with other types of pneumonia, including various forms of B-lines, an irregular or fragmented pleural line, consolidations, pleural effusion, and absence of lung sliding [27]. In the COVID-19 patients described in this study, LUS mostly showed multiform vertical artifacts and separate and coalescent B-lines, classified as score of 1 or 2 from Soldati classification. Subpleural consolidations < 1 cm have been found to be the most predominant pattern, and alveolar consolidation was described in some cases. These results and patterns have been equally defined in adults [8, 27]. However, consolidations are less common in our pediatric patients than what is typically described in adults [27].
The classification of both findings seems to be correlated with the severity of the lung injury. A recent paper concludes that there is a high concordance between radiologic and LUS findings, suggesting that LUS is a reasonable method to detect lung abnormalities in children with COVID-19 [20].
Recently, clusters of children and adolescents with a multisystem inflammatory condition sharing features with Kawasaki disease and toxic shock syndrome have been described. In our sample, four patients presented with MIS-C [16, 28,29,30]. Even though three of those patients presented with non-respiratory symptoms, LUS showed severe loss of aeration in all of them. This was probably secondary to the associated capillary leakage, and also to the cardiogenic shock in those who required PICU admission.
LUS findings may differ depending on the presence of respiratory symptoms and their severity. In our experience, we would say that on the one hand, patients with acute COVID-19 disease with severe respiratory failure have a moderately or severely altered LUS, with no cases of a normal or mildly altered LUS. On the other hand, patients with mild or non-respiratory symptoms may have LUS alterations, but milder than those with severe respiratory failure [13, 31]. LUS findings always should be interpreted in light of the clinical context [20].
We would like to mention that we are aware that there may be concern about the safety of using this technique in these patients due to the contagiousness of COVID-19. However, it has been demonstrated that the same clinician can safely perform the clinical examination and the bedside LUS during the same exploration [13, 32]. Therefore, no other clinicians need to come into contact with the patient [13]. When pulmonary condition can be monitored using LUS, the patient does not need to be moved around the hospital to undergo a CT scan or a chest X-ray, so neither people moving in the corridors nor the radiology technicians come into contact with the patient. All these strategies help to reduce physicians’ exposure and halt the spread of the virus. Moreover, combined with the clinical evaluation, LUS may help clinicians to monitor the evolution of lung disease until its resolution [26, 32]. We would like to highlight that no physician got infected despite doing bedside LUS.
Based on our experience, we consider that LUS might have major utility for the management of children with COVID-19, regardless of whether they have respiratory symptoms, due to its easy access, safety, low cost, and point-of-care use. It could be used to quickly assess the severity of acute COVID-19-induced pneumonia, and to track the evolution of the disease during follow-up. It could also allow physicians to identify the patients who are at a higher risk of respiratory failure evolution depending on the LUS alteration, so they could be monitored more intensively and rapidly enhance the treatment if needed.
Recent international evidence-based guidelines on Point-of-Care Ultrasound (POCUS) [33] for critically ill neonates and children have been published. POCUS is increasingly being utilized in neonatal and pediatric critical care as a valuable adjunct to clinical examination. It involves a focused assessment and provides anatomical and/or physiological information to be integrated with clinical and laboratory data and make timely and accurate decisions possible. Lung POCUS is helpful to semi-quantitatively evaluate lung aeration, to detect pneumonia and pleural effusions in neonates and children. Following POCUS guidelines which define a scope of practice may help in standardizing clinical practice across acute care settings. Lung POCUS is helpful to semi-quantitatively evaluate lung aeration, to detect pneumonia and pleural effusions in neonates and children.
We acknowledge that this study has several limitations. Firstly, it was carried out at a single center, so the results may not be able to be extrapolated to other populations. Secondly, LUS is a lung-image technique that should be performed by experienced physicians with a standard LUS training and should always be combined with a proper physical examination and other laboratory analysis. Finally, research on COVID-19 pneumonia diagnosis is hampered by the difficulties in obtaining a systematic comparison with CT scan [10]. Despite this, we believe that it provides valuable information, as there is limited data regarding pediatric patients with this condition.