Materials and Methods:
An observational study including children (<18 years) admitted to the Pediatric Unit at Meyer Children University Hospital (Florence, Italy) for documented COVID-19 from 1st March to 27th April, 2020, was performed. Clinical charts data on contact history and previous history, clinical symptoms, coinfections (defined as a concurrent infection of a patient with two or more pathogens simultaneously) and radiological examinations (chest X-ray or CT scan) were gathered. Nasopharyngeal swab samples of all the subjects were collected, and SARS-CoV-2 RNA was identified by reverse transcription‐polymerase chain reaction. One or more subsequent lung POCUS were obtained from all subjects by two expert pediatricians with specific POCUS training, during the routine daily medical examination. All the images were stored and blinded reviewed by an experienced POCUS emergency medicine pediatrician with 10 years POCUS experience, to provide agreement within lung US reports. The study protocol was approved by the Ethics Committee of Meyer Children’s Hospital and parental informed consent was obtained. Lung US was performed with a portable laptop-size POCUS machine using a linear probe (L12-4s mHz). In order to minimize the risk of device contamination and subsequent nosocomial spread, the US machine and the probe were each covered in a sterile plastic. The operator entered the isolation room, using personal protective equipment (PPE) as for WHO recommendations, with the US machine on a sanitizable tray and performed both the clinical examination and lung US. At the end of the procedure, the operator took off the covers and the PPE in a dedicated clean room and subsequently sterilized probe, wire, machine and tray. The thorax was scanned in 6 lung areas to provide a focused and rapid picture of involvement of key regions of the lung: anterior, lateral and posterior, bilaterally.14 In our Institution lung ultrasound is routinely included in the management of patients with respiratory conditions. Lung US features were evaluated ‘a priori’ as follows (Figure1): (a) A-lines pattern; (b) focal separate B-lines; (c) focal coalescent B-lines; (d) confluent B-lines appearing as a “white lung”; (e) subpleural consolidations (dimension < 1 cm) associated with single or coalescent B-lines; (f) consolidations (dimension > 1cm); (g) pneumothorax; (e) pleural effusion.15