Reliability of a Pocket Sized Ultrasound Scanner in the Evaluation Covid-19 Pneumonia

Coronavirus disease 2019 (COVID-19), caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in China in December 2019 and quickly spread all over the globe. The clinical features are fever, dyspnoea, dry cough, fatigue and diarrhoea (1). Pharyngodynia, nasal congestion, rhinorrhoea and anosmia have also been reported . Interstitial pneumonia is very common and a high percentage of patients (9-11%) develop severe acute respiratory distress syndrome (ARDS) and require intensive care. Current therapeutic strategy involves agents counteracting viral invasion and replication, and inhibitors of cytokine-sustained inflammatory reactions. No specific antiviral therapy has yet been identified.

Ultrasound imaging of the lung (LUS) and associated tissues has demonstrated clinical utility in COVID-19 patients, due to the typical sonographic characteristics of affected lungs. It provides indications for clinical decisions and the management of associated respiratory failure and lung injury.

The aim of the present study was to evaluate the possibilities of a portable pocket-sized ultrasound scanner in the evaluation of lung involvement in patients with COVID-19 pneumonia.

We will perform 34 LUS (lung ultrasound scan) evaluations on patients admitted to the COVID Unit of Siena University Hospital with symptoms compatible with COVID-19, a positive SARS-CoV-2 nasal-pharyngeal swab and radiological evidence of interstitial pneumonia.

The patients will be divided into three severity categories based on respiratory impairment: Mild PaO2/FiO2 > 300 in room air or oxygen flow; Moderate PaO2/FiO2 between 150 and 300 in room air or oxygen-therapy, CPAP, NIV or HFNC; Severe PaO2/FiO2 < 150 on oxygen-therapy, CPAP, NIV, HFNC or mechanical ventilation.

The lung ultrasound scans will be performed on the same day with a standard ultrasound scanner (GE Healthcare, Venue GO) and a pocket-sized ultrasound scanner (Butterfly Network Inc., Butterfly iQ) for clinical purposes; lung preset will be used with both scanners. Up to six regions of the chest will be identified: anterosuperior (A); anteroinferior (B); lateralsuperior (C); lateralinferior (D); posterosuperior (E); posteroinferior (F). One of four different aeration patterns will be recorded according to a specific scoring system: A = 0 points (normal aeration, presence of lung sliding with A lines or less than two isolated B lines), B1 = 1 point (moderate loss of lung aeration, multiple well-defined B lines), B2 = 2 points (severe loss of lung aeration, multiple coalescent B lines), C = 3 points (lung consolidation and tissue-like pattern). Pleural effusion and pneumothorax were also recorded. A score of 0 was normal and 36 was the worst. Due to clinical conditions, the upper posterior region (E) could not be explored in some patients, so the mean of the regions explored will be calculated for the purposes of statistical analysis (total sum (0 to 36) divided by number of regions explored (5 or 6 on each side).