Lung ultrasound
LUS was performed with the ultrasound machine ESAOTE MyLab ™ 40, which complies with the Medical Device Directive (MDD) 93 \ 42 \ EEC and subsequent amendments. In accordance with this directive, Esaote has classified it as Class IIa devices. The preset used was small parts. Linear probe (12 - 6 MHz) was used in preschool children. In older children, we used a curved probe (8 - 5 MHz). The focus was always positioned at the level of the pleural line. Images and clips were stored and archived. The ultrasound scans were performed by pediatricians and pediatric residents with certifications and / or with an experience of at least 3 years of practice with LUS.
The scans were made by investigating the anterior, lateral and posterior regions of the bilaterally thorax and placing the probe transversally and longitudinally along the lines considered traditional ultrasound findings: the parasternal line, the axillary line and the paravertebral line so as to fully explore the chest wall according to a methodical scheme first described by Copetti et al.22
To investigate the anterior and lateral lung fields patients were positioned, according to age, in a seated or supine position. The posterior lung fields have been explored in lateral decubitus and in sitting position.
LUS was performed at the time of first evaluation - and before the start of any treatment - of all children with acute or previous history of heart disease (with and without signs and symptoms of respiratory distress) or with signs and symptoms of suspected disease. systemic inflammatory/sepsis (with and without signs and symptoms of respiratory distress).
All lung regions were scanned with LUS to assess pleural slip and pleural line regularity, presence of A lines, density and characteristics of B lines or vertical artifacts, pleural effusion, and presence of subplerural lung consolidations.
The regular movement of the pleura during breathing defines the pleural sliding which in some circumstances may be absent or have irregularities of the hypercogeneity of the pleruic line. 23
The A lines were horizontal, regularly spaced, hyperechoic lines representing reverberations of the pleural line (repetition artifacts): this model is considered the physiological lung model.23
B lines or vertical artifacts were defined as vertical lines arising from the pleural line. These artifacts show a narrow base, extend to the bottom of the screen without fading, and move synchronously with the lung slide.23 However, according to the evidence that the B lines appear different in different pathological and deflationary conditions, depending on the variable distribution of the full-to-void ratio along the pleural line7,24,25, in this study the presence of short B lines also have been considered.
Finally, a fluid-filled anechoic space between the parietal and visceral pleura identified the trasudative pleural effusion1,3,26 and lung consolidations were diagnosed by the presence of poorly ventilated or solid images adjacent to the pleura, according to the usual descriptions in the literature. 1,3,26
The following lung ultrasound finding were detected (Figures 1, 2 and 3):
- the presence of short vertical artifacts;
- the presence of long vertical artifacts, their characteristics (multiple or single, confluent or non-confluent, without or with spared areas) and their position (predominantly localized to the pulmonary bases or widespread also in other fields; unilateral or bilateral);
- the presence of anechoic pleural effusion and its location (at the unilateral or bilateral bases);
- the presence of subpleural consolidations;
- the characteristics of the pleural line (regular, irregular, regular with areas of irregularity).