Artifacts are important signs in lung ultrasound and provide information on the underlying lung density.1 A-lines are horizontal reverberation artifacts; B-lines are vertical hyperechoic laser-shaped artifacts. In the differential diagnosis of acute respiratory failure,2 three or more B-lines per scan define a B-pattern and suggest cardiogenic edema while ruling out chronic pulmonary obstructive disease decompensation and pneumothorax.2 Moreover, the number of B-lines progressively increases with lung density1 : a B-lines reduction indicates good response to antibiotics in ventilator-associated pneumonia or to positive end-expiratory pressure trial in adult respiratory distress syndrome; an increase in B-lines after fluid resuscitation is an early sign of overload.3 A correct visualization of B-lines and their number is therefore essential.
In Panel A, multiple B-lines are visualized in transversal scan; this B-pattern corresponds to moderate loss of aeration.1 Also see Video 1 (Supplemental Digital Content 1, http://links.lww.com/ALN/B816). However, all the B-lines here derive from the same pleural point and are oblique; this suggests that the machine setting is not adequate. In this modern ultrasound machine, artifact-erasing software and harmonics are active: these settings improve real-image visualization but can affect lung ultrasound by altering artifact visualization. In Panel B, the same scan is examined with no harmonics and no artifact-erasing software: a single straight B-line is visualized; this corresponds to normal aeration.1 Also see Video 2 (Supplemental Digital Content 2, http://links.lww.com/ALN/B817).
Modern machines are perfectly suitable for lung ultrasound,1–3 but a dedicated setting is useful and may be requested of manufacturers. We suggest setting a depth of 6 to 8 cm, placing a single focus on the pleural line, and abolishing artifact-erasing software and harmonics.
Competing Interests
The authors declare no competing interests.
