Pitfalls

Lung ultrasound relies on artefacts generated by the pleural line, so the operator must ensure the probe is positioned perpendicular to the chest and pleural line to maximize visualization of these artefacts. An obliquely oriented probe can obscure the visualization of normal lung artefact.

Small, vertical projections from the pleural line that do not cross A-lines or project to the end of the screen are often seen in normal lung due movement at the visceral-parietal pleural interface. These artefacts are known as z-lines or comet tail artefacts and should not be confused with B-lines (figure 6).

Figure 6:  Z-line or comet tail artefact—small vertical line arising from the pleura that fades quickly and does not cross A-lines

It is also important to note, some areas of lung are difficult to access and image with ultrasound including the supraclavicular, scapular, axillary and peri bronchial areas.