It is important to understand that

It is important to understand that PLUS involves an understanding of how to interpret artifacts as healthy lungs contain air which impedes ultrasound transmission, rendering it impossible to visualize the lung itself. Fortunately, the normal findings of PLUS change as a result of underlying pleura and lung pathology, which allows pathology to be identified via artifact interpretation with relatively high sensitivity and specificity (see relevant chapters). There are 6 key “lines and signs” that should be identified and interpreted during PLUS which include; 1) the pleural line, 2) A lines, 3) the bat sign, 4) the glide sign, 5) B lines, and 6) the curtain sign. In addition, knowing how to identify the pericardio-diaphragmatic window, define dry lung, identify the ski jump sign, the lung pulse, Z-lines, I-lines, and the 5 sonographically-defined pleural space and lung borders is also essential.