TABLE 1.

Grading of sonographic features

Grade	Value	Ultrasonic features
0	Pneumothorax	B mode: lung sliding absent, repetitive A lines present, lung point present, no fluid detectable and B lines absent M mode: seashore sign absent and stratosphere sign present
1	Pleural effusion	B mode: hypoechoic structure or echo-free space between both pleura, and gliding sign absent M mode: sinusoid sign if a small amount of liquid
2	Lung sliding	B mode: gliding sign and B lines present M mode: seashore sign present
3	Pleural symphysis	B mode: gliding sign questionable or absent, B lines absent, and pleural thickening with posterior enhancement M mode: seashore sign absent