Incremental value of thoracic ultrasound in intensive care units: Indications, uses, and applications

Table 4 Acute respiratory disorders

Pleural effusion	Pleural effusion is an echo-free zone (dark zone) that causes lung consolidation and floating in the pleural effusion
	TUS allows the nature of the fluid to be distinguished:
	Transudate: Anechoic and echo-free pattern
	Exudate: Echogenic, with small moving dots (e.g., leukocytes, erythrocytes, fibrin, and protein particles), fibrous strings, and mobile or immobile septations with encapsulated liquid
	TUS allows for the quantification of pleural effusion volume
	Ultrasound may guide thoracentesis and biopsy of the parietal pleura
Pneumothorax	The interposition of gas between the visceral and parietal pleural layers, lack of lung sliding, and B-lines; only horizontal A-lines can be seen. Stratosphere sign is the characteristic pattern of the lack of lung sliding evaluated by M-mode. The lung point is the precise area of the chest wall where visceral and parietal pleura regain contact with each other, as well as where the regular reappearance of lung sliding replaces the pneumothorax pattern
Diaphragmatic function	A diaphragm study can be made by placing the probe below the costal margin and using M-mode to display the motion of the anatomical structures; normal inspiratory diaphragmatic movement is caudal, while normal expiratory trace is cranial. In M-mode, diaphragmatic excursion, speed of diaphragmatic contraction, inspiratory time, and duration of the cycle can be measured

TUS: Thoracic ultrasound.