This video shows both ”lung pulse” and ”lung sliding”.

Notice that ”lung pulse” is rhythmic and in synchrony with the cardiac pulsation. If in doubt it can be useful to palpate the peripheral pulse to check for synchrony.

“Lung sliding” appears in synchrony with the respiratory cycle. Lung sliding is easier to see with higher tidal volumes, and disappears with apnea.

Both lung signs indicate that the visceral and parietal pleural surfaces are juxtaposed at the location of probe.

This is why lung sliding and lung pulse can be used to rule out the presence of air in between the two pleural sheets (i.e. pneumothorax).

Lung sliding is movement of the pleural line synchronous with the respiratory cycle.

In addition, the pleural line may move in synchrony with the cardiac pulse.

This movement, termed “lung pulse”, is caused by the force of the cardiac pulsation being transmitted to the lung and hence to the visceral pleura.

Like lung sliding, lung pulse indicates that the visceral and parietal pleural surfaces are juxtaposed at the location of the probe.

In case of pneumothorax, there will be no lung pulse.

In case of failed intubation to right main bronchus there will be lung pulse on the left side but no sliding.

The video shows six different presentations of normal lung-sliding sign. Observe the horizontal movement of the white pleural line.

The most important dynamic sign to be checked is the ‘‘lung sliding’’. It is a subtle and bright horizontal movement of the pleural line in synchrony with the respiratory cycle indicating sliding movement of the visceral pleura against the parietal pleura.

Lung sliding is due to the up and down movement of the lung in synchrony with the piston-like respiratory movement of the diaphragm.

The sonographic resolution does not allow distinction between the two pleural layers – they present as a white pleural line.

When air separates the two pleural layers, the movement disappears and cannot be detected with LUS; in that case, the parietal pleura is still visible but is immobile.

Pleural signs are used for lung ultrasound evaluation of the pleura between the ribs.

These signs include:

– Lung sliding
– B-lines
– Lung pulse

The signs will be explained in detail in the following topics.

The term ”bat sign” was described by Dr. Daniel Lichtenstein, in respect of the capacity of this animal to use ultrasound navigation very accurately.

Identification of the ”bat sign” confirms that the ultrasound image represents the space between two ribs, and the hyperechogenic (white) linear structure between the ribs is pleura.

In addition, the depth of the ultrasound image can be adjusted in order to align the pleura to the centre of the ultrasound screen.

The ”bat sign” should always be obtained, before the pleura is evaluated.

Costae
The costae are identified by the hyperechogenic (white) surface and the hypoechogenic (black) shadow below the costa.

Pleura
Pleura is seen as a hyperechogenic (white) structure between the costae.

Things are not always what they seem!

OBSERVE: Image structures below the pleura line do not represent lung tissue – the air in the lungs absorbs the ultrasound waves and returns no echoes.

Structures seen in the image below the pleura line are not lung tissue but represent image artefacts from the echoes from the skin, muscle, costae and pleural line.

The lungs are protected and contained inside the chest cavity by the chest wall. The chest wall consists of ribs (syn: costae), and the soft tissues including muscles between the ribs in the intercostal space.

The inside of the chest wall is covered by the parietal pleura, and the lung by the visceral pleura. The pleural space is delimited by the visceral and the parietal pleura.

The visceral and parietal pleura normally lie close together with just a thin film of fluid in the pleural space.

The visceral and parietal pleura slide against each other in synchrony with respiration.

In this lesson you will learn about:

• Anatomy of the normal lung and chest wall
• Ultrasound presentation of the chest wall, pleura, lung and diaphragm
• The “bat sign” used to identify the pleura
• Lung sliding
• Lung pulse
• B-lines
• Ultrasound M-mode presentation of the normal pleura

In this lesson you have learned which equipment and skills are needed for focused lung ultrasound (FLUS):

Equipment – the ultrasound system:
– Ultrasound machine
– Different types of transducers
– Preset selection
– Orientation marker (OI) presentation on screen (Left/Right)

Skills:
– Placement of the transducer and finding the right windows
– Optimisation of the ultrasound image by changing depth, gain and focus
– Identify structures, and looking for pathology