A pneumothorax is ruled out

What is a lung point?
In pneumothorax, the edge of the collapsed lung will appear as a “lung point”.

The lung point represents the transition zone between the area of air-filled pleura and the reunion of the pleural blades.

The lung point moves back and forth in synchrony with the patient’s breathing.

Anterior to the lung point, with air-filled pleura, no lung sliding is seen.

Posterior to the lung point, with contacting pleural blades, normal lung sliding is seen.

Right at the lung point both can be observed as seen on the image to the right.

Lung point and pneumothorax
Lung point is diagnostic of pneumothorax.

Lung sliding
Lung sliding is a horizontal movement of the bright pleural line in synchrony with the respiratory cycle indicating sliding movement of the visceral pleura against the parietal pleura.

Lung pulse
Lung pulse is a variation of the same phenomenon, but is caused by projection of the heart beats through the lung tissue, causing small frequent movements of the pleural blades.
Lung pulse is only clearly seen when there is no respiration/ventilation.

Pathologies
Absence of lung sliding and lung pulse is seen in any condition causing the visceral and the parietal pleura to be either separated (e.g. pneumothorax) or joined (e.g. pleurodesis).

Presence of lung sliding or lung pulse is 100% specific and rules out pneumothorax at the location of the transducer.

Can pneumothorax be confirmed or excluded?

The lung ultrasound signs Lung sliding/lung pulse, B-lines and Lung point are used in diagnosing or excluding pneumothorax. These signs are explained in the following topics.

Use the signs:
Ruling out pneumothorax:

What are B-lines?
B-lines are hyperechoic, laser-like, vertical artefacts that visually originate from the pleural line and continue to the bottom edge of the screen without fading in intensity.

B-lines and pneumothorax
Visualisation of the B-line artefact is only possible when there is no air between the two pleural blades and they are in contact with each other.

The finding of one or more B-lines can be used to rule out pneumothorax.

B-lines also play a role in diagnosing pulmonary edema (discussed later).

Pleural line
If the pleural line and the lung signs cannot be clearly separated from the surrounding structures:

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

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

Things are not always as 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 is not lung tissue but represent image artefacts from the echoes from the skin, muscle, costae and pleural line.

In the posterolateral pleural view, the following structures can be seen:

Right side
Liver
Kidney (not seen in the image to the right)
Diaphragm
Spine

Left side
Spleen
Kidney
Diaphragm
Spine

Rotation
Generally, a slight rotation of the transducer, so the OM aims more towards the mattress, can improve image quality (counter-clockwise on right side, clockwise on left side).

Fluid follows gravity
Always make sure that the transducer is placed as posterior as possible – your hand needs to touch the mattress.

That hard left side
On the left side it is generally more difficult to obtain good images than on the right side – but the tips for optimising the image are the same: