Teaching Medicine - Tutorial: Lung Ultrasound

Ultrasound

Level 1

Tutorial: Lung Ultrasound

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Tutorial: Lung Ultrasound

Learn ultrasound of the lung. Identify pneumothorax, pleural effusions and wet lungs.

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Tutorial: Lung Ultrasound Pleural Effusion

Lessons

Times Practiced

1284

Cases Completed

1h 24m

Total Time spent

1m 24s

Average Time

Progress

Accuracy

Efficiency

Accuracy

Efficiency

	1	Normal Lung Ultrasound Normal Lung Ultrasound
	2	A lines A lines
	3	B lines B lines
	4	Comet tails Comet tails
	5	Seashore and Barcode in M mode Seashore and Barcode in M mode
	6	Pleural Effusion Pleural Effusion
	7	Pneumothorax Pneumothorax
	8	Interstitial Lung Patterns Interstitial Lung Patterns

Pleural Effusion

Pleural Effusions

Normally there are 2-10 ml of fluid in pleural space.

In pathological conditions causing pleural effusions, the volume of fluid is increased. We can identify this fluid with non-invasive imaging:

upright CXR - 100 -150 ml is required to blunt the costophrenic angle
supine CXR - 200 - 300 ml is required to be identified
ultrasound - as little as 20 ml of fluid can be identified

Probe Selection: a low frequency probe (2-5 Mz.) for deeper penetration is best.

a smaller footprint is easier to get between ribs
the phased array ("cardiac" probe) or the curved array ("abdominal" probe) are good choices
do not use the linear array ("vascular" probe) - the images are too shallow

Phased array is good:

Curved array is good:

Linear array is not good:
linear array probe

Patient position

the patient can be either supine, semi-sitting or totally sitting up
raise the arm to increase space between the ribs

Step 1 – Palpate the xiphoid

place the probe with marker toward head on the posterior axillary line at the level of the xiphoid

Step 2 – Locate the diaphragm

the diaphragm is a skinny, curved and bright white (hyperechoic)
if you are on the patient's right, you will see the liver below the diaphragm
if you are on the patient's left, you will see the spleen below the diaphragm

Step 3 – Center the diaphragm

slide the probe toward (cephalad) or away from (caudad) the head to bring diaphragm into the center

Step 4 – Identify the pleural cavity

remember that the orientation marker on the screen is on the left
the marker on the probe is toward the head
therefore, "screen left" = toward the head (cephalad)
the pleural cavity is cephalad to the diaphragm
therefore, the pleural cavity is to the left of the diagphragm on the screen

Step 5 – Sweep anterior and posterior to view

identify the region where the effusion is largest
select this space for inserting a needle or tube, if indicated

Normal Lung findings

the lung is normally filled with air
air in lung scatters the ultrasound beam and therefore produces a snowstorm appearance

Effusions

fluid does not reflect ultrasound waves. Therefore, fluid is anechoic = black.
pleural effusions are black
frequently you will see atalectatic (collapsed) lung within the effusion. Lung without air takes on the appearance of a solid organ and will be white.
collapsed lung is white

if the lung is separated from the chest wall or diaphragm by more than 3 cm. of effusion, the pleural space contains at least 500 ml of fluid

The Spine Sign

Since the beam passes though the liver to the midline, it will often encounter a series of white lines representing the spine. Bone reflects all sound back to the probe, so deep to the white line will be shadowing.

since air does not transmit sound, you will not be able to see the spine above the diaphragm
if there is pleural effusion, then there will be no air superior to the diaphragm as the lung is displaced by fluid
in this situation, the sound waves will be able to travel all the way to the midline, revealing the spine
if you can see the spine on the left of the liver/diaphragm, this finding supports the presence of a pleural effusion

Here is example of a normal ABSENT spine sign (no effusion):
spine sign on ultrasound

Here is an example of a PRESENT spine sign with pleural effusion:
spine sign on ultrasound

Here is a video showing a small effusion and the spine sign:

Loculated Effusions:

Loculated complex effusion have a variety of appearances. Clotted blood and empyemas may take on the ultrasound characteristics of a solid organ.

Conclusions:

The pleural space is to the left of the diaphragm if screen marker on left and probe marker toward head
Liquid effusions are black
Effusions > 3 cm suggest effusion is > 500 ml
Collapsed lung (atalectasis) is white
Spine sign occurs with effusions
Loculated effusions will have white stranding
Clotted effusions or empyema can mimic a solid organ