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 Pneumothorax
Lessons
42
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
Current lesson 7 Pneumothorax Pneumothorax
8 Interstitial Lung Patterns Interstitial Lung Patterns
Pneumothorax
Lung Ultrasound – Pneumothorax
 

Created by Dr. Danny Peterson, Dept of Emergency Medicine, University of Calgary.

Detection of pneumothorax1,2
  • by ultrasound:
    • sensitivity 98%, specificity 95%
  • by chest x-ray:
    • sensitivity 67%, specificity 85%

Probe Selection:

A high frequency probe (10-12 Mz.) for high resolution is best. The linear array probe is best for assessing pneumothoraces.

Phased array is not good for pneumothorax.
ultrasound probe for pneumothorax

Phased array is not good for pneumothorax
ultrasound probe for pneumothorax

Linear array is good for pneumothorax
ultrasound probe for pneumothorax

Step 1 - Position the patient and probe
  • position the patient supine (air will rise to anterior chest)
  • place probe in midclaviular line, 2nd or 3rd intercostal space
  • orient the probe with the marker facing the patient's head
  • air is lighter than lung tissue. Therefore, it will be anterior when the patient is supine (on their back)
  • therefore, detection of pneumothorax by ultrasound is most sensitive by scanning the anterior chest

Step 2 - Optimize your intercostal space and ribs
  • Slide the transducer caudad & cephalad to maximize the intercostal spaces on the screen
  • do not need to sweep, as you would when scanning the abdomen
  • adjust your depth to optimize visualization of the pleural line  (likely < 6 cm)
 
Step 3 – Identify the Pleural Line
  • the images seen "above" the pleural line are not artifact (ribs, muscle, fat)
  • there is a lot of reflection and scatter of the ultrasound waves by air
  • therefore, the images seen "below" the pleural line (lung) is mostly artifact
  • in the image below, a mirror artifact of the rib is also seen within the lung
rib artifact on ultrasound

A lines:
  • A lines are generated between the U/S probe and the pleura
  • A lines can exist with pneumothorax
  • presence or absence of A lines is non-contributory to the diagnosis of pneumothorax.

Lung Sliding
  • lung sliding is a normal finding
  • relative to the ultrasound probe, the chest wall does not move, but the lung does
Here is an example of lung sliding:


Here is an example of ABSENT lung sliding:
 
  • if you can see lung sliding, there is no pneumothorax
  • absence of lung sliding is suggestive but not diagnostic of a pneumothorax
  • other causes of absent sliding lung include: 
    • pleurodesis or scarring (lung is stuck to the chest wall)
    • severe COPD  (lung tissue might be bullous and not moving much)
    • severe consolidated pneumonia (no air going in and out of the lung = no movement)

Comet Tails and B lines:
  • comet tails and B lines are generated only when the parietal and visceral pleural surfaces interact with each other
  • if there is a pneumothorax, then the pleural surfaces will be separated and will not interact with each other
  • therefore, comet tails and B lines will be absent with pneumothorax
  • if you have B lines and no lung sliding, then there is no pneumothorax. Think about this for a second: B lines indicate pleural surface interaction; therefore, this combination is suggestive of pleurodesis or severe consolidated pneumonia
  • review the video above: there are no comet tails or B lines and there is also no lung sliding
Lung Point:
  • the lung point is the edge of the pneumothorax
  • the larger the pneumothorax is, the more lateral and posterior it will extend
  • therefore, the further lateral and posterior the lung point is, the bigger the pneumothorax is
M-Mode signs:
  • we will discuss 2 signs found on M mode for lung ultrasound:
    • Seashore (Waves on the Beach) sign
    • Barcode sign
Seashore (Waves on the Beach) Sign
  • the seashore sign is a normal finding and represents lung sliding
  • the thick bright white line on the tracing is the pleural line
  • superficial to the pleura (chest muscles, skin, fat) is not moving, creating the solitary linear lines indicating a lack of motion
  • deep to the pleura is lung sliding causing irregular grainy artifact

Now use your imagination: the superficial (top) part of the image looks like waves approaching the beach. The pleural line is the surf break. The deeper (bottom) part of the image looks like the sand on the beach. Go grab your Speedos!
seashore sign on lung ultrasound    

Barcode or Stratosphere Sign
  • when there is no movement, M mode creates straight lines (as in the ocean above)
  • if there is no lung sliding, then there is no movement anywhere on the screen
  • the barcode sign occurs when when lung sliding is absent
  • the barcode or stratosphere sign is an abnormal finding
  • tip a barcode on its side to see the similarities (this is the barcode from my pair of men's Speedos
barcode sign on ultrasound  

Conclusions:
  1. Presence of lung sliding rules out a pneumothorax at that location.
  2. Presence of comet tails or B lines rules out a pneumothorax at that location.
  3. Presence of lung pulse rules out a pneumothorax at that location.
  4. Absence of the following are all required for Dx of pneumothorax:
    1. Lung sliding
    2. Comet tails
    3. B lines
    4. Lung pulse
  5. Absence of lung sliding with presence of comet tails, B lines or lung pulse suggests important pathology other than pneumothorax.
  6. The lung point helps determine size/location of the pneumothorax.
  7. Presence or absence of A lines is non-contributory to the Dx of pneumothorax.
  8. Lung sliding in M mode = Seashore sign.
  9. Absense of lung sliding in M mode = Stratosphere or Barcode sign.
 
References
  1. Lichtenstein, D; Mezier, G, Bidman, P; Gepner, A. The “lung point”, an Ultrasound sign specific to pneumothorax. Intensive Care Med 2000:26 (10) 1434-40
  2. Blaivas, M; Lyon, M, Duggal S. A Prospective Comparison of Supine Chest Radiographs and Bedside Ultrasound for the Diagnosis of Traumatic Pneumothorax. Acad Emerg Med 2005; 12(9); 844-9