POCUS - Lungs Flashcards
True or false: lung should not be sliding in an US.
False
Lung sliding is normal (the ants on a log are good!). If there is no lung sliding then that is pathognomonic for a pneumothorax.
B lines must be differentiated from comet tails. How can you do this?
Comet tails are shorter (B lines technically need to be 16 cm to count) and comet tails typically do not obliterate A lines whereas B lines do.
What are the rule of fours for pulmonary US?
Four positions: mid-clavicular, medial to nipple, lateral to nipple, mid axillary
What is a differential for bilateral B-lines?
CHF
Multifocal PNA
Pulmonary fibrosis
Pulmonary contusions
How much depth should you have for lung sliding?
Only enough to see the pleura and a little beyond (usually ~ 6 cm)
The definitive diagnosis of a pneumothorax is by getting what view?
The lung point, which is the point at which you can see lung sliding and then lung not sliding
Beware of scanning for lung points lower down. The liver, spleem, and heart can all mimic a lung point.
Which transducers should you use for lung evaluation?
- PTX: linear
- Pleural effusion and B lines: usually cardiac probe but can use curvilinear
It’s important to remember that the parietal pleura is ______ to the ribs.
deep
There are soft tissue lines that can appear like the pleura, but these are anterior to the ribs.
Why is it important to have the right setting for lungs?
Other settings have motion-reducing features that can eliminate lung sliding.
The interval distance of the A line is what?
The distance from the probe to the bright, hyperechoic line that produces the A lines.
Other than being an artifact, A lines can also _________-
suggest PTX (if accompanied by absence of lung sliding)
Importantly, A lines with lung sliding is good evidence that there is no interstitial syndrome such as consolidation or effusion at the spot scanned.
To speed up your thoracic exam, ______________.
put “stripes” of gel along the anterior chest wall; this allows you to pass through multiple intercostal spaces without having to pause and apply more gel
Review the BLUE (bedside lung US in emergencies) protocol.
Essentially, you look for lung sliding, B lines, and A-lines and then group into categories:
- Sliding present, B lines present = pulmonary edema, atypical PNA, or fibrosis (if lines diffuse) or PNA or contusion (if localized)
- Sliding present, A lines present = PE, PNA, COPD, or Asthma
- Sliding absent, B lines present = PNA
- Sliding absent, A lines present with lung point = PTX
- Sliding absent, A lines present without lung point = need for other imaging
- Sliding w/ A and B lines: pulmonary contusion or PNA
B lines originate from the __________ on the screen.
pleura
Many B lines that converge on the probe is called the ________ sign.
rocket
True B lines will do what to an A line?
Cross over it
Bilateral anterior B lines is highly sensitive and specific for ____________.
volume overload
You see lung that is consolidated (hepatisized). Why are air bronchograms helpful in this scenario?
Air bronchograms are seen in PNA but not atelectasis.
Importantly, lung sliding is an __________ test.
all-or-none
There is no “diminished” lung sliding.
What is the sensitivity and specificity of lung sliding for pneumothorax?
95% and 95%
A lung point is 100% specific and sensitive for PTX.
What things other than PTX can present with the absence of lung sliding?
- A person who’s had a pleurodesis
- Apnea (lung have to be moving to generate lung sliding)
- Severe atelectasis
- Fibrosis
- Incorrect machine settings
The most sensitive area to scan for a PTX is _____________.
the part of the lung that is least dependent
Do not confuse __________ with lung sliding.
cardiac motion
One aspect of pneumothoraces that can make lung sliding difficult to appreciate is ____________.
subcutaneous air
Air can cause a ring-down effect that will obliterate the pleural line.
If a patient is supine and they have a PTX, how will the lung point present?
In a sagittal view, the lung will be sliding in the superior portion and not sliding in the inferior position. This happens because the bell shape of the thorax makes the least dependent portion the anterior-inferior aspect in a supine person.
This pattern will be reversed in a person sitting upright.
True or false: in severe pneumothoraces, you sometimes will not see lung points.
True
The lungs have to be in contact with the parietal pleura to make a lung point. If the PTX is so severe that there is no contact, you will not see a lung point.
How many superior to inferior scans of the thorax should you do to evaluate for PTX?
At least three for each hemithorax — parasternal, midclavicular, midaxillary
You can obtain pseudo-lung points in what three areas?
Liver, spleen, and heart
All of the peripheral areas that will not move with respiration
True or false: the sandy beach appearance is suggestive or pneumothorax?
False
The sandy beach is normal. The “sand” is the movement of the lung. The barcode appearance is generated by the static lungs causing unmoving hyperechoic lines.
US can detect as little as _________ of fluid in the pleural space. How does this compare to XR?
20
Supine XR detects at 175 mL and upright detects 50 mL.
How do you quantify pleural effusions?
Measure the pleural distance at the thoracic base during the expiratory phase. If it is greater than 45 mm on the right and 50 mm on the left then it is sensitive for effusions greater than 800 mL.
The spine sign can be produced by effusion or __________.
lung consolidation
An article in the journal Pediatric Pulmonology showed that lung US had what sensitivity and specificity for diagnosing pneumonia?
95% for both
A meta-analysis showed that in adults it was high 80s for both.
Describe the lung zones 1-6.
1: anterior-superior
2: anterior-inferior
3: mid-axillary-superior
4: mid-axillary-inferior
5: posterior-superior
6: posterior-inferior
This applies to each lung.
In infections, you can see __________ of the pleural line.
thickening and irregularity
Describe the pathophysiology and appearance of the shred sign.
The shred sign happens when there is a lung consolidation that meets an area of healthy, aerated lung. What you see is a ragged (“shred”) border of bright white where the consolidation meets the air.
This typically happens only in lobar pneumonia where one diseased lobe is adjacent to a healthy, uninfected lobe.
What are the two categories of air bronchograms?
Dynamic and static
Static air bronchograms go with atelectasis. Dynamic (moving) go with consolidation.
In addition to air bronchograms, you can also see _________ bronchograms.
fluid
Be sure ot throw color on to verify that it is not a vessel.
A retrospective cohort study in 2021 showed that POCUS lungs had a higher sensitivity than _______ in diagnosing CHF exacerbation.
CXR
True or false: inserting a chest tube will usually lead to the reappearance of lung sliding on US.
True
What does BLUE stand for?
Bedside Lung Ultrasonography in Emergency
What are E lines?
Vertical lines that arise from air in the chest wall
How does Jacob Avila do lung US?
Probe:
- Linear for PTX
- Curvilinear for everything else
Scanning:
- Sagittal while scanning the fields for abnormalities -> transverse (through the ribs) for better view of pathology.
What is the VPPI?
Visceral Parietal Pleural Interface (where lung sliding happens)
Avila gives what definition of diffuse B lines?
3 or more B lines per zone in at least two zones per side (he divides each hemithorax into four zones)
True or false: the mirror sign at the diaphragm indicates presence of a pleural effusion.
False
The absence of it suggests pleural effusion.
Exudative effusions often have the _________ sign.
plankton
What are C lines?
Sub pleural consolidations seen in the setting of trauma
They are specific for contusions.
What are the six possible findings of PNA?
B lines (focal)
Sub pleural consolidations
Air bronchograms
Fluid bronchograms
Pleural effusions
Hepatization
Thickened, irregular pleural line
Sub pleural consolidations
What are the size rules for sub pleural consolidations?
< 0.5 cm: likely contusion, viral PNA
0.5 - 3.0 cm: PE (also more suspicious for PE if pleural effusion)
> 3.0 CM: cancer, PNA
What are the size rules for sub pleural consolidations?
< 0.5 cm: likely contusion, viral PNA
0.5 - 3.0 cm: PE (also more suspicious for PE if pleural effusion)
> 3.0 CM: cancer, PNA
