Lung EDE

Question 1

What is the external landmark when scanning for a pneumothorax?

Answer 1

Most anterior part of the lung in the mid-
clavicular line
(Least dependent area where air is most likely to escape)

Question 2

What is the internal landmark when scanning for a pneumothorax?

Answer 2

Ribs and rib shadows

Question 3

What are the findings that make a determinate NEGATIVE when scanning for a pneumothorax?
(Hint: need one of three things, in a certain # of spaces, and need to see two other structures)

Answer 3

One of the following constitutes a NEGATIVE scan for PTX:
1) Lung sliding
2) comet tails
OR 3) Lung pulse
…In at least three lung spaces on each side
… Also need to see the cardiac and liver lung points

Question 4

What is the definition of lung sliding?

Answer 4

Visceral and parietal pleura moving against each other with respiration (“Glistening” appearing or “ants on a log”)

Question 5

What is a lung pulse?

Answer 5

Cardiac pulsations transmitted to the pleural line in a poorly aerated lung (e.g. if pt is holding breath, mainstream intubation, atelectasis)

Question 6

What three things make a determinate POSITIVE scan for pneumothorax?
In how many spaces?
For how long?

Answer 6

Absence of lung sliding, comet tails AND lung pulse = positive for PTX
Needs to be in at least 1 space
For at least 3 respirations

Question 7

What technique is used to find the best image of the pleural line once you have placed the probe on the anterior chest at MCL?

Answer 7

1) slide probe cephalic or caudal to place one rib on either side of screen
2) identify pleural line
3) Sweep probe side to side to generate clearest image of pleura

Question 8

What are the physiologic lung points you need to identify in each hemithorax?
Bonus: what are two other lung points you may see but aren’t mandatory to identify

Answer 8

1) Liver lung point (R hemithorax)
2) Cardiac lung point (L Hemithorax)

Bonus:
There is also a splenic lung point and gastric lung point but don’t need to identify for CPOCUS

Question 9

What is a (pathologic) lung point?

Answer 9

The point where an area WITHOUT lung slide/comet tails/lung pulse intersects with an area where there IS lung slide/comet tails/lung pulse
(i.e. the area where the pneumothorax meets the area of normal lung)

Question 10

If you suspect a pneumothorax in a stable patient (no lung slide/comet tail/pulse for 3 breaths), what is the next thing you must identify to declare a pneumothorax?

Answer 10

A lung point (pathologic lung point).

NOTE: This may be used to identify the size of the PTX, but you may not find an identifiable lung point in a very large PTX

Question 11

How do you identify a (pathologic) lung point in a suspected pneumothorax?

Answer 11

Move the probe towards the posterior axillary line. If lung slide is identified at any point, move the probe back medially until a lung point (no slide) is identified

Question 12

Where is the lung point identified in a small/large pneumothorax?

Answer 12

Small- lung pont is located anteriorly, between mid-clavicular and anterior axillary lines
Large- lung point located posteriorly (posterior axillary line)

NOTE: may not be able to identify a lung point if it is very large

Question 13

What is the next step if you cannot identify a lung point in a patient with a suspected pneumothorax?

Answer 13

Stable patient- confirmatory test (upright CXR or CT)
Unstable patient- It’s okay to declare positive in this case. At the discretion of provider, immediate intervention if tension pneumothorax suspected

Question 14

What are six trouble shooting manoeuvres to use when having difficulty identifying lung slide?

Answer 14

1) Sweep probe to magnify pleura
2) Decrease depth to magnify pleura
3) Decrease gain
4) Adjust (increase) probe frequency
5) Rotate probe to elongate pleura
6) Change to linear probe if using abdominal probe initially

Question 15

What is a troubleshooting manoeuvre to differentiate a physiologic from a true lung point?

Answer 15

Increase depth to allow yourself to appreciate the solid organ tissue in a physiologic lung point

Question 16

What are pitfalls that may cause you to declare a false positive pneumothorax (saying there is a pneumothorax when there actually isn’t)?

Answer 16

1) Declaring a pneumothorax based solely on the absence of lung slide (e.g. R mainstream intubation that has no lung slide but has comet tails)
2) Mistaking a physiologic lung point for a true lung point

Question 17

What are conditions that may cause absent lung slide, but are not pneumothoraces (and are at risk for being interpreted as a false positive scan)?

Answer 17

1) R mainstem intubation
2) Esophageal intubation in an apneic patient (+/- cardiac arrest)
3) Phrneic nerve palsy
4) Conditions where visceral and parietal pleura are adherent to each other (e.g ARDS, adhesions)
5) Pulmonary fibrosis
6) Large pulmonary infiltrates
7) Large bullae in COPD pts
8) Pulmonary contusions

Either comet tails or lung pulse should be seen in these conditions in the absence of pneumothorax, even if there is no lung slide

Question 18

What are pitfalls that could cause you to declare a false NEGATIVE scan for pneumothorax (saying there isn’t a pneumothorax when there actually is)?

Answer 18

1) Large pneumothoraces (hard to find lung point)
2) Misidentifying movement at the pleural line due to poor hand control

Question 19

What is the external landmark for a pleural effusion scan?

Answer 19

Posterior axillary line at level of xiphoid process (same as abdominal)

Question 20

What are the internal landmarks for when scanning for pleural effusion?

Answer 20

1) Kidney to define the interface
2) Diaphragm to define the thorax

Question 21

What are the areas of interest when scanning for a pleural effusion?

Answer 21

Area cephalad to diaphragm– medially (6 to 9 o’clock) and laterally (12 o’clock)

Question 22

What is the ideal interface when scanning for a pleural effusion?

Answer 22

Where the greatest possible portion of the kidney is seen/kidney is brightest

Question 23

Once you have the ideal interface to look for a pleural effusion, what is your next steps?

Answer 23

Visualize the the entire medial aspect of the hemithorax (6-9 o’clock) and sweep anteriorly/posteriorly until the diaphragm disappears, looking for pleural fluid or a spine sign.
During the sweep, interrogate the entire visible diaphragm for pleural fluid– if possible up to the lateral hemidiaphragm (12 o’clock). However the lateral diaphragm is not visible in every patient.

Question 24

What is a positive spine sign?

Answer 24

Visualization of the thoracic spine above the diaphragm. The presence of this makes the presence of pleural fluid very likely.

Question 25

What do you need for a determinate pleural effusion scan?

Answer 25

You must be able to visualize the medial diaphragm from 6 to 9 o’clock

Question 26

What are the systematic troubleshooting steps when trying to visualize the diaphragm?

Answer 26

“Ice cream cone approach”
1) Find the best view of the kidney by moving anterior/posterior
2) Move cephalad in the longitudinal plane
3) Rotate the probe in line with the ribs
4) Move anterior, sweep posterior OR move posterior sweep anterior

Question 27

If the “ice cream cone approach” to troubleshooting doesn’t work to visualize the diaphragm, what is another technique ?

Answer 27

Move caudal and heel through solid organ (spleen or liver)

CPOCUS suggests using this before the ice cream cone approach in the RUQ because the liver provides such a good window, but use this as a last resort in the LUQ

Question 28

What are pitfalls that could cause you to declare a false POSITIVE for pleural effusion? (i.e. calling pleural effusion when there isn’t one)

Answer 28

1) Mistaking mirror artifact of solid organ for an effusion. If it’s artifact only, there wont be a spine sign.
2) Mistaking dark gas scatter from lung tissues as pleural effusion. Again, there won’t be a spine sign if this is the case.

Question 29

What are pitfalls that could cause you to declare a false NEGATIVE for pleural effusion? (i.e. calling a scan normal when there is an effusion)

Answer 29

Missing a pleural effusion in the presence of an empyema or delayed trauma with clotted blood

Question 30

If you see gas in the stomach obscuring the kidney in the LUQ, what can you do to optimize your view of the diaphragm?

Answer 30

Move the probe posteriorly (if you see stomach, you’re too anterior)

Question 31

True or false: You should ask a patient to take a deep breath in and hold it to optimize your view of the diaphragm?

Answer 31

False!
This just slides lung tissue caudad and obscures image more.
If anything, ask them to breath OUT and hold it.

Question 32

What is the plankton sign?

Answer 32

Black pleural fluid with scattered echogenic material floating in it. Seen in empyema or complex pleural effusion’s.

Question 33

What are the requirements for a determinate NEGATIVE scan for pleural effusion?

Answer 33

No pleural fluid or spine sign visible when the medial aspect of the diaphragm (6-9 o’clock, cephalad to diaphragm) is swept anterior/posteriorly until diaphragm disappears

AND

No pleural fluid or diaphragm is visible when the lateral (9 to 12 o’clock) aspect of the lung cephalad to diaphragm is interrogated

Question 34

What findings are determinate POSITIVES for pleural effusion?

Answer 34

1) Pleural fluid seen in medial or lateral area
2) Diaphragm visible laterally (well beyond 9 o’clock)
3) Spine sign