Obtain the:
• Intercostal pleural view on the anterior, lateral and posterior part of the chest
• Posterolateral pleural view
Answer the focused questions:
• Can pneumothorax be confirmed or excluded?
• Are signs of pulmonary edema present or can pulmonary edema be excluded?
• Can pleural fluid be confirmed or excluded?
• Are signs of atelectases present?
Is fluid/blood present in the pleural space?
Definition: Pleural fluid collection indicates any liquid accumulation in the pleural cavity. Common causes include pleural effusion due to heart failure, infections, malignancies, and hemothorax primarily from thoracic trauma.
Visualization of fluid: Typically, pleural fluid is evident as a black border just above the diaphragm, often alongside basal lung consolidation. Fluid follows gravity; hence positioning is vital. For instance, if a patient in the Trendelenburg position shows no fluid, it could be concealed in the apical part of the pleural cavity. Repositioning to a horizontal or semi-upright stance might help.
Spine sign: Normally, the thoracic spine and mediastinum aren’t seen via ultrasound because aerated lung tissue doesn’t convey ultrasound waves. With pleural fluid substituting aerated lung tissue in the phrenicomediastinal recess, the spine become visible through the pathology which has replaced the normal lung tissue – this is known as the ‘spine-sign’
Curtain sign: This phenomenon involves the expanded lung obstructing the view between the transducer and the diaphragm during deep inspiration, causing the diaphragm to vanish on the ultrasound screen. The expanded lung interspaces between the transducer and the diaphragm making the diaphragm disappear in the ultrasound screen – this is called the ‘curtain sign‘. It indicates the absence of significant pleural fluid. If fluid is present, this sign disappears due to fluid and lung consolidation interceding. Not even in healthy patients can the curtain sign always be seen if the breathing is shallow. Asking the patient to take a deep breath might be needed to discern this sign.
Evaluation on right thorax: To evaluate pleural effusion on the right side, place the ultrasound transducer in the posterior axillary line at the lower right thorax limit. Identify the liver, move the transducer cranially till the diaphragm is spotted, and then confirm or rule out a black area between the diaphragm and the right lung.
Evaluation on left thorax: To evaluate pleural effusion on the left side, place the ultrasound transducer in the posterior axillary line at the lower left thorax limit. Identify the spleen, move the transducer cranially till the diaphragm is spotted, and then confirm or rule out a black area between the diaphragm and the left lung.
In the Trendelenburg position, pleural fluid may move to the apical area of the lung, potentially making it undetectable.
Lung consolidation: Lung consolidation in the lower lobe can act as an acoustic window, revealing the ‘spine-sign’. Given the distinct treatments for various conditions, it’s imperative to meticulously examine and identify all signs that can confirm or rule out pleural effusion. Ensuring an accurate diagnosis is critical for appropriate patient management
Below, you’ll find a curated selection of cases that vividly illustrate instances of the pathology in question, in this case, pleural effusion. These real-life examples serve to reinforce understanding and provide a practical context to the theoretical knowledge presented. Familiarizing oneself with these examples can enhance diagnostic accuracy and confidence in clinical settings.
High sensitivity
Multiple B-lines (>2 in each intercostal view) in more than one view bilaterally is very sensitive of pulmonary edema (98-100%).
Specificity high, but not as high
Unfortunately, diffuse multiple B-lines can also be found in e.g. pulmonary fibrosis and ARDS, and the finding is thus less specific unless combined with other findings (i.e. signs of decreased left ventricular function and pleural fluid collection as discussed later).
However, the absence of multiple B-lines generally ‘rules out’ pulmonary edema.
Ok, I got it! But how to do the examination?
– Look at the video on the next page
What are B-lines?
As mentioned previously, B-lines are hyperechoic vertical artefacts visually originating from the pleural line that continue to the bottom edge of the screen.
B-lines represent air-water interfaces in the lung tissue closest to the pleura and single B-lines can be seen in healthy people especially in the basal part of the lungs.
B-lines and pulmonary edema
Pathological amounts of B-lines (> 2 in each intercostal view) are seen with any condition that causes increased water in the lung tissue and can be found localised in pneumonia etc.
In contrast to localised lung disease, pulmonary edema involves the lungs globally and bilaterally and multiple B-lines can therefore be found when pulmonary edema is present.
Are signs of pulmonary edema present or can pulmonary edema be excluded?
The following ultrasonographic signs are suggestive of pulmonary edema:
• Multiple B-lines (>2) between two costae in more than one view bilaterally
The following ultrasonographic signs rule out pulmonary edema:
• Absence of multiple B-lines between two costae in more than one view bilaterally
Facts
Pulmonary edema is fluid accumulation in the air spaces and parenchyma of the lungs.
“Cardiogenic pulmonary edema” is caused by failure of the left ventricle of the heart.
“Noncardiogenic pulmonary edema” is due to a number of other causes than left ventricular failure, including toxic lung damage and fluid overload.
Are signs of pulmonary edema present or can pulmonary edema be excluded?
The following ultrasonographic signs are suggestive of pulmonary edema:
• Multiple B-lines (>2) between two costae in more than one view bilaterally
The following ultrasonographic signs rule out pulmonary edema:
• Absence of multiple B-lines between two costae in more than one view bilaterally
What are B-lines?
As mentioned previously, B-lines are hyperechoic vertical artefacts visually originating from the pleural line that continue to the bottom edge of the screen.
B-lines represent air-water interfaces in the lung tissue closest to the pleura and single B-lines can be seen in healthy people especially in the basal part of the lungs.
B-lines and pulmonary edema
Pathological amounts of B-lines (> 2 in each intercostal view) are seen with any condition that causes increased water in the lung tissue and can be found localised in pneumonia etc.
In contrast to localised lung disease, pulmonary edema involves the lungs globally and bilaterally and multiple B-lines can therefore be found when pulmonary edema is present.
High sensitivity
Multiple B-lines (>2 in each intercostal view) in more than one view bilaterally is very sensitive of pulmonary edema (98-100%).
Specificity high, but not as high
Unfortunately, diffuse multiple B-lines can also be found in e.g. pulmonary fibrosis and ARDS, and the finding is thus less specific unless combined with other findings (i.e. signs of decreased left ventricular function and pleural fluid collection as discussed later).
However, the absence of multiple B-lines generally ‘rules out’ pulmonary edema.
Ok, I got it! But how to do the examination?
– Look at the video below.
A pneumothorax is ruled out
• When lung sliding/pulse or B-lines can be seen on the anterior part of the thorax (in a patient lying on the back)
A pneumothorax is suspected
• When neither lung sliding/pulse nor B-lines can be seen on the anterior part of the thorax
A reliable diagnosis of pneumothorax can be established
• When neither lung sliding/pulse nor B-lines can be seen on the anterior part of the thorax AND
• A lung point is detected
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.
