More lung ultrasound tips and examples from Drs. Jim Tsung and Brittany Pardue Jones!
Bacterial pneumonia will manifest as lung consolidation with air bronchograms. The A-line pattern of normal lung will begin to be replaced by B-lines in the area of affected lung:
Here we’ve highlighted the consolidation from the above video as well:
In contrast, subpleural consolidations and confluent B-lines are more suggestive of viral pneumonia.
So what do these look like?
and another example:
occur when multiple B-lines coalesce. In contrast, the next example demonstrates multiple discrete B-lines.
And now for something completely different
Z-Lines: Comet tails that arise from the pleural line but DO NOT make it to the bottom of the ultrasound screen. These are not B-lines. These artifacts have not been associated with any pathology, and they do not obliterate A-lines.
For more details on the sonographic appearance of viral lung pathology, check out this article by Jim Tsung.
Counter-intuitively, when insonating the lungs of healthy patients, we don’t “see” lung tissue. Instead we see and interpret artifacts arising from the pleural lines and the diaphragm. These artifacts change with pulmonary disease processes. In pneumonia, the airway spaces become inspissated with bacterial byproducts and consequently the sonographic appearance of lung tissue changes.
The transformation of lung tissue is termed hepatization: the lung tissue now appears similar to liver tissue.
This can be confusing in the lower lung fields, especially adjacent to the diaphragm because we use the mirror image artifact of the liver and spleen to indicate that lung tissue is normal. This mirrored, artifactual splenic or liver appearance could then be called pseudo-hepatization.
So, how do we differentiate hepatized lung versus pseudo-hepatized lung?
Never use a single image for your diagnosis, scan through area and convince yourself (then save a representative image or clip for QA).
Be systematic and scan down from the lung apices to the diaphragm.
Hunt for the diaphragm and use it as a dividing line between the lung and the abdominal organs.
Hepatized lung will often have a rim of fluid around it.
Ultrasound is quite sensitive in detecting even very small pleural effusions; it has been demonstrated to perform better than chest x-ray and nearly as well as CT scan. In order to assess for pleural fluid, the transducer should be directed through the liver (Right side) or spleen (Left side) and diaphragm. In a normal thorax, a mirror image artifact will generally be seen above the diaphragm. When effusion is present, fluid eradicates this artifact, creating an anechoic appearance in the costophrenic angle.
The image above demonstrates a common pitfall in abdominal and thoracic ultrasound. The liver is visible in the near field, and a dark anechoic structure is evident just deep to the liver. Some see this fluid and may note a positive FAST examination or free intraperitoneal fluid. Others may see this appearance and diagnose pleural effusion or hemothorax. While it is true the anechoic area represents fluid, there is a more correct response.
The inferior vena cava can generally be seen posterior to the liver, towards the patient midline. As it is filled with blood it will appear anechoic. below the diaphragm it will course parallel and to the [patient's] right of the Aorta. Just above the diaphragm it will quickly merge into the Right Atrium.
As with most scanning, fanning through multiple planes will generally sort out the true anatomy. In the clip below we see the IVC as the operator sweeps medially, and the the pleural effusion is more evident in the lateral portions of the sweep. One (of many) giveaways is that the hepatic veins drain into the IVC, and even in this brief sweep through the IVC a hepatic vein is visible anteriorly, draining into the IVC.
Congratulations to Sinai’s own Dr. Jim Tsung, who recently coauthored a major evidence-based consensus guideline on point-of-care lung ultrasound. The manuscript is the result of a multi-national effort by pioneering clinician-sonographers, and was just published in the journal Intensive Care Medicine:
Volpicelli G, Elbarbary M, Blaivas M, Lichtenstein DA, Mathis G, Kirkpatrick AW, Melniker L, Gargani L, Noble VE, Via G, Dean A, Tsung JW, Soldati G, Copetti R, Bouhemad B, Reissig A, Agricola E, Rouby JJ, Arbelot C, Liteplo A, Sargsyan A, Silva F, Hoppmann R, Breitkreutz R, Seibel A, Neri L, Storti E, Petrovic T; International Liaison Committee on Lung Ultrasound (ILC-LUS) for the International Consensus Conference on Lung Ultrasound (ICC-LUS).
Intensive Care Med. 2012 Mar 6. [Epub ahead of print]
32 year old female with no past medical history presents with cough for two weeks, no fever, no sputum. Multiple sick contacts with same symptoms at work. She acutely presents with left rib pain for several days. She reports no trauma, and noted the sharp, positional pain during a fit of coughing. Her vital signs are all within normal limits. She is breathing comfortably, with good air movement, no wheezes, rales, or ronchi. She displays point tenderness over her anterior left 8th rib at the anterior axillary line. A chest x-ray was ordered; images are below.
Sonopalpation of the tender area revealed the following:
Thoracic ultrasound is one of the hottest topics in emergency and critical care sononography. Assessment for pneumothorax is accurate and relatively easy to learn.
One important sign when assessing for pneumothorax is the lung point. This is the point where normal pleural interface contacts the boundary of the pneumothorax. It is the most specific sign for pneumothorax using ultrasound.
Using B-mode ultrasound, the lung point will appear as the boundary between normal lung sliding and still lung.
Data from the TRUST (Thoracic Rapid Ultrasound in Trauma) study was presented at the fifth EM Congress in Valencia, Spain on 9/17/2009. The project was selected as one of the top 50 abstracts at the conference. Special thanks to Danny Duque, Vicki Noble, and Betty Chang, our co-investigators on the study.