Ultrasound Case #4 – The Shortness of Breath
Patient is an 81-year-old female with a history of hypertension, type 2 diabetes, CKD, recent left knee replacement approximately 5 days ago.
She presents back to Emergency Department today due to hypoxia at 69% on home monitor. Patient states she is short of breath. She denies any chest pain, nausea, vomiting and dizziness, increased lower extremity edema.
Vitals on presentation: BP 160/68, Pulse 63, Temp 97.5 °F (36.4 °C) , Resp 22, SpO2 95% on 2L NC
Patient desaturates to 86% when taken off oxygen. You obtain the following images:
What do you see in these images and what is your next step in management?
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Clip 1: Here is a clip of the right anterior lug, showing two B-lines. If you look closely right as you see the 2 B-lines you can also make out a small sub-pleural consolidation.
Clip 2: Here is a clip of the right lateral lung base. You can see several more B lines, a large sub pleural consolidation and multiple air bronchograms located within a lung consolidation.
Click to reveal learning points
The combination of findings here of sub-pleural consolidations as well as what appear to be dynamic air bronchograms within a consolidation favor a diagnosis for pneumonia. So what are air Bronchograms?
Air bronchograms refers to the phenomenon of air-filled bronchi (normally dark) being made visible due to opacification of surrounding alveoli (gray/white).This is nearly always due to airspace/alveolar process
Spotting air Bronchograms should give you a list of differentials that includes the following:
-Pulmonary consolidation (e.g. pneumonia)
-Pulmonary edema (especially alveolar edema)
-Non-obstructive atelectasis
-Severe interstitial lung disease
-Pulmonary infarct
-Pulmonary hemorrhage
Now air bronchograms can be broken up into two types, dynamic and static. It is somewhat hard to tell in our image but if the bright white portion within the consolidation seems to move independently of the lung tissue, this is a dynamic air bronchogram. If the bright white spots sit still, this would be considered static. So…
-Dynamic: move centrifugally with respiration and this is thought to represents fluid mixed with air inside larger bronchi- indicates suggesting that air is not trapped within the bronchi and therefore this is consolidation from pneumonia and not atelectasis.
•Dynamic air bronchograms have a 94% specificity and 97% PPV for pneumonia as cause of consolidation. (1)
-Static: lack detectable movement. So as you can imagine this would suggest atelectasis over pneumonia.
•Isolated, trapped air consistent with atelectasis
(1) Lichtenstein D, Mezière G, Seitz J. The dynamic air bronchogram. A lung ultrasound sign of alveolar consolidation ruling out atelectasis. Chest. 2009 Jun;135(6):1421-1425. doi: 10.1378/chest.08-2281. Epub 2009 Feb 18. PMID: 19225063.
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