Case
A 72 year-old male with a complicated past medical history including COPD, ESRD, CAD, CHF presented with shortness of breath and generalized weakness. He also had a history of prior right-sided pleural effusion requiring thoracentesis and recent pneumonia. He presented to the Emergency Department with worsening shortness of breath over one day. He was tachypneic to a respiratory rate of 28, although pulse oximetry was 99% on his baseline 2L oxygen. On his physical exam he appeared volume overloaded with bilateral pitting edema. Breath sounds were decreased right > left. A POCUS was performed which demonstrated the following:
Case Conclusion
POCUS demonstrated pleural effusion and consolidated lung tissue with air bronchograms consistent with atelectasis vs. pneumonia. A CT chest showed multifocal pneumonia in the right middle and lower lobes and a moderate-sized right pleural effusion. He was admitted for further workup.
Pneumonia and Atelectasis on Ultrasound
Pleural effusions are easily visualized on ultrasound as anechoic (black) fluid just above the ultrasound.
Alveolar consolidation, whether from pneumonia and atelectasis, can also easily be visualized on ultrasound. Pneumonia on ultrasound is often described as “hepatization” as the the lung tissue, usually full of air, becomes dense as the alveoli fill with pus and debris. As the lung becomes consolidated, it subsequently takes on the sonographic appearance of solid organ tissue (such as the liver). Atelectasis can appear similar as the lung tissue collapses. An finding called air bronchograms can be visualized in the consolidation; thought to be air trapped within small airways, air bronchograms appear as hyperechoic (bright white) lines and dots within the hypoechoic consolidated tissue.
Pneumonia and atelectasis will appear very similar on ultrasound. Occasionally, pneumonia can be differentiated from atelectasis by looking closely at the air bronchograms. Pneumonia can sometimes have dynamic or mobile air bronchograms, which is considered pathognomic. In this phenomenon, you see what appears to be movement or sliding in the air bronchogram. Atelectasis, by comparison, will have only static or immobile air bronchograms (as in the clip above). Static bronchograms can also been seen in pneumonia.
Ultrasound has a high sensitivity for detecting pneumonia (93-100%) when compared to CT scan as gold standard, compared to a sensitivity of 47-77% for chest XR.
- Jessica Patterson, M.D., Emergency Ultrasound Fellow
References
1. Bourcier JE, Paquet J, Seinger M, et al. Performance comparison of lung ultrasound and chest x-ray for the diagnosis of pneumonia in the ED. Am J Emerg Med. 2014;32(2):115-8
2. Cortellaro F, Colombo S, Coen D, Duca PG. Lung ultrasound is an accurate diagnostic tool for the diagnosis of pneumonia in the emergency department. Emerg Med J. 2012;29(1):19-23
3. Parlamento S, Copetti R, DiBartolomeo S. Evaluated of lung ultrasound for the diagnosis of pneumonia in the ED. Am J Emerg Med. 2009;27;379-84.
4. https://www.ultrasoundoftheweek.com/uotw-34-answer/
5. https://blogs.brown.edu/emergency-medicine-residency/pocus-focus-lung-ultrasound-for-pneumonia/