Case vignette
A 64yo M w/ COPD, CHF, DM2 presents with 1d dyspnea, productive cough, fevers. No recent hospitalizations.
BP 120/80, HR 110, RR 24, SpO2 93%, T 38.1
Diminished breath sounds and crackles in right lower lobe.
What do you see?
CXR: no focal opacity or pneumothorax
What do you do next?
You have high clinical suspicion for pneumonia and consider empiric treatment. To provide further support for your diagnosis, you perform bedside pulmonary ultrasound.
What do you see?
CP6 US1: using phased array transducer, we see hepatization (lung looks like liver), dynamic air bronchograms (hyperechoic "dots" moving with inspiration), trace anechoic parapneumonic effusion
CP6 US 2: using curvilinear transducer, we see hepatization (lung looks like liver), dynamic air bronchograms (hyperechoic "dots" moving with inspiration), trace anechoic parapneumonic effusion
What do you do next?
Based on the patient's risk factors, presentation, and PSI/PORT score, you admit for observation and initiate antibiotics. You decide to start ceftriaxone and azithromycin. COVID and influenza tests are negative.
The patient is discharged 24 hours later after improvement in symptoms and vital signs and goes on to successfully finish a 5 day total course of PO antibiotics.
Teaching points. Chest XR has notoriously high (and variable) false negative rates for diagnosing pneumonia, especially early in the disease process. (You can also have false positives.) When your clinical suspicion for pneumonia is high, use ultrasound to further augment your pre-test probability. Early pneumonia often shows B-lines and sub-pleural consolidations. Over time, purulent fluid in the alveoli can make the lung look like liver tissue ("hepatization"). In addition, you will often see "dynamic air bronchograms," which represent air movement in small bronchi. You can also sometimes see the "shred sign," irregular borders between affected and unaffected lung tissue.
Atelectasis can appear similar; differentiate based on clinical suspicion and lack of dynamic air bronchograms (static air bronchograms may be seen).
CT can be considered but requires more time and resources. It is ideally used for critically ill or immunosuppressed patients, those with atypical imaging findings, or those not improving as expected with treatment.
Sources:
-The Dynamic Air Bronchogram. Lichtenstein D, Meziere G, Seitz J. Chest. 2009; 135:1421-25. PMID 19225063 (https://pubmed.ncbi.nlm.nih.gov/19225063/)
-Helman, A., Sommer, L., Morris, A. Episode 130 – Community Acquired Pneumonia – Emergency Management. Emergency Medicine Cases. September, 2019. https://emergencymedicinecases.com/community-acquired-pneumonia. Accessed 4/12/21
-Lung Ultrasound: Pneumonia. James Rippey. Life in the Fast Lane. Nov 3, 2020. https://litfl.com/lung-ultrasound-pneumonia/. Accessed 4/12/21
RLL Pneumonia