POCUS FOCUS: Lung Ultrasound for Pneumonia

BY: MAX RUBINSTEIN, MD

The Case: A 5 year old previously healthy boy presents to the ED with three days of fever and progressive shortness of breath. His exam is notable for course rhonchi and decreased aeration in the right anterior lung. There was no personal or family history of asthma, eczema, or food allergies. He received an albuterol nebulizer with no effect.

The Diagnostic Intervention: Lung Ultrasound

Point of Care Lung Ultrasound:

Point of care lung ultrasound is highly useful in detecting pulmonary pathology commonly encountered in the emergency department, most notably pneumothorax, pulmonary edema, and pneumonia.  The basic technique of lung ultrasound in children is the same no matter what underlying process is suspected. The linear probe is used and oriented perpendicular to the rib in the longitudinal axis. This allows detailed visualization of the pleural line. This is perhaps the most important aspect of lung ultrasonography as 90% of respiratory dysfunction attributable to the lungs affects the pleura.1 Differences in the appearance of the pleural line help the clinician distinguish between causes of respiratory distress. There are several techniques described to adequately assess the lungs by ultrasound, the simplest of which is to image at three interspaces in the midclavicular, mid-axillary, and posterior lung fields.1,2

Figure 1.  Normal Lung Anatomy on Ultrasound

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Pneumonia on Ultrasound:

Pneumonia on lung ultrasound has a characteristic appearance. One can see “hepatization” of the lung as this normally echogenic and artifact filled tissue (see Figure 1) becomes echo-poor and increasingly tissue-like, resembling the liver on ultrasound (see Figure 2).  This is accompanied by “dynamic air bronchograms,” a branching lesion that courses through affected lung and moves with breathing. 3 This mobility helps distinguish pneumonia from atelectasis. A recent study found that dynamic air bronchograms have a 97% positive predictive value for pneumonia.4

How good is lung ultrasound for detecting pneumonia?

  • Sensitivity & Specificity in children > 90%5
  • When performed by emergency medicine physicians who have received a 1 hour training session, sensitivity drops to 86% but specificity is 97%.6
  • Ultrasound may also be better at detecting small pneumonias than standard chest x-ray.6 However, the clinical significance of this finding has yet to be determined.

  Back to the case:    POCUS revealed the following in the right anterior lung.

Figure 2.  Right sided pneumonia. Note hepatization of the lung with solid tissue appearance and loss of normal A-lines (arrow).

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This was in concordance with a chest x-ray which was performed shortly afterwards for confirmation.

Figure 3.  Patient’s chest x-ray. (Note RML pneumonia)

Pneumonia US

The patient was started on ampicillin for community acquired pneumonia and admitted for further treatment.

Author: Max Rubinstein, MD

Editors/Reviewers: Robyn Wing, MD & Erika Constantine, MD

Sources:

  1. Fein D, Ryu PH, and Kory P (2015). Lung and Pleural Ultrasound Technique. Chapter in Point of Care Ultrasound. Elsevier
  2. Lichtenstein D.A., and Mezière G.A.: Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest 2008; 134: pp. 117-125
  3. Blaivas M. Lung Ultrasound in Evaluation of Pneumonia. Journal of Ultrasound Medicine 2012; 31:823-826
  4. Liechtenstein D, Meziere G, and Seitz J. The Dynamic Air Bronchogram: A Lung Ultrasound Sign of Alveolar Consolidation Ruling Out Atelectasis. Chest 2009; 135(6): 1421-1425
  5. Pereda MA, Chavez MA, Hooper-Miele CC, Gilman RH, Steinhoff MC, Ellington LE, et al. Lung Ultrasound for the Diagnosis of Pneumonia in Children: A Meta-analysis. Pediatrics 2015; 135)4): 714-722
  6. Shah VP, Tunik MG, and Tsung JW. Prospective Evaluation of Point-of-care Ultrasonography for the Diagnosis of Pneumonia in Children and Young Adults. Journal of the American Medical Association Pediatrics 2013; 167(2): 119-125

 

 

 

 

 

 

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