Is lung ultrasound useful in evaluating patients with dyspnea?

Yes! Increasingly, lung ultrasound (particularly point-of-care ultrasound-POCUS) is performed at bedside to help explain the cause of dyspnea.  Here are some tips.

First, obtain images by placing the transducer in the intercostal space (usually 3 regions/hemithorax) with the orientation marker pointing cephalad. 1,2  Now look at the pleural line, the horizontal hyperechoic structure between 2 ribs  (Figure 1). To and fro movement of the pleural line reflects apposition of the visceral and parietal pleura and is a normal finding (“lung sliding”).  Then look for additional horizontal hyperechoic lines visualized deep to the pleural line (“A-lines”) which are reverberation artifacts, reflecting air below the pleura (Clip/Figure 1).2 

You should also look for vertical laser like hyperechoic artifacts that arise from the pleural line and extend to the bottom of the display which may represent  “comet tails” or “B-lines” (Clip/Figure 2).1,3,4 These are reverberation artifacts created by the acoustic impedance difference between widened, fluid filled septa and air-filled alveoli.3,5  Three or more B-lines within a single intercostal space is considered pathological.4

One of the practical uses of lung ultrasound is in the evaluation of dyspnea in a patient with Chronic Obstructive Pulmonary Disease (COPD).6 The presence of lung sliding and bilateral A-lines in the absence of B-lines can help rule out pneumothorax, pneumonia and pulmonary edema and steer you toward other diagnoses (eg, COPD exacerbation) as cause of dyspnea.

You can even take it a step further. Focal unilateral B-lines suggest possible pneumonia while diffuse bilateral B-lines (interstitial syndrome) would be more consistent with pulmonary edema.

As usual, the patient’s history, physical examination and available laboratory data must be taken into consideration when interpreting lung ultrasound findings.2,4

Contributed by Woo Moon, D.O., Department of Medicine, Mercy-St. Louis, St. Louis, Missouri

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Figure 1 

 

 

Clip 1

 

 

Figure 2

 

Clip 2

 

References

  1. Lichtenstein DA. Lung ultrasound in the critically ill. Ann Intensive Care 2014;4(1): https://pubmed.ncbi.nlm.nih.gov/24401163/ 
  2. Soni MD MS NJ, Arntfield MD FRCPC R, Kory MD MPA P. Point of Care Ultrasound. 2nd ed. St. Louis, MO: Elsevier; 2019.
  3. Lichtenstein DA, Mezière GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest 2008;134(1):117–25. https://pubmed.ncbi.nlm.nih.gov/18403664/ 
  4. Volpicelli G, Elbarbary M, Blaivas M, et al. International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med 2012;38(4):577–91. https://pubmed.ncbi.nlm.nih.gov/22392031/ 
  5. Lichtenstein D, Mézière G, Biderman P, Gepner A, Barré O. The comet-tail artifact. An ultrasound sign of alveolar-interstitial syndrome. Am J Respir Crit Care Med 1997;156(5):1640–6. https://pubmed.ncbi.nlm.nih.gov/9372688/
  6. Qaseem A, Etxeandia-Ikobaltzeta I, Mustafa RA, et al. Appropriate Use of Point-of-Care Ultrasonography in Patients With Acute Dyspnea in Emergency Department or Inpatient Settings: A Clinical Guideline From the American College of Physicians. Ann Intern Med 2021;174(7):985–93. https://www.acpjournals.org/doi/10.7326/m20-7844 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

Is lung ultrasound useful in evaluating patients with dyspnea?

What’s the connection between traumatic rib fractures and pulmonary embolism?

Pulmonary embolism (PE) may be a complication of traumatic rib fractures but not necessarily associated with the number of ribs involved.1,2 PE or venous thromboembolism (VTE) is likely related at least in part to the hypercoagulable state that often follows traumatic injury.3

Diagnosis of PE may be challenging because chest pain and shortness of breath attributed to rib fractures can also be a manifestation of PE. Nevertheless, we should consider PE in any patient with chest pain following rib fracture who has hypoxemia or has other risk factors for this complication (eg, obesity, hospitalization, malignancy, history of prior VTE, postoperative state, estrogen use, heart failure, COPD).4 In a retrospective study of 548 patients with traumatic rib fracture, 1.1% were diagnosed with PE.1 The true incidence of PE in patients with rib fracture is unclear, however.

Hypercoagulability following rib fracture likely contributes to the risk of PE. A prospective cohort study of patients admitted to ICU following trauma (97% blunt), found a high prevalence of hypercoagulability (62% on day 1 and 26% on day 4) based on thrombelastography analysis. Women were more hypercoagulable than men early after injury.  Among those classified as hypercoagulable, 10% developed VTE.3

Bonus Pearl: Did you know that in patients with blunt chest trauma, age >65 y and 3 or more rib fractures are associated with increased risk of mortality?

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References

  1. Sirmali M, Turut H, Topcu S, et al. A comprehensive analysis of traumatic rib fractures: morbidity, mortality and management. Eur J Cardio-Thoracic Surg 2003;24:133-138.
  2. Flagel BT, Luchette FA, Reed R, et al. Half-a-dozen ribs: The breakpoint for mortality. Surgery 2005;138:717-25.
  3. Schreiber MA, Differding J, Thorborg P, et al. Hypercoagulability is most prevalent early after injury and in female patients. J Trauma 2005;58:475-81.
  4. Belohlavek J, Vytrych V, Linhart A. Pulmonary embolism, part I: Epidemiology, risk factors and risk stratification, pathophysiology, clinical presentation, diagnosis and nonthrombotic pulmonary embolism. Exp Clin Cardiol 2013;18:129-138.
  5. Battle CE, Hutchings H, Evans PA. Risk factors that predict mortality in patients with blunt chest wall trauma: A systematic review and meta-analysis. Injury 2012;43:8-17. 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

What’s the connection between traumatic rib fractures and pulmonary embolism?