Pneumothorax Imaging

Aka: Pneumothorax Imaging, Chest XRay in Pneumothorax

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II. Images

  1. Complete Pneumothorax
    1. lungPtxComplete_PA.jpg
  2. Reexpansion Pulmonary Edema following Chest Tube placement
    1. lungPtxCompleteReExpansionPulmonaryEdema.jpg

III. Imaging: Chest XRay

  1. Findings
    1. Medial
      1. Thin, line representing visceral pleura
    2. Interspace
      1. Radiolucent band without lung markings, typically at the apex on upright film
      2. Air-fluid level may be present (assume Hemothorax in Trauma)
    3. Lateral
      1. Chest wall
  2. Posteroanterior (PA) Standard View - Inspiratory
    1. Best overall XRay to view to identify Pneumothorax
    2. Obtain upright image, as supine Chest XRay is unreliable and likely to yield a False Negative study
    3. Inverting the image (digitally reversing white-black) may highlight Pneumothorax lines
    4. End Expiratory views were used in past to enhance Pneumothorax
      1. Theoretically should enhance the Pneumothorax which is constant, by reducing the air in lung
      2. In practice, may add little additional diagnostic value to that seen on inspiratory films
  3. Lateral decubitus view (affected side up)
    1. May identify a small Pneumothorax suspected but not seen on upright Chest XRay
  4. Supine AP Portable XRay (Trauma)
    1. Unilateral deep sulcus sign at the costophrenic angle (laterally)
    2. Lung will appear hazy and indistinct (air rises anteriorly on a supine view)
    3. Apical pleural line will not typically be seen on supine view
    4. Heart border may appear very sharp on the side of Pneumothorax on a supine view film
  5. Criteria for large Pneumothorax
    1. British Thoracic Society
      1. Band or rim around lung margin of 2 cm or greater (50% pleural volume)
    2. American College Chest Physicians
      1. Apex to Cupola distance >3 cm (15-20% of pleural volume)
  6. Efficacy
    1. Test Sensitivity: <85% (compared with CT Chest)
      1. Lateral Decubitus XRay: 88%
      2. Upright PA CXR: 59%
      3. Supine AP CXR: 37%
  7. False Positives
    1. Pulmonary Bleb (COPD) - may require CT chest to distinguish
    2. Skin folds
    3. Scapula border

IV. Imaging: Advanced

  1. Ultrasound chest
    1. See Lung Ultrasound for Pneumothorax (Sliding Lung Sign)
    2. Test Sensitivity 94% and Test Specificity 100% for Pneumothorax
  2. CT Chest
    1. Gold standard in Pneumothorax
      1. Even large pneumothoraces on CT may be missed on Chest XRay
      2. Rodriguez (2019) Ann Emerg Med 73(1):58-65 +PMID:30287121 [PubMed]
    2. Indicated where Chest XRay cannot distinguish bleb in COPD from Pneumothorax
    3. In those with Secondary Spontaneous Pneumothorax due to blebs, contralateral blebs are seen in >50% of cases
      1. These contralateral blebs have a 25% chance of future secondary Pneumothorax
    4. May identify a clinically insignificant Pneumothorax that would resolve without treatment
    5. Identifies other associated thoracic Traumatic Injury
      1. See Nexus Chest CT Decision Rule in Blunt Trauma

V. References

  1. Noppen (2003) Respiration 70(4): 431-8 [PubMed]
  2. Majoewsky (2012) EM:RAPC3 2(2): 3-4
  3. Tranchell (2013) Crit Dec Emerg Med 27(7): 11-8

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