Imaging of pneumothorax
- Paul Stark, MD
Paul Stark, MD
- Professor of Radiology
- University of California San Diego
- Section Editors
- Nestor L Muller, MD, PhD
Nestor L Muller, MD, PhD
- Section Editor — Pulmonary Imaging
- Professor of Radiology
- University of British Columbia
- Polly E Parsons, MD
Polly E Parsons, MD
- Editor-in-Chief — Pulmonary and Critical Care Medicine
- Section Editor — Critical Care
- Professor of Medicine
- University of Vermont College of Medicine
Pneumothorax refers to gas within the pleural space [1-3]. Its clinical manifestations are widely variable. Small pneumothoraces can be asymptomatic and self-limited, but need to be monitored for progression. Large pneumothoraces can cause hypoventilation, hypoxemia, and/or hemodynamic instability. If such pneumothoraces are not promptly treated, progression to cardiac arrest and death is possible.
Radiographic imaging of a pneumothorax is reviewed here. The causes and management of a pneumothorax are discussed separately. (See "Primary spontaneous pneumothorax in adults" and "Secondary spontaneous pneumothorax in adults".)
IDENTIFYING A PNEUMOTHORAX
The first-line imaging modalities used to identify a pneumothorax are chest radiography and computed tomography (CT). While some investigators have reported using ultrasound to diagnose pneumothorax, particularly in bedridden patients, ultrasound is not a preferred modality for imaging the chest.
Chest radiographs — The main feature of a pneumothorax on a chest radiograph is a white visceral pleural line, which is separated from the parietal pleura by a collection of gas (image 1). In most cases, no pulmonary vessels are visible beyond the visceral pleural line (the collection of pleural gas is avascular). A pneumothorax may be identified on an upright, supine, or lateral decubitus chest radiograph. The lateral decubitus view tends to be the most sensitive, while the supine view is the least sensitive.
●Upright – In an upright patient with a pneumothorax, most pleural gas accumulates in an apicolateral location (image 2). The visceral pleural line appears either straight or convex towards the chest wall. As little as 50 mL of pleural gas may be visible on a chest radiograph . Although a pneumothorax is generally accompanied by a considerable loss of lung volume, the collapsed lung preserves its transradiancy because hypoxic vasoconstriction diminishes the blood flow to the collapsed lung.
The value of upright expiratory chest radiographs in detecting pneumothoraces has been grossly overstated. In one study, inspiratory and expiratory upright chest radiographs detected pneumothorax with equal sensitivity . These findings, combined with the limitations of expiratory radiographs, have led us to recommend only inspiratory imaging for the initial examination of a potential pneumothorax in our clinical practice.
- O'Connor AR, Morgan WE. Radiological review of pneumothorax. BMJ 2005; 330:1493.
- Stark, P. The Pleura. In: Radiology, Diagnosis, Imaging, Intervention, Taveras and Ferrucci (Ed), Lippincott, Philadelphia 2000.
- Greene, R, McLoud, TC, Stark, P. Pneumothorax. Semin Roentgenol 1977; 4:13.
- Carr JJ, Reed JC, Choplin RH, et al. Plain and computed radiography for detecting experimentally induced pneumothorax in cadavers: implications for detection in patients. Radiology 1992; 183:193.
- Seow A, Kazerooni EA, Pernicano PG, Neary M. Comparison of upright inspiratory and expiratory chest radiographs for detecting pneumothoraces. AJR Am J Roentgenol 1996; 166:313.
- Jalli R, Sefidbakht S, Jafari SH. Value of ultrasound in diagnosis of pneumothorax: a prospective study. Emerg Radiol 2013; 20:131.
- Kirkpatrick AW, Sirois M, Laupland KB, et al. Hand-held thoracic sonography for detecting post-traumatic pneumothoraces: the Extended Focused Assessment with Sonography for Trauma (EFAST). J Trauma 2004; 57:288.
- Wilkerson RG, Stone MB. Sensitivity of bedside ultrasound and supine anteroposterior chest radiographs for the identification of pneumothorax after blunt trauma. Acad Emerg Med 2010; 17:11.
- Mandavia DP, Joseph A. Bedside echocardiography in chest trauma. Emerg Med Clin North Am 2004; 22:601.
- Moore CL, Copel JA. Point-of-care ultrasonography. N Engl J Med 2011; 364:749.
- Lichtenstein D. General ultrasound in the critically ill. Springer 2005; 105.
- Raja AS, Jacobus CH. How accurate is ultrasonography for excluding pneumothorax? Ann Emerg Med 2013; 61:207.
- Alrajhi K, Woo MY, Vaillancourt C. Test characteristics of ultrasonography for the detection of pneumothorax: a systematic review and meta-analysis. Chest 2012; 141:703.
- Alrajab S, Youssef AM, Akkus NI, Caldito G. Pleural ultrasonography versus chest radiography for the diagnosis of pneumothorax: review of the literature and meta-analysis. Crit Care 2013; 17:R208.
- Light, RW. Pneumothorax. In: Pleural Diseases, 3rd, Light, RW (Eds), Williams and Wilkins, Baltimore 1990. p.242.
- Noppen M, Alexander P, Driesen P, et al. Quantification of the size of primary spontaneous pneumothorax: accuracy of the Light index. Respiration 2001; 68:396.
- MacDuff A, Arnold A, Harvey J, BTS Pleural Disease Guideline Group. Management of spontaneous pneumothorax: British Thoracic Society Pleural Disease Guideline 2010. Thorax 2010; 65 Suppl 2:ii18.
- Woodring JH, Baker MD, Stark P. Pneumothorax ex vacuo. Chest 1996; 110:1102.
- Engeler CE, Olson PN, Engeler CM, et al. Shifting pneumothorax after heart-lung transplantation. Radiology 1992; 185:715.
- Chan F, Stark P. Bilateral pneumothoraces after coronary bypass suregery – a case of “buffalo chest”. Clin Intensive Care 1997; 8:154.
- Jacobson, F, Stark, P. Pneumothorax or giant bullae? Clin Intensive Care 1992; 3:188.
- Stark, P, Eber, C. Pneumothorax or skin fold?. Clin Intensive Care 1993; 4:45.
- Chasen MH. Practical applications of Mach band theory in thoracic analysis. Radiology 2001; 219:596.
- Buckle CE, Udawatta V, Straus CM. Now you see it, now you don't: visual illusions in radiology. Radiographics 2013; 33:2087.