Lung Ultrasound in the Evaluation of Pneumothorax Size (LUS-PNXsize)

Background

• Assessment of the percentage of lung collapse is crucial in the therapeutic decision-making of pneumothorax.
• The methods normally used to this purpose are radiological. Computerized tomography scan (CT) is highly accurate because it allows the exact evaluation of the volume of the air layer. However, in clinical practice assessment of the volume of pneumothorax mainly relies on the measurement of the inter-pleural distance at conventional chest radiography (CXR). This latter method is inaccurate.
• Lung ultrasound is a new method highly accurate in the first diagnosis of pneumothorax, with a sensitivity superior to CXR and similar to CT in case of traumatic pneumothorax.
• The scientific community is actually debating about the usefulness of lung ultrasound in the quantification of pneumothorax []. Lung ultrasound can assess the superficial extension of the pneumothorax, but cannot evaluate its volume.

Aim

• Main purpose of the study is to compare measurement of the superficial extension of pneumothorax on the chest wall obtained by lung ultrasound, to the evaluation of the air volume performed by CT in patients with pneumothorax.
• The main hypothesis of the study is that the cut-off between small (<11% of lung collapse) and large (>11% of lung collapse) pneumothorax can be identified by a lung ultrasound evaluation of the superficial extension of pneumothorax.
• Second purpose of the study is to compare the accuracies of lung ultrasound and CXR in predicting the volume of pneumothorax assessed by CT.
• Secondary hypothesis is that lung ultrasound demonstrates greater accuracy in the prediction of volume of pneumothorax and percentage of lung collapse.

Methods

• Patients with a diagnosis of pneumothorax confirmed at CT are prospectively enrolled and submitted to lung ultrasound within 20 min from the CT study.
• Different locations of the sonographic "lung point" on the chest wall (i.e. the point on the chest wall where the sonographic pattern of the normally aerated lung alternates with the pathologic sonographic pattern of pneumothorax) are compared with different volumes of pneumothorax measured by CT.

Patients from the Emergency Department Patients admitted to the Hospital Outpatients from the Radiology Department who undergo invasive thoracic procedures

• Blaivas M, Lyon M, Duggal S. A prospective comparison of supine chest radiography and bedside ultrasound for the diagnosis of traumatic pneumothorax. Acad Emerg Med. 2005 Sep;12(9):844-9.
• Soldati G, Testa A, Sher S, Pignataro G, La Sala M, Silveri NG. Occult traumatic pneumothorax: diagnostic accuracy of lung ultrasonography in the emergency department. Chest. 2008 Jan;133(1):204-11. Epub 2007 Oct 9.
• Reissig A, Kroegel C. Accuracy of transthoracic sonography in excluding post-interventional pneumothorax and hydropneumothorax. Comparison to chest radiography. Eur J Radiol. 2005 Mar;53(3):463-70.
• Lichtenstein D, Mezière G, Biderman P, Gepner A. The "lung point": an ultrasound sign specific to pneumothorax. Intensive Care Med. 2000 Oct;26(10):1434-40.
• Baumann MH, Strange C, Heffner JE, Light R, Kirby TJ, Klein J, Luketich JD, Panacek EA, Sahn SA; AACP Pneumothorax Consensus Group. Management of spontaneous pneumothorax: an American College of Chest Physicians Delphi consensus statement. Chest. 2001 Feb;119(2):590-602. Review.
• Engdahl O, Toft T, Boe J. Chest radiograph--a poor method for determining the size of a pneumothorax. Chest. 1993 Jan;103(1):26-9.
• Volpicelli G, Elbarbary M, Blaivas M, Lichtenstein DA, Mathis G, Kirkpatrick AW, Melniker L, Gargani L, Noble VE, Via G, Dean A, Tsung JW, Soldati G, Copetti R, Bouhemad B, Reissig A, Agricola E, Rouby JJ, Arbelot C, Liteplo A, Sargsyan A, Silva F, Hoppmann R, Breitkreutz R, Seibel A, Neri L, Storti E, Petrovic T; International Liaison Committee on Lung Ultrasound (ILC-LUS) for the International Consensus Conference on Lung Ultrasound (ICC-LUS). International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med. 2012 Apr;38(4):577-91. Epub 2012 Mar 6.

Inclusion Criteria:

• Radiologic diagnosis of pneumothorax
• Clinical need to perform a CT scan
• Ability to perform the lung ultrasound imaging within 20 minutes from the CT study

Exclusion Criteria:

• age less than 16 years