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Pitfalls in the ultrasound diagnosis of pneumothorax: the authors respond
American Journal of Emergency Medicine xxx (2014) xxx
Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Correspondence
Pitfalls in the ultrasound diagnosis of pneumothorax: the authors respond A. Aspler MD, MSc M.B. Stone MB Brigham and Women’s Hospital, Boston, MA E-mail address: [email protected]
To the Editor, The readers’ letter highlights accurately that the article by Aspler et al [1] raises challenges around the real-time diagnosis of pneumothorax with ultrasound. Computed tomographic (CT) scan is the criterion standard for diagnosis of pneumothorax, not ultrasound. Although the transmitted still image of the CT may prove difficult to appreciate the extent of the pneumothorax, the CT was independently read and interpreted by board-certified radiologists with fellowship training in thoracic CT imaging. The pneumothorax was reconfirmed on subsequent CT imaging and Chest X-rays during the patients’ intensive care unit admission, read by multiple board-certified radiologists. The diagnosis of pneumothorax was not based only on absence of pleural gliding but also on presence of A lines, absence of B lines, and absence of lung pulse at the site. All of these features point specifically toward pneumothorax and not pleural adhesion as the diagnosis. Nonetheless, we do not shy away from acknowledging that alternative diagnoses, such as pleural adhesion, may be possible despite the CT diagnosis and are careful to not overstate our conclusions. “In a review article, it is hypothesized double lung point sign can be detected in pneumothorax secondary to trauma when pulmonary contusions cause pleural adhesions, but this has yet to be substantiated in the published literature.” “Our case, with corresponding CT imaging, demonstrates one instance of contusion-associated double lung point sign.” Although Volpicelli et al [2] have alluded to double lung point sign in trauma, none has published a report with CT imaging confirming the diagnosis. As we noted, the patient was otherwise healthy with no history of smoking, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, thoracic surgery, cancer, nor any other reason to suspect an alternative pathology. In a hypoxic trauma patient where multiple possible pulmonary and cardiac etiologies may be possible, and timely intervention is critical, this case report provides helpful guidance. A double lung point sign may suggest a clinically insignificant pneumothorax and guide the trauma team leader or emergency department physician toward an alternative etiology to explain and address hypoxia. The review article by Volpicelli [3] is a very useful reference to understand the significance of the double lung point sign in the setting of trauma and the short communication by Volpicellli et al [2] on diagnosis of complicated pneumothorax, excerpts below.
http://dx.doi.org/10.1016/j.ajem.2014.03.044 References [1] Aspler A, Pivetta E, Stone MB. Double lung point sing in traumatic pneumothorax. Am J Emerg Med 2014. http://dx.doi.org/10.1016/j.ajem.2013.12.059. [2] Volpicelli G, Boero E, Stefanone V, Storti E. Unusual new signs of pneumothorax at lung ultrasound. Crit Ultrasound J 2013;5(10). http://dx.doi.org/10.1186/2036-7902-5-10. [3] Volpicelli G. Sonographic diagnosis of pneumothorax. Intensive Care Med 2011;37(2):224–32.
Excerpts Volpicelli 2011 Double lung point “The principle that the more lateral the lung point is in the supine patient, the more the PNX is extended, is always acceptable when the air layer moves freely in the pleural space. However, on occasions, that air is trapped between two areas, where the visceral and parietal pleura for some reason adhere. In this case, the laterality of the lung point fails to indicate the real extension of the PNX, while two lung points surrounding the air bubble may be visualized. Between the two lung points, an area of lung without pleural sliding will be visualized (Online Resource 1). Location of the most lateral lung point could be misleading in the assessment of the extension of PNX, suggesting a large PNX volume and therefore a useless therapeutic drainage. Moreover, presence of regular sliding along the parasternal chest area (ie, the least-dependent chest region in the supine patient) could lead to miss the diagnosis of PNX. A double lung point can be detected in PNX secondary to trauma when pulmonary contusions can cause pleural adhesion or, less frequently, even in spontaneous PNX of young adults.” Volpicelli 2013 Sonographic signs of complex pneumothorax “Double lung point: when for some reason, the air of a pneumothorax is not free to float inside the pleural space, a minimal amount of pleural air may remain in the lateral or dorsal chest without migrating in the most superior area in a supine patient, which corresponds to the anterior-inferior chest zone. In this case, the operator may visualize two lung points, ie, the alternating patterns of sliding and non-sliding lung intermittently appearing at the two opposite sides of the scan. These two lung points represent the visualization of the two edges of the air trapped in the pleural space. Pneumothorax with air trapping may be caused not only by pleural adherences in chronic pleural and pulmonary diseases but also by acute lung contusions in blunt torso trauma. Even without abnormal pleural adherences, very small spontaneous pneumothoraces may not have enough pressure to allow complete detachment of the pleural layers and the floating of air towards the most superior chest areas. Being aware of this condition or in case of strong suspicion, the operator should always complete the scan of the lateral chest in the supine patient to confirm lung siding even when this latter is first visualized in the parasternal anterior-inferior chest. In the unstable patient, this extension of the technique is less important. Presence of lung sliding in the anterior-inferior chest may conclude the ultrasound examination, unless the patient is intubated for pressure ventilation or is going to be transported by helicopter. In these two latter cases, the lateral chest should always be scanned to rule out even the smallest pneumothorax that may need to be monitored or warrant prophylactic drainage.”
0735-6757/© 2014 Elsevier Inc. All rights reserved.
Please cite this article as: Aspler A, Stone MB, Pitfalls in the ultrasound diagnosis of pneumothorax: the authors respond, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2014.03.044
Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Correspondence
Pitfalls in the ultrasound diagnosis of pneumothorax: the authors respond A. Aspler MD, MSc M.B. Stone MB Brigham and Women’s Hospital, Boston, MA E-mail address: [email protected]
To the Editor, The readers’ letter highlights accurately that the article by Aspler et al [1] raises challenges around the real-time diagnosis of pneumothorax with ultrasound. Computed tomographic (CT) scan is the criterion standard for diagnosis of pneumothorax, not ultrasound. Although the transmitted still image of the CT may prove difficult to appreciate the extent of the pneumothorax, the CT was independently read and interpreted by board-certified radiologists with fellowship training in thoracic CT imaging. The pneumothorax was reconfirmed on subsequent CT imaging and Chest X-rays during the patients’ intensive care unit admission, read by multiple board-certified radiologists. The diagnosis of pneumothorax was not based only on absence of pleural gliding but also on presence of A lines, absence of B lines, and absence of lung pulse at the site. All of these features point specifically toward pneumothorax and not pleural adhesion as the diagnosis. Nonetheless, we do not shy away from acknowledging that alternative diagnoses, such as pleural adhesion, may be possible despite the CT diagnosis and are careful to not overstate our conclusions. “In a review article, it is hypothesized double lung point sign can be detected in pneumothorax secondary to trauma when pulmonary contusions cause pleural adhesions, but this has yet to be substantiated in the published literature.” “Our case, with corresponding CT imaging, demonstrates one instance of contusion-associated double lung point sign.” Although Volpicelli et al [2] have alluded to double lung point sign in trauma, none has published a report with CT imaging confirming the diagnosis. As we noted, the patient was otherwise healthy with no history of smoking, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, thoracic surgery, cancer, nor any other reason to suspect an alternative pathology. In a hypoxic trauma patient where multiple possible pulmonary and cardiac etiologies may be possible, and timely intervention is critical, this case report provides helpful guidance. A double lung point sign may suggest a clinically insignificant pneumothorax and guide the trauma team leader or emergency department physician toward an alternative etiology to explain and address hypoxia. The review article by Volpicelli [3] is a very useful reference to understand the significance of the double lung point sign in the setting of trauma and the short communication by Volpicellli et al [2] on diagnosis of complicated pneumothorax, excerpts below.
http://dx.doi.org/10.1016/j.ajem.2014.03.044 References [1] Aspler A, Pivetta E, Stone MB. Double lung point sing in traumatic pneumothorax. Am J Emerg Med 2014. http://dx.doi.org/10.1016/j.ajem.2013.12.059. [2] Volpicelli G, Boero E, Stefanone V, Storti E. Unusual new signs of pneumothorax at lung ultrasound. Crit Ultrasound J 2013;5(10). http://dx.doi.org/10.1186/2036-7902-5-10. [3] Volpicelli G. Sonographic diagnosis of pneumothorax. Intensive Care Med 2011;37(2):224–32.
Excerpts Volpicelli 2011 Double lung point “The principle that the more lateral the lung point is in the supine patient, the more the PNX is extended, is always acceptable when the air layer moves freely in the pleural space. However, on occasions, that air is trapped between two areas, where the visceral and parietal pleura for some reason adhere. In this case, the laterality of the lung point fails to indicate the real extension of the PNX, while two lung points surrounding the air bubble may be visualized. Between the two lung points, an area of lung without pleural sliding will be visualized (Online Resource 1). Location of the most lateral lung point could be misleading in the assessment of the extension of PNX, suggesting a large PNX volume and therefore a useless therapeutic drainage. Moreover, presence of regular sliding along the parasternal chest area (ie, the least-dependent chest region in the supine patient) could lead to miss the diagnosis of PNX. A double lung point can be detected in PNX secondary to trauma when pulmonary contusions can cause pleural adhesion or, less frequently, even in spontaneous PNX of young adults.” Volpicelli 2013 Sonographic signs of complex pneumothorax “Double lung point: when for some reason, the air of a pneumothorax is not free to float inside the pleural space, a minimal amount of pleural air may remain in the lateral or dorsal chest without migrating in the most superior area in a supine patient, which corresponds to the anterior-inferior chest zone. In this case, the operator may visualize two lung points, ie, the alternating patterns of sliding and non-sliding lung intermittently appearing at the two opposite sides of the scan. These two lung points represent the visualization of the two edges of the air trapped in the pleural space. Pneumothorax with air trapping may be caused not only by pleural adherences in chronic pleural and pulmonary diseases but also by acute lung contusions in blunt torso trauma. Even without abnormal pleural adherences, very small spontaneous pneumothoraces may not have enough pressure to allow complete detachment of the pleural layers and the floating of air towards the most superior chest areas. Being aware of this condition or in case of strong suspicion, the operator should always complete the scan of the lateral chest in the supine patient to confirm lung siding even when this latter is first visualized in the parasternal anterior-inferior chest. In the unstable patient, this extension of the technique is less important. Presence of lung sliding in the anterior-inferior chest may conclude the ultrasound examination, unless the patient is intubated for pressure ventilation or is going to be transported by helicopter. In these two latter cases, the lateral chest should always be scanned to rule out even the smallest pneumothorax that may need to be monitored or warrant prophylactic drainage.”
0735-6757/© 2014 Elsevier Inc. All rights reserved.
Please cite this article as: Aspler A, Stone MB, Pitfalls in the ultrasound diagnosis of pneumothorax: the authors respond, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2014.03.044