Article

Emergency ultrasound in the diagnosis of traumatic extrathoracic lung herniation

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American Journal of Emergency Medicine

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Emergency ultrasound in the diagnosis of traumatic extrathoracic lung herniation?,??,?,??

Abstract

Traumatic extrathoracic lung herniation is an extremely rare and poorly described complication of blunt trauma. Diagnosis has been limited to computed tomographic imaging, which takes both time and requires the patient to leave the emergency department (ED). Focused assessment with sonography in trauma has become routine in the evaluation of blunt trauma in the ED before obtaining computed tomographic imaging. We report a case on use of the extended focused assessment with sonography in trauma examination in aiding the immediate diagnosis of traumatic extrathoracic lung herniation in blunt trauma. Use of the extended focused assessment with sonography in trauma routinely as part of the primary survey in blunt trauma can hasten the diagnosis of traumatic lung herniation, thereby expediting interventions and disposition of the blunt trauma patient.

Traumatic extrathoracic lung herniation is a poorly described entity, having been reported less than 300 times in the literature since the injury was first described 5 centuries ago [1]. Cervical, thoracic, and diaphragmatic lung hernias have been described and defined, and these can be congenital or acquired [2,3]. Blunt trauma and motor vehicle accidents appear to be causing most lung herniations based on case reports [2,4]. Certain preexisting conditions, including chest wall weakness or atrophy and hyperinflation syndromes, can increase the likelihood of traumatic or spontaneous lung herniation [5].

A 33-year-old man presented to the emergency department after being struck by a motor vehicle while driving his motorized scooter. He sustained blunt trauma to the left chest. On arrival, he was tachycardic and tachypneic with a SpO2 of 92% on room air. He endorsed dyspnea and left chest wall tenderness to palpation but without deformities, ecchymoses, or crepitus to the area. Extended Focused Assessment with Sonography in Trauma was remark- able for a left pulmonary defect, specifically the lack of an echogenic pleural line between rib spaces (Fig. 1). At the time of eFAST, the etiology of the pulmonary defect was uncertain. Chest x-ray revealed radiodensity in the left perihilar region, left sternoclavicular Joint dislocation, and superior displacement of the left clavicle. Radiodensity was thought to represent pulmonary contusion.

? Meetings: None.

?? Grants: None.

? Conflicts of interest: None.

?? Author contributions: None.

The patient’s SpO2 improved to 99% after placement on non- rebreather; however, he continued to endorse significant left chest pain, worse with palpation. A stat computed tomography (CT) was obtained and showed a large left-sided lung herniation through the anterior chest wall via dislocation of the sternoclavicular and first costosternal joints (Fig. 2). subcutaneous emphysema was noted in the midline, transcending up the neck, and within the chest wall musculature.

On return from CT, the patient continued to endorse dyspnea and chest pain, requiring continued use of the nonrebreather to maintain oxygen saturations greater than 92%. Based on continued tachycardia, tachypnea, and oxygen requirements, the patient was intubated. Once in the operating room, trauma surgery repaired the left chest wall defect, and mesh was placed over area of lung herniation. Dislocations were repaired by orthopedics.

Diagnosis of extrathoracic lung herniation has been difficult and was limited before the common use of CT [4]. CXR rarely adequately demonstrates lung herniation although can raise suspicion if Joint dislocations or focal increased lung densities are noted [4,6]. To our knowledge, emergency ultrasound has not previously been used to aid in the diagnosis of traumatic lung herniation. The eFAST has a higher sensitivity than CXR in identifying hemothoraces and pneu- mothoraces, with CXR missing an estimated 30% to 40% of pneumo- thorax cases [7]. Although the sensitivity is comparable to CT, the eFAST has the advantage of being immediately available, portable, can be readily used in unstable patients, requires no radiation, and can be used quickly for patient re-evaluation [7]. Pulmonary injuries often require immediate intervention in the trauma patient, and these live-saving procedures should not be postponed while awaiting CT imaging.

This case demonstrates that use of the eFAST in blunt trauma patients can be used to aid in the diagnosis of traumatic lung herniation. The rarity of traumatic lung herniations limits the availability of ultrasound images, which can be used for teaching pathologic diagnoses. We were able to determine that pulmonary pathology existed, which was neither a pneumothorax nor hemothorax by noting the lack of an echogenic pleural line between rib spaces, demarcated as pleural gap in Fig. 1. This pleural gap contained a hypoechoic structure suggestive of pulmonary parenchy- ma, continuous with the underlying hypoechoic area where pulmo- nary parenchyma normally lies. Normal hyperechoic pleural lines were noted on superior and inferior edges of the rib spaces, with pleural gap between ribs. The combination of a normal sliding lung sign superiorly and inferiorly, normal seashore sign throughout lung fields, and the apparent tip of the lung entering the intercostal space on inspiration in the pleural gap, we determined lung pathology

0735-6757/$ – see front matter.

Fig. 1. Extended FAST image of left lung showing pleural gap (left) and of right lung showing pleural line between ribs (right). Images are taken at second intercostal space.

Fig. 2. Axial CT image showing left-sided lung hernia.

existed, which we had not previously encountered on eFAST. With stronger evidence-based eFAST diagnosis during the primary survey, the patient may have gone directly to the operating room without delay for CT imaging. Surgical repair of lung herniations has been the

mainstay of treatment [4,6,8]. Proficient use of emergency ultrasound, specifically the eFAST, will aid in the rapid diagnosis and disposition of pulmonary injuries requiring immediate intervention.

Stacey Marlow MD Tabitha Campbell MD Ashley Davis BS Hershel R. Patel BS

Department of Emergency Medicine University of South Florida at Tampa General Hospital

Tampa, Florida, USA E-mail address: [email protected]

http://dx.doi.org/10.1016/j.ajem.2012.09.030

References

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  8. Lang-Lazdunski L, et al. Traumatic extrathoracic lung herniation. Ann Thorac Surg 2002;74:927-9.

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