Continuing Education Activity

Lung torsion is a life-threatening pathology that occurs when the lung or a pulmonary lobe rotates causing vascular and airway obstruction. This is a rare pathology that occurs when there is a disturbance in the thoracic cavity. To avoid high mortality, this must be diagnosed in a timely manner. With immediate management, the affected lung or pulmonary lobe can be salvaged. Overall, however, lung torsion has a poor prognosis due to misdiagnosis and delay in treatment. This activity reviews the evaluation and treatment of lung torsion and highlights the management of patients with lung torsion, to help the interprofessional team maintain a high index of suspicion for this disease in the appropriate clinical setting and improve patient outcomes.

Objectives:

• Identify the etiology of lung torsion.
• Review the evaluation of lung torsion.
• Outline the treatment and management options available for lung torsion.
• Describe interprofessional team strategies for improving care coordination and communication to advance lung torsion and improve outcomes.

Introduction

Lung torsion is a rare pathology that is classically seen when there is a disruption in the thoracic cavity. Disruptions can include thoracotomy, lung transplantation, and trauma. Lung torsion is a life-threatening disease that requires a timely diagnosis because lung rotation can cause vascular compromise and airway obstruction, which can result in necrosis of the lung tissue. With immediate management, the affected lung or pulmonary lobe can be salvaged. Overall, lung torsion has a poor prognosis due to misdiagnosis and delay in treatment. If detorsion occurs and the lung is fixed in place, then it can recover to full function.

Etiology

A history of intrathoracic procedures is common in patients with lung torsion, although spontaneous etiologies are known as well.[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The causes of lung torsion in adults include: 

• Thoracic or abdominal trauma
• Lung transplantation
  • Unilateral
  • Bilateral
• Video-assisted thoracoscopic surgery (VATS) procedure
• Thoracentesis
• Thoracic Procedures
  • Transesophageal operation
  • Aorta repair
  • Transthoracic correction of hiatal hernia
  • Transthoracic needle aspiration
  • Transabdominal surgical diaphragmatic hernia
• Spontaneous etiology
  • Pneumothorax
  • Pleural effusion
  • Lobar atelectasis
  • Pulmonary sequestration

Commonly known causes of lung torsion in pediatric patients include: 

• Blunt thoracic and abdominal trauma
• Tracheoesophageal repair
• Thoracotomy for hiatal hernia
• Ductus arteriosus closure

Epidemiology

Lung torsion incidence was reported to be 0.089%-0.3% in one case series.[16] In this case study, lung torsion was found in 62.4% of patients post-operatively, in 8.3% of patients after trauma, and in 29.4% of patients, lung torsion occurred spontaneously. 

It was found that 21.6% of lung torsion cases occurred after VATS and 78.4% after thoracotomy. The case series also reviewed the site of lung torsion most commonly involved. In the study, 74.4% of the lung torsions occurred after a right upper lobe lobectomy. The right middle lobe was the most common site, occurring in 29.4% of patients among the case study. The incidence among genders was not significantly different. In the case series, it was reported that 58.3% of the cases occurred among males, and 41.7% occurred among females.[16]

Pathophysiology

Lung torsion is a result of a disruption in the thoracic cavity. This can vary from thoracotomy, pleural effusion, pneumothorax, trauma, or anything that can disturb the vasculature or lung tissue. Fluid accumulation from pleural effusion, inflammatory infiltrates from atelectasis, opacities from pneumonia, or any other invasive procedures can compress the lung, vasculature, or airways and may cause the lung to rotate and obstruct the pulmonary vessels. The large space in the thoracic cavity is a risk factor that allows mobility for the lung or lobes to rotate after segmentectomy or lobectomy. Even complete fissures without pleural adhesions or long bronchovascular vessels can cause lung torsion.[3][9][10][11][12][13][17]

Lung torsion results in either part of the lobe or the entire lobe twisting along an axis. This results in the obstruction of the bronchovascular tree, which eventually compromises the pulmonary arterial and venous circulation along with the bronchial circulation. It is found that if the lobe is rotated more than 180 degrees, the bronchovascular pedicle would be acutely obstructed, resulting in atelectasis followed by pulmonary infarction and necrosis. Bronchovascular obstruction will result in decreased arterial oxygen content as the lung will not get enough blood supply.[13]

Hypoxemia may result from intrapulmonary shunting, alveolar hyperventilation, and ventilation/perfusion (V/Q) mismatch. Intrapulmonary shunting occurs if lobular veins are partially obstructed in an unventilated lung with some venous return. Alveolar hypoventilation occurs because the bronchus is kinked, decreasing the airflow from the airway to the bronchus. This may also increase airway secretions adding to the obstruction. If ventilation/perfusion mismatch occurs, it means that there is partial bronchial obstruction but no venous return to the lobe because of complete vascular obstruction. Without proper oxygen requirements, the lung tissue can become non-viable. If the lung is not operated on early, the lung tissue can become necrotic.[13][18][19][20]

Histopathology

Histopathology of the rotated lung reveals visceral pleural fibrosis of the affected lung, and the tissue is filled with alveolar macrophages.[18]

History and Physical

There are no specific clinical signs or physical exam findings that can suggest lung torsion as the diagnosis. Non-specific clinical signs range from fever, chest pain, shortness of breath, and cough. Most of these symptoms appear 4 to 14 days after having a thoracic procedure or trauma or any other triggering effect. Some patients were even asymptomatic and showed no clinical signs.

Physical exam findings will reveal hypoxia, dyspnea, productive cough, and hemoptysis. Respiratory discomfort and tachypnea can also be seen. Lung torsion is diagnosed with radiological imaging.[13][16][21][18][10]

Evaluation

Initial laboratory work can show leukocytosis, but it's not always present. Arterial blood gas may appear normal and not reflect the hypoxia; therefore, the diagnosis is made through radiologic imaging.[1]

An X-ray can show worsening consolidation, and sometimes abruption of the pulmonary artery may be seen. Anatomic abnormalities and pulmonary opacities can also be seen in X-ray imaging. Serial X-rays can show consolidation progression, especially if pneumonia is superimposing on lung torsion.[16][22][23]

Bronchoscopy can also reveal findings indicating lung torsion. In previous case studies, bronchoscopy revealed obstruction where the bronchoscope could not advance into the bronchus due to the narrowing of the passageway. The bronchial stenosis and a "fish mouth" orifice could be seen through bronchoscopy. Bronchoscopy does not always reveal narrowing or diagnose lung torsion; therefore, a computed tomography (CT) scan is required to confirm the diagnosis.[16][18][24]

CT scan can show obstruction of bronchial arteries, lobar opacification, or atelectasis and lobular collapse. Vascular and bronchial structures can appear to be stenosed, blocked, or inverted on imaging and may be seen as the "antler sign". Obstruction in the airway can reveal tracheobronchial tree narrowing of the affected bronchus. Rotation of the lung can occur at a variety of angles; however, one case series has shown that in most cases, the lobe was rotated about 180 degrees. Follow up CT scans can show a change in the position of the lesions as the lung torsion progresses.

CT angiography can show abrupt truncation and pulmonary artery obstruction. These images have also revealed interlobular septal thickening in the displaced lobe along with venous congestion. Sometimes abnormal lobe displacement can reveal a fissure. If the lung tissue has already become necrotic, imaging will reveal the loss of parenchymal and pulmonary vascular sites.[16][24][18][25]

Treatment / Management

Patients that are treated early on before necrosis occurs can have viable tissue saved. Case studies show that patients who underwent detorsion of the rotated lung were able to have full function returned with the lung re-expanding. Once the lungs go through detorsion, they have to then be fixed in place between the involved lung and the surrounding tissue with sutures or staples.

If it is not possible for the lung to go through detorsion or if detorsion fails, then lobectomy must occur. To save viable lung, detorsion must be performed within the first few hours of diagnosis. Any longer, the lung may already have irreversible ischemic damage, where it may be safer to perform a resection without detorsion. This would prevent the inflammatory markers that build up during the torsion from leaking out into the rest of the body and causing multiorgan failure. For the damaged tissue, it is best to keep the lung rotated until the pulmonary veins have been clamped to prevent the systemic release of the inflammatory markers. Once safely clamped, a clinical decision can be made whether the lung can go through detorsion or if resection should occur. 

Delayed treatment can also cause a clot to form, resulting in pulmonary embolism or stroke. Heparin drip can be used as prophylactic measures to prevent this complication. Conservative management was found to have recurrent pneumonia, eventually leading to death. Very few cases had complications of pneumonia, air leaks, or emphysema after fixation. Most procedures occurred without any complications intra-operatively and post-operatively.[18][26][27][28]

Differential Diagnosis

Studies have found that misdiagnosis occurred 18.3% of the time in patients with lung torsion. Most of the differentials can be excluded by CT scan, CT angiography, or bronchoscopy from the abnormal lobular placement. Diagnosis is confirmed with the vascular obstruction and airway obstruction seen on the CT scan. Differential diagnosis of lung torsion includes the following:[13][14][16][29][30]

• Hemothorax
• Hemorrhage
• Pneumonia (infectious versus aspiration)
• Contusion (after sub-lobar resection - can appear like airspace consolidation that resolves after a few days)
• Lung gangrene
• Parenchymal infection
• Atelectasis
• Tumor
• Loculated effusion
• Emphysema
• Inadvertent ligation of the hilum
• Diaphragmatic herniation
• Leakage of the anastomosis site 

Prognosis

Prognosis is poor if lung torsion management is delayed or the patient becomes septic resulting in ischemia of the lung tissue. The mortality rate was found to be as high as 8.3%. Higher mortality rates were associated with whole lung torsion as compared to lobar torsion. Studies have found similar survival rates among reposition and direct reposition. Indirection resection had higher mortality. Mortality from lung torsion was found to be highest in trauma patients at 22.2%, followed by thoracic surgery at 8.8%, and spontaneous lung torsion at 3.1%.[16][31]

Complications

Correction of lung torsion is an emergent surgical procedure, with a multitude of associated complications. These include:[13][32][33][34][35][36]

• Pneumonia
• Cerebrovascular accident
• Necrosis of the lung tissue
• Hemorrhage
• Vocal cord injury
• Bronchopleural fistulae
• Pulmonary embolism
• Post-thoracic surgery non-cardiogenic pulmonary edema
• Atelectasis
• Bronchospasm
• Respiratory Failure
• Air leak - pneumothorax, pneumomediastinum, pneumopericardium
• Emphysema 

Deterrence and Patient Education

Patients should be advised to avoid any blunt trauma to the thoracic or abdominal cavity after having a thoracic procedure to minimize the risk of post-operative lung torsion.

Pearls and Other Issues

Lung torsion is a diagnosis that can be made from chest X-ray, CT scan, or bronchoscopy. It is confirmed with a CT scan. It is a life-threatening pathology. It causes bronchovascular and airway compromise. If not treated in a timely fashion, then necrosis of the lung can occur. It is treated through detorsion of the lung or lobectomy.

If a thoracic procedure occurs, pneumopexy of the lung lobe should be completed to prevent lung torsion. After lobectomy or segmentectomy, the remaining lobe should be stabled or sutured, so it stays fixed; this, however, is not commonly practiced as prophylactic treatment. Post-care followup would require monitoring for air leaks. Practitioners should consider heparin drip for prophylactic prevention of pulmonary embolism.

Enhancing Healthcare Team Outcomes

If a thoracic procedure, such as VATS or lobectomy was done, then stapling the lung or pneumopexy of the lobe should be considered to prevent lung torsion. Lung torsion is a diagnosis that must be made in a timely manner, classically done through radiologic imaging. Once a diagnosis is made, it is imperative to contact the thoracic surgical team to salvage the lung. Coordination and rapid, effective communication between interprofessional care team members is essential to ensure a timely diagnosis and correction of this potentially fatal disease.