Introduction:
Postpneumonectomy is a rare complication of the procedure of pneumonectomy. It is an airway obstruction due to extreme rotation and shift of the mediastinum. This shift causes airway obstruction. This condition is corrected by repositioning the mediastinum. The airway obstruction arises due to the compression of the tracheobronchial tree and esophagus. The group of symptoms that arises due to the shift is called postpneumonectomy syndrome.
What Is Pneumonectomy?
The surgical removal of one lung due to cancer, trauma, or other disorder is called a pneumonectomy. During this procedure, an incision is made at the side, and the surgeon removes the affected lung. The sac that contains the lung automatically fills with air and takes up space. It is performed in cases of traumatic lung injury, bronchiectasis, pulmonary tuberculosis, lung defect at birth, or cancer that has affected or spread to the lung.
What Causes Postpneumonectomy Syndrome?
After the procedure, the mediastinum shifts to occupy the space, thereby compressing the airway. The heart and mediastinum rotation causes two after effects:
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Herniation and hyper-expansion of the lung.
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Compression of the airway between the pulmonary artery and the aorta or vertebral column. Airway being trachea, bronchus, or lobar orifice.
Previously it was believed that this syndrome only took place in patients with left-sided aortic arches and underwent pneumonectomy at the right side or in patients with right-sided aortic arches and underwent left pneumonectomy. But recent studies have shown that it can arise irrespective of this. For example, in patients with left-sided aortic arches who underwent left pneumonectomy, it was observed that bronchus intermedius would be compressed and elongated between the thoracic spine and pulmonary artery.
What Are the Clinical Features of Postpneumonectomy Syndrome?
Postpneumonectomy syndrome is a late complication. The patients often present with the syndrome about 20 years after the procedure. The symptoms of airway obstruction include:
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Dyspnea: Difficult or labored breathing.
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Acute Respiratory Distress: In some patients, it is caused when fluid enters the lungs; this reduces the oxygen capacity of the lungs. This ultimately causes less oxygen to be available for the organs.
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Stridor: High-pitched sounds during breathing, caused by blockage of the airway, and heard while inhaling.
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Difficulty in Clearing Secretions: Mucus secretions are a part of the defense mechanism of the respiratory pathway. It increases during inflammation and infection to prevent further damage. The patients have difficulties in clearing these increased secretions.
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Scoliosis: Abnormal curvature of the spine.
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Dysphagia: In rare cases, if an esophageal obstruction is present, patients may experience dysphagia (difficulty swallowing).
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Dysphonia: In extremely rare conditions where the laryngeal nerve is compressed, dysphonia (difficulty in speaking) has been observed.
What Are the Risk Factors?
It is difficult to estimate the risk factors, but studies have shown that the syndrome is more prevalent in youth, although it has been reported in all age groups. The reason for this is a pliable cartilaginous airway, increased lung compliance, and increased mobility of the mediastinum. It has been proposed that these conditions make it more likely for the mediastinal shift to occur.
How Is Postpneumonectomy Syndrome Diagnosed?
Since the postpneumonectomy syndrome arises after the procedure, a patient should be monitored for possible symptoms. If symptoms arise, they should be investigated.
If respiratory insufficiency arises, the cause should be found. A diagnosis is arrived upon if there is evidence for tracheobronchial compression by any neighboring or vascular structures.
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Radiographic Findings: The characteristic radiographic findings are: extreme shift of heart and mediastinum into hemithorax, overdistension (excessive stretching) of the remaining lung, and obliteration(complete covering) of postpneumonectomy space.
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Computed Tomography: This can be used to identify the point of airway obstruction. CT, while inspiration and expiration are useful to find dynamic airway obstruction. Airway obstruction can be codified as (for example, in the right postpneumonectomy syndrome):
Compression of the airway(main bronchus or trachea), a shift of the mediastinum to the right, and excessive stretching (overdistention) of the left lung. Rotation of the heart and great vessels in the counterclockwise direction, tracheomalacia: abnormality in tracheal cartilage that leads to the collapse of its wall, and thereby, airway obstruction.
How Is Postpneumonectomy Syndrome Treated?
Prompt treatment is necessary once the syndrome has been diagnosed. This is so as to prevent acute respiratory distress. Since the symptoms arise due to the mediastinal shift and overextension of the lungs, treatment consists of reversing these precipitating factors.
Surgical Management Includes:
Surgically, the space left by the pneumonectomy position is refilled, and the mediastinum that got shifted is repositioned. It is done by correcting the position of herniated lung and restoring the normal patency and position of the compressed airway.
The following steps should be performed during treatment:
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Monitoring: While performing correctional procedures, the patient should be monitored to detect the hemodynamic (blood flow inside the organs and tissues) changes. These can arise during repositioning the mediastinum, changing the position of the patient to a supine position, or chest closure. That is, the tamponade physiology should be monitored. Cardiac tamponade is the accumulation of fluids, such as pus, in the pericardial region leading to compression of the heart.
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Complete Adhesiolysis: Adhesiolysis is the surgical procedure done to reposition organs to the anatomical position. It also helps in removing any abnormal organ adhesions that may have occurred. Therefore this surgical procedure is done in this case to reposition the heart, lung, and mediastinum. The Pneumonectomy stump has to be fully mobilized for successful airway clearance, as it may be tethered to the posterior mediastinum or vertebra.
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Bronchoscopy: It is done to assess the patency of the airway during the procedures.
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Filling the Postpneumonectomy Space: It is important to fill the space left by pneumonectomy to prevent relapse. It is done by filling the space with saline-filled breast implants. In pediatric patients, the placement of a prosthesis helps in allowing adjustments as the child grows.
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Final Assessment: After chest closure, the patient is placed in a supine position, and a bronchoscopy and chest X-ray is performed. This is done to confirm that the mediastinum is intact in the midline and if the remaining lung has not collapsed. Adjustments to the volume of the saline prosthesis may be made if necessary.
Conclusion:
Postpneumonectomy arises after the surgical removal of the lung and when the adjacent structures reposition to fill the space. This results in airway obstruction as the mediastinum compresses the vascular and airway structures. It is a rare complication and often arises much later in life. Patients with such symptoms should undergo prompt treatment. Treatment includes shifting the organs to the original position and filling the space with saline-filled prosthetic implants. This can significantly reduce mortality and morbidity and can provide immediate relief to the patient.
