Pneumonectomy

The lungs are highly dynamic thoracic structures that are essential for respiration, pH equilibrium, enzyme production, and host defense, among many other functions. Thus, the lungs are susceptible to a wide variety of pathologic conditions, both malignant and benign, that may require pneumonectomy (complete resection of a lung).[1, 2]

Extrapleural pneumonectomy is an expanded procedure that includes resection of the parietal and visceral pleurae, diseased lung, ipsilateral hemi-diaphragm, ipsilateral pericardium, and mediastinal lymph nodes.[3, 4]  Although the procedure carries a risk for morbidity, including cardiac and pulmonary complications, it can be beneficial in patients with malignant mesothelioma and extensive thymomas.[1, 2, 3, 5, 6] This surgical approach often is coupled with radiation and chemotherapy to improve survival in both diseases.[2, 5, 7, 8]

Sarot described the first extrapleural pneumonectomy in 1949,[1] and it was initially used in the treatment of tuberculosis empyema, but became more commonly used in the 1980s and 1990s in the treatment of mesothelioma.[2]

In general, pneumonectomy is indicated for both malignant and benign diseases.

Malignant indications for pneumonectomy include the following[1] :

• Pulmonary metastasis (uncommon)

• Non-small cell lung carcinoma[9]

Benign indications for pneumonectomy include the following[2] :

• Chronic lung infection (multiple abscesses, bronchiectasis, fungal infection, tuberculosis)

• Traumatic lung injury

• Bronchial obstruction with destroyed lung

• Congenital lung disease

Although the most common indication for an extrapleural pneumonectomy is malignant mesothelioma, the technique can also be used to treat disseminated thymomas and occasionally tuberculosis in a more limited fashion.[5, 6, 7]

The patient’s pulmonary function should be assessed and a ventilation-perfusion scan considered for any patient with a forced expiratory volume in 1 second (FEV1) of less than 2 L. The combined results of these tests can be used to adequately predict postoperative lung function. Patients with a predicted postoperative FEV1 of less than 0.8 L are often treated with other means and not considered for pneumonectomy. Although surgeons base candidacy for extrapleural pneumonectomy on pulmonary function studies, patients should be individualized and performance status taken into account for resection.

Echocardiography also may be performed before the procedure to evaluate for valvular disease, pulmonary hypertension, and ventricular function. Severe valvular disease, confirmed severe pulmonary hypertension, and poor ventricular function may preclude surgery.

Positron emission tomography and CT scanning of the chest are used to assess the extent of disease involvement.[1, 2, 10, 11] Surgery is prohibited in patients with disease extending past the diaphragm to be intra-abdominal, extending to the contralateral hemithorax, invading into structures of the mediastinum or, most commonly, invading the ribs. Since chest MRI and CT scanning are unreliable determinants of chest wall invasion; this is also assessed intraoperatively.[1, 2]

Anatomy

The lungs are two in number in the thorax and are separated by the mediastinum. The left lung is divided into two lobes, an upper and lower, by an oblique fissure, whereas the right lung is divided into 3 lobes (superior, middle, inferior) by an oblique and horizontal fissure. The right lung is heavier and has a larger capacity than the left lung yet is shorter in consequence of the liver.

Each lung is lined directly by serous membrane, creating the visceral portion of the pleura. The inner lining of the thorax is lined by the parietal portion of the pleura.

The hilum of the lung is a triangular depression on the mediastinal surface of each lung. It consists of pulmonary vessels, bronchi, and bronchial vessels and lymph nodes.

Complication Prevention

A low volume of fluid is administered. The pulmonary artery and vein are carefully controlled.

Mortality rates of 2%-7% have been reported.

Potential complications of pneumonectomy and extrapleural pneumonectomy include the following:

• Atrial fibrillation

• Cardiac herniation

• Tamponade

• Diaphragmatic/pericardial patch dehiscence

• Bronchopleural fistula

• Deep venous thrombosis

• Pulmonary embolism

• Pneumonia

• Pulmonary edema

• Respiratory insufficiency

• Myocardial infarction

• Bleeding

• Wound infection

• Urinary tract infection

• Sepsis

• Postpneumonectomy syndrome

• Empyema[1, 2]

Thoracotomy instruments are used for pneumonectomy and extrapleural pneumonectomy.

Prior to the start of surgery, a thoracic epidural catheter, arterial line, central venous catheter, and oximeter are placed for monitoring during the procedure.

The patient is intubated with a double-lumen tube or endobronchial blocker and placed in the lateral decubitus position. A nasogastric tube can then be placed and used intraoperatively for palpation of the esophageal position and postoperatively for stomach decompression.

Anesthesia

General anesthesia with an epidural or alternative is used.

Positioning

The patient should be positioned in the lateral decubitus position to allow proper surgical access and secured to the operating table with a safety belt across the upper thighs or tape across the hip.

A chest tube is unnecessary but often is used.[6]

The postpneumonectomy space is expected to slowly fill with fluid and air.[12]

Pain relief should be established via epidural blocks, along with patient-controlled analgesia and/or pain pumps.[4]

Thrombolytic prophylaxis is necessary in all thoracotomy patients and can include sequential compression devices only.

Several anatomic changes are expected: mediastinal shift, spleen, and liver position changes.[6]

A posterolateral thoracotomy incision over the fifth or fourth intercostal space is used with possible resection of the rib for additional access. This can be done for resurgery or in the case of an extrapleural pneumonectomy.

Focus is then directed toward division of the pulmonary vessels and bronchus.

The superior and inferior pulmonary veins are isolated and stapled; occasionally, they must be clamped and oversewn.

After isolating the right main pulmonary artery, a stapler usually is used to divide the vessel, although some surgeons prefer clamping and oversewing.

The right mains stem bronchus is isolated and divided near the carina, usually with a stapler.

A standard lymph node dissection is conducted with malignant disease.

A subcostal incision or laparoscopy can be used to investigate abdominal extension when imaging suggests transdiaphragmatic involvement.

An extended posterolateral thoracotomy incision over the fifth intercostal space is then used, with adequate exposure for extrapleural dissection achieved via resection of the fifth rib. The extrapleural dissection proceeds from superiorly to inferiorly in the anterior compartment followed by the posterior compartment. Special care is taken not to avulse the internal mammary artery and vein anteriorly or the subclavian artery and vein posteriorly. Additional attention is given to the superior vena cava and azygous vein when dissecting around the apex of the lung to avoid a traction injury.

Invasion of the aorta and esophagus is assessed during the posterior dissection, as well as the pericardium via the anterior dissection.

Diaphragmatic division and dissection starts anteriorly and continues around posterolaterally, avoiding injury to the peritoneum.

The nasogastric tube can be used during posterior dissection to palpate the esophagus and to help prevent its injury. This is usually the most challenging portion of the dissection.

A rim of the crus of the diaphragm is left with the esophagus to provide a source for attachment of a patch during later stages of the surgery.

As the dissection continues and reaches the medial aspect, the pericardial incision is extended for better visualization of the inferior vena cava and hilar vessels.

Focus is then directed to division of the pulmonary vessels and bronchus. After the right main pulmonary artery is isolated, an endovascular stapler usually is used to divide the vessel from inside the pericardium adjacent to the inferior vena cava. Next, the superior and inferior pulmonary veins are isolated and stapled in the same manner.

The right mainstem bronchus is isolated and divided near the carina, usually with a stapler.

A standard lymph node dissection is conducted.

Contents of the complete dissection include the lung with parietal and visceral pleurae, ipsilateral pericardium, right hemidiaphragm, and lymph nodes.

Once the specimen is removed, the reconstruction phase of the procedure ensues.

A pericardial fat pad can be used to cover the bronchial stump.

Next, an oversized patch is sewn circumferentially to the chest wall, the rim of the crus left around the esophagus, and the edge around the pericardium.

Attempts to avoid cardiac herniation are made by placing a prosthetic patch to the pericardial defect and to the diaphragmatic patch.

The chest is then closed and a chest tube is placed to be clamped after the completion of the procedure.

The patient usually is extubated in the operating room.

This procedure is conducted in a similar manner to the right-sided technique but with the patient in the right lateral decubitus position, with a few other differences.

Additional important structures to avoid injuring include the left recurrent laryngeal nerve while dissecting the aortic arch and the intercostals vessels in posteromedial dissection.

The left main pulmonary artery may be dissected outside of the pericardium owing to its shorter length but certainly can be divided intrapericardially.

In addition, during a left-sided procedure, the aortopulmonary lymph nodes are also resected.[13, 14]