SSCTS

A Pneumonectomy is an operation in which one entire lung is removed.

Indications

These can be classified as benign or malignant; however, the most common indication is the management of non-small cell carcinoma. In general, surgery is only indicated for stage I and II disease as defined by the 2007 International Association for the Study of Lung Cancer Staging Project (Table 1).

Table 1: Lung cancer staging

Pulmonary Anatomy

To understand this surgical procedure we need a basic knowledge of the anatomy involved.

The Lungs:

• The right lung is larger than the left (ratio of 55% to 45%)

• The left lung has 2 lobes (upper with lingular segment and lower) divided by the oblique fissure while the right is made up of 3 lobes (upper, middle and lower) divided by the oblique and transverse fissures.

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

The Posterior Chest Wall:

• Superficial muscles: Trapezius and lattissimus dorsi

• Deep muscles: Serratus anterior and the rhomboids

• Intercostals: External, internal and innermost groups

Pre-Operative

·         Imaging will most likely take the form of a CXR in addition to a CT and/or positron emission tomography scan.

·         Pulmonary function tests are used to predict the patient’s postoperative lung function following pneumonectomy and assess whether the procedure is viable. A postoperative predicted FEV₁ of less than 40% indicates high risk.

·         If pneumonectomy is for malignancy further investigations such as CT head may be required to stage the disease.

Incisions

The patient is positioned in the lateral decubitus position to allow the best surgical access. A double-lumen endotracheal tube is placed to allow deflation of the diseased lung while continuing ventilation of the other.

Posterolateral thoracotomy is the incision most commonly used with the incision centred around the tip of the scapula.

• Three major muscles encountered are the trapezius, latissimus dorsi and serratus anterior.

• This is a curvilinear incision from the anterior axillary line passing 3-4cm below the tip of the scapula and continuing superiorly midway between the medial border of the scapula and vertebral column.

Post operative considerations

Following pneumonectomy air fills the space previously occupied by the lung. A number of further changes will then occur over time. The size of this space will gradually decrease, with hyperinflation of the remaining lung and a shift of the mediastinum to the operated side. In addition, there is resorption of the air and replacement with fluid.

Pain relief

• This is an extremely important aspect of post-operative care with good control leading to better outcomes.

• Pain relief is usually achieved with a combination of regional block (epidural or paravertebral catheter) and patient controlled analgesia (PCA).

Thromboembolic prophylaxis

·         All thoracotomy patients require prophylaxis usually in the form of TEDs stockings and low-molecular weight heparin.

Complications

Pneumonectomy remains a procedure associated with considerable risk and a peri-operative mortality of 6%. Post-operative complications can be classified as general and specific.

General complications include wound infection, pulmonary embolism or deep vein thrombosis, arrhythmia and atelectasis.

Specific complications:

• Injury to a large vessel (pulmonary artery or vein) leading to massive bleeding or haemothorax post-operatively.

• Infection or empyema of the pneumonectomy space.

• Bronchopleural fistula, a communication between the bronchial stump and pleural cavity, occurs in 5% of patients undergoing pneumonectomy and is more common on the right side.

• Post-pneumonectomy pulmonary oedema: a form of acute lung injury seen following lung resection surgery. Associated with a high mortality (30-60%).

Other less common problems include oesophageal damage, chylothorax secondary to thoracic duct injury and damage to thoracic nerves (phrenic or recurrent laryngeal nerves).

References

·         Oxford Handbook of Cardiothoracic Surgery. Chikwe, Beddow, Glenville, 2006

·         Stephan F et al. Pulmonary Complications Following Lung Resection. A Comprehensive Analysis of Incidence and Possible Risk Factors. Chest 2000; 118(5):1263-70

·         James, TW, Faber, LP. Pneumonectomy for malignant disease. Chest Surg Clin N Am 1999; 9:291.

Table 1

·         Rami-Porta R et al. The IASLC Lung Cancer Staging Project: proposals for the revision of the T descriptors in the forthcoming (seventh) edition of the TNM classification for lung cancer. Journal of Thoracic Oncology 2007; 2(7):593-602.