Lung Segmentectomy and Limited Pulmonary Resection

Although lung segmentectomy has always been popular for resection of suppurative lesions and nonmalignant masses, some experts have also recommended it for very early lung cancer. ^{[1, 2, 3]} The choice for patients with lung cancer is usually a lobectomy, but in some patients with minimal lung reserve, lung segmentectomy may be an option. ^{[4, 5, 6]}

The essence of lung segmentectomy is to remove the lung disease without removing excess normal lung. Because the technique is technically demanding, some surgeons simply prefer to wedge out the lung lesion using a stapler. However, the recurrence rate after a wedge resection remains higher. ^[7]

With the resurgence of Mycobacterium tuberculosis and development of drug-resistant strains, lung segmentectomy is again becoming a popular technique. ^[8] Segmentectomy and extended lung resection are also used to treat various fungal infections and congenital lung malformations.

Both lobectomy and pneumonectomy are widely used to treat cancerous lesions of the lung. However, many thoracic patients have chronic obstructive pulmonary disease (COPD) or emphysema and have minimal lung reserve. These patients simply are not able to tolerate extensive lung resections. Segmentectomy is a good option in such patients.

Both segmentectomy and lesser lung resections can be performed via thoracotomy or via video-assisted thoracoscopic surgery (VATS). ^{[9, 10, 11]} VATS is fast becoming an option for most patients with thoracic pathology. The technique has been shown to yield better outcomes, less pain, and shorter recovery than traditional techniques.

VATS is currently the criterion standard for both lesser lung resections and segmentectomy. VATS is a better choice than thoracotomy in these settings and is performed with general anesthesia using a camera and a small non-rib-spreading incision. The technique of lesser lung resection and segmentectomy is very similar to the open technique, except that instruments are used to retract and dissect the segmental planes. ^[9]

Many surgeons remove isolated lung lesions with a wedge resection using VATS. ^[12] Wedge resection saves time but involves removal of a significant amount of normal lung tissue. Wedge resection is appropriate only for noncancerous lesions or for resecting metastatic lesions. The standard of care for malignant lesions is still lobectomy. ^[13]

Indications for segmentectomy and lesser lung resections include the following:

• Bronchiectasis
• Early stage I cancer (usually in a patient who has significantly limiting cardiopulmonary disease)
• Lung nodules
• Tuberculosis
• Suppurative lesions

Segmentectomy and lesser lung resections should not be performed in people who have no pulmonary reserve or have numerous comorbidities for a thoracotomy.

Relative contraindications include the following:

• Coagulopathy
• Skin infection over the site
• Diffuse lung disease
• Extensive metastases

Anatomy

When operating on the right side of the chest, the surgeon should be aware that the bronchus is the most posterior hilar structure. The upper-lobe branches of the pulmonary artery are the most superior hilar structures in the chest. When the major fissure is opened, the pulmonary artery can be visible, allowing the surgeon to follow its continuation into the lower lobe. ^[7]

In the middle lobe, the medial and lateral branches are always opposite one another. In most cases, a posterior segmental artery may arise and supply the posterior segment of the upper lobe.

In the left chest, the pulmonary artery again crosses superiorly above the left mainstem bronchus to become the most posterior hilar structure. The apical posterior, anterior, and segmental branches are readily visible in the anterior and superior direction. As on the right side, a separate posterior segmental artery may be found posteriorly on the main pulmonary artery, either just at or above the major fissure.

In the major fissure, the lingular branches anteriorly and the superior segment branch posteriorly often form a cross on the continuation of the pulmonary artery.

During segmentectomy, it is vital for the surgeon to be aware of the high degree of arterial variability. Each branch must be identified and correctly ligated.

In all cases of segmentectomy, the artery and respective bronchus are divided and ligated. The order of the division depends on which segment is being removed.

When performing segmentectomy of the apical and anterior segment of the right upper lobe, the artery is always ligated first and then gently elevated to locate the segmental bronchus.

For segmentectomy of the posterior right upper lobe, it is sometimes easier to dissect the bronchus first and then ligate the artery. The artery is often deep and not readily visible. Great care must be taken; inadvertent injury can lead to massive bleeding.

On the left side, the pulmonary artery branches to the upper lobe are more easily identified chiefly because the bronchus is the middle structure on that side.

If unsure about the bronchial anatomy, the surgeon may alternatively inflate and deflate the lung on that side to determine the plane of dissection. However, even if a segment is deflated, it may fill via collateral ventilation from accessory bronchi. ^[7]

After excision of noncancerous lesions with either segmentectomy or wedge resection, most patients do well. ^[14] However, when these procedures are performed in patients with compromised lung function, the morbidity can be high. In addition to the removal of the lung mass, the thoracic incision and general anesthesia also carry high morbidity in people with no lung reserve. Old data suggest that the overall mortality in healthy people is about 1% but may run as high as 4-6% in individuals with compromised lung function. Even with VATS, more recent mortality figures are in a similar range. ^[15]

Morbidity and mortality after a segmentectomy are similar to those after a lobectomy. The major complications that increase morbidity include prolonged bronchopleural fistula, empyema, and persistent airspace. All of these are interrelated and may occur in combination. These complications generally arise when the dissection in the intersegmental planes is difficult or there is significant inflammation.

Patients with tuberculosis experience the highest morbidity associated with segmentectomy. As many as 33% of patients with tuberculosis who are candidates for lung resection (lobectomy, wedge resection, or segmentectomy) develop persistent airspace problems, which inevitably result in infection. The resulting pleural cavity empyema is then treated initially with thoracostomy tube drainage and antibiotics.

Morbidity after a lesser lung resection (wedge resection) is minimal. Potential complications include either retention of secretions or pleural problems. Persistent airspace occurs with an incidence of less than 10%.

Segmentectomy is a much less benign procedure than lobectomy or pneumonectomy. Mortality is usually below 1% when the procedure is performed in patients with good pulmonary function. However, in patients with poor lung function and in those who have undergone prior lung surgery, mortality can be as high as 4-6%. ^[7]

Several large studies have examined wedge resections performed in patients with metastatic lesions. ^[16] On average, the 5-year survival rate in patents with colon or breast cancer and isolated lung metastases has been about 35%. ^[17]