Lung Segmentectomy and Limited Pulmonary Resection Technique

Several small studies indicate that thoracoscopic segmentectomy for lung cancer or for congenital and acquired lung disease leads to greater preservation of lung function and exercise capacity as compared with a formal lobectomy. However, there is a need for continued follow-up to ensure that there is no disease recurrence. ^{[19, 20, 21, 22, 23, 24]}

Segmentectomy is performed with the patient in the standard lateral decubitus position. Proper padding of the knees, elbows, and dependent axilla is provided. ^[7]

Various instruments should be used to hold the patient stable in this position, including placement of sandbags under the operating table mattress, rolled sheets in the front and back, and a beanbag.

The dependent arm is flexed at the elbow. If shaving is necessary, only the hair in the incision line should be removed. It is often helpful to outline the proposed incision with a marking pen. Most segmental resections are ideally performed via a fifth interspace incision.

The standard incision usually starts in front of the anterior axillary line and curves about 4 cm under the tip of the scapula. The incision then proceeds vertically between the posterior midline over the vertebral column and the medial edge of the scapula. It is usually unnecessary to go farther than the level of the spine of the scapula. The procedure can also be performed minimally invasively, either with video-assisted thoracoscopic surgery (VATS) or via a robotic approach.

A double-lumen endotracheal tube is preferred.

Once the chest cavity is entered, the lung is collapsed and the entire pleural cavity is examined.

Before the segmentectomy is started, the hilum is identified. All surgeons who perform segmentectomy via VATS or an open approach must be familiar with the anatomy of the bronchus, pulmonary artery, and veins. ^{[25, 26, 27]}

With a double-lumen endotracheal tube, it is easy to inflate the entire lung and clamp the bronchus concerned. Once the segment is identified, the rest of the lung can be deflated. The inflated segment will remain filled with air for some time, allowing easier dissection. Once the bronchus has been identified, it can be divided manually or with the use of a mechanical stapler. Unlike with a lobectomy, additional coverage of bronchial closure is usually unnecessary. ^[7]

Once the artery and bronchus are ligated, traction is applied on the bronchus, and the segment is removed in a retrograde fashion. This plane is developed with gentle blunt dissection, but the pleura is usually divided with scissors. The pulmonary veins come into view as they cross in the intersegmental planes. The segmental veins provide the best view of segmental anatomy. All the individual vein branches are isolated and divided sequentially. This can also be done with a stapler to avoid possible air leakage. (See the image below.)

Apical segmentectomy.

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After the lung specimen is removed, the raw surfaces of the lung parenchyma are examined for bleeding. The lung must be expanded gently and assessed for any bleeding or air leakage. If the dissection was done in a segmental fashion, air leakage should be minimal or nonexistent. Minor air leaks often seal within a few minutes after lung expansion.

If an air leak is present, however, it should be addressed. Moderate-sized leaks caused by segmentectomy can persist and lead to infections and residual airspace. If the moderate leak persists, the area may have to be reinforced with a pleural flap or a pulmonary sealant. Suturing the two adjacent lung segments is not recommended, because it may lead to tearing of the lung parenchyma. ^[28]

Once the lung is expanded, one or two chest tubes should be placed: one in the apex (size 20) and one in the base (size 28). The tubes should be connected to an underwater drainage system, but suction should be avoided until after extubation. Suction with positive-pressure ventilation often leads to an increase in air leaks. Once the patient is breathing spontaneously, the tubes can be connected to suction. At no time should these chest tubes be clamped during transfer of the patient from the operating room (OR) to the recovery room or the intensive care unit (ICU).

Subsequent management of the chest tubes is the same as that for any other lung surgery.

Because of the complexity of performing segmental resection, most surgeons today simply perform a nonanatomic lung resection, better known as wedge resection (see the image below). This technique is widely used to resect lung masses, metastatic lesions, and even localized suppurative infections. Almost any metastatic lesion can be excised by using a wedge resection technique. The technique can also be used to excise multiple lesions from the same lobe or to excise segment(s) from multiple lobes.

Pulmonary wedge resection.

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The one negative aspect of performing an anatomic lung resection is that it removes a significant amount of normal lung. This may be of no significance in healthy people, but it may compromise breathing in patients with limited lung reserve. ^[7]

Limited lung resection may be approached via a standard thoracotomy; sternotomy may be an option in patients with bilateral lung disease. The procedure can also be performed by means of VATS. ^{[29, 16]}

Most patients who undergo the procedure via lateral thoracotomy undergo general anesthesia. A double-lumen endotracheal tube is preferred. After the chest cavity is entered, the entire pleural cavity is examined for disease. The lung should be thoroughly palpated to identity any metastatic lesions. Today, the use of staples has made nonanatomic resection very easy.

The lung is grasped along the edges and a stapler is fired. These staplers fire a row of staples while simultaneously transecting the lung tissue. The lesion may be wedged out in a V- or U-shaped incision.

If an electrocautery device is used, a superficial linear incision is first made over the lung with a staple or a clamp. The cautery device is then used to cut out the lung tissue. However, the edges of the lung must be reinforced with a running suture to ensure hemostasis and to avoid air leaks. At higher power, the electrocautery coagulates most small blood vessels. The biggest disadvantage of this approach is that the cautery tip persistently sticks to lung tissues and needs to be scraped constantly.

Postoperative care is the same as that for lobectomy.

Three major complications that can occur during surgery include massive hemorrhage due to injury to the pulmonary artery or its branches, cardiac arrhythmias, and development of a contralateral pneumothorax.

The complications following a segmentectomy and those following a wedge resection are very similar. ^{[30, 31]}  The most common complications include the following:

• Air leakage - Most leaks seal within a few days, but large leaks may persist for weeks
• Bleeding can occur at the suture line or if the ligature from the blood vessel has slipped off; thus, it is vital to ensure good hemostasis before leaving the OR
• Residual airspace is uncommon but can occur when a large amount of lung is resected
• Infection of the pleural space can occur when a residual airspace persists; in some cases, the patient may need a muscle flap or an apical tent to close off the residual space and eliminate the infection
• Respiratory failure is not a direct complication of surgery; patients who have borderline lung function are more likely than healthy people to develop respiratory distress in the postoperative period; if the preoperative workup was not adequate or if a high-risk patient underwent surgery, he or she may require prolonged ventilation and even a tracheostomy
• Cardiac complications may include acute myocardial infarction and arrhythmias