The patient is placed in lateral decubitus position and intubated under general anesthesia with a double-lumen endotracheal tube. An epidural catheter is placed for pain. The chest is usually entered through the fifth intercostal space or one rib higher if there is a concern for pathology at the lung apex. The operation can be performed using open or video-assisted thoracic surgery (VATS) technique. For the open procedure described later, we routinely perform a muscle-sparing posterolateral thoracotomy with division of the latissimus dorsi and mobilization and retraction of the serratus anterior (see Chapter 2).
After entering the chest, the hemithorax is inspected and lung palpated to rule out evidence of advanced disease that would preclude segmental resection. If there is any uncertainty about the preoperative diagnosis, tissue is obtained for frozen-section analysis before proceeding. Central lesions may be sampled via needle biopsy. Frozen sections then are obtained of N1 and N2. The presence of metastatic disease in any lymph node constitutes an indication to proceed with lobectomy,5 provided the patient is surgically fit based on the preoperative assessment. Frozen section of the resection margin is also recommended.6
Although any bronchovascular segment can be removed, certain operations are more commonly performed. These include taking or sparing the superior segment for lower lobe cancers and taking or sparing the lingula for left upper lobe cancers. It is generally easier to remove the superior segment of the lower lobe (S6), the lingular segments (S4 + S5), and the basilar segments of the lower lobe (S7–S10), whereas the individual segments in the upper lobe (S1, S2, S3) and lower lobe (S7, S8, S9, S10) are more challenging. Although the spatial approach and the order of dividing the individual bronchovascular structures may vary depending on the individual segment(s), the overall principles remain the same.
Regardless of which segment is being resected, the fissure is opened first to reveal the pulmonary arterial branch. The appropriate segmental artery(ies) are identified and divided in the usual manner to expose the underlying segmental bronchus. Gentle traction on the segment with an atraumatic clamp may help to expose segmental branches that are hidden deep within the lung parenchyma (Fig. 73-2).
Traction on the segment itself can aid in identifying the appropriate arterial branches and segmental bronchus.
The S4, S5, and S6 segments each have an individual central vein that can be ligated or clipped, whereas the veins in other segments run close to the periphery and cannot be identified until dissection of the intersegmental plane has commenced and drainage into the superior or inferior venous trunks becomes visible. In some cases, early division of the individual central segmental vein can facilitate visualization of the pulmonary artery. However, these veins cannot be identified upon stapling of the parenchyma, so it is important to identify the anatomy of the venous trunks carefully before dividing the segmental vessels to avoid inadvertent ligation of veins draining blood from adjacent segments. This may result in venous thrombosis, lobar infarct, and potentially disastrous complications postoperatively.
Intraoperative bronchoscopy can be very helpful if there is confusion regarding the segmental anatomy or concern about potential compromise of the adjacent segmental bronchial orifice. A pediatric bronchoscope fits easily through the lumen of a double-lumen endotracheal tube to reveal the endobronchial view. In addition, the light on the scope illuminates the airway which can be visualized from the operative field.
Before dividing the parenchyma, it can be difficult to identify the appropriate plane, especially when VATS techniques are used. Observing the differential ventilation of the individual segments by clamping the segmental bronchus before (or after) full inflation can better delineate the intersegmental plane (Fig. 73-3). The segmental bronchus is then divided with a stapler or scalpel and closed in routine fashion. For suturing the bronchial stump, we prefer two over-and-over running 4-0 absorbable monofilament sutures after folding the membranous part inside the lumen of the bronchus and bringing the cartilaginous rings together according to the technique previously described by the Dutch surgeon Klinkenberg. Finally, the parenchyma between the involved and adjacent segments needs to be divided for which two techniques have been described: the open and stapled division.
A simple technique for determining the appropriate plane for parenchymal division is shown. After the segmental bronchus is clamped, the anesthetist is asked to gently inflate the lung while the surgeon observes the demarcation between the inflated and the deflated segment.
For the open technique, the intersegmental plane is teased apart by using a clamp to place traction on the stump of the transected segmental bronchus, whereas the rest of the lung is well ventilated. Sharp and blunt finger dissection may also help to open the intersegmental plane (Fig. 73-4). Cautery, harmonic scalpel, or small vascular clips are used to ensure hemostasis. Small air leaks can be oversewn with fine sutures. In addition, the raw surface of the adjacent segment can be covered with pleural or pericardial fat pad. Care has to be taken to avoid compression or kinking of the remaining bronchovascular structures which can result in a nonfunctional lobe thereby eliminating the benefit of segmentectomy versus lobectomy. The advantage of the open technique is that reexpansion of the adjacent parenchyma is maximal, but it carries a higher risk of prolonged air leaks.
For open division of the segmental parenchyma, traction is applied to the distal transected segmental bronchus, and the intersegmental plane is developed sharply or bluntly with finger dissection.
For the stapled technique, the virtual fissure is compressed and cut with the aid of a linear stapler. We prefer an endovascular linear cutting stapler. This technique results in better pneumostatic control in the remaining lung but it comes at the expense of volume loss as the visceral pleural layers are drawn together when closing the device. The remaining parenchyma is then somewhat trapped by the individual staplers, which blocks reexpansion of the lobe to its maximum volume (Fig. 73-5). The “extended” segmentectomy is accomplished by deploying the stapler lateral to the intersegmental plane so as to include the adjacent subsegments in the specimen.7
The segmental parenchyma is divided using open or staple division. Shown here is the staple technique, which can cause volume loss when the visceral pleural layers are drawn together during the act of stapling.
VATS segmentectomy is a safe and feasible operation, as confirmed by published reports from several high-volume centers. The benefits of using VATS with segmental resection seem to mirror the more robust data available for VATS lobectomy in terms of decreased morbidity, length of stay, postoperative pain, and other metrics. However, caution must be exercised as these resections can be quite challenging and one should always proceed as if performing an open procedure with careful individual dissection and ligation of the bronchial and vascular structures. Port placement can literally make or break VATS segmentectomy. In general, the standard port sites described by McKenna or Flores are the most versatile. McKenna routinely uses four incisions, whereas Flores8 describes only three for VATS lobectomies. We have found both to be appropriate for performing segmental resections. There are certainly times when it is quite easy to perform an operation through only three ports, while at other times, the fourth port significantly increases the options and ease of the resection. In general, we start with three and add a fourth port anteriorly, as described by McKenna, or at the scapular tip as needed.
Right Upper Lobe Segments
The apical segment dissection begins by incising the mediastinal pleura. The apical branch of the anterior arterial trunk is identified and divided. The apical segmental bronchus is then approached posteriorly and isolated after ligating the bronchial artery branches. For right upper lobe segmentectomy, the vein is usually encompassed in the staple line.
The anterior segment is approached from the medial aspect, beginning with incision of the mediastinal pleura. The anterior segmental artery is identified as it branches from the anterior arterial trunk. The anterior segmental vein is likewise identified and ligated, taking care not to compromise other segmental tributaries to the superior pulmonary vein. The horizontal fissure is completed, the anterior segmental bronchus is divided, and the segment is excised.
In performing a posterior segmentectomy, the major fissure is opened posteriorly and the pulmonary artery is traced proximally to identify the posterior segmental artery. Once identified, it is ligated. The posterior segmental bronchus is deep and lies slightly medial to the artery. Again, the vein is taken with the intersegmental plane. Alternatively, the artery branch may be ligated after dissection and transection of the segmental bronchus, which can be tracked posteriorly along the right upper lobe bronchus.
Superior Segment, Right Lower Lobe
If the major fissure is well developed, the pulmonary artery can be approached directly in the fissure. If the fissure is incomplete, it must first be developed to expose the artery. The pleura is opened posteriorly at the bifurcation of the right upper lobe bronchus and the bronchus intermedius and continued anteriorly to identify the recurrent artery to the posterior segment of the upper lobe and the superior segmental artery to the lower lobe. With these bifurcations visualized, the posterior portion of the major fissure can be developed. A stapler can be used to divide this parenchyma, taking care to exclude the arteries and bronchi from the jaws of the stapler. Sometimes it is helpful to place a ¼ in Penrose drain through the “window” that has been created and feed the lower jaw of the stapler into the drain. The drain can then be used to guide the stapler through the window without risk of falsely passing the stapler and injuring or dividing a vessel or bronchus. The posterior fissure can be a difficult spot to manipulate the stapler. Passing the stapler through the future chest tube site may afford a more benevolent angle of attack.
Once the posterior portion of the major fissure is opened, the artery can be isolated and divided. This will provide exposure to the bronchus, which runs deep to the artery. The superior segmental vein can usually be identified posteriorly as a separate tributary running into the inferior vein. Again, care must be taken not to compromise the remainder of the vein.
Basal Segment, Right Lower Lobe
This operation begins in the major fissure with dissection of the pulmonary artery to identify the right middle lobe artery, the superior segmental artery, and the basilar segmental artery. Circumferential dissection of the artery allows it to be divided. The basal segmental bronchus lies deep to artery. The inferior pulmonary vein is identified by first taking down the inferior pulmonary ligament. The anterior and posterior hilum is dissected to complete the inferior pulmonary vein isolation. Further dissection into the lung parenchyma permits visualization of the confluence of the segmental pulmonary veins. The bronchus is then dissected and divided. This allows demonstration of the veins deep to the bronchus. The superior segmental vein is identified and the intersegmental plane is completed using this vein as a guide, making sure that it is not compromised.
Left Upper Lobe Upper Division (Lingular Sparing)
Proximal control of the pulmonary artery may facilitate left upper lobe segmentectomy, but it is not mandatory. First, the anterior mediastinal pleura is opened to permit identification of the superior pulmonary vein. The lingular vein is identified and preserved. We begin by dividing the upper division segmental vein. A lymph node is normally encountered at this bifurcation and sent for frozen section. If positive, the segmentectomy should be abandoned in favor of lobectomy. Dividing this vein facilitates identification of the left main pulmonary artery. The dissection is continued distally along the main pulmonary artery to expose the segmental arteries, which are divided. At this point we find it beneficial to complete the oblique fissure. With this accomplished and the arterial branches divided, only the bronchus remains. The upper lobe bronchus can then be dissected up to the bifurcation of the upper division and lingula. This allows the upper division bronchus to be stapled and divided. Placing the stapler along the pulmonary vein from the lingula and heading toward the lingular bronchus, the intrasegmental fissure can be developed and completed.
As with most segmental resections, the ease of dissection is a function of the completeness of the fissure. If the fissure is complete, it is quite easy to identify and isolate the artery and all its branches. If the fissure is incomplete, it must first be developed and this is best accomplished by tracing the pulmonary artery into the fissure. Commonly, a plane can be developed between the lobes using sharp dissection or a very low setting on the electrocautery to avoid significant air leaks. If raw parenchyma is encountered as the fissure is developed, we complete the fissure with a stapling device. The lingular arteries may arise separately as a common trunk from the ongoing pulmonary artery. The lingular bronchus will be found under the divided arteries. Care must be taken to avoid compromise of the superior divisional bronchus to the upper lobe when dividing the lingular bronchus. The lung is then retracted posteriorly, and the hilar pleura is incised to expose the superior pulmonary vein. The lingular branch is then identified and divided (Fig. 73-6). Finally, the parenchyma is divided as described for other segments. The other option for this procedure is to begin with identification and division of the lingular vein in the hilum. Attention then turns to the fissure for dissection and division of the appropriate branches of the pulmonary artery and bronchus.
The segmental artery to the lingula when arising as common trunk from the pulmonary artery, must be divided first to expose the lingular bronchus.
Basal Segment, Left Lower Lobe
After releasing the inferior pulmonary ligament, attention is turned to the hilum. The inferior pulmonary vein is identified and circumferentially dissected. There is usually a lymph node that can be dissected from the posterior superior aspect of the inferior pulmonary vein, and this aids in completing the dissection. The subcarinal lymph nodes are dissected next. The branches of the inferior pulmonary vein are further delineated. Attention is turned to the pulmonary artery in the major fissure. The fissure is completed and the segmental artery to the basal segments is circumferentially dissected. It sits directly anterior the basal segmental bronchus. This artery (sometimes arteries) is divided. The basal segment bronchus is then dissected between the inferior pulmonary vein and the bronchus. The stapler then comes from anteriorly and the bronchus is stapled and divided. Care must be made to not compromise the superior segmental bronchus. With the basal segmental bronchus divided, the veins are easily identified and divided. The intersegmental fissure is completed using the superior segmental vein and artery as a guide.
Superior Segment, Left Lower Lobe
This resection is accomplished in a similar fashion to the right lower lobe superior segmentectomy. The oblique fissure is completed first which permits identification of the main pulmonary artery. The branch(es) of the pulmonary artery to the superior segment are then dissected and divided, allowing visualization of the segmental bronchus that lies immediately behind and inferior to the divided pulmonary artery. The segmental bronchus is then dissected out and the N1 lymph nodes are removed. Once this is done, the segmental bronchus is divided. If the segmental vein is identified, it can either be individually ligated or incorporated into the completion of the intersegmental fissure using a staple technique.