SUBLOBAR RESECTION AND SURGICAL LUNG BIOPSY
Resection of lung tissue anatomically less than a lobe is carried out for localized lesions such as benign tumors, granulomas, tuberculous foci, bronchiectasis, metastatic cancers, and others and to obtain tissue specimens required for the diagnosis of diffuse pulmonary disease processes. Recent evidence suggests anatomic segmentectomy may provide survival equivalent to lobectomy for small (2 cm) primary lung cancers in the absence of regional node involvement.
Segmentectomy requires a detailed anatomic knowledge of
secondary and tertiary hilar structures. Intersegmental cleavage planes are best
defined at operation when, by selective bronchial occlusion, adjacent portions
of lung tissue are maintained, one inflated and the other atelectatic. Resection
of only one or more segments has the advantage of removing only diseased
structures and leaving healthy, functioning lung tissue that ordinarily would
be removed if the excision involved the whole lobe. When the resection is for
cancer, the oncologic principle of inclusion of regional draining lymphatics
and nodes is preserved.
Segmental resection is commonly performed through the
standard posterolateral thoracotomy incision, although video-assisted
thoracoscopic surgery (VATS) segmentectomies are now acceptable. Depending on
individual circumstances, the segmental bronchus is identified and approached
first by palpation or the segmental artery first by dissection. Whenever
feasible, it is preferable to locate and divide the arterial supply to the
segment first because this minimizes chances of major bleeding during the
procedure. The main pulmonary artery, or the continuing pulmonary artery, is
identified in its proper anatomic location, and the perivascular sheath is
entered. The segmental artery or arteries are located, carefully dissected
free, and divided after appropriate proximal and distal ligation.
The segmental bronchus is closely adjacent and then may
be palpated and dissected free. To ensure correct identification of the proper
bronchus after it is dissected free, one carries out temporary atraumatic
occlusion of this structure while the remainder of the lobe is being inflated by
the anesthesiologist. After division and closure by stapling or by suture, a
clamp is left on the distal portion of the severed bronchus, subsequently to be
used for traction. If the draining vein or veins are seen, these are divided
between ligatures. However, the veins are frequently identified only as branches
in the intersegmental plane.
Separation of the intersegmental plane is performed
either with a stapling device, which simultaneously controls the veins and
parenchyma, or by blunt dissection with the fingers, working toward the pleural
surface while exercising traction on the clamp attached to the distal divided
bronchus. Venous branches on the segmental surface are grasped by small
hemostats before cutting and subsequently ligated with fine suture material.
These veins can serve as a helpful guide to the intersegmental plane as
dissection proceeds.
Wedge Resection
Wedge resections are useful when one is dealing with
small peripheral lesions or for diagnosis of a diffuse disease process. Less
lung tissue is removed, as a rule, than with segmental resection, and the
procedure is simpler, safer, and quicker.
Wedge resection has been made easier by the availability of stapling-cutting instruments that lay down two or three rows of staples on either side and divide lung tissue in between these rows. Bleeding is rarely a problem requiring only one or two suture ligatures if it is present and air leaks are negligible. These mechanical staplers have been modified for minimally invasive procedures so that most wedge resections can be performed by VATS, eliminating the morbidity of thoracotomy.
