LOBECTOMY
Lobectomy is a more difficult procedure to perform than pneumonectomy, particularly in the presence of chronic inflammatory changes or where tumor (or involved lymph nodes) involves the lobar hilum. Not only must the critical lobar structures be individually identified and controlled by the surgeon, but the remaining structures must be painstakingly protected and preserved. Incomplete fissures may add to the problem, and the surgeon must possess a precise knowledge of hilar anatomy and common anomalies.
The standard approach is a posterolateral musclesparing
thoracotomy. Video-assisted lobectomy is gaining popularity and is now routine
in many centers. The key steps to performing a lobectomy involve mobi- lization
of the lobe, dissection of the fissure, and vessel and bronchus division.
Dissection of the lobe can be complicated by an
incomplete fissure. Pulmonary vein branches pass between bronchopulmonary
segments and lobes, but pulmonary arterial branches generally follow the
bronchial tree. An incomplete fissure may be congenital or the result of
inflammation or a pathologic process extending across the fissure. Separating the
lobes often requires sharp and blunt dissection and may require the use of a
mechanical stapling device. Interlobar venous branches should be isolated and
divided when encountered.
The key to anatomic pulmonary surgery is a detailed
understanding of bronchopulmonary anatomy with careful dissection directly on
the branch pulmonary arteries. Next, the perivascular sheath surrounding the
pulmonary artery is entered and, with the lobe drawn downward and backward,
each arterial branch is dissected free with a right-angle clamp as it is
encountered. The segmental artery is then ligated close to its point of origin.
After proximal ligation has been accom- plished, it is usually possible to
dissect distally along the branch so that placement of the distal tie will
permit leaving a long proximal stump when the branch artery is divided. The
first branch found is usually the apical posterior artery. Often segmental
branch arteries have a common trunk, which can be ligated proximally while
distal control is obtained of each segmental vessel.
The main artery is followed down the oblique fissure,
exposing its anterior and posterior aspects. The lowermost branches to the
upper lobe supply the lingula and come off anteriorly. Directly opposite, on
the posterior aspect of the continuing left main pulmonary artery, the artery
to the superior segment of the lower lobe takes origin, and this should be
carefully preserved.
The lung is then retracted posteriorly for dissection of
the superior pulmonary vein, which drains the upper lobe, including the lingula
on the left side. This vein is proximally and distally ligated and divided.
Alternatively, a vascular stapler may be used given sufficient length of the
dissected vein.
After dissection of the fissures and vessels has been
completed, the lung is left attached only by the bronchus, which is cleared by
sweeping lymph nodes and connective tissue distally toward the specimen. An
atraumatic bronchial clamp or noncutting stapler is then placed across the
bronchus, and the anesthesiologist is asked to inflate the lung. Correct
identification of the bronchus clamped is ensured when the lower lobe inflates
and the upper remains collapsed. Despite the confidence of the surgeon in his or
her dissection and perception of the anatomy, this simple maneuver, requiring
only a few moments, may avoid considerable trouble later on. The stapling
device is then fired across the bronchus close to its origin and the bronchus is
amputated on the distal aspect of the anvil after stapling. The stump is then
tested for an air leak.
Resection of the left upper lobe can be more difficult
than a similar procedure on the right side. The main pulmonary artery is
exposed as it emerges from beneath the arch of the aorta, and care is exercised
to avoid the left recurrent nerve as it passes beneath the aortic arch. In
contrast to the right side, the artery passes behind the bronchus. The arterial
branches of the left main pulmonary artery may number five or more, and there
are considerable variations in their location. If a problem situation is
anticipated (e.g., bulky hilar lesion), the left main pulmonary artery should
be freed up and an umbilical tape passed around it. Thus, if an arterial tear
or hemorrhage occurs later on, it becomes a simple matter to place a vascular
clamp or tourniquet across the vessel and gain control.
When an upper lobe lobectomy is performed for cancer, the mediastinum should be opened and all lymph nodes cleared to the carina ( or beyond) if suspicion of lymphatic metastasis exists.
