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Steps of the Procedure
The extent of surgery is determined during the planning stages and not during the procedure. The type of primary malignancy, options for adjuvant therapy, number of lesions, locations of lesions and the history of the current metastases need to be considered. Adjuvant options for eradication should be performed prior to considering surgery. The number of lesions will dictate the possibility of surgical success. The more lesions the more challenging it is to achieve a complete resection and the less likely that a cure will be obtained. If there are multiple lesions within a lobe it may be best to consider lobectomy rather than segmental resections especially if there are lesions near the hilum . A pneumonectomy needs to be weighed carefully due to the impact on postoperative pulmonary function . Pleurectomy is performed if there is pleural involvement and complete eradication of the disease will require removal of the pleura .
The provision of single lung ventilation either using a bronchial blocker or double lumen endotracheal tube (with its position checked with a flexible bronchoscope), optimizes visualization on the operative side. A thoracic epidural should be placed to provide postoperative analgesia .
The ipsilateral side is positioned up to allow access to the ribs with either a bag or rolls for support to maintain the position. An axillary roll and padding is used to ensure that pressure points are protected and prevent nerve or soft tissue injury. The patient is positoned such that the break in the bed allows the ribs to separate slightly to assist access to the thoracic cavity. The patient is secured in this position with straps and/or tape.
In a video assisted thoracoscopic (VATS) procedure it is important to know the location of the lesion(s) prior to setting up the room. The camera port is inserted so the lesion is between the operator and the monitor. The working ports are placed closer to the operator and to the right and left of the camera port. At least one port should be tunneled in the subcutaneous tissue and located appropriately to become the site for the tube thoracostomy. Usually the largest port is placed closest to the diaphragm where the rib space is liberal.
After the ipsilateral lung is collapsed the ports are inserted and 5 mm Hg of CO2 pneumothorax is provided to improve visualization. The 30 degree angled telescope is used to identify the lesion(s) or the surface adjuvant markers placed by radiology. The surrounding lung is grasped and the resection is performed with a stapler. The specimen is placed into a bag and removed via a port site. The specimen should be examined at the back table to assure the lesion has been removed. This process is continued until all lesions have been resected. It is important that specimens be sent fresh to pathology rather than in formalin. Sending specimens for both histology and culture should be considered when the differential includes a possible infectious etiology. A tube thoracostomy is placed and the port sites are closed with absorbable suture.
The incision is placed dependent upon the position of the lesion(s). The skin incision is made below the tip of the scapula and the underlying muscle is split (i.e. muscle sparing). This is assisted by raising generous skin flaps to allow the muscle to be able to be pushed away from the incision. A thoracotomy through the fifth interspace allows access to the upper and lower thoracic region. If there are lesions higher or lower in the chest or this is a repeat thoracotomy it may be preferable to use the fourth or sixth intercostal spaces.
The lesion(s) are identified either by visual inspection or palpation. Lung grasping forceps will help pull the lung up into the field. Releasing the inferior pulmonary ligament mobilizes the lower lobe into the field. Once identified the lesion is removed with a stapler or locking absorbable sutures. After all the lesions are removed an appropriately sized chest tube is placed and the incision is closed in layers with absorbable sutures .
This is the most commonly performed procedure for metastases whether it be done via thoracoscopic or open approach. The key points are to assure that the lesion is within the specimen, there is a margin of normal lung around the specimen and that the lung is sealed adequately. During VATS a lesion on the surface will be visible. For lesions below the surface the use of visible markers will be required as guides during the procedure.
A margin of normal appearing tissue is necessary to avoid cutting across the lesion and causing tumor spill. There is no generally accepted standard distance from the lesion. Rather the amount of resection must be a balance between complete lesion removal and maintaining as much normal lung parenchyma as possible.
Options for sealing the lung include suture, ndoloops®, sealing devices (e.g. Ligasure®, Harmonic Scalpel®) and staplers . For small superficial lesions using sutures are easier and more cost effective. Lesions that are approached with thoracoscopy and are small and superficial may be closed with any of the sealing devices or an endoloop. Staplers are more appropriate when larger amounts of lung tissue need to be resected.
An anatomic lobe resection should be considered when there is a single lesion very close to the lobar hilum or if there are mutiple lesions in one lobe such that the resection(s) would leave a minimally functioning lobe. A lobectomy can be performed via thoracoscopy or thoracotomy . The technique involves isolating the lobe and carefully separating the fissures with a sealing device if necessary. The inferior pulmonary ligament is divided to assist in visualization of the lower lobe.
Once the lobe(s) are mobilized the pulmonary hilum needs to be well-visualized. Division of pleura and removal of hilar nodes with sharp dissection allows identification of each hilar structure and is generally performed anterior to posterior. Division of structures may be dependent on the exposure but usually the arterial supply is divided first to prevent continued oozing and engorgement of the lobe. The veins are divided next followed by the bronchus. Care must be made to create sufficient space to place the stapling device onto vessels and the bronchus . In smaller children a Ligasure® or ligation with ties may be sufficient for the vessels and the bronchus can be dealt with by staplers, an endoloop or sutures. In lower lobectomies care must be taken to ensure that only the structures of that lobe are divided. Reinflation of the upper lobe to ensure proper bronchus identification prior to cutting the lower lobe bronchus is important. This can easily be done with open or minimally invasive procedures.
see also Pulmonary Resection for Congenital Lesions
Pneumonectomy must be carefully weighed in terms of the potential for cure and pulmonary function sequela. This requires that the contralateral side have minimal disease. Pneumonectomy is considered for central lesions that can not otherwise be removed via wedge or lobectomy alone . The isolation of the vessels and the bronchus is similar to that as described under lobectomy. Very little lung tissue usually needs to be divided unless it obscures visualization of the hilar structures. If tumor is encroaching closely to the hilum the central structures may best be approached from within the pericardium. A potential postoperative complication is postpneumonectomy syndrome (PPS) which is characterized by respiratory failure resulting from contralateral bronchial compression caused by severe mediastinal shift to the ipsilateral side. Various methods have been used to avoid PPS including aortopexy, insertion of plastic balls, silastic implants and saline filled prostheses .
Occasionally pulmonary metastases may cross from the lung to the adjacent pleura. In this situation the pleural metastasis should be removed if possible to attempt cure. If there is a connection between the two surfaces a combined resection of both should be attempted to minimize the chance of spill .