MIS Lung: Minimally Invasive Surgery of the Lung
World Small Animal Veterinary Association Congress Proceedings, 2016
MaryAnn Radlinsky, DVM, MS, DACVS
Surgery, VetMed, Phoenix, AZ, USA

Video-assisted thoracoscopic surgery (VATS) has advanced dramatically in recent years and will likely continue to do so as technology becomes more involved and allows expansion of methods of operating with minimal surgical trauma of the approach. VATS and completely endoscopic pulmonary surgery can be done for a variety of conditions including: primary pulmonary neoplasia, secondary pulmonary neoplasia, diffuse pulmonary disease requiring biopsy, and spontaneous pneumothorax. The latter condition is still controversial among endoscopic surgeons, however.

The most simple procedure is pulmonary biopsy for cases of diffuse lung disease. Pre-tied loop ligatures can be used to sample the distal 2 cm of lung and provide a seal against hemorrhage and air leakage after resection of the sample. Pre-tied loops have also been reported for the use in partial lung lobectomy for peripheral pulmonary neoplasia.

The chest should first be explored in all cases of primary or secondary neoplasia. Often the first "exploration" is via thoracic CT scanning to evaluate the other lungs and thoracic lymph nodes for abnormalities. Following CT, the side of the lesion is known and the approach can be done via lateral intercostal thoracic ports. In every case of pulmonary neoplasia, the lymph nodes must be sampled for proper staging and for providing the best prognosis for the owner. True VATS is done with endoscopic exploration and freeing of the lung lobe if required; the caudal lobes have a dorsal ligament that requires transection. The lung lobe is then exteriorized by elongating a port site and placing an Alexis wound retractor for protection of the thoracic wall to minimize the risk of seeding that surface. Traditional techniques are then used for resection of the lung. Note that the ribs are not distracted by this method, minimizing the trauma associated with an open approach. This technique can also be utilized to perform multiple partial lung lobectomies for spontaneous pneumothorax.

There is controversy as to the positioning of the patient for a complete evaluation: the dorsal aspects of the lungs are missed with the patient in dorsal recumbency and the ventral aspects are missed with the patient in sternal recumbency; however, the patient's position can be changed and the lungs reassessed if necessary. Alternatively, bilateral lateral thoracoscopy can be done. CT scan has not always been helpful at avoiding the need for evaluating both hemithoraces, unfortunately. A single report of approximately 50% successful treatment of spontaneous pneumothorax should alert the reader that conversion to an open approach should be made if any question exists as to the completeness of the exploration and identification of the abnormal lung(s).

Completely endoscopic lung lobectomy was initially deemed somewhat difficult, particularly for the accessory and middle lung lobes on the right; however, more recent reports show that with time and training, thoracoscopic lung lobectomy can be done with concurrent lymph node sampling for neoplasia. The patient must be large enough to accommodate and endoscopic gastrointestinal anastomotic stapler and endoscopic retrieval bags are required to protect the thoracic wall during extraction of the sample. Staging of neoplasia can be assisted with the use of particularly interesting dyes and specialized imaging with expensive cameras and video processors. Indocyanine green and a near infrared imaging allows lymph node localization with thoracoscopy.

The field is rapidly expanding, but some things are known requirements for thoracoscopic lung lobectomy. Complete pneumolobectomy done with endoscopy requires one lung ventilation (OLV) as well, which complicates anesthesia somewhat and makes the procedure slightly more challenging for anesthetic maintenance; however, the duration of OLV is only for the time required to remove the lung itself and not necessarily during lymph node identification and sampling. Intraoperative complications (20%) include damage to adjacent lung, loss of OLV interfering with visualization, intercostal arterial hemorrhage, postoperative pneumothorax, and aspiration pneumonia. Pulmonary endosurgery continues to be the most demanding type of surgery done with endoscopy and represents the biggest anesthetic, visualization, and technically challenging type of endosurgery. The complications can be treated endoscopically, but require the most knowledge and ingenuity of all types of endosurgery. Conversion to VATS or open surgery may be required frequently until the surgeon is adept and confident to proceed totally endoscopically.

  

Speaker Information
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MaryAnn Radlinsky, DVM, MS, DACVS
Surgery
VetMed
Phoenix, AZ, USA


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