The Anatomy of an Extra Pleural Pneumonectomy (EPP) Broken Down, Step by Step.
Eligibility and Objective
All patients will undergo surgery unless there is (1) objective evidence of progression of disease or (2) deterioration of functional status occurs which is felt to significantly increase operative mortality/morbidity. Surgery should occur at least 3 weeks post last dose of chemotherapy, to a recommended maximum interval of 8 weeks. Extrapleural pneumonectomy shall be performed in all cases to achieve a complete resection of all gross residual tumor. Recognizing that there are individual variations required in surgical technique from patient to patient and surgeon to surgeon, the following describes a standardized recommended approach to the operation.
Preparation
The patient is given a general anesthetic and intubated with a double lumen endotracheal tube. Intraoperative monitoring includes use of a central venous pressure line, and arterial line and a pulse oximeter. The patient is placed in the lateral decubitus position. The patient's operative side is prepped and draped in the usual sterile manner. The patient's hemithorax is approached via an extended posterolateral thoracotomy incision, the anterior part of which is taken down towards the costal margin to facilitate exposure to the hemidiaphragm. An additional parallel incision at the 9th or 10th intercostal space posteriorly may be used, but is not recommended and generally not required for diaphragmatic resection. Access to the extrapleural plane of dissection is facilitated by rib resection, usually the 6th rib.
Dissecting the Pleural Tumor
The parietal pleural tumor is mobilized away from the chest wall in the extrapleural plane, carrying the dissection to the apex of the hemithorax superiorly down to the diaphragm inferiorly, to the sternum anteriorly and to the spine posteriorly. Thoracoscopy and thoracotomy sites used previously for biopsy purposes may be excised but this is not necessary because of the postoperative radiation ministered in this study. The chest retractor is inserted and dissection is continued circumferentially in the extrapleural plane, mobilizing the parietal and mediastinal pleural tumor back to the hilum in all directions.
Resection of Diaphragm
Once this has been accomplished, attention is turned to the diaphragmatic resection. The diaphragmatic tumor is mobilized along with the partial or full thickness of the diaphragm. Care is taken not to violate the underlying peritoneum. Sometimes the peritoneum has to be opened in a small area at the level of the central tendon of the diaphragm. If this occurs, the peritoneum should be immediately reclosed, usually with absorbable suture. Dissection of the diaphragmatic tumor and diaphragm is carried from the lateral towards the medial aspect back to the pericardium, and then up on the pericardium to the level of the inferior pulmonary vein. For right sided resections, care should be taken to identify the small branches ofthe front vessels which drain from the diaphragm into the inferior vena cava and to ligate and divide those branches.
Lymph Node Dissection
At this point, a subcarinal lymph node dissection is usually carried out and the mainstem ronchus fully mobilized. Lymph node sampling or dissection of additional levels of mediastinal lymph nodes should be performed for staging purposes. On the right side levels 4R and 10R should be sampled or dissected. On the left side levels 5 and 6 should be sampled or dissected. In both cases, levels 7 (subcarinal lymph nodes) are removed during mobilization of the mainstem bronchus. Additional lymph nodes at levels 8, 9 and in the internal mammary region should be identified and biopsied if possible. Examination of the N1 lymph nodes within the resected specimen should be requested from the pathologist. Once the mainstem bronchus has been mobilized, it should be ligated with a stapling device and divided. The hilar vessels can then be ligated and divided, again with vascular stapling devices.
Pericardial Resection
Resection of the pericardium is not required if the pleural tumor can be mobilized away from the pericardium completely. In situations where pericardial resection is required for complete resection of all gross tumor, that should be performed. Pericardial resection is most safely accomplished at the time of division of the hilar vessels. Tacking sutures should be placed on the anterior border of pericardial resection to prevent retraction of the pericardium toward the contralateral hemithorax as the pericardial resection is performed. The pericardial defect can be reconstructed with either an absorbable (Dexon) or non-absorbable (preferably Gortex) patch. Non-absorbable material is required for diagrammatic and pericardial replacement left sided resections. Either absorbable or non-absorbable material can be used for the right sided diaphragmatic reconstruction.
Diaphgragmatic Patch
The prosthetic diaphragmatic patch is secured in place to the rim of remaining diaphragm along the pericardium medially. Care should be taken to secure this appropriately to and around the esophagus to prevent postoperative intrathoracic herniation of abdominal contents at that level. Posteriorly the prosthetic patch is secured to the endothoracic fascia. Laterally it is secured with sutures placed around the ribs. The prosthetic patch should be placed as low as possible to mimic the normal position of the diaphragm. Therefore, the lateral sutures should be placed around the 8th, 9th and 10th ribs. This is particularly important to reduce the radiation exposure of the liver on the right and the stomach on the left during postoperative adjuvant therapy. Hemostasis in the operated hemithorax is facilitated by use of the Argon Beam Electrocoagulator.
Closing Up
At the end of the procedure a chest tube is inserted which is then placed to balanced drainage (such as a pneumonectomy Pleur-Evac). Reinforcement of the bronchial stump with a pericardial fat pad may be used but is not required. Use of an intercostal muscle flap for this purpose is not recommended. The thoracotomy incision is closed in the usual manner but care should be taken to achieve a completely watertight seal during the closure. It is particularly important to achieve good approximation and watertight closure of the intercostal muscles to prevent pleural fluid from leaking out of the hemithorax in the immediate postoperative period.
The Chest Tube
The chest tube is usually left in place for up to 72 hours, until the pleural fluid draining through the chest tube has become serous or serosanguinous, rather than bloody. Chest tube removal should be accompanied by closure of the chest tube site with a skin suture to prevent postoperative fluid leakage from that site (Rusch 1994. Sugarbaker 1996).
Post Operative Medication
Perioperative antibiotic coverage should be provided according to institutional guidelines. This may include the entire length of time that the chest tube is in place. Perioperative antiarrhythmia prophylaxis should be considered, again according to institutional guidelines. Routine postoperative use of diltiazem has been shown to be effective in this setting although other antiarrhythmic drugs can be used to prevent postoperative supraventricular tachyarrhythmias.
Reasons to Abort EPP
In the instance where exploration reveals disease that cannot be completely resected, the operation should be aborted and the reasons for abandoning the surgery documented. Common reasons for unresectability include diffuse invasion of tumor through the endothoracic fascia, extrathoracic subcutaneous disease in discontinuous sites, direct extension of tumor though the diaphragm or metastatic disease involving the peritoneum which is not suspected preoperatively by imaging studies. These findings are usually stages as T4 or M1 disease. Postoperative pathway will be determined at the discretion of individual surgeons.
