General description of procedure, equipment, technique
Thoracic surgery encompasses a broad spectrum of procedures. Frequently performed, less invasive procedures include mediastinoscopy, tube thoracostomy, pleuroscopy or thoracoscopy, and video-assisted thoracoscopic surgery (VATS).
Mediastinoscopy
Mediastinoscopy is a procedure in which a mediastinoscope is inserted into the mediastinum through a small incision. The procedure is typically used for sampling mediastinal tissues or lymph nodes. Biopsy forceps or other instruments may be passed through the mediastinoscope to dissect tissues and to biopsy lymph nodes and other tissues, as warranted. Either cervical mediastinoscopy or, less frequently, parasternal (or anterior, Chamberlain Procedure) mediastinoscopy may be performed.
Tube Thoracostomy
Tube thoracostomy is a bedside procedure in which a drainage tube is placed into the pleural space via a small incision. The tube is connected to a closed drainage system that can be placed to suction. Tube thoracostomy may be performed relatively quickly to drain fluid or evacuate air from the chest.
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Pleuroscopy, Thoracoscopy, and VATS
Pleuroscopy, thoracoscopy, and video-assisted thoracoscopic surgery (VATS) represent a continuum of minimally invasive procedures. Each involves a small incision or series of incisions in the chest wall through which a scope may be placed in order to visualize the chest cavity. Pleuroscopy, sometimes referred to as medical thoracoscopy, usually involves only one small incision and may be performed under moderate sedation and local anesthesia. Pleuroscopy is useful for the diagnosis and management of pleural diseases, as the procedure permits drainage of pleural fluid, collection of pleural fluid for cytologic analysis, performance of pleural biopsies (mainly parietal pleural biopsies), and pleurodesis.
VATS, which is typically performed under general anesthesia, usually involves the use of single-lung ventilation through a larger double lumen tube and multiple port sites. A small access incision may also be used for instrumentation of the chest. With the enhanced access afforded by these additional incisions, a number of more complex surgical procedures in addition to those that can be performed with pleuroscopy may be performed with VATS. These include pulmonary resections that range from simple wedge resections to anatomical lobar resections.
Anterior Mediastinotomy (Chamberlain Procedure)
This is a procedure which is ideal for obtaining tissue biopsies of anterior mediastinal masses especially those requiring enough tissue for structural information such as certain lymphomas. Percutaneous biopsies are often small, failing to demonstrate tumor architecture and may be non-diagnostic in the setting of a heterogeneous mass. It involves a small medial incision (3-6 cm) overlying the second intercostal space.
Mediastinoscopy
Mediastinoscopy is usually performed for staging non-small cell lung cancer (NSCLC). Paratracheal and subcarinal lymph nodes may be sampled via cervical mediastinoscopy to assess the degree of mediastinal lymph node involvement in patients with NSCLC. Aorto-pulmonary window lymph nodes may be sampled via parasternal mediastinoscopy. These techniques may also be used to obtain tissue from patients suspected of having other types of malignancies, such as lymphoma or esophageal cancer.
Cervical mediastinoscopy is routinely performed as part of the pre-operative evaluation of all patients who are undergoing surgery for resectable NSCLC in some centers. While routine use of mediastinoscopy is controversial, most experts agree that lymph nodes that are larger than 1 cm or that demonstrate hypermetabolic activity on positron emission tomography (PET) scanning should be sampled prior to proceeding with resection and that patients with locally advanced or large primary tumors should undergo cervical mediastinoscopy prior to surgical resection of their lung cancers. Mediastinal lymphadenopathy is a feature of unresectable NSCLC.
Tube Thoracostomy
Tube thoracostomy, or chest tube placement, may be used effectively for the diagnosis and management of a number of conditions, including pneumothorax, hemothorax, and pleural effusion from a variety of etiologies. A chest tube should be placed emergently in any patient with evidence of tension pneumothorax. This can be preceded by needle decompression whereby a needle and syringe half filled with saline is inserted into the midclavicular line in the second intercostal space. Tube placement may follow needle decompression if immediate placement of a chest tube is not possible. A patient with a pneumothorax who is undergoing positive pressure ventilation should also undergo tube thoracostomy because of the risk of tension pneumothorax. Hypoxia and increasing size of pneumothorax are other factors that should prompt urgent chest tube insertion.
Chest tube placement should be considered in hemodynamically unstable patients who have suffered chest trauma in order to establish the diagnosis of hemothorax or pneumothorax, and as the initial step in management of these conditions. Chest tubes may also be used as part of the management of infectious processes that are contaminating the pleural spaces. Although more definitive therapy may be required, initial drainage of an empyema or fluid from a perforated esophagus may be accomplished with chest tube insertion. In early, non-loculated collections tube thoracostomy and antibiotics can be sufficient. Benign and malignant pleural effusions may also be drained via tube thoracostomy, including semi-permanent drainage systems such as indwelling tunneled pleural catheters amenable to home drainage.
Pleuroscopy, Thoracoscopy, and VATS
All these procedures require single lung ventilation. Patients must have sufficient respiratory reserve to tolerate the procedure, notwithstanding the influence of hypoxic pulmonary vasoconstriction which will result in preferential perfusion of the ventilated (non-operative) lung.
Pleuroscopy is indicated in patients with suspected benign or malignant pleural disease when pleural fluid sampling and pleural biopsies are needed to gain insight into the nature of the disease. The pleura is a rich source of data including histology, cytology and tumor markers. Pleuroscopy may also be useful in patients with known malignant pleural involvement in order to evaluate whether the lung will expand after evacuation of a pleural effusion. If adequate expansion of the lung occurs, pleurodesis may be performed in the same setting. If there is no apposition of the parietal and visceral pleurae, then pleural symphysis is unlikely to be successful, and placement of a long-term transcutaneous catheter for intermittent drainage of the effusion may be more appropriate (indwelling tunneled pleural catheter).
If additional access is required to perform any of these maneuvers safely or if further dissection is required, VATS is a more suitable technique. VATS is also an option for performing wedge biopsies of the lung. When diffuse parenchymal lung disease is present, a VATS wedge biopsy is easily completed, as no specific localization is required, but biopsy of small or deep lung nodules can be challenging using a VATS approach. A superficial location of the lung nodule facilitates identification of the nodule and allows wedge biopsy to be completed by VATS more easily. A VATS approach is well-suited for evacuation of retained hemothorax after trauma or cardiac surgery. Anatomic pulmonary resections may be performed via a VATS or VATS-assisted approach unless there are specific contraindications.
Anterior Mediastinotomy (Chamberlain Procedure)
The typical situation involves a young patient presenting with chest pressure, pain or dyspnoea with a newly documented mediastinal mass. While transthoracic biopsies may be sufficient to make broad diagnoses, often detailed structural information is required from pathologic analysis to direct therapies targeted to some lymphomas.
Contraindications
Mediastinoscopy
Neck extension is required for the performance of cervical mediastinoscopy, therefore cervical mediastinoscopy is contraindicated if the patient’s neck cannot be extended. During cervical mediastinoscopy, the plane that is dissected lies immediately posterior to the innominate artery and aortic arch. If the innominate artery and aortic arch are heavily calcified or contain mobile atheroma, performance of cervical mediastinoscopy may carry increased risk of stroke or vascular complication.
In addition, a large cervical goiter may preclude performing cervical mediastinoscopy, and a previous sternal or cervical incision may increase the difficulty of performing mediastinoscopy because of scar tissue.
Tube Thoracostomy
Extreme caution should be exercised during tube thoracostomy if there is any evidence of adhesion of the lung to the chest wall and if the patient has had previous surgical intervention on the side of the planned tube thoracostomy. If the patient has a known coagulopathy that requires an elective procedure, tube thoracostomy should be postponed until the coagulopathy is corrected, although postponement may not be feasible in emergencies.
Pleuroscopy, Thoracoscopy, and VATS
Pleuroscopy, which is typically performed in patients under elective circumstances, should be avoided if the patient is coagulopathic or hemodynamically unstable until these conditions are corrected. A complex effusion is a relative contraindication to pleuroscopy as a suitable entry site into a dominant collection may be identified in most cases by bedside transthoracic ultrasound. A fused pleural space is an absolute contraindication to the procedure.
If there is evidence that the lung is adherent to the chest wall, caution must be exercised when gaining access to the pleural space in order to prevent lung injury. VATS is typically avoided in these circumstances as well. VATS should also be avoided for anatomic lung resections if the size of the tumor is so large that it precludes removal through a small access incision, if the tumor significantly impairs the mobility of the lung, and if there is chest wall or hilar involvement by the tumor. While sleeve resections have been performed using a VATS approach, they are usually performed through a thoracotomy. An incomplete fissure is not an absolute contraindication to a VATS lobectomy, but it can make the procedure more challenging.
Anterior Mediastinotomy (Chamberlain Procedure)
This is generally a poor approach in those who have had previous chest surgery. The pre-operative CT scan should be studied in detail to ensure the approach is most appropriate, since this approach provides relatively little access to the chest and due to the proximity of the mediastinal structures.
Details of how the procedure is performed
Mediastinoscopy
Cervical mediastinoscopy may be performed to assess paratracheal and subcarinal lymph nodes or tissues, and it may be performed as an outpatient procedure. The patient is taken to the operating room, general anesthesia is induced, and an endotracheal tube is inserted. The patient is then positioned in the supine position with the neck extended, with care taken that the head is supported. The neck and chest are prepped and draped, with the entire sternum included in the sterile field, as otherwise uncontrollable bleeding may necessitate sternotomy.
Next, a small incision is created just above the sternal notch, the subcutaneous tissues and platysma are divided with electrocautery, and the strap muscles are separated in the midline, also using electrocautery. The pretracheal fascia is divided sharply and the pretracheal space entered. The mediastinoscope is inserted and cautious blunt dissection performed to identify lymph nodes or structures of interest. Aspiration of tissues may be performed prior to biopsy to be certain that a blood vessel has not been mistakenly identified as tissue for biopsy.
Biopsy forceps may be utilized to obtain tissue biopsies. Care should be taken not to pull with force on any tissue, as significant bleeding may occur as a result. Bleeding should be addressed with electrocautery and packing. After satisfactory hemostasis is achieved, the platysma and skin are closed in layers with absorbable sutures and a sterile dressing placed.
Anterior mediastinoscopy may be used to obtain tissue samples from the anterior mediastium or aorto-pulmonary window. General anesthesia is induced and the patient placed in the supine position on the operating room table. The operative field is prepared and draped in a standard sterile fashion. Either a vertical or horizontal incision is usually made over the second intercostal space, usually on the left side, and dissection is continued through the pectoralis muscle. The costal cartilage may be resected, if necessary. The mediastinum or pleural space is entered and biopsies obtained as described for cervical mediastinoscopy. The pectoralis fascia and skin are then closed in layers and a sterile dressing placed.
Tube Thoracostomy
The patient is placed in the supine position, and the ipsilateral arm is flexed and elevated over the patient’s head for maximal exposure of the chest. The site for insertion of the chest tube is identified–usually the fourth or fifth intercostal space, roughly at the midaxillary line. This site usually corresponds to the level of the nipple in a man or the inframammary crease in a woman. The chest is prepped and drapes are placed. Lidocaine is administered to anesthetize the site from the skin to the pleura. Transthoracic ultrasound may be used to help identify an optimal entry site particularly in the setting of pleural effusion.
A small, transverse incision of roughly 2-3 cm is made in a location slightly inferior to the intercostal space. Using a Kelly clamp, the clinician dissects the subcutaneous tissues in a cephalad direction, traversing just over the rib. Just above the rib, the intercostal muscle is dissected with the Kelly clamp. The tract is palpated with a finger to evaluate the progress and location of the dissection.
When the parietal pleura is reached, the tip of the Kelly clamp is inserted through the parietal pleura into the pleural space. (Only the tip of the instrument should be inserted in order to avoid injuring structures in the chest.) Next, a finger is inserted into the chest to confirm that entry into the chest has been achieved and that there are no adhesions between the lung and the chest wall. The chest tube is then inserted. A Kelly clamp may be placed on the end of the tube to guide it through the newly created tract.
If the tube is being placed to drain fluid, it may be directed more posteriorly for optimal drainage; if the tube is being placed for a pneumothorax, then a more anterior and apical location may be desired. A 28 French chest tube is often used, but a smaller-diameter tubes have been shown to have equivalent efficacy particularly for pneumothorax or simple pleural fluid collections.
After the tube has been placed, it should be secured to the skin with sutures, and the tube should be connected to a closed suction device. At the completion of the procedure, a sterile dressing is placed.
Pleuroscopy, Thoracoscopy, and VATS
Some clinicians use only local anesthesia and moderate sedation when performing pleuroscopy. However, general anesthesia and a double lumen endotracheal tube are typically used for VATS to allow for single-lung ventilation.
The patient is placed in the lateral decubitus position. After creating a sterile field, an incision of roughly 2 cm is created in approximately the seventh or eighth intercostal space. Electrocautery is used to dissect through the subcutaneous tissues and intercostal muscle, and the chest is entered with caution to avoid injuring the lung. A blunt trocar is placed through the incision, the thoracoscope or pleuroscope is inserted, and the pleural cavity is inspected. An additional instrument may be inserted for obtaining biopsies or manipulating tissues by enlarging the existing incision. For pleuroscopy, the access site is generally identified by transthoracic ultrasound and electrocautery is usually not performed.
For VATS procedures, additional port sites are created in similar fashion. These sites are usually made (1) just posterior, (2) just inferior and (3) more anterior to the tip of the scapula. The three sites are arranged in a triangular fashion. A larger access incision may also be created to facilitate performance of more complex procedures, such as lobectomy. Samples may be obtained from the pleural surface, and electrocautery is used to control bleeding. Biopsy of the pleura is generally limited to the parietal pleura when pleuroscopy is performed.
Wedge resections may be performed with the use of stapling devices. Anatomic lung resections are performed according to principles developed for the traditional open operations.
After completion of the procedure, the surgical field, including port sites, is evaluated for hemostasis. Once hemostasis is obtained, the operative field is irrigated. Chest tubes are placed as indicated and the port sites are closed in layers using absorbable suture. Sterile dressings are placed.
Anterior Mediastinotomy (Chamberlain Procedure)
The patient is intubated with a single lumen tube and is in the supine position. Either the right or left side can be accessed. A small horizontal incision is made (approximately 3-5 cm) starting at the sternal border and extending laterally in the second interspace. Dissection continues through muscle to get down to the superior border of the rib, which is freed of its intercostal muscles. The internal mammary artery or vein may be encountered, and should be preserved whenever possible. The pleura may or may not be violated, but if the pleura is breached a chest tube should be placed. Biopsy forceps or even careful use of a number 15 scalpel can yield generous biopsy tissue. Bleeding should be controlled, a chest tube placed if needed and then the incision is closed in layers.
Interpretation of results
Mediastinoscopy
Biopsy material obtained from mediastinoscopy is sent to the pathology laboratory for microscopic evaluation. While frozen sections may be obtained to yield immediate information, tissue is evaluated in a more detailed fashion using permanent sections.
In the setting of NSCLC, nodal tissue is evaluated for the presence or absence of metastases. If a mass of unknown etiology has been biopsied, histologic evaluation with or without immunocytochemistry may be used to establish a diagnosis. If lymphoma is suspected, flow cytometry may be performed.
Tube Thoracostomy
Valuable information may be obtained upon chest tube placement. A rush of air expelled from the chest when the pleural cavity is entered is diagnostic of a tension pneumothorax. If blood is evacuated in the setting of a hemothorax, the volume may be quantified and ongoing bleeding measured. Insight may be gained into the etiology of the effusion by collecting pleural fluid and measuring levels of lactate dehydrogenase (LDH), protein, albumin, amylase, glucose, pH, and cell count and differential. Gram stain and culture may reveal the causative organism when infection is the cause of the effusion.
Pleuroscopy, Thoracoscopy, and VATS
Pleuroscopy, thoracoscopy, and VATS may be used to gain information on disorders of the pleura or lung. Pleuroscopy or thoracoscopy may be used to visualize the pleural surfaces, obtain biopsies of pleural lesions, and collect pleural fluid for cell counts, cytology, and biochemical analysis. Molecular evaluation and tumor markers may readily be performed on pleural tissue. In cases of parenchymal lung disease of unclear etiology or indeterminant nodules, wedge biopsies of the lung may be obtained using a VATS approach. In some cases, VATS biopsy can be both diagnostic and therapeutic. For example, if a generous wedge is taken and found to metastatic disease, this is often considered therapeutic. Likewise, a suspicious effusion which results in VATS pleural biopsy can be converted to pleurodesis when frozen section reveal inflammatory disease.
Anterior Mediastinotomy (Chamberlain Procedure)
Enough biopsy material is obtained to send for frozen section and permanent pathologic analysis as well as flow cytometry etc.
Performance characteristics of the procedure (applies only to diagnostic procedures)
Mediastinoscopy
Cervical mediastinoscopy is highly effective for staging of NSCLC. In a pooled analysis of available evidence, the sensitivity of cervical mediastinoscopy was found to be 81 percent, while the negative predictive value was 91 percent.
Tube Thoracostomy
Tube thoracostomy may be useful as both a diagnostic and a therapeutic tool, particularly in cases of trauma to establish a diagnosis of hemothorax or pneumothorax and to quantify ongoing blood loss. When tubes are inserted for pleural collections of unknown etiology, examination and biochemical analysis of the fluid may yield insight into the etiology.
Pleuroscopy, Thoracoscopy, and VATS
Pleuroscopy, thoracoscopy, and VATS are highly effective in providing tissue for diagnosis of pleural disorders; VATS is a useful tool for obtaining lung biopsies.
Anterior Mediastinotomy (Chamberlain Procedure)
This is an extremely successful approach to obtaining adequate, architecturally accurate diagnostic tissue. In a randomized study of 95 lymphoma patients, it was significantly more likely to yield a diagnosis (96%) than mediastinoscopy (80%).
Outcomes (applies only to therapeutic procedures)
Mediastinoscopy is only a diagnostic procedure.
Tube thoracostomy is highly effective for acute management of pneumothorax and drainage of pleural fluid.
Pleurosocpy has been shown to be a safe procedure with a low complication rate. Both pleuroscopy and VATS have utility in the diagnosis of pleural effusions but also in their management. Good results have also been observed with VATS lobectomy, the complication and mortality rates of which are similar to those observed with the traditional open operation.
Alternative and/or additional procedures to consider
Mediastinoscopy
If there are contraindications to mediastinoscopy, a number of alternative procedures may be used to obtain similar data. Endobronchial ultrasound (EBUS) or endoscopic ultrasound may be used to guide needle aspiration of lymph nodes or other lesions near the large airways, percutaneous transthoracic needle biopsy may be utilized to sample tissues in the anterior mediastinum, and VATS may be employed for biopsy of aorto-pulmonary window lymph nodes or mediastinal masses. The most appropriate procedure may be guided by the location of the lesion and adenopathy of concern. The highest stage lesion should be sampled in all cases.
Tube Thoracostomy
While tube thoracostomy serves as an efficacious technique for evacuating air or fluid from the pleural space, alternative methods can also be helpful. Thoracentesis may be used to drain fluid from the chest for diagnostic purposes and relief of symptoms, although repeat thoracentesis may be required should re-accumulation of fluid occur.
Small-bore percutaneous catheters may also be used to drain the pleural space. Radiographic guidance, including the use of ultrasound or computed tomography, may be used for catheter placement. The ability to place these catheters precisely in a percutaneous manner can be advantageous, but doing so may be more time-consuming than traditional tube thoracostomy. Small-bore catheters have a higher propensity to become clogged than do larger chest tubes. Tactile feedback in the setting of complex pleural space can help mitigate accidental lung injury.
Pleuroscopy, Thoracoscopy, and VATS
Rather than using these techniques to obtain pleural fluid for analysis, thoracentesis or small-bore chest tube placement may yield sufficient fluid for analysis. If there are large, pleural-based masses, needle biopsy may be used to obtain tissue for microscopic examination. Transthoracic needle aspiration of lung nodules is an alternative to performing VATS wedge biopsies.
Complications and their management
Mediastinoscopy
Mediastinoscopy is a relatively safe procedure with low incidence of significant complications and a low mortality rate (less than 1%). Although complications are infrequent, they can be serious.
Significant bleeding is one potential serious complication of mediastinoscopy. A number of large blood vessels, including the pulmonary artery, innominate artery, aortic arch, superior vena cava, and azygous vein, may be injured during the procedure. Bleeding from bronchial arteries may also occur. The first step in management of bleeding is to pack the wound, but if there is significant bleeding, transfusion should be initiated. If bleeding is massive and it cannot be controlled with serial packing, a median sternotomy should be performed so vascular repair can be undertaken. If bleeding is clearly coming from the azygous vein, then a right thoracotomy may be the preferred approach. The innominate artery can be controlled by digital compression against the sternal border, until sternotomy is made. Ligation or primary repair are acceptable alternatives. Remarkably few patients suffer neurologic or upper extremity disability from emergent innominate artery ligation.
Other potential complications of mediastinoscopy include pneumothorax, which may require chest tube placement, and recurrent laryngeal nerve injury, which is more common on the left. The latter complication may be managed conservatively or may require vocal cord injection if the problem persists.
Tube Thoracostomy
One of the more common complications from chest tube placement is bleeding that is due to injury of the intercostal vessels. This complication can be avoided by paying particular attention to placing the tube over the selected rib. Bleeding may be self-limited, but it may require surgical intervention if it is severe or ongoing.
Other complications include injury to major structures in the chest. Caution must be exerted when placing tubes on the left side to avoid an injury to the left ventricle. To help avoid injuries to the lung parenchyma, hilum of the lung, aorta, heart, superior vena cava, or other major structures in the chest, only the tip of the Kelly clamp should enter the chest cavity when dissecting through the intercostal space. If injury to any of these structures occurs, immediate surgical intervention is warranted.
Malposition of the chest tube into the extra-pleural space or fissure of the lung may occur. To help avoid complications such as these, it is useful to confirm entry into the pleural space by palpation and to guide the tube into appropriate position.
Pain is an unavoidable complication of chest tube placement, but it may be minimized by providing adequate analgesia. This is often best achieved by mild sedation and intravenous opioids and encouragement. It is important to consider the respiratory depression which may accompany sedation or opiate analgesia.
Pleuroscopy, Thoracoscopy, and VATS
Bleeding from access sites and biopsy sites is one of the more common complications of these minimally invasive techniques. Depending on the severity of the bleeding, transfusion or re-operation may be required. If bleeding cannot be managed through the incisions created for the procedure, then conversion to a thoracotomy may be required.
Anterior Mediastinotomy (Chamberlain Procedure)
When the pleura is violated, and the air is not evacuated during closure, a pneumothorax may develop, needing either intraoperative or post-operative tube thoracostomy.
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