Videomediastinoscopy

Patient Selection

Videomediastinoscopy is applicable to all patients undergoing routine mediastinoscopy.  Until recently, videoscopic capability necessitated an awkward separate attachment to the standard mediastinoscope.  Newly re-designed mediastinoscopes incorporate the video attachments within the handle of the instrument.  This greatly facilitates its use.  The 17 power magnification has, in our experience, led to the following results: (1) safer and more effective teaching of the technique; (2) increased interest and communication during the procedure by scrub nurses and anesthesiology personnel; and (3) more complete sampling of mediastinal node stations.

The most common indication for mediastinoscopy is pre-operative nodal staging of lung cancer. Other less common indications are: (1) re-staging non-small cell lung cancer after neoadjuvant therapy [1]; (2) evaluation of middle mediastinal masses; (3) treatment of cystic mediastinal masses [2]; and (4) evaluation of mediastinal adenopathy in the absence of lung masses or in the presence of diffuse lung disease of undetermined etiology [3].  Extended mediastinoscopy describes a mediastinoscopic technique in which the dissection plane is anterior to the aortic arch and its branches.  This is used by some thoracic surgeons to stage aorto-pulmonary window nodes or to diagnose anterior mediastinal masses or adenopathy [4,5].

The introduction of PET scanning in the staging of lung cancer has influenced but not replaced the role of mediastinoscopy. In our experience, the combined selective use of PET and mediastinoscopy has increased the accuracy of both modalities in staging the mediastinum.

Operative Steps

Figure 1. Patient positioned with video monitor and anesthesiologist to their right. Patient's neck is hyperextended and their sternal and neck area prepped and draped.

The position of the operating room table and the patient in relation to the anesthesiologist and the videomonitor is important. We place the table 45 degrees to the right of its normal position to allow the surgeon to stand at the patient’s head. This places the anesthesiologist to the patient’s right and thus permits constant right upper extremity monitoring for inadvertent innominate artery occlusion by the mediastinoscope.

The patient’s neck is hyper-extended by placing a roll under their shoulders. Care must be taken to avoid inadvertent turning of the patient’s chin to the right as this results in an off-center incision and also makes subsequent dissection more difficult. Although massive bleeding is an exceedingly rare problem, we always prep and drape the entire sternum and have a sternal saw in the room in order to save time if bleeding of this magnitude is encountered (Figure 1).

A transverse incision is made 1 cm above the sternal notch and then continued vertically between the strap muscles. It is crucial to dissect deep enough to identify and divide the pre-tracheal fascia in order to develop a safe plane of dissection immediately adjacent and anterior to the trachea. Once this plane is found, most of the subsequent dissection down to the carina is performed with a finger. This allows identification of the location of the innominate artery anteriorly and is quicker and safer than using the mediastinoscope and the suction cautery for dissection. Subsequent insertion of the mediastinoscope is often assisted by use of a deep phrenic retractor or by grasping the tissues anterior to the pre-tracheal plane with an Allis clamp.

If bilateral nodal staging is indicated, we generally identify the innominate artery first. The innominate artery is recognized as a pulsatile structure crossing the trachea anteriorly in a transverse or diagonal manner at the proximal end of the pre-tracheal plane of dissection (Figure 2; Video 1).

Figure 2. View of innominate artery during videomediastinoscopy.	Video 1. Pulsating innominate artery.

Elevate the artery off of the trachea with the tip of the mediastinoscope, then start blunt dissecting with the suction cautery tip to the right of the trachea looking for any high right paratracheal lymph node (2R). We next work distally by identifying the tracheal bifurcation and dissecting out the right lower paratracheal nodes (4R). One must be careful here to avoid injury to the SVC or azygos vein, which are dark structures and therefore may look like pigmented lymph nodes. The videomediastinoscope is then positioned anterior to the trachea and the precarinal nodes are dissected out, taking care to identify and avoid injury to the right pulmonary artery. This vessel lies anterior to the carina and the left and right proximal main bronchi (Figure 3; Video 2).

Figure 3. View of pulmonary artery during videomediastinoscopy.	Video 2. Pulsating pulmonary artery..

The videomediastinoscope is then directed to the left of the precarinal area. The proximal left main bronchus is identified and the scope is withdrawn slightly and the left lower paratracheal nodes (4L) are looked for. The scope is retracted further cephalad and the left high paratracheal notes (2L) are sought. These are often the hardest to identify. When all desired nodal stations have been sampled, hemostasis is obtained and the videomediastinoscope is removed. We generally close the vertical deep tissues with one suture, then the transverse platysma muscle layer with a small running suture. The skin is closed with a continuous subcuticular suture and reinforced with Steristrips®. When no thoracotomy follows a staging mediastinoscopy, patients are generally discharged home several hours after their recovery in the post-anesthesia unit if their post-operative chest x-ray is unremarkable, their wound shows no bleeding, and their vital signs are stable.

Our experience doing this operation has taught us several general principles to try to minimize complications. (1) Always blunt dissect through the paratracheal fascial planes until the suspected node “ bulges” into the operative field (Figures 4, 5).

Figure 4 . Left lower paratracheal lymph node before dissection.	Figure 5 . Left lower paratracheal lymph node after dissection showing characteristic “bulge” into operative field.

If a suspected dark “pigmented node” in the right paratracheal area does not “bulge” it may be a venous structure. If a suspected “white tumor-filled node” in the subcarinal area or left paratracheal area does not “bulge,” it may be a white pulmonary or innominate artery or the outer muscular layer of the esophagus. (2) Always perform needle aspiration of a suspected node before committing to forceps biopsy. This confirms that the tissue is not a vascular structure (Figures 6, 7; Video 3).

Figure 6. Needle aspiration of lymph node prior to biopsy.	Figure 7. Biopsy of lymph node.	Video 3. Video clip of node aspiration, the use of cautery for hemostasis of minor bleeding, and the subsequent node biopsy.

(3) Use cautery for hemostasis very sparingly in the left paratracheal area in order to avoid inadvertent injury to the left recurrent nerve. (4) Always have gauze pledgets with strings attached available on the OR table for immediate use in case significant bleeding occurs [6]. Packing the area while keeping the mediastinoscope in place will temporarily control all sources of bleeding except for systemic arterial vessels (Figure 8).

Figure 8. Neurosurgical packing with attached blue string in place at site of bleeding.

When significant bleeding occurs, we pack area as described above, alert anesthesiology to the problem (the video picture will give them a head start!), wait several minutes, then cautiously remove the packing. Most bleeding will have stopped. Persistent moderate bleeding can be managed by inserting Surgicel® packing followed by gauze packing. We then wait several minutes. If bleeding is controlled after removing the gauze, we have not found it necessary to do anything else. Major systemic arterial bleeding will require either compression of the vessel (usually the innominate artery) against the underside of the sternum with the tip of the mediastinoscope or removal of the instrument and immediate digital compression of the artery against the sternum. With temporary hemostasis, volume resuscitation can be performed and a sternotomy incision can be made for definitive open control of the bleeding site.

Preference Card

• Lerut Storz videomediastinoscope
• Pulse oximeter on right upper extremity to monitor possible innominate artery compression
• Neurosurgical pledgets
• Sternal saw in the room or on the scrub nurse’s table.

Tips & Pitfalls

• Always have a game plan in place for managing the different levels of bleeding that may be encountered.  Be prepared!
• Be aware that the SVC and azygos vessels can look like pigmented lymph nodes and that the pulmonary artery, the innominate artery, and the esophagus can look like white tumor-filled nodes.  Always aspirate before any biopsy!
• If you cannot find a node in its usual station, retract the mediastinoscope several centimeters and rock the tip of the instrument up anteriorly.  Dissection in this more anterior area often reveals the node.

• Figure 9. View of subcarinal lymph node and proximal left and right main bronchi.

  The right main bronchus often comes off the trachea at a plane slightly more posterior than the left main bronchus, making positive identification of the carinal area difficult (Figure 9).

• If bronchoscopy is being done at the same time as the mediastinoscopy, we have occasionally found it helpful to do the procedures simultaneously, using the light from the end of the mediastinoscope as seen by the bronchoscopist as a guide to just what part of the tracheobronchial anatomy one is seeing with the mediastinoscope (Figure 10).  This is a particularly useful maneuver when trying to determine the proximal extent of a tumor around the right mainstem bronchus.

• Figure 10. View through bronchoscope showing bright blue-white light of mediastinoscope shining through the tracheal wall at right lower paratracheal level.

  Insist that the anesthesiologist constantly monitors the right upper extremity arterial waveforms in order to avoid innominate artery compression and possible CNS injury.

Results

The only videomediastinscopy series reported in the literature was from Venissac and colleagues from the Hospital Pasteur in Nice, France in 2000 [7].  They used a modified standard mediastinoscope and not the newer unified handle instrument.  They reported its use in 15 patients.  They experienced no major complications and no fatalities and commented on the “ optimal visualization of the mediastinum”.

At the University of Virginia Health System, 304 patients have undergone videomediastinoscopy from July 1999 through June 2002.  There has been no operative mortality.  There were 2 esophageal perforations with immediate intraoperative repair using a left thoracotomy with no subsequent morbidity.  There were 2 strokes (1 intraoperative and 1 post-operative) and 2 significant bleeds, which were followed by immediate sternotomy for control with no subsequent morbidity.

Hammond and colleagues from the Washington University School of Medicine reported a retrospective review of 2137 mediastinoscopies performed between January 1988 and September 1998 [8]. No video attachments were used.  They reported morbidity and mortality rates of 0.6% and 0.2% respectively. Only one death was directly related to the mediastinoscopy and this was an aortic tear in a patient whose tumor invaded the aorta.  They reported a sensitivity of 85.2% in the accurate staging of N2 and N3 disease when used preoperatively in patients with lung cancer.

References

1. Mateu-Navarro M, Rami-Porta R, Bastus-Piulats R, Cirera-Nogueras L, Gonzalez- Pont G. Remediastinoscopy after induction chemotherapy in non-small cell lung cancer. Ann Thorac Surg 2000;70:391-5.
   
2. Smythe WR, Bavaria JE, Kaiser LR. Mediastinoscopic subtotal removal of mediastinal cysts. Chest 1998;114:614-7.
   
3. Rizzato G. The role of thoracic surgery in diagnosing interstitial lung disease. Curr Op Pulm Med 1999;5:284-6.
   
4. Ginsberg RJ. Extended cervical mediastinoscopy. Chest Surg Clin N Am 1996;6:21-30.
   
5. Metin M, Sayar A, Turna A, Gurses A. Extended cervical mediastinoscopy in the diagnosis of anterior mediastinal masses. Ann Thorac Surg 2002;73:250-2.
   
6. Urschel JD. Conservative management (packing) of hemorrhage complicating mediastinoscopy. Ann Thorac Cardiovasc Surg 2000;6:9-12.
   
7. Venissac N, Alifano M, Karimdjee BS, Guillot F, Rabary O, Mouroux J. Video-mediastinoscopy in management of patients with lung cancer: a preliminary study. Surg Laparosc Endosc Percut Tech 2000;10:71-5.
   
8. Hammond ZT, Anderson RC, Meyers BF, Guthrie TJ, Roper CL, Cooper JD, Patterson GA. The current role of mediastinoscopy in the evaluation of thoracic disease. J Thorac Cardiovasc Surg 1999;118:894-899.