EXPERT ANALYSIS AT THE STS ANNUAL MEETING
PHOENIX (FRONTLINE MEDICAL NEWS) – According to Dr. Moishe Liberman, promising lesions for bronchoscopic endoluminal treatment include endobronchial lesions and intraluminal exophytic tumors within the trachea or main bronchus, provided that the distal airway lumen is visible and you can get past the tumor with a flexible endoscope.
“We always teach the fellows that if you get pus back when you’re trying to get around the tumor or play with the tumor, you’re usually going to have a very good result,” said Dr. Liberman, a thoracic surgeon who directs the endoscopic tracheo-bronchial and oesophageal center at the Centre hospitalier de l’Université de Montréal, Quebec, Canada. “If you play with the tumor and you get the tumor out and you get nothing back, usually the CT scan or the X-ray postoperatively is going to look just like it did preoperatively, even though endoscopically you might have a good result.”
Central lesions are also excellent candidates for endoluminal therapy, he said in a video interview at the meeting. Distal lesions in the small bronchi “are candidates but are much more difficult and require more specialized tools. The shorter the lesion, the more likely you are to have good success.”
Available options for delivering energy endoscopically include electrocautery, argon plasma coagulation, laser, and cryotherapy. A disadvantage of all of the thermal modalities except for cryotherapy “include the potential for airway fire and you have to work with low FiO2s [fraction of inspired oxygen],” Dr. Liberman noted. “A lot of these patients need high FiO2s to saturate, so I think that’s always an issue. We never go on cardiopulmonary bypass to do these cases and we never cannulate patients to do these cases. You also have to worry about gas emboli, especially when you open up big vessels. These modalities can also cause inadvertent airway injury, delayed effects, and bronchoscope damage.”
In general, he continued, laser-tissue interactions depend on the power and the wavelength of the laser as well as the color and the water content of the target tissue. “The power density of the wavelength you choose determines its ability to cut, coagulate, or vaporize the tissue,” he said.
“As the power density increases, the laser fiber approaches the target tissue. Power density is more important than the energy delivered.”
The Nd:YAG (neodymium-doped yttrium aluminium garnet) laser, which causes more destruction in the deep tissue than on the surface, is the most common laser used in interventional airway procedures, he said. Two other commonly used lasers include the KTP (potassium titanyl phosphate) and the CO2. “I like CO2s a lot for upper airway and subglottic problems as well as vocal cord problems,” Dr. Liberman said. “It’s very precise and has low penetration. The Nd:YAG is very good for deep penetration. You need familiarity with these. I don’t think you can just take one of these off the shelf if you’ve never used it before. Sometimes your ENT [ear nose and throat] or urology colleagues can help you, because they’re using a lot more of these lasers than we are.”
Contraindications for laser bronchoscopy include operable lesions. Dr. Liberman said that while he and his associates use lasers in a preoperative setting, “we’re very careful not to damage proximal or distal airway when we know we’re going to do a sleeve resection or pneumonectomy.”
Other contraindications for laser bronchoscopy include patients with a poor short-term prognosis, severe coagulation disorder, extrinsic airway obstruction, tracheoesophageal fistula or T-Med fistula, those with extensive submucosal disease causing obstruction, and those with lesion adjacent to the esophagus or to a major vessel.
Dr. Liberman reported having received research grants from Ethicon, Boston Scientific, Olympus, Covidien, and Baxter.