Pulmonary Medicine

Interventional Bronchoscopy: Endoscopic Palliative Care

General description of procedure, equipment, technique

Endoscopic Palliative Care

Initially defined in 1995 and subsequently described in European Respiratory Society (ERS) and American Thoracic Society (ATS) guidelines, interventional pulmonology is "the art and science of medicine as related to the performance of diagnostic and invasive therapeutic procedures that require additional training and expertise beyond that required in a standard pulmonary medicine training program." Clinical entities encompassed within the discipline include complex airway management, benign and malignant central airway obstruction, pleural diseases, and pulmonary vascular procedures.

Diagnostic and therapeutic procedures pertaining to these areas include rigid bronchoscopy, transbronchial needle aspiration, autofluorescence bronchoscopy, endobronchial ultrasound, transthoracic needle aspiration and biopsy, laser bronchoscopy, endobronchial electrosurgery, argon-plasma coagulation, cryotherapy, airway stent insertion, balloon bronchoplasty and dilatation techniques, endobronchial radiation (brachytherapy), photodynamic therapy, percutaneous dilatational tracheotomy, transtracheal oxygen catheter insertion, medical thoracoscopy, and image-guided thoracic interventions. This presentation focuses on endoscopic palliative care.

Benign or malignant tracheobronchial obstructions may lead to acute respiratory distress. asphyxia, or death. If curative resection is not possible, endoscopic methods for palliation, including Nd: YAG laser therapy, cryotherapy, electrocautery, and Argon Plasma Coagulation (APC), are available. For extraluminal lesions, palliation using balloon dilatation, stent placement, or external beam radiation may be helpful.

Patients usually present with dyspnea, cough, chest discomfort, hemoptysis, stridor, and/or a localized wheeze. The history may include known cancer, aspiration of a foreign body, prior airway surgery or intubation, recurrent pneumonia, or other underlying illnesses that may involve the airways, such as sarcoidosis or tuberculosis.

Lasers have proved particularly useful in palliative management. Laser technology makes use of the power of radiant energy and the properties of light amplification. "Laser" is an acronym for “light amplified by the stimulated emission of radiation.” For "stimulated emission of light" to occur, an adequate population of excited electrons must be generated, with subsequent release of photons. The phenomenon is termed "population inversion" and requires an outside energy source that excites a designated medium. Almost any solid, liquid, or gas may act as a medium; placing the substance to be excited in a chamber with mirrors at either end further facilitates population inversion. The effectiveness of laser light, as compared with naturally occurring light, is a function of wavelength, spatial coherence, and temporal coherence.

The amount of energy delivered to a lesion depends on the power setting of the laser (expressed in watts), the distance from the laser tip to the target, and the duration of impact. Light directed at a surface may also be reflected, scattered, transmitted, or absorbed. Therefore, the depth of penetration depends not only on the properties of the light itself, but also on inherent tissue properties. The characteristics of the light produced also depend on the medium used.

With a carbon dioxide (CO2) laser, light is produced in the infrared spectrum wavelength,10,600 nanometers). The CO2 laser may be used as a precise cutting tool with only minimal blood loss because of the relatively shallow depth of penetration. CO2 laser therapy is usually used in management of laryngeal lesions involving the area around the glottic opening. The CO2 laser serves as an excellent "scalpel," since energy scattering is minimal, tissue vaporization is rapid, and damage to surrounding tissues minimal.

The most widely used laser for palliating tracheobronchial lesions is the Nd: YAG laser, which is produced by stimulation of an yttrium-aluminum-garnet glass that is coated with neodymium. The Nd: YAG laser, which has a wavelength of 1064 nanometers, is easily transmitted through pale tissues, with sizeable scatter and a potential penetration of up to 10 mm distal to the focal point. Nd: YAG lasers, unlike CO2 lasers, may cause deep-tissue vasoconstriction, with a penetration depth of up to 10 mm. The laser has very good coagulation properties.

Indications and patient selection

Laser therapy may be used in a variety of palliative circumstances. Patients with benign and malignant airway endobronchial lesions that cause symptomatic or obstructive complications may benefit from endoscopic laser photo resection. Laser therapy has also been performed for airway stenosis related to prolonged intubation, stricture produced by inflammatory granulation tissue caused by mycobacterial infection, anastomosis granulation tissue following lung transplantation, and suture-related granulomas, and in systemic inflammatory conditions caused by collagen vascular diseases, such as Wegner's granulomatosis, Bechet’s syndrome, and relapsing polychondritis.

Endobronchial laser therapy has been used in patients with symptomatic obstruction secondary to broncholithiasis and in patients with benign or low-grade tumors, such as hamartomas, spindle cell carcinomas, endobronchial Kaposi’s sarcomas, and even diffuse papillomatosis.

Contraindications

The use of palliative endobronchial laser therapy must be considered when the potential depth of laser-associated injury causes destruction of tissue that demarcates the boundaries between the target lesion and associated structures, such as the esophageal lumen, mediastinum, or major blood vessels.

Clinical contraindications are relevant in patients who may not tolerate conscious sedation or general anesthesia because of comorbidities. In addition, patients in whom atelectasis distal to airway obstruction has been present for more than six weeks will probably not benefit from endoscopic laser resection because re-expansion of the involved lung is unlikely.

Details of how the procedure is performed

Physicians tend to prefer to perform laser therapy using rigid bronchoscopy and general anesthesia, although procedures may be performed through the flexible fiberoptic bronchoscope using topical anesthesia alone.

Laser resection is performed initially with photocoagulation of the tumor. Coagulated tissue is then removed using the beveled edge of the rigid bronchoscope, forceps, and suction. Complete laser vaporization of tissue may also be performed, but it carries a high risk of endobronchial fire. The laser beam is always aligned parallel to the bronchial wall and is never discharged when perpendicular to the wall. Laser pulses of one second or less are usually employed. When a flexible bronchoscope is used, the removal of devitalized tissue can be slow and difficult. In addition, the flexible bronchoscope is, itself, combustible.

A number of important precautions must be taken during the procedure. The patient's eyes should be protected using saline-soaked pads and aluminum foil to avoid injury from accidental laser scatter, and all medical personnel should wear protective goggles. Several precautions are necessary to minimize the risk of combustion. The fraction of inspired oxygen should be kept below 40 percent; flammable materials, such as endotracheal tubes, should be kept far away from the operating field; and silicone stents should be removed prior to laser use. The laser should always be placed in standby mode when tissue is removed from the bronchoscope, and if a flexible bronchoscope is employed, the laser must be kept a sufficient distance beyond the tip of the bronchoscope to avoid combustion. Power settings higher than 40 watts are never necessary.

Interpretation of results

Not applicable.

Performance characteristics of the procedure (applies only to diagnostic procedures)

Not applicable.

Outcomes (applies only to therapeutic procedures)

In a series of 185 patients who had benign tumors and underwent resections of the tracheobronchial tree, laser resection results were considered "very good" in 62 percent and "good" in 38 percent. Complications were minimal.

In another series of one hundred patients referred for palliative treatment of tracheobronchial malignancies, improvements in peak flow and alleviation of hemoptysis were noted in 63 percent of patients with airway obstruction and in 29 percent of patients with lung collapse.

In nineteen patients with inoperable non-small cell carcinoma and symptomatic bronchial obstruction who underwent Nd: YAG laser therapy with the goal of debulking the airways before conventional external-beam radiation therapy, those with "satisfactory debulking" and subsequent radiation therapy had a significantly better outcome (mean survival, 340 days versus fewer than 100 days) than those with "unsatisfactory" laser therapy. A significant increase in survival was noted among the subset of fifteen patients who underwent emergency palliative photoresection as the initial therapeutic intervention compared with a subset of eleven patients who received palliative radiation alone.

When a group of patients who underwent a combination of Nd: YAG photo-resection and subsequent external-beam radiation therapy was compared with a group that underwent external-beam radiation therapy plus brachytherapy, those in the laser treatment group demonstrated significantly longer survival than those treated with radiation alone.

Finally, in a report of a large number of patients treated for malignant airway obstructions using therapy that incorporated Nd:YAG laser, stents, and brachytherapy, 93 percent of those who received laser resection achieved immediate airway patency and improvement in quality of life.

Alternative and/or additional procedures to consider

None

Complications and their management

Complications of laser therapy are related to the equipment used, anesthesia, and perioperative developments. Despite the possibility of severe, often fatal, complications, overall risk is low if the operator is experienced. One series described only sixty complications, including twelve deaths in 2610 resections using Nd: YAG laser therapy .

One potential catastrophic intraoperative complication of laser therapy is endotracheal fire. In order to minimize the risk, use of combustible anesthetic gases must be avoided, and the concentration of supplemental oxygen must be kept under 40 percent. Silicone stents should be removed from the airway prior to use of laser therapy.

Although metal rigid bronchoscopes are not combustible, use of the Nd: YAG laser through an endotracheal tube deserves special consideration. An immediate danger to the patient and operating room personnel is that of intratracheal explosion, with anesthetic gases or oxygen producing a “torch effect” and igniting the endotracheal tube.

Longer-term complications may result from the subsequent lower airway inhalation injury, with mucosal sloughing and airway obstruction caused by granulated tissue.

Fatal hemorrhage may arise from airway perforation into an involved or contiguous vascular structure. Perforation may also occur into adjacent structures, with development of pneumothorax, pneumomediastinum, or tracheoesophageal fistula. Systemic air embolism, which has been reported, is associated with development of vascular communication with the tracheobronchial tree.

What’s the evidence?

Brutinel, WM, Cortese, DA, Edell, ES. "Complications of Nd:YAG laser therapy.". Chest. vol. 94. 1988. pp. 903-904.

An early description of the American experience with endobrochial laser therapy.

Cavaliere, S, Venuta, F, Foccoli, P. "Endoscopic treatment of malignant airway obstructions in 2,008 patients.". Chest. vol. 10. 1996. pp. 1536-1542.

One of the largest series on the use of the Nd:YAG laser.

Dumon, MC, Dumon, JF, Fein silver, SH, Fein, AM. "Laser bronchoscopy". Textbook of Bronchoscopy. Williams & Wilkins. 1995. pp. 393-399.

A useful description of the use of laser bronchoscopy and details of the technique.

Eichenhorn, MS, Kvale, PA, Miks, VM. "Initial combination therapy with YAG laser photoresection and irradiation for inoperable non-small cell carcinoma of the lung". Chest. vol. 89. 1986. pp. 782-785.

An early report on the American experience with the use of laser therapy.

Kvale, PA, Eichenhom, MS, Radke, JR. "YAG laser photoresection of lesions obstructing the central airways". Chest. vol. 87. 1985. pp. 283-288.

A now classic paper on the American experience with the use of laser therapy.

Macha, HN, Becker, KO, Kemmer, HP. "Pattern of failure and survival in endobronchial laser resection". Chest. vol. 105. 1994. pp. 1668-1672.

A report describing patterns of technique failure using laser bronchoscopy.

Maimon, T-I. "Stimulated optical radiation in ruby". Nature. vol. 187. 1960. pp. 493-494.

A discussion of the physics behind the use of lasers.

Mehta, AC, Lee, FYW, DeBoer, GE, Wang, KP, Mehta, AC. "Flexible bronchoscopy and the use of lasers". Flexible Bronchoscopy. Blackwell Science. 1995. pp. 247-274.

A description of the use of lasers in conjunction with flexible fiberoptic bronchoscopes.

Ramser, ER, Beamis, JF. "Laser bronchoscopy". Clin Chest Med. vol. 16. 1995. pp. 415-426.

An excellent review of the topic.

Shah, H, Garbe, L, Nussbaum, E. "Benign tumors of the tracheobronchial tree: Endoscopic characteristics and role of laser resection". Chest. vol. 107. 1995. pp. 1744-1751.

A classic paper on the use of laser therapy in the management of benign lesions.

Toty, L, Personne, C, Colchen, A. "Bronchoscopic management of tracheal lesions using the neodymium yttrium aluminum garnet laser". Thorax. vol. 36. 1981. pp. 175-178.

One of the earliest reports on the use of the Nd: YAG laser.
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