Version May 2024
INTRODUCTION — Bronchoscopic laser therapy is a thermally ablative technique [1]. It has cutting and coagulant properties, which make it a useful tool to treat symptoms associated with airway disease. Its indications, efficacy, contraindications, equipment, and technique are reviewed here. Other bronchoscopic techniques used to manage airway obstruction are described separately. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults" and "Endobronchial electrocautery" and "Endobronchial photodynamic therapy in the management of airway disease in adults" and "Bronchoscopic argon plasma coagulation in the management of airway disease in adults" and "Airway stents" and "Flexible bronchoscopy balloon dilation for nonmalignant airway strictures (bronchoplasty)" and "Endobronchial brachytherapy" and "Bronchoscopic cryotechniques in adults".)
INDICATIONS AND EFFICACY — In general, bronchoscopic laser therapy is an immediate-acting, palliative, or adjunctive therapy used to relieve central airway obstruction (CAO; trachea and main stem bronchi) due to malignant or nonmalignant conditions [2-4]. Ideal lesions are intraluminal and short (ie, <4 cm) such that the region beyond the obstruction can be visualized and the distal lung is functional. It is not suitable for lesions causing CAO from extrinsic compression or distal lesions (ie, beyond the mainstem bronchus). Lesions that extend a long distance in the trachea or mainstem bronchus are generally not suitable for laser debulking but laser may be used to photocoagulate and devascularize tumor tissues prior to mechanical debulking. Less commonly, it is used to treat hemoptysis, and rarely, it is used to treat inoperable radiographic occult lung cancer that is limited to the airway.
The approach to and choice of modality used to treat patients with central airway obstruction as well as a comparison between the locally ablative bronchoscopic techniques are discussed separately (table 1 and table 2). (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults".)
Malignant central airway obstruction
Patient or tumor characteristics — CAO from bronchogenic carcinoma is the most common indication for laser resection (table 3) [5-11]. In general, it is a palliative therapy used in patients for whom other first-line treatment modalities are not feasible (eg, surgery or radiation therapy), and/or in patients who require immediate relief from serious life-threatening obstruction. Occasionally, it is used adjunctively before salvage chemotherapy, radiation (eg, external beam radiation or brachytherapy), or surgical resection. Ideal lesions that are suited to laser resection are short tumors (ie, <4 cm) with a significant intraluminal component with or without concomitant bleeding. Its effects are not generally long lasting such that it is either combined with other bronchoscopic therapies (eg, stenting, and brachytherapy), external/systemic therapy (eg, external beam radiation or chemotherapy), or repeated (usually for palliative purposes). (See "Endobronchial electrocautery" and "Airway stents" and "Flexible bronchoscopy balloon dilation for nonmalignant airway strictures (bronchoplasty)" and "Endobronchial brachytherapy" and "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults" and "Bronchoscopic cryotechniques in adults".)
Non-small cell lung cancer (NSCLC), particularly squamous cell carcinoma, is the most common malignancy subjected to laser resection. However, case reports of successful management of other types of malignancy have been described including carcinoid, cystic carcinoma, mucoepidermoid carcinoma, and endobronchial metastases from melanoma, colon, kidney, and breast cancer [12-14].
Efficacy — Outcome data regarding bronchoscopic laser resection for patients with airway malignancy are derived from retrospective case series [2,15-26]. Outcomes studied are usually airway patency and symptom palliation (eg, hemoptysis, dyspnea) as well as weaning from mechanical ventilation, and survival. As examples:
●One case series that included 2610 laser resections in 1838 patients with malignant airway obstruction, some of whom also received stents and brachytherapy, reported that airway patency improved and symptoms were palliated in over 90 percent of patients [16]. Treatments were often repeated with the median time between a first and second palliative treatment of 102 days. Smaller series have reported similar results [17,19-21].
●In another case series of 17 patients with respiratory failure from malignancy-associated airway obstruction, laser ablation resulted in extubation and provided the opportunity for further treatment modalities in seven patients [23]. Improved outcome was more notable in those with obstructing endobronchial tumor as the main cause of the respiratory insufficiency when compared with patients with intraluminal lesions that had large components of additional extrinsic compression. Similar results were reported in a case series of 32 patients with acute respiratory failure from both benign and malignant-associated CAO where treatment with laser resection resulted in successful weaning from mechanical ventilation and transfer to a lower level of care [11].
●A case series of 351 laser resections performed in 273 patients with lung cancer, 108 of whom also had stents placed, reported airway caliber improvement in 89 percent of patients [24]. A significant proportion of patients (22 percent) also went on to receive induction chemotherapy and/or surgical resection.
●In a report of 256 procedures performed in 121 patients with tracheal or bronchial obstruction mostly from malignancy, patency was achieved in over 70 percent of patients and hemoptysis was controlled in the proportion of patients who presented with airway bleeding [9].
Comparison with other bronchoscopic techniques — There are no high quality studies comparing the use of laser with other locally ablative therapies, although when used appropriately, they all appear to result in similar rates of airway patency and symptom palliation. In general, choosing a bronchoscopic therapy is dependent upon the tumor location, the degree of extrinsic versus intrinsic compression and local expertise, and should be individualized for each patient. Among these modalities, only laser resection, argon plasma coagulation, and electrocautery can destroy tissue rapidly and, therefore, have an immediate life-saving effect. Laser resection has excellent debulking capacity and may be as efficient at achieving hemostasis as APC but has a higher risk of airway perforation. The advantages and disadvantages of each bronchoscopic modality and choosing among the therapeutic options in patients with CAO are discussed in detail separately (table 1 and table 2). (See "Endobronchial electrocautery" and "Airway stents" and "Flexible bronchoscopy balloon dilation for nonmalignant airway strictures (bronchoplasty)" and "Endobronchial brachytherapy" and "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults" and "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults", section on 'Patients with lung cancer' and "Bronchoscopic cryotechniques in adults".)
Nonmalignant central airway obstruction — Patients who have significant symptoms of CAO from nonmalignant airway strictures due to causes other than infection are generally considered for surgical resection (table 3) [5,6]. Thus, laser resection is generally a second line therapy used for those who decline or are not candidates for surgery due to poor overall medical status, severity of other underlying disease, or the extent, location, and degree of the stricture. Similar to patients with malignancy, nonmalignant lesions best suited to bronchoscopic laser resection are short (ie, <4 cm) intraluminal masses/strictures particularly those associated with concomitant bleeding. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults".)
Data to support treating this population with bronchoscopic laser are derived from isolated reported cases that have been successfully treated with this modality [27-34]. Examples include:
●Nonmalignant tumors of the airway (eg, leiomyoma, hemangioma)
●Inhaled foreign bodies associated with granulation tissue
●Tracheal or bronchial stenoses from granulation tissue, intubation/tracheostomy injuries, radiation, lung transplantation, tracheal or bronchial reanastomosis, or inhalation injury
●Strictures due to amyloidosis
●Fibrous bands following an infection with Corynebacterium diphtheriae, Klebsiella rhinoscleromatis, tuberculosis, or fungus
●Exophytic disease/inflammatory masses due to papillomatosis, granulomatosis with polyangiitis, tuberculosis, or endometriosis
●Disintegration of a large obstructing broncholith
Some nonmalignant conditions are not amenable to laser therapy including endobronchial infections and extrinsic compression from vascular rings, mediastinal lymphadenopathy or goiters.
Hemoptysis — Since bronchoscopic laser has coagulant properties, it is effective at achieving hemostasis in patients with hemoptysis due to visible airway lesions (large or small). While treating bleeding areas, the zone around the bleed itself is usually photocoagulated so as to cause vasoconstriction. If using the Neodymium-yttrium-aluminum-garnet (Nd:YAG) laser, avoidance of direct laser application to the bleeding source itself is helpful to prevent carbonization (red rapidly absorbs the Nd:YAG laser wavelength).
Radiographic occult lung cancer — Whether bronchoscopic laser can cure micro-invasive radiographically occult lung cancer (ROLC) in patients who are not eligible for surgical cure is not fully established. While no large prospective trials have rigorously compared laser to other bronchoscopic modalities, case reports suggest that locally ablative therapies including laser have the potential to be effective as a treatment for early lung cancer that is inoperable and limited to the airways. These data are discussed separately. (See "Endobronchial electrocautery", section on 'Malignant tumors' and "Bronchoscopic cryotechniques in adults", section on 'Inoperable microinvasive carcinoma' and "Endobronchial photodynamic therapy in the management of airway disease in adults", section on 'Radiographic occult lung cancer' and "Bronchoscopic argon plasma coagulation in the management of airway disease in adults", section on 'Early airway lung cancer not amenable to surgery'.)
CONTRAINDICATIONS
Patients with extrinsic compression — When central airway obstruction (CAO) is solely due to extrinsic compression of the airway, this is a contraindication to bronchoscopic laser resection since heat must be directly applied to the lesion for laser to be effective. However, for patients who have a lesion with both extrinsic and intrinsic components, the latter may be subjected to laser resection, if necessary. Similarly, patients with CAO from a cartilaginous disorder (eg, tracheobronchomalacia) are not suitable for laser.
Patients with stents — Since laser is a thermally ablative technique, the presence of a stent (risk of melting and fire) is also a relative contraindication to bronchoscopic laser. Thus, most operators remove airway stents, when feasible, prior to using laser (or other heat generating modalities) in the airways. (See "Airway stents".)
Patients on high flow oxygen — Patients on high flow oxygen (fraction of inspired oxygen >0.4) are at risk of airway fire and are not candidates for bronchoscopic laser therapy. However, laser debulking can still be performed if these patients can tolerate short periods of apnea (usually less than one minute) or an FiO2 <0.4.
Patients with extensive or distal lesions — Patients with long lesions (>4 cm in length) or lesions involving the distal airway, or lesions with evidence of significant obstruction (eg, tumor involving the distal mainstem bronchus that extends into all components of the right lower lobe) are not suitable for laser resection because of unproven and reduced efficacy in this population. In addition, the use of laser in smaller airways may theoretically increase the risk of airway perforation. However, in some instances of long extensive lesions, laser may be used to photocoagulate and devascularize tumor tissues prior to mechanical debulking.
EQUIPMENT AND TECHNIQUE
Types of laser — There are many types of biomedical lasers, including the following:
●Neodymium-yttrium-aluminum-garnet (Nd:YAG) laser
●Neodymium-yttrium-aluminum-perovskite (Nd:YAP) laser
●Carbon dioxide laser
●Argon ion laser
●Excimer laser
●Potassium titanyl phosphate (KTP) laser
●Alexandrite laser
●Semiconductor laser
●Pulse dye laser
●Holmium YAG laser
Each has a different balance of cutting and coagulating properties; Nd:YAG laser is most commonly used because it has good resection and coagulation properties. These lasers are described in detail separately. (See "Basic principles of medical lasers".)
Principles of laser resection — Laser has both cutting and coagulating properties so it can simultaneously resect as well as coagulate tissue, making it suitable for airway lesions that are associated with obstruction and bleeding. The laser that is most commonly used bronchoscopically is Nd:YAG laser. Its energy is delivered through flexible fibers that are inserted through either a rigid or flexible bronchoscope. The wavelength of this laser (1064 nm) is invisible; thus, a red helium-neon beam is used to indicate where the laser energy will be applied.
An Nd:YAG laser can remove an obstructing airway lesion in two ways:
●Resection – Resection involves directing the laser at the target lesion, devitalizing the lesion via photocoagulation of the feeding blood vessels, and then extracting (forceps removal or suction) the devitalized tissue through the bronchoscope (movie 1). The laser penetrates tissue to a depth of up to 10 mm in an inverted cone fashion and provides reliable photocoagulation at this depth. Its power density can be altered by moving the laser closer to or farther from the target tissue. Resection is generally performed with rigid bronchoscopy.
●Vaporization – Vaporization involves aligning the laser parallel to the bronchial wall and aiming at the edge of the intraluminal lesion (the laser is rarely discharged perpendicular to the airway wall because of an increased risk of perforation) (movie 2 and movie 3). Laser pulses of one second or less are used to vaporize the tissue. Vaporization is possible because the energy/heat from the laser tissue contains water. Vaporization requires higher power densities and more tissue heat than resection. Vaporization can be performed with either rigid or flexible bronchoscopy.
Selecting which form of laser treatment to use is dependent upon the lesion characteristics. As an example, for dark tissues (eg, charred or hemorrhagic tissue) resection is less effective because the dark color enhances tissue absorption, limits deep tissue penetration, and reduces deep photocoagulation, leading to poor devitalization of the target lesion, such that vaporization is preferred in this group. In contrast, for large lesions, vaporization should be avoided because it is time consuming and requires high tissue heat, which increases the risk of airway fire and perforation.
Procedural technique
Anesthesia and ventilation — Since most laser resections are performed using a rigid bronchoscope, general anesthesia is used for most cases and the patient’s oxygenation and ventilation are supported throughout the procedure by spontaneous-assisted ventilation, jet ventilation, or volume ventilation [35-37]. (See "Overview of anesthesia" and "Management of the difficult airway for general anesthesia in adults".)
Muscle relaxants and paralytic agents can occasionally be helpful during general anesthesia because they prevent the patient from coughing during resection and they facilitate insertion of the rigid bronchoscope. (See "Induction of general anesthesia: Overview" and "Airway management for induction of general anesthesia".)
For patients who undergo moderate sedation for flexible bronchoscopy, good topical anesthesia with 1 percent lidocaine and systemic sedation should be ensured to reduce the risk of complications. The choice of agent depends upon the procedure as well as the patient’s need for sedation. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications".)
Choosing flexible versus rigid bronchoscopy — Most experts prefer rigid bronchoscopy, but will occasionally use flexible bronchoscopy if the airway abnormality is small and within a distal segmental bronchus [5,16]. We prefer rigid bronchoscopy because bleeding complications, although infrequent, can be more readily controlled (bleeding lesions are easily visible and tamponade can be achieved), and the larger lumen of the rigid bronchoscope allows passage of multiple instruments including large-bore suction. However, we also use a flexible bronchoscope introduced through the barrel of the rigid bronchoscope for the clearance of small fragments of distal bronchial debris. So, in essence both pieces of equipment are often needed.
The choice of rigid bronchoscopy (performed under general anesthesia in the operating room) versus flexible bronchoscopy (performed under moderate sedation) also depends upon the bronchoscopists experience as well as whether vaporization or resection of the lesion is planned (see 'Principles of laser resection' above). Vaporization can be performed with either rigid or flexible bronchoscopy. However, resection is generally performed with rigid bronchoscopy because the devitalized tissue can be more easily removed with the beveled edge of the bronchoscope, with large forceps, or with suction. Removal of debris is important because distal displacement of debulked tissue may result in retained fragments that can cause distal atelectasis and can promote infection. However, we keep a flexible bronchoscope available to remove blood and debris from the distal airways with aggressive saline lavage in the event it occurs. In contrast, large amounts of tissue are difficult to remove with a flexible bronchoscope in which instance, a rigid bronchoscope is required.
Personnel and equipment
●Personnel – Bronchoscopic laser therapies should only be performed by bronchoscopists who have advanced training and experience. Most laser resection teams are comprised of a bronchoscopist, an anesthesiologist experienced with interventional pulmonology techniques and airway management, an OR/endoscopy nurse familiar with the equipment, as well as a second endoscopy nurse who assists the bronchoscopist and controls the laser settings. Team members should remain familiar with techniques, potential complications, and necessary precautions [38].
Equipment – Equipment needed includes the following:
•Laser source
•Flexible and rigid bronchoscopes
•Laser goggles
•Saline lavage
•Suction
•Forceps, balloons, and any other necessary adjunctive equipment
Precautions during laser resection include wearing protective goggles, protecting the patient's eyes to avoid injury from accidental laser scatter, and minimizing the risk of combustion [39,40]. To prevent combustion and airway fire, we suggest the following:
•The fraction of inspired oxygen should be kept below 0.40 prior to and during laser firing.
•Flammable materials should be kept far away from the operating field, including endotracheal tubes.
•Silicone stents should ideally be removed prior to laser firing, when feasible. Occasionally experienced bronchoscopists can carefully apply laser when granulation forms at the ends of stents ensuring not to apply it directly to the stent itself.
•The laser should always be placed on standby mode while tissue is removed from the bronchoscope.
•Adequate suction must be available to remove the combustible laser plume (the smoke caused by vaporization of tissues).
•Power settings should not exceed the maximum recommended for the laser being used (eg, 40 watts or short-pulse mode for the Nd:YAG laser).
•If a flexible bronchoscope is employed, the laser must be kept a sufficient distance beyond the tip of the bronchoscope.
Video systems allow all personnel to observe the procedure, which makes it easier for assistants to anticipate the needs of the bronchoscopist and the patient. Many bronchoscopic laser resection procedures are performed in less than one hour [41].
Procedure — There are many resectional techniques that vary depending upon the laser type, the equipment, the patient, and the lesion location. It is necessary and highly recommended that anyone wishing to learn laser resection undergo sufficient training on how to practice and become acquainted with these techniques to ensure a safe and effective procedure.
COMPLICATIONS — Complications of bronchoscopic laser resection are infrequent, occurring in approximately 2 percent of cases or less, with hemorrhage and airway perforation being the most common.
Types — Common complications include:
●Hemorrhage
●Airway wall perforation
●Airway wall necrosis/ulceration
●Fistula formation (acute and chronic)
Rare complications include airway fire, air embolism, and death.
Many of these complications occur due to the operator's inability to predict the extent of deep tissue damage based upon the surface appearance. If the power density increases at a sufficient depth below the surface of the target tissue, the temperature can increase above the boiling point of water. Explosion of a pocket of steam causes a "popcorn effect," which may result in tissue perforation, rupture, and hemorrhage [42].
Although hemorrhage is commonly encountered during laser, and is in fact the indication for the procedure, most cases can be treated locally due to the coagulant effect of laser itself. Should uncontrollable hemorrhage occur, intubation is necessary (if not already performed) so that measures can be taken to achieve hemostasis, the details of which are discussed separately. (See "Evaluation and management of life-threatening hemoptysis".)
The risk of airway perforation may be minimized by avoiding aggressive vaporization of large lesions, discharging the laser perpendicular to the airway wall, and in general applying safe practice rules to the procedure. (See "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients", section on 'Tracheoesophageal fistula'.)
Severe injury and even death have been associated with laser-induced airway fires. In case of spark or flame, it is necessary to immediately cool the tissues and remove any flammable objects. Clearly, if the airway (eg, plastic endotracheal tube that has caught on fire) is removed, the airway will need to be resecured as rapidly and safely as possible. Saline washing is warranted (eg, iced saline), and removal of any heated materials should be immediate. Patients will require follow-up bronchoscopy to assure absence of burn injury and collateral damage. Airway fires can be minimized by avoiding high flow oxygen (ie, avoiding fraction of inspired oxygen >0.4) as well as avoiding laser in patients with stents and adhering to the precautions listed above. (See 'Personnel and equipment' above and "Inhalation injury from heat, smoke, or chemical irritants".)
Although arterial air embolism is rare, air may enter the bronchial or systemic veins during the procedure. The risk may be minimized by maintaining the laser fiber coolant airflow at the minimum level and avoiding direct contact between the laser probe and tissue [43]. Patients with gas embolism may present with sudden onset cardiovascular collapse or signs and symptoms suggestive of a cerebrovascular event. The procedure should be stopped immediately should embolism be suspected. The manifestations and treatment of patients with suspected embolism are presented separately. (See "Air embolism".)
Frequency — Rates of complications may be underreported and vary from series to series and depend upon operator experience as well as individual tumor characteristics [16-25]:
●In one series of 261 procedures performed on 99 patients, the overall complication rate was 2.3 percent and mortality <1 percent [26].
●Another case series reported serious complications occurred in only 119 out of 5049 patients (2.4 percent) and mortality was 0.3 percent [21].
●Most deaths are thought to be due to the presence of extensive malignant lesions or to underlying cardiopulmonary disease [21,22,26].
POSTOPERATIVE CARE — Bronchoscopic laser does not require any particular immediate follow-up care in the absence of complications, other than routine post-bronchoscopy care. Patients usually can return home the same day when performed as an outpatient procedure. Many experts will perform follow-up bronchoscopy to carefully inspect the airway a few weeks after the procedure. Follow-up of patients with central airway obstruction is discussed separately. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults", section on 'Follow-up' and "Flexible bronchoscopy in adults: Overview" and "Flexible bronchoscopy in adults: Preparation, procedural technique, and complications", section on 'Postprocedure monitoring'.)
SUMMARY AND RECOMMENDATIONS
●Indications – Bronchoscopic laser therapy is a thermally ablative technique. It has cutting, coagulation, and vaporization properties, which make it a useful tool for the treatment of airway disease. (See 'Indications and efficacy' above.)
•Bronchoscopic laser resection is a palliative or second-line therapy used to relieve central airway obstruction (CAO) due to malignant or nonmalignant conditions.
•Ideal lesions are intraluminal, short (ie, <4 cm), and located in the proximal airways (trachea and mainstem bronchus).
•Non-small cell lung cancer is the most common malignancy subjected to laser treatment, although case reports of successful management other types of airway malignancy have also been described (eg, carcinoid, endobronchial metastases). Nonmalignant tumors and strictures that are not suitable for surgical resection have also been successfully treated with bronchoscopic laser. (See 'Malignant central airway obstruction' above and 'Nonmalignant central airway obstruction' above.)
●Contraindications – Contraindications to bronchoscopic laser include the presence of extraluminal lesions causing extrinsic compression, stents, an FiO2 >0.4, and/or extensive or distal lesions. However, for long extensive lesions, it can be used to photocoagulate and devascularize tumor tissues prior to mechanical debulking. (See 'Contraindications' above.)
●Equipment – The type of laser that is most commonly used for bronchoscopic laser is the neodymium-yttrium-aluminum-garnet (Nd:YAG) laser. It relieves airway obstruction by either resecting or vaporizing the obstructing lesion. (See 'Types of laser' above and 'Principles of laser resection' above.)
●Technique – Our approach is the following (see 'Procedural technique' above and 'Principles of laser resection' above):
•Most experts prefer using rigid bronchoscopy for laser resection. However, flexible bronchoscopy is occasionally used if the airway abnormality is small and within a distal segmental bronchus or as a supplement to rigid bronchoscopy when debulked tissue has moved distally and requires aggressive saline lavage for removal. (See 'Choosing flexible versus rigid bronchoscopy' above.)
•Bronchoscopic laser should only be performed by bronchoscopists who have advanced training and experience. Laser teams generally consist of the bronchoscopist, an anesthesiologist, and two nurses. Many procedures are performed in less than one hour. Precautions should be taken to avoid injury to the patient and team from accidental laser scatter and/or combustion. (See 'Personnel and equipment' above.)
●Complications – Complications of bronchoscopic laser are infrequent, occurring in approximately 2 percent of cases or less, with hemorrhage and airway perforation being the most common. Additional complications include airway wall necrosis, fistula formation, airway fire, air embolism, and death. (See 'Complications' above.)
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