providing a better effectiveness/power ratio. Coagulation is particularly good.

Thulium laser has recently been considered for endobronchial application. The 2 μm wavelength emitted by Cyber TM (Thulium) laser is strongly absorbed by water resulting in an outstanding coagulation and aero-hemostatic effects with preservation of the surrounding tissue. Since 2-μm laser wavelength is strongly absorbed by water which is ubiquitous in all tissues, the speed of cutting and vaporizing will remain relatively constant regardless of tissue vascularization. Energy from the Thulium Laser penetrates only a fraction of millimeter in the tissue, with a high degree of control and substantially reduced risk of inadvertent injury.

In practice, the ideal laser in bronchoscopy should be transmissible by ber, safe, easy to setup­ and use, cheap, and portable. It should produce many and sometimes opposite speci c effects: excellent coagulation so as to control bleeding and different resecting modes according to clinical occurrence. For cicatricial stenosis, mainly post-intubation tracheal stenosis, lasers should be as precise as a scalpel to spare the surrounding tissues; on the contrary, for endoluminal neoplastic masses, a vaporizing effect on large volumes is needed. More important, high penetration of energy without loss of substance, producing deep thermal damage and consequently a cytocidal effect, is required to treat the tumor base in depth and delay (malignant tumors) or even prevent recurrences. This is the principle for cure in benign, strictly endoluminal tumors, typical carcinoids, carcinoma in situ, and early cancers. All these characteristics do not perfectly coexist in the same laser, so the interventional pulmonologist has to choose the best compromise or use more than one tool.

Application of the Technique

Mechanical resection with a biopsy forceps or the distal tip of a rigid bronchoscope entails a high risk of bleeding and usually, if successful, provides only short-lasting results. Bronchoscopic laser therapy, more than cryotherapy or electro-

surgery, is the most useful technique for treating tracheobronchial obstruction [28].

Despite some authors using laser with the fexible bronchoscope with limited safety and ef cacy, most bronchoscopic laser resections will be performed via rigid bronchoscopy in the operating room or endoscopy suite equipped for general anesthesia [28–30]. In fact, laser therapy normally integrates rigid bronchoscopic mechanical resection; this procedure is known worldwide as Laser Assisted Mechanical Resection (LAMR) and represents the safest and more effective way to obtain all potential effects of laser in bronchoscopy. LAMR is performed using general anesthesia, the patient’s oxygenation and ventilation are supported through the rigid bronchoscope by spontaneous-assisted ventilation or jet ventilation [14, 24, 34]. Intermittent Negative Pressure Ventilation applied to the chest wall through a poncho or cuirass has shown to prevent intraoperative apneas and respiratory acidosis in non-paralyzed patients. In paralyzed patients it allows opioid sparing, shortened recovery time, prevents respiratory acidosis, reduces the need for manually assisted ventilation and the amount of O2 required, while maintaining optimal surgical condition [35]. Also, muscle relaxants and paralytic agents can be helpful during general anesthesia because they prevent cough during resection and they facilitate insertion of the rigid bronchoscope.

Laser treatment requires well trained teamwork with a bronchoscopist, an anesthesiologist experienced with interventional pulmonology techniques and airway management, an endoscopy nurse familiar with the equipment, and a second endoscopy nurse who assists the bronchoscopist and controls the laser settings. General anesthesia is comfortable for both the patient and the operator, it allows maximal control of ventilation, optimal visualization of the lesions, and immediate management of complications. Ideal anesthetic agents allow spontaneous ventilation with maximum suppression of the cough refex. They should be rapidly eliminated or readily reversible so that the patient can be rapidly awakened at the end of the procedure and postoperative mechanical ventilation or Non-Invasive

Ventilation (NIV) can be avoided. Regardless of the type of anesthesia, the interventional pulmonologist and the anesthesiologist need to work in close agreement throughout the procedure, adapting to mutual needs.

For endobronchial tumors, which represent the most common indication for laser treatments, the use of a rigid bronchoscope is crucial since tumor mass removal is mechanically performed. Rigid suction tubes and the laser ber are simultaneously passed through the rigid bronchoscope as its working channel is wide enough to ensure ventilation. In this setting Laser is more ef - ciently used to coagulate the endoluminal mass before the mechanical resection to avoid or reduce bleeding. Simultaneous coagulation of a bleeding site with laser and suction of blood and clots is most important when dealing with an airway hemorrhage. The fexible bronchoscope can be passed through a rigid bronchoscope for treating cancer in the upper lobe bronchi or to reach a distal implantation base of the tumor in order to treat it in depth and delay recurrences or to achieve cure in case of benign tumors, selected typical carcinoids, early cancers, and carcinoma in situ [36].

The four main effect laser can produce are Coagulation, Resection, Vaporization, and Incision (Table 11.1).

Laser Resection is generally facilitated by the use of the rigid scope in the so-called Laser Assisted Mechanical Resection already mentioned before. It follows Laser Coagulation which involves directing the laser at the target lesion, devitalizing the lesion via photocoagulation of the feeding blood vessels, so that the devitalized tissue can be more easily removed with the beveled edge of the bronchoscope, forceps, or suction minimizing the risk of bleeding. Coagulation is possible because 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. Laser Vaporization is possible because energy from the laser is relatively well absorbed by water. It involves aligning the laser parallel to the bronchial wall and aiming at the edge of the

Table 11.1  Laser Techniques

Techniques

intraluminal lesion (the laser should never be discharged perpendicular to the airway wall because of an increased risk of perforation). It can also be performed through the fexible scope; in this setting laser pulses of only 1 s or less are used to vaporize the tissue to prevent thermal injury to the scope and airways. On the contrary, when performed in rigid bronchoscopy, laser can be used for longer periods of time reaching higher temperatures with higher power densities. This is possible because laser debris and smokes can be effectively suctioned by the suction tube inserted through the scope minimizing the risk of injury. Laser vaporization applied using a beroptic bronchoscope should be limited to small non-­ bleeding lesions, to re ne and complete treatments previously performed with the rigid scope and, through a tracheal tube, for treating neoplasms in the upper lobe bronchi, in distal locations and for distal tracheobronchial toilette.

The channel of the rigid bronchoscope is wide enough to ensure ventilation and passage of telescopes, suction tubes, and the laser ber. Simultaneous laser coagulation of a bleeding site and suction of blood and clots is very important

when dealing with airway hemorrhage. In addition, the rigid bronchoscope allows mechanical resection of polypoid tumors, previously coagulated with laser, which saves considerable time over laser vaporization. For all these reasons most bronchoscopists prefer rigid bronchoscopy, although a fexible bronchoscope is to be available if the airway abnormality is within a distal segmental bronchus and also to remove blood and debris from the distal airways. In the treatment of cicatricial tracheal stenosis (e.g., post-­ intubation web-like stenosis), laser is used in contact mode to perform radial incisions before a mechanical dilatation is obtained with rigid bronchoscopes of progressive caliber. The radial incisions permit to reduce tension with minimum heating of the adjoining tissue thus limiting recurrence [37–39]. Other authors described a different technique with repeated small radial incisions in contact mode through the fexible bronchoscope [40].

Several types of lasers have been used in the airway, including CO2 and argon but the commonest in use today is neodymium: yttrium, aluminum, garnet (Nd:YAG).

Nd:YAG via a fexible quartz ber is currently the laser best suited for use in bronchology because it has suf cient power to vaporize tissue while also producing an excellent coagulating effect. It penetrates deeper int tissues than CO2 and argon and its wavelength is less absorbed by hemoglobin. Nd:YAG effects on living tissues are signi cantly higher than those visible: power setting and pulse duration determine the volume of ablation [12]. A proposed technique for laser treatment of endobronchial tumors consists in initial low power Nd:YAG laser ring (<30 W) to coagulate the tumor followed by removal of the endoluminal portion of the lesion with the tip of the rigid bronchoscope, the biopsy forceps and the suction tube. High power settings (50–60 W) are then employed to vaporize the residual endoluminal tumor. Vaporization is easily performed on dark tissue with high power density and usingber close to pathological tissue. When destruction effects begin tissue became dark and vaporization local effect increase. At the end of the procedure, the base of the lesion is exposed to

low power settings with long pulses (20–30 W for 4–5 s; 2000 J/cm2) to obtain a cytocidal effect in depth within the airway wall. Dark colored tissues (e.g., charred or hemorrhagic tissue) and large lesions require special consideration. With respect to dark tissues, laser coagulation in depth is limited because the dark color enhances tissue absorption, limits deep tissue penetration, and reduces deep photocoagulation. To avoid charring and vaporization due to radiation absorption on the surface and to obtain coagulation in depth, the laser ber must be kept at a suf cient distance from the tumor surface and directed a little bit more tangentially to the bronchial wall, thus obtaining, because of the divergence of the beam, an increase of the diameter of the spot and therefore a reduction of the power density. Not only distance and laser position are aspects to consider: tissue radiation for 10–15 s in the same position could determine a “popcorn like effect” with tissue explosion. For this reason, it’s important to use laser discontinuously, especially if not experienced, reducing risk of excessive heating.

Firing with laser in full tumor is not advisable. It is time-consuming and uselessly risky to reduce the whole endoluminal mass by charring and vaporizing it with laser. Bronchoscopic laser resection should only be performed by bronchoscopists who have advanced training and experience. Bronchoscopists and team members should remain familiar with techniques, potential complications, and necessary precautions [41]. To minimize the risk of combustion fraction of inspired oxygen should be kept below 40% during laser ring [42]. Power settings should not exceed the maximum recommended for the laser being used (60 Watts for the Nd:YAG laser), fammable materials (including silicone stents) should be kept far away from the operating eld. Adequate suction must be available to remove the combustible laser plume (the smoke caused by vaporization of tissues) [43]. If a fexible bronchoscope is employed, the laser must be kept at a suf cient 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 bronchosco-

pist and the patient. Many bronchoscopic laser resection procedures are performed in less than 1 h [44].

Evidence Based Review

Bronchoscopic laser resection appears to be a quick and safe method to relieve airway obstruction due to invasive lung cancer; this applies to both primary and secondary lung cancer [45]. In fact, in literature multiple studies have been carried out in order to investigate the safety and feasibility of this procedure.

A large case series including more than 2000 laser resections in 1838 patients with malignant airway obstruction showed that airway patency improved and symptoms were palliated in over 90% of patients [24]; rigid bronchoscope was used in 92% of the treatments, almost always performed under general anesthesia, whereas theberoptic bronchoscope alone was used in less than 10% of the cases. In 93% of the patients affected by endobronchial malignant obstruction, Nd:YAG laser therapy allowed to obtain the patency of the central airways, avoiding the most distressing and invalidating symptoms of the disease (such as dyspnea and respiratory failure), therefore enhancing the patient’s quality of life.

The location and macroscopic appearance of the lesion play a crucial role in determining the success of the procedure: when the trachea and/ or the main bronchi were invaded and obstructed by the tumor, almost every patient reported immediate results (>95%). The median time between the rst and second palliative treatment was 102 days, whereas mortality was <1% within 7 days of the procedure, making it a safe procedure.

In literature smaller studies have reported similar results [14], whereas in a larger series of patients death occurred in only 15 out of 5049 procedures (0.3%), whereas severe complications occurred in 119 out of 5049 patients (2.4%) [46].

In another series, including 38 typical carcinoids and more than 150 benign tumors, laser therapy was considered curative; in all these

lesions, the base of the tumor could be easily reached by the bronchoscope, especially in endoluminal polypoid tumors, when coagulation of the tumor and mechanical resection was possible. These procedures were followed by a systematic treatment of the base of the tumor with low power setting and long exposure time, in order to avoid tissue loss, yet obtaining a deep cytocidal effect on the mucosa. Overall mortality rate was 0.25% [47].

In benign stenosis and particularly in post-­ intubation tracheal stenosis, it has been observed that laser-assisted mechanical dilation can guarantee cure in up to two-thirds of the cases; this value raised to 100% when only cicatricial web-­ like stenosis are considered [11].

Complications of bronchoscopic laser resection are infrequent, and include a wide range of clinical manifestations: hypoxia, hemorrhage, airway wall perforation, airway wall necrosis, and stula formation. Hypoxia, whether due to the use of general anesthetics or to major bleeding, can lead to irreversible cardiovascular complications and thus must be corrected promptly by bleeding suction and ventilation control. Adequate control of hemorrhage and ventilation, which are fundamental, can only be assured with the rigid bronchoscope. Other possible complications include perforation of the airway: in these cases, due to the air leak, it is possible to observe mediastinal emphysema, pneumothorax, and infection. Luckily, perforation of the airway is unlikely if the procedure is performed by experienced endoscopists who are familiar with rigid bronchoscopy. Airway res, although extremely rare, have been reported, particularly when fexible beroptic instruments are used. Furthermore, arterial air embolism has been rarely reported as a complication of bronchoscopic laser resection. Studies of continuous transesophageal echocardiographic monitoring during rigid bronchoscopy laser treatment suggest that air emboli may be caused by coolant gas (this gas exits the bronchoscope under high fow and pressure conditions in order to cool the laser probe), entering the pulmonary venules and gaining access to the systemic circulation [48]. The incidence of this complication may be reduced by maintaining the