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Initial Report of Neodymium: Yttrium-Aluminum-Perovskite (NdYAP) Laser Use During Bronchoscopy

Lee, Hans Joo MD; Malhotra, Rajiv DO; Grossman, Cathy MD; Wesley Shepherd, Ray MD

Journal of Bronchology & Interventional Pulmonology: July 2011 - Volume 18 - Issue 3 - p 229–232
doi: 10.1097/LBR.0b013e3182296615
Original Investigations
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Background: Neodymium:yttrium-aluminum-garnet laser used during bronchoscopy has been effective in treating airway obstruction. Other lasers with different properties have not been well described during bronchoscopy. The neodymium:yttrium-aluminum-perovskite (Nd:YAP) laser has different characteristics than the Neodymium: yttrium aluminum garnet laser.

Methods: A single center retrospective review was conducted to assess safety and efficacy of the Nd:YAP laser during bronchoscopy. The review encompassed all bronchoscopies using the Nd:YAP laser. The data included the indication (photocoagulation before debulkment or stenting, vaporization of tumor or granulation tissue, stenosis, hemoptysis), laser power settings, airway location, method of delivery (flexible or rigid bronchoscopy), complications (bleeding, death, hypoxia), and outcome of the procedure (successful debulkment and recanalization, stent placement, resolution of bleeding, release of stenosis).

Results: Forty-four patients underwent bronchoscopy using the Nd:YAP laser (24 rigid bronchoscopy, 7 flexible bronchoscopy, 5 flexible through a rigid bronchoscope). All patients with an obstructed airway were recanalized. All 18 patients that had mechanical core out of tumor with a rigid bronchoscope with previous photocoagulations were successful. Airway stent deployment was successful after pretreatment with the laser in all but one case (24 of 25 patients). Two patients with attempted tumor vaporization required additional debulking methods. All 4 cases of tracheal stenosis required additional cutting methods for stenosis release. Two patients with hemoptysis resolved their bleeding after treatment. One of 2 patients with granulation tissue was treated successfully with laser alone. There was no mortality or complication directly related to laser application.

Conclusions: The Nd:YAP laser is a safe and effective tool for bronchoscopy.

Virginia Commonwealth University Medical Center, Division of Pulmonary/Critical Care Medicine, Section of Interventional Pulmonology

Disclosure: No financial support was received for this work. The authors have no conflicts of interest to disclose.

Reprints: Hans Joo Lee, MD, Virginia Commonwealth University Medical Center, PO Box 980050, Richmond, VA 23298-0050 (e-mail: hjlee@vcu.edu).

Received June 7, 2011

Accepted June 15, 2011

Laser treatment during bronchoscopy has been used in the treatment of various tracheobronchial diseases for 30 years.1 It has been particularly successful in treating tumors obstructing central airways and for benign airway stenosis.2,3 Perhaps, its greatest advantage lies in the ability to photocoagulate tissue before mechanical manipulation. This potentially allows for decreased bleeding and greater control of bleeding in the airway during bronchoscopy.

Although there are several forms of laser, the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser is the best described laser for use with bronchoscopy. The Nd:YAG laser emits light at 1064 nm, which is in the infrared portion of the spectrum. The properties of the Nd:YAG laser make it appealing to use in the airway with its ability to photocoagulate or vaporize tumor and cut stenotic lesions.

A laser with similar qualities to the Nd:YAG laser is the neodymium:yttrium-aluminum-perovskite (Nd:YAP) laser. This laser emits light at 1340 nm and thus the Nd:YAP laser is absorbed by water approximately 20 times more avidly than the Nd:YAG laser. The qualities that differentiate the laser properties depend primarily on these differences in wavelength and power. The slightly higher wavelength compared with the Nd:YAG laser may theoretically provide better coagulation and devascularization of lesions by the Nd:YAP laser. This would also suggest theoretically a less effective laser compared with the Nd:YAG for cutting and vaporization.

To our knowledge, there have been no published studies examining the Nd:YAP laser safety and efficacy with bronchoscopy. Other specialties have reported the safety and efficacy with the Nd:YAP laser.4,5 We report our series of patients using the Nd:YAP laser during flexible and rigid bronchoscopy.

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METHODS

Internal review board approval was obtained for a retrospective review of collected data at Virginia Commonwealth University Medical Center. The review encompassed 24 months starting from January 2009 of all flexible and rigid bronchoscopies using the ND:YAP laser (Lokki dt., Vienne, France) by an interventional pulmonologist. The cases were identified through referrals to the Interventional Pulmonary practice at Virginia Commonwealth University Medical Center.

All bronchoscopies using the Nd:YAP laser were performed under general anesthesia in the operating room, using conventional or jet ventilation with a delivered Fio2 <40% during laser treatment. An institutional laser safety protocol was used for all cases. The Nd:YAP laser delivery was through a noncontact method using a gas-cooled fiber and variable pulse duration (0.5 to 1 s) (Fig. 1). The power and repetition rate were variable and decided by the interventional pulmonologist.

FIGURE 1

FIGURE 1

Study data were collected and managed using REDCap (Research Electronic Data Capture) electronic data (CTSA Awared - Award Number UL1RR031990) capture tools hosted at Virginia Commonwealth University.6 The data collected included the indication (photocoagulation before debulkment/rigid core out/stenting, vaporization of tumor or granulation tissue, stenosis, hemoptysis), laser power settings, airway location, method of delivery (flexible or rigid bronchoscopy), complications (bleeding, death, hypoxia), and outcome of the procedure (successful recanalization of the airway, coring out of tumor by rigid bronchoscopy after tumor photocoagulation, airway stent placement, incisional cuts to release the stenosis, or absence of additional ablative methods for vaporization of tumor or granulation tissue destruction).

Complications of the Nd:YAP laser were defined by perforation of the airway, bleeding, hypoxia, or cardiac arrest immediately after laser usage. Bleeding was further categorized as mild, moderate, and severe. Mild bleeding was defined by management with suctioning alone, moderate as requiring additional modalities (ie, cauterization, balloon tamponade) other than suction to control bleeding, and severe as leading to cardiac arrest or hypoxia.

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RESULTS

There were 44 patients that had the Nd:YAP laser used during bronchoscopy. Twenty-four patients had rigid bronchoscopy, 7 patients had flexible bronchoscopy, and 5 patients had a flexible bronchoscope within a rigid bronchoscope as the mode of delivery for the Nd:YAP laser. The most common setting was 20 W/30 Hz (36 patients) followed by 10 W/30 Hz (5), 30 W/30 Hz (2), and 20 W/20 Hz (1). The most common indication for Nd:YAP laser was photocoagulation of tumor before debulkment in 34 patients (Table 1). All 34 patients had their airway successfully recanalized at the end of the bronchoscopy. All 4 cases of tracheal stenosis required a different method to release the stenosis, including electrocautey knife incision and rigid endoscissors. The 2 patients with the intent to vaporize tumor required additional debulking methods (electrocautery, microdebrider, forceps debulkment) to recanalize the airway.

TABLE 1

TABLE 1

Two patients with hemoptysis resolved their bleeding after laser treatment of an endobronchial lesion. Two patients with granulation tissue resulted in 1 patient requiring the laser alone and the other requiring additional forceps for debulkment.

Eighteen patients had a rigid bronchoscopy core out of tumor after pretreatment with Nd:YAP laser cauterization of the tumor. Three of these 18 patients had moderate bleeding postcoring, but all cases were successful in debulking the tumor. Twenty-two of 23 patients had a successful airway stent deployed after using the Nd:YAP laser.

There were 4 complications encountered in the series (Table 2). None of the complications were directly related to the application of the Nd:YAP laser. Three patients had moderate bleeding after rigid bronchoscope coring of tumor. There was 1 patient with a brief cardiac arrest due to an arrhythmia from hypercapnia before stent deployment. In all 4 complications, the core out of a tumor was accomplished successfully. In all 3 moderate bleeding patients, a stent was also placed successfully. The single patient with a cardiac arrest failed to have a planned stent placement due to the arrhythmia and was aborted before deployment. There was no periprocedural mortality, airway perforation, or hypoxia due to the Nd:YAP laser application.

TABLE 2

TABLE 2

There were a total of 56 laser application sites in the 44 patients. The ratio of flexible:rigid applications in various airways were as follows: 2:12 in trachea, 3:9 in right main bronchus, 2:0 in right middle lobe bronchus, 1:4 in bronchus intermedius, 3:0 in right lower lobe bronchus, 3:7 in left main bronchus, 1:5 in left upper lobe, and 4:0 in left lower lobe.

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DISCUSSION

Laser therapy during bronchoscopy is an important therapeutic tool and the use of the Nd:YAG laser has been established by earlier investigators.7–9 As there are now a variety of ablative methods available during bronchoscopy, further characterization of each method or combination of methods would be useful.10 Certainly, a “one tool fits all” model is not realistic, given the variety of clinical scenarios that may present. Knowledge of the optimal tool or combination of tools will be important when performing therapeutic bronchoscopy. Although there have been limited reports from other investigators in case reports and abstracts, to our knowledge, this is the first series to describe the usage of the Nd:YAP laser during bronchoscopy.11–13

In our experience with the Nd:YAP laser, the theoretical physics of the Nd:YAP laser is clinically relevant (Table 3). The higher wavelength of the Nd:YAP and increased absorption of tumor offered good photocoagulation and devascularization of obstructing tumors. The combination of laser photocoagulation followed by mechanical debulkment was highly successful in our series; all 34 patients had successful debulkment and patency restored of the airway. Although there was moderate bleeding reported in 3 of 34 patients after using this method, we suspect the number of moderate and possibly severe bleeding would have been significantly higher if laser devascularization was not accomplished before mechanical debulkment.

TABLE 3

TABLE 3

The failure of the Nd:YAP laser to be the sole instrument for managing tracheal stenosis and vaporization of tumor was also consistent with the theoretical disadvantages of the Nd:YAP compared with other lasers in cutting/vaporization. In these cases, lasers with a shorter wavelength (ie, KPC or Excimer) may provide better cutting and vaporization. In addition, the absorption and scatter of energy by benign tissue may play a role in the effectiveness of the Nd:YAP laser. A bare cutting fiber is also available for the Nd:YAP laser but was used only once in our series unsuccessfully for tracheal stenosis.

The optimal delivery of the laser through flexible versus rigid bronchoscopy has been controversial.14 In our series, both modes of delivery were equally safe with no direct complications in both groups. The predominant mode was rigid bronchoscopy for the larger proximal airways. This was to facilitate a rigid coring of central tumors. However, for the distal segments such as the bilateral lower lobe and middle lobe bronchus, the laser was applied solely by flexible bronchoscopy. The flexible bronchoscope allowed easier access to the more distal airways that may require greater angulation compared with the rigid bronchoscope. The optimal delivery of the laser is primarily determined by the anatomic location and the need for rigid bronchoscopy debulking.

The obvious weakness of our series is its retrospective nature. In addition, because we did not compare the Nd:YAP with other ablative instruments (ie, electrocautery, cryotherapy, Nd:YAG), it is not known whether other modalities would have performed better or worse than the Nd:YAP. To our knowledge, there has not been a direct comparison of bronchoscopic ablative technologies. Our goal was to describe our success and shortcomings with using the Nd:YAP laser and not to make direct comparisons. There were a small number of patients who had tracheal stenosis, laser vaporization of tumor, and granulation tissue, which makes convincing conclusions difficult. It seems that the Nd:YAP did not perform as well in these groups, but larger studies comparing the Nd:YAP for these indications and other ablative tools will be needed.

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CONCLUSIONS

The Nd:YAP laser is an effective tool for debulking tumor during flexible and rigid bronchoscopy, especially photocoagulation.

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REFERENCES

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Keywords:

Nd:YAP; laser; bronchoscopy

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