Value and utility of 532 nanometre pulsed potassium-titanyl-phosphate laser in endoscopic laryngeal surgery

Photoangiolysis with the 445-nm Blue Laser and the Potassium-Titanyl-Phosphate Laser: A Comparison

OBJECTIVES

Photoangiolytic lasers have yielded significant innovation in laryngeal surgery in the last 25 years. After the discontinuation of the potassium titanyl phosphate (KTP) laser, a novel 445-nm blue laser was developed. The optimal balance between a laser's desired tissue effects and collateral tissue damage is a major determinant of laser selection in microlaryngeal surgery. The shell-less incubation system for the chick chorioallantoic membrane (CAM) simulates the microvasculature of the human vocal fold and is useful for testing effects of laser settings and in simulated surgery. The aim of this study is to compare the tissue effects of the KTP and blue lasers using the shell-less CAM model.

METHODS

The shell-less incubation system contains: polymethylpentene film (used as a culture vessel), calcium lactate and distilled water supplementations. By using this system, the chick chorioallantoic membrane (CAM) can be fully exposed with a good field for surgery simulation. The effects of the 2 lasers (532 nm KTP and 445 nm blue) were quantified at clinically relevant energy settings and laser distances from target. Measures included imaging real-time vascular reactions in the CAM model, post-procedure histologic analysis of CAM tissue and temperature changes.

RESULTS

Vessel coagulation and rupture rates were less common with the blue laser compared with the KTP laser. Histologic analysis demonstrated less tissue disruption with the blue laser. Temperature changes were less with the blue laser.

CONCLUSION

In this CAM model with specific conditions, the blue laser reveals less tissue damage than the KTP laser. Suitable working distance and power setting of the laser are necessary for desired tissue effects.Level of Evidence: Level 3.

Prospective Outcomes of Microlaryngoscopy Versus Office Laser Photoangiolysis for Vocal Fold Polyps

OBJECTIVE(S)

The objective of this study is to compare treatment outcomes for vocal fold polyps (VFPs) between operating room microlaryngoscopy and office-based photoangiolysis with the potassium titanyl phosphate (KTP) laser.

METHODS

Prospective nonrandomized cohort study of patients with VFPs undergoing microlaryngoscopy ("OR group") or KTP laser photoangiolysis ("KTP group"). Voice outcomes (patient-reported outcome measures [Voice Handicap Index-10 (VHI-10) and Singing VHI-10 (SVHI-10)], auditory-perceptual measures [Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V)], videostroboscopic characteristics [Voice-Vibratory Assessment of Laryngeal Imaging (VALI)], and acoustic and aerodynamic measures) were performed at baseline and regular intervals after intervention.

RESULTS

Forty-four subjects (17 OR group, 27 KTP group) with VFPs were enrolled. Mean VHI-10 significantly improved from baseline to each follow-up interval in both groups, except for the 1-2-week interval in the OR group. Mean SVHI-10 improved for both groups at some intervals. Growth curve models and time-to-event analyses for patient-reported outcomes did not differ between groups. There were significant improvements in all categories of auditory-perceptual voice quality and some categories of videostroboscopic characteristics in both groups. No significant trends were identified in acoustic and aerodynamic measures. Improvements in most outcomes did not significantly differ between groups or based on polyp size. There were no major complications.

CONCLUSIONS

Significant improvements in patient-reported voice outcomes measures, auditory-perceptual voice evaluation, and videostroboscopic characteristics occur following surgical treatment of vocal fold polyps with either microlaryngoscopy or office-based KTP laser. Long-term voice outcomes do not significantly differ between treatment modalities.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:S1-S20, 2024.

Comparison of Angiolytic Effects Between the 445-nm Blue Laser and 532-nm Pulsed KTP Laser

OBJECTIVE

This study aimed to compare the selective absorption of the 445-nm Blue laser (BL) and the 532-nm pulsed potassium-titanyl-phosphate (KTP) laser by blood vessels.

METHODS

Thirty-six chicken eggs at day 14 of incubation were dissected to expose the chick chorioallantoic membrane (CAM). Third-order vessels of the CAM were identified and irradiated using BL and KTP lasers using various settings at a laser-to-vessel distance of 3 mm using 0.4 mm fiber size. In total, 494 vessels segments were irradiated. Mean (standard deviation) number of irradiations for each setting was 26.0 (4.6), range from 15 to 39. Outcome measures included ablation rate (AR) and rupture rate (RR).

RESULTS

The two lasers were compared for AR and RR at long and medium pulse width (PW) associated with different power levels. At long PW (above 100 ms), BL showed significantly higher AR than KTP at high energy (600 mJ/pulse) and low energy (400 mJ/pulse); they did not show different AR and RR at medium energy levels (500 mJ/pulse). Using medium PW settings plus high and medium energy levels, BL and KTP showed relatively high AR and did not significantly differ in performance. However, at medium PW plus low energy (400-450 mJ/pulse), KTP showed significantly higher AR compared to BL.

CONCLUSION

At long PW, BL appeared to show higher AR than KTP at high or low energy levels, but they showed equivalent performance at medium energy. At medium PW, both performed similarly from high to medium energy, but KTP appeared to perform better than BL at lower energy settings.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:3220-3225, 2024.

Surgical outcome of different surgical modalities for adult recurrent respiratory papillomatosis

BACKGROUND

Surgical debulking remains the mainstay of treatment of adult-onset recurrent respiratory papillomatosis (AO-RRP). But there are no guidelines for decision-making of surgical modality.

OBJECTIVES

This retrospective study aims to obtain a better understanding of AO-RRP, and select the best surgical modality for RRP among microdebrider, CO₂ laser, and KTP laser.

MATERIAL AND METHODS

Medical records of 72 AO-RRP patients were reviewed, with at least a 6-month follow-up. We focused on demographic data, the median treatment intervals (MTI) (Days), the survival curves, and treatment-related complications.

RESULTS

Seventy-two AO-RRP and a total of 172 surgical procedures were included, with either the microdebrider (n = 46), CO₂ laser (n = 102), or KTP laser (n = 24). The MTI of all patients was 230.0[132.0, 455.0] (median[P25-P75]), with microdebrider group (267.50[152.5, 449.5]), CO₂ laser group (247.5[145.5, 474.7]), and KTP laser group (107.5[68.3, 330.5]), and there were no significant differences among three surgical modalities on MTI or survival curves (p > .05). The duration of surgery was 44.9[25.6] in the microdebriders group, 48.4 [29.5] in the CO2 laser group, and 51.3[18.4] in the KTP laser group, but there was no significant difference in the operation duration among the three groups (p > .05). Postoperative glottic webs and scar formations were found in 4.3% of patients in microdebrider group, 16.7% of patients in CO₂ laser group, and 8.3% of patients in KTP group.

CONCLUSION AND SIGNIFICANCE

Microdebrider surgery for RRP took the shortest time and had the lowest rate of postoperative complications. However, different surgical modalities are equally effective in controlling recurrence after RRP surgery.

Safety of different surgical modalities for recurrent respiratory papillomatosis resection: A systematic review and meta-analysis

BACKGROUND

Currently, the most common surgical modalities used for recurrent respiratory papillomatosis (RRP) resection are microdebrider, carbon dioxide (CO₂ ) laser and potassium-titanyl-phosphate (KTP) laser. However, complication rates vary among different surgical modalities and have been controversial in different studies.

OBJECTIVE OF REVIEW

This study systematically reviews the available studies which reported intra-operative and post-operative complications, aiming to compare the safety of microdebrider, CO₂ laser and KTP laser.

TYPE OF REVIEW

Meta-analysis.

SEARCH STRATEGY

Seven electronic databases (PubMed/MEDLINE, EMBASE[Ovid], Scopus, Cochrane Library and Web of Science) were searched from inception through 28 April 2022. Randomised controlled, prospective or retrospective observational studies that recorded the complications of three different surgical modalities for RRP resection were included in the meta-analysis.

EVALUATION METHOD

Outcomes of interest were intra-operative and post-operative complications, and complication rate was calculated to evaluate the safety of surgical methods.

RESULTS

Twenty different studies were included in quantitative synthesis. Only one study compared outcomes of those three kinds of treatment modalities simultaneously, two studies compared microdebrider and CO₂ laser, and the remaining studies focussed on only one of three treatments. The weighted average complication rate for microdebrider was 0.03 (95% confidence interval [CI] 0.00-0.21), n = 6, for CO₂ laser treatment was 0.16 (95% CI 0.09-0.25), n = 14 and for KTP laser treatment was 0.04 (95% CI 0.00-0.14), n = 4.

CONCLUSION

The limited evidence demonstrated that CO₂ lasers in the surgical treatment of RRP may lead to more surgical complications, and microdebrider and KTP lasers may be safer. However, the heterogeneous data limit any strong comparison of outcomes of different treatment of laryngeal papillomas. Future randomised controlled trials that directly compare the safety of different surgical modalities are needed.

Use of 532 nm Potassium Titanyl Phosphate Laser on Vocal Fold Scars Under Topical Anesthesia: A Pilot Study

OBJECTIVE

This pilot study aims to evaluate the efficacy of 532 nm potassium titanyl phosphate (KTP) laser under topical anesthesia in patients with vocal fold scars.

METHODS

A series of 18 patients with vocal fold scars of varying degrees were treated. The KTP laser was used under local anesthesia in the outpatient clinic. It was set to deliver 6 W of power using a continuous output mode. Close-to-contact mode was used for laser irradiation, and contact mode was used for ablation and excision of the lesions. Some of the patients received laser scar ablation on both vocal folds; the scarred vocal fold on one side and the hypertrophic vocal fold on the other. Parameters include glottic closure, amplitude, and mucosal wave pattern were measured using laryngeal stroboscopic examination. Aerodynamic and voice evaluations were carried out using maximum phonation time (MPT), jitter, shimmer, Voice Handicap Index questionnaire (VHI-30), and GRBAS scale.

RESULTS

In total, 21 surgeries were performed on 18 patients. Glottic closure, amplitude, and mucosal wave pattern showed improvement 2 months postoperatively (P < .05). There was significant improvement in the postoperative scores for VHI-30, VHI-emotional sub-scale, VHI-physical sub-scale, and GRBAS (P < .05). There was no significant difference in the MPT and VHI-functional sub-scale before and after the operation (P > .05). Re-adhesion of the anterior commissure was observed in 2 patients with Type III scars.

CONCLUSION

The 532 nm KTP laser is an effective tool for the treatment of vocal fold scars. Further research is required to determine if serial laser applications could improve outcomes for this challenging condition.

LEVEL OF EVIDENCE

Level IV.

Effects of 445-nm Laser on Vessels of Chick Chorioallantoic Membrane with Implications to Microlaryngeal Laser Surgery

Objective

Previous research has shown that effective application of angiolytic lasers in microlaryngeal surgery is determined by wavelength, pulse width (PW), and fluence. Recently, a 445‐nm (blue) laser (BL) has been developed with a potentially greater hemoglobin absorption than previous lasers. The chick chorioallantoic membrane (CAM) represents a suitable model for testing various settings to find out the most optimal settings of this laser. This study used the CAM model to examine whether successful photoangiolytic effects could be obtained using BL.

Methods

Seven hundred and ninety three third‐order vascular segments of viable CAM were irradiated using BL via 400‐μm diameter fiber, 1 pulse/second, with PW and power varied systematically at standardized fiber‐to‐vessel distances of 1 and 3 mm. Outcome measures including vessel ablation rate (AR), rupture rate (RR), and visible tissue effects were analyzed using Chi‐square test.

Results

Energy levels of 400, 540, and 600 mJ (per pulse) were most effective for vessel ablation. A working distance of 3 mm resulted in higher ablation and less vessel rupture compared with 1 mm at these optimal energy levels. At 3 mm, a longer PW resulted in higher AR. At 1 mm, AR increased with shorter PW and higher power. The 1‐mm working distance resulted in lower tissue effects than 3 mm.

Conclusion

Findings in this study showed that BL was effective in vessel ablation using relevant combination of working distance, PW, and energy levels. To obtain high AR, longer working distance plus longer PW was required and if working distance was reduced, shorter PW should be set.

Level of Evidence

NA Laryngoscope, 131:E1950–E1956, 2021

Implication and Management of Incidental Oropharyngeal Papillomas-A Retrospective Case Series Review

INTRODUCTION

Incidental papillomas of the pharynx can be found while examining the nasopharynx, oropharynx, and hypopharynx for other disorders of the head and neck. Purpose of the study is to explore the location, biopsy protocol, and decision to perform office-based versus operative management via potassium titanyl phosphate (KTP) laser when an oropharyngeal papilloma is discovered incidentally.

METHODS

A retrospective review of the senior author's patient population was performed using Current Procedural Terminology and/or International Classification of Diseases codes to identify patients who had KTP laser removal of incidental oropharyngeal papillomas. Patients were included based on the incidental nature of the papilloma and confirmed pathology report of squamous papilloma. Demographics, presenting complaint, lesion location, pathological analysis, type of intervention, and outcomes were recorded. When available, human papillomavirus (HPV) subtype was noted.

RESULTS

A total of 26 cases were identified, 13 females and 13 males. The median age at time of surgery was 58 years (range: 21-77). The most common presenting symptoms were difficulty swallowing and throat pain. The most common locations were the base of tongue, uvula, tonsils, and the soft palate. Of the 26 patients, 23 patients received KTP laser ablation therapy as an office-based procedure, while the remaining 3 were performed under general anesthesia in the operating room. Only 5 patients had a recorded recurrence that required reoperation. There were no operative or postoperative complications. There were 16 biopsy samples tested for HPV, where 12 were negative for HPV and 4 were positive for HPV.

CONCLUSION

Oropharyngeal papillomas, when present, can be found incidentally during examination of the oropharynx for other symptoms. Office-based biopsy and KTP laser is a safe and efficient means of identifying and removing most oropharyngeal papillomas.

Carbon debris and fiber cleaving: Effects on potassium-titanyl-phosphate laser energy and chorioallantoic membrane model vessel coagulation

OBJECTIVES/HYPOTHESIS

Photoangiolytic precision afforded by the 532-nm potassium-titanyl-phosphate (KTP) laser relies on predictable energy delivery. Inadequate energy output can cause vessel rupture, and excessive energy can cause thermal damage. The quality of the cleaved surface and carbon deposits from ablated tissue are two factors that could negatively impact fiber performance. The effects of these on energy output and blood vessel coagulation were assessed using a chorioallantoic membrane (CAM) model.

STUDY DESIGN

Comparative analysis.

METHODS

Laser fibers with carbon debris, optimal fiber cleaving, and suboptimal cleaving were inspected at three times magnification, and the light dispersion pattern of each fiber was rated. The average energy output from consecutive pulses through each fiber configuration was recorded. The effect of these fiber conditions on clinical efficacy was estimated by measuring vessel coagulation versus rupture in the CAM model. Repeated measures analysis of variance compared results.

RESULTS

Carbon debris and suboptimal cleaving resulted in decreased energy output in comparison to optimal cleaving ([-Δ244 mJ, d = 4.31, P < .001] and [-Δ195 mJ, d = 6.04, P < .001]). Optimal cleaving resulted in immediate coagulation of vessels. Fibers with suboptimal cleaving and carbon debris had unpredictable outcomes, requiring multiple pulses for coagulation or causing vessel rupture.

CONCLUSIONS

KTP laser fiber function is significantly affected by fiber tip condition. Carbon debris and suboptimal cleaving create significant attenuation of energy, which results in an unpredictable angiolytic effect, as demonstrated by increased vessel rupture in the CAM model. Optimal recleaving of KTP laser fibers restores prior energy output and predictable coagulation. Care should be taken to avoid carbon debris on laser-fiber tips and to cleave fibers properly.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2244-2248, 2019.

The Art and Craft of Phonomicrosurgery in Grammy Award–Winning Elite Performers

Background:

Since the renowned opera maestro Manuel Garcia presented “Observations on the Human Voice” using mirror laryngoscopy in 1855, there has been an inextricable link between performing vocalists and laryngologists. Today, specialized laryngeal surgeons continue the tradition of integrating medical and surgical management of performers with those skilled in vocal arts, voice science, and voice therapy. With advances in surgical instrumentation and techniques, increasing opportunities have evolved to surgically restore lost performing voices. However, it is especially challenging because of a range of factors, including the need for optimal technical precision, management of expectations, complexity of informed consent, public visibility of these patients, and the economics related to the success and failure of surgery. A number of these key issues apply to phonomicrosurgical procedures in nonsingers as well. Consequently, reviewing the art and craft of phonomicrosurgery in elite performers provides valuable insights into the optimal management of any patient.

Methods:

A retrospective review was done of microlaryngeal procedures for the past 20 years, and 18 elite performers were identified who were Grammy Award winners. Microsurgical methods for different lesions are illustrated. Composite analyses of the group along with their associated pathology was done to provide insights into key issues.

Results:

The 18 patients in this cohort have won 80 Grammy Awards, which were garnered from 242 nominations. All 18 had substantial deterioration in voice quality and could retain more than 1 pathology. Significant loss of superficial lamina propria (SLP) pliability was present in 15 of 18, varices and/or ectasias leading to vocal hemorrhage in 6, vocal polyps in 9, fibrovascular nodules in 6, arytenoid granuloma in 1, sulcus from prior microlaryngeal surgery leading to vocal fold SLP scarring in 4, sulcus from long-term phonotrauma leading to vocal fold SLP scarring in 4, benign cyst in 1, precancerous dysplasia in 2, and invasive carcinoma in 2. Subsequent to phonomicrosurgery, all reported improvement in their performance.

Conclusions:

Laryngologists and laryngeal surgeons have shouldered a burden of responsibility for elite performing vocalists since the origin of our specialty. Most lesions and diagnoses that are encountered result from phonotrauma. Optimizing singers’ care provides surgeons with extremely complex technical, emotional, social, and financial challenges. Focused analysis of managing elite performing vocalists effectively integrates a range of essential issues, which provide key insights to assist clinicians treating nonperforming patients requiring phonomicrosurgery.

Treatment of early-stage laryngeal cancer: A comparison of treatment options

Over the course of the last several decades, the treatment options for early laryngeal cancers (T1 and T2) have evolved; however, simultaneously the mortality rate has increased. As larynx preservation approaches have become the standard of care, the selection of the proper treatment modality has become paramount. Radiation therapy or transoral laser microsurgery are the most common options for treatment of these early lesions. Oncologic and functional outcomes are considered equivalent between the two modalities for early glottic cancers; however, no direct comparisons exist for robust analysis. In terms of larynx preservation, there also is not compelling data favoring one treatment option or another. For early stage lesions, the goal for any larynx-sparing technique, either radiation or surgery, should be the intent to cure with single modality treatment and minimal short- and long-term toxicity. This article is designed to create a frame of reference for managing early stage disease with respect to lesions of the glottis and supraglottis while weighing treatment implications from an oncologic, functional, and cost perspective.

Current and future management of recurrent respiratory papillomatosis

Objectives

Recurrent respiratory papillomatosis (RRP) is a chronic disease of the respiratory tract that occurs in both children and adults. It is caused by the human papillomavirus (HPV), in particular low‐risk HPV6 and HPV11, and aggressiveness varies among patients. RRP remains a chronic disease that is difficult to manage. This review provides perspectives on current and future management of RRP.

Results

The current standard of care is surgical excision, with adjuvant therapies as needed. Surgical management of RRP has evolved with the introduction of microdebriders and photoangiolytic lasers; the latter can now be used in the office setting. Numerous adjuvant pharmacologic therapies have been utilized with some success. Also, exciting preliminary data show that HPV vaccines may prolong the time to recurrence in the RRP population. There is also optimism that wide‐spread HPV vaccination could reduce RRP incidence indirectly by preventing vertical HPV transmission to newborns.

Conclusion

To date, the biology of RRP is not well understood, although it has been noted to become more aggressive in the setting of immune suppression. Additional research is needed to better understand immune system dysfunction in RRP such that immunomodulatory approaches may be developed for RRP management.

Level of Evidence

4

KTP 532 nm laser for laryngeal lesions. a systematic review

OBJECTIVE

To evaluate the effectiveness and safety of the 532 nm potassium titanyl phosphate (KTP) laser for vocal fold surgery.

STUDY DESIGN

Systematic literature review.

METHODS

Our systematic review was conducted using the meta-analysis of observational studies in epidemiology guidelines. We applied the criteria of the Oxford Centre for Evidence-based Medicine to assess the level of evidence.

RESULTS

We identified seven observational studies of eight case series, which reported a total of 243 KTP procedures carried out for vocal fold lesions: two series each concerning ectasias and varices, early glottic cancer, and recurrent papillomatosis, and one series each for keratosis with dysplasia and various benign laryngeal pathologies. There was also a retrospective review of the use of KTP laser in 387 endoscopic laryngeal surgeries. No studies compared the use of KTP laser with that of other technologies. Thus, according to the Oxford criteria, there is only level 4 evidence of KTP's efficacy and safety. In selected cases, the KTP instrument can be used without general anesthesia in the clinic setting.

CONCLUSIONS

The use of KTP laser for laryngeal surgery is still relatively innovative. Several surgeons have found KTP laser to be the equivalent of, or superior to, the CO2 or pulsed dye lasers, and none have reported inferiority. However, there are currently no published data to support these conclusions. To establish equality/superiority, it is desirable that further evidence of efficacy and safety be obtained, either through randomized controlled trials or at least through well-documented prospective observational studies with reporting of all relevant input and outcome data.