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.

Microlaryngeal Laser Surgery Using High-flow Nasal Ventilation at Two Oxygen Concentration Deliveries.

OBJECTIVES: Ventilation using 100% oxygenation creates a risk of fire during laser microlaryngeal surgery (MLS). The purpose of this study is to describe the technique of transnasal high-flow ventilation using laser safe (30%) oxygen conditions, measure the intraoperative real-time laryngeal oxygen concentration, and examine patient saturation status using this technique. METHODS: Prospective IRB approved study of patients undergoing tubeless laser MLS using high-flow nasal oxygenation. Delivered oxygen concentration was reduced from 100% to 30% before lasering using an oxygen-air blender then increased to 100% post-laser procedure. Outcome measures included time for laryngeal oxygen concentration to equalize to laser safe levels; time to, methods of and duration of rescue ventilation; and desaturation rates and apnoeic times at both 100% and 30% oxygen deliveries. RESULTS: Fifty patients were recruited (mean age = 47.4 years). Mean laryngeal oxygen concentration (%) at 100% and 30% deliveries was 98.46 and 31.45, respectively. Mean (SD) of laryngeal oxygen concentration equalization time to 30% (seconds) was 9.4 (3.69). At 30% oxygen delivery desaturation rate was faster and apneic time shorter compared with 100%. Eighteen patients required rescue (jet) ventilation and they had a faster apneic desaturation rate (%/minute) than patients not requiring rescue. Mean (SD) apneic time (minutes) at 30% delivery was 4.56 (2.25) and 4.41 (2.18) in rescue versus non-rescue groups respectively. BMI was the only significant predictor of desaturation rate at 30% oxygen delivery. CONCLUSION: It is possible to achieve a safe time window for use of laser during MLS using transnasal humidified high-flow ventilation by delivering 30% oxygen concentration. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:634-639, 2023.

Telehealth voice assessment by speech language pathologists during a global pandemic using principles of a primary contact model: an observational cohort study protocol.

INTRODUCTION: SARS-CoV-2, a highly contagious severe acute respiratory syndrome, has spread to most countries in the world and resulted in a change to practice patterns for the assessment and diagnosis of people with voice disorders. Many services are transitioning to telehealth models to maintain physical distancing measures and conserve personal protective equipment used by healthcare workers during laryngoscopy examinations. The speech-language pathology primary contact (SLPPC) assessment for patients referred to ear, nose and throat (ENT) services in Australia has been shown to reduce waiting times for assessment while streamlining access to ENT assessment and allied health practitioner treatment pathways. METHODS AND ANALYSIS: A prospective observational cohort study will see patients in a newly developed telehealth model which uses the principles from a usual care SLPPC assessment protocol. Participants will be offered an initial telehealth assessment (speech-language pathology primary contact telehealth (SLPPC-T)) prior to being prioritised for a face-to-face laryngoscopy assessment to complete the diagnostic process. The telehealth assessment will collect sociodemographic information, personal and family medical history, key symptoms, onset and variability of symptoms, red-flag signs or symptoms for laryngeal malignancy, and clinical voice assessment data for auditory-perceptual and acoustic analysis. The study outcomes include (1) association of signs, symptoms and specific voice measures collected during SLPPC-T with voice disorder classification provided after laryngoscopy; (2) degree of concordance between voice disorder classification after SLPPC-T and after laryngoscopy; (3) health service and patient-related costs and health outcomes of the SLPPC-T; (4) patient and stakeholder views and beliefs about the SLPPC-T process. ETHICS AND DISSEMINATION: Ethical approval has been granted prior to commencement of the study enrolment by the Gold Coast Hospital and Health Service Human Research Ethics Committee (reference number HREC/2020/QGC/62832). Results will be shared through the publication of articles in peer-reviewed medical journals and presentation at national and international scientific meetings. TRIAL REGISTRATION NUMBER: ACTRN12621000427875.

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.

A laryngographic and laryngoscopic study of Northern Vietnamese tones.

A laryngographic and laryngoscopic study of tone production in Northern Vietnamese, a language whose tones combine both fundamental frequency (f0) modulations and voice qualities (phonation types), was conducted with 5 male and 5 female speakers. Results show that the f0 contours of Northern Vietnamese tones are not only attributable to changes in vocal fold length and tension (partly through changes in larynx height), but that f0 drops are also largely caused by the glottal configurations responsible for the contrastive voice qualities associated with some of the tones. We also find that voice quality contrasts are mostly due to glottal constriction: they occasionally involve additional ventricular fold incursion and epiglottal constriction, but these articulations are usually absent.