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

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.

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

Use of the KTP laser in totally endoscopic cholesteatoma surgery

OBJECTIVE

This paper reviews our experience of potassium titanyl phosphate (KTP) laser in transcanal totally endoscopic cholesteatoma surgery.

METHODS

A prospective cohort study was conducted in a tertiary referral centre, involving a consecutive series of children with cholesteatoma who underwent totally endoscopic cholesteatoma surgery with a KTP laser.

RESULTS

The patients' mean age was 10.5 years (range, 1.8-18 years). A KTP laser was used in 70 of the 83 cases (84 per cent). The laser was not used in 13 'clean' cases, in which disease was removed more easily. Residual disease was detected in five cases (6 per cent), of which the KTP laser had been used in four (5 per cent). No complications were associated with KTP laser use.

CONCLUSION

The combination of KTP laser use with endoscopic visualisation is effective for minimising the risk of residual disease using a minimally invasive surgical approach. The thin, semi-flexible fibre carrier of the KTP laser is ideally suited to work alongside the endoscope within the narrow confines of the ear canal.