Comparative ex vivo Investigations on the Cutting Quality of the CO2 Laser and the Diode Pumped Er:YAG Laser

Holger Wurm; Patrick Johannes Schuler; Florian Hausladen; René Graesslin; Thomas Karl Hoffmann; Karl Stock; Elisabeth Friederike Reins

doi:10.3389/fsurg.2021.764450

Comparative ex vivo Investigations on the Cutting Quality of the CO₂ Laser and the Diode Pumped Er:YAG Laser

Front Surg. 2021 Dec 14:8:764450. doi: 10.3389/fsurg.2021.764450. eCollection 2021.

Authors

Holger Wurm¹, Patrick Johannes Schuler², Florian Hausladen¹, René Graesslin², Thomas Karl Hoffmann², Karl Stock¹, Elisabeth Friederike Reins²

Affiliations

¹ Institut für Lasertechnologien in der Medizin und Meßtechnik, Ulm University, Ulm, Germany.
² Department of Otorhinolaryngology, Head and Neck Surgery, Ulm University Medical Center, Ulm, Germany.

Abstract

Objectives: A sufficient histological evaluation is a key pillar in oncological treatment, especially in situations of cancer of unknown primary. CO2 laser technology is used in clinical routine of soft tissue surgery because of its cutting quality and availability. Diode pumped solid state Er(bium):YAG laser systems promise a higher cutting efficiency and minor thermal damages. The aim of this study was to compare both laser systems with respect to their suitability for cutting soft tissue. Methods: A setup was realized which enables comparable experiments with the clinical CO₂ laser (AcuPulse 40ST DUO, Lumenis) and the Er:YAG laser system (DPM 40, Pantec Biosolutions AG). Fresh mucosal samples of porcine tongues were used to determine the influence of laser power and sample velocity on cutting depth and thermal damage width for both lasers. In addition, for the Er:YAG laser, the influence of the pulse repetition rate was examined additionally. For analysis, images of histological sections were taken. Results: In all experiments, the Er:YAG laser shows a significantly higher cutting depth (P < 0.0001) and less thermal damage width (P < 0.0001) than the CO₂ laser. For example, at an average power of 7.7 W and a sample velocity of 5 mm/s the Er:YAG laser shows a mean cutting depth of 1.1 mm compared to the CO₂ laser with 500 μm. While the Er:YAG laser shows a mean thermal damage width of 70 μm compared to 120 μm. Furthermore, the Er:YAG enables the adjustment of the cutting depth and thermal damage width by varying the irradiation parameters. A decrease of the repetition rate leads to a reduction of thermal damage. For example, a repetition rate of 100 Hz results in a thermal damage width of 46 μm compared to 87 μm at 800 Hz at an average power of 7.7 W and a cutting velocity = 5 mm/s while a homogenous cutting quality can be achieved. Conclusions: In conclusion, the results of these ex vivo experiments demonstrate significant advantages of the diode pumped Er:YAG laser system for soft tissue ablation compared to the CO₂ laser, in particular regarding cutting efficiency and thermal damage width.

Keywords: 2.94 μm; CO2 laser; Er:YAG laser; diode pumped; head and neck surgery; high repetition rate; oncology.