Reduction of thermocoagulative injury via use of a picosecond infrared laser (PIRL) in laryngeal tissues.

The carbon dioxide (CO2) laser is routinely used in glottic microsurgery for the treatment of benign and malignant disease, despite significant collateral thermal damage secondary to photothermal vaporization without thermal confinement. Subsequent tissue response to thermal injury involves excess collagen deposition resulting in scarring and functional impairment. To minimize collateral thermal injury, short-pulse laser systems such as the microsecond pulsed erbium:yttrium-aluminium-garnet (Er:YAG) laser and picosecond infrared laser (PIRL) have been developed. This study compares incisions made in ex vivo human laryngeal tissues by CO2 and Er:YAG lasers versus PIRL using light microscopy, environmental scanning electron microscopy (ESEM), and infrared thermography (IRT). In comparison to the CO2 and Er:YAG lasers, PIRL incisions showed significantly decreased mean epithelial (59.70 µm) and subepithelial (22.15 µm) damage zones (p < 0.05). Cutting gaps were significantly narrower for PIRL (133.70 µm) compared to Er:YAG and CO2 lasers (p < 0.05), which were more than 5 times larger. ESEM revealed intact collagen fibers along PIRL cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 and Er:YAG laser incisions. IRT demonstrated median temperature rise of 4.1 K in PIRL vocal fold incisions, significantly less than for Er:YAG laser cuts (171.85 K; p < 0.001). This study has shown increased cutting precision and reduced lateral thermal damage zones for PIRL ablation in comparison to conventional CO2 and Er:YAG lasers in human glottis and supraglottic tissues.

Use of a microsecond Er:YAG laser in laryngeal surgery reduces collateral thermal injury in comparison to superpulsed CO2 laser.

Despite causing significant thermocoagulative insult, use of the carbon dioxide (CO2) laser is considered gold standard in surgery for early stage larynx carcinoma. Limited attention has been paid to the use of the erbium:yttrium-aluminium-garnet (Er:YAG) laser in laryngeal surgery as a means to reduce thermal tissue injury. The objective of this study is to compare the extent of thermal injury and precision of vocal fold incisions made using microsecond Er:YAG and superpulsed CO2 lasers. In the optics laboratory ex vivo porcine vocal folds were incised using Er:YAG and CO2 lasers. Lateral epithelial and subepithelial thermal damage zones and cutting gap widths were histologically determined. Environmental scanning electron microscopy (ESEM) images were examined for signs of carbonization. Temperature rise during Er:YAG laser incisions was determined using infrared thermography (IRT). In comparison to the CO2 laser, Er:YAG laser incisions showed significantly decreased epithelial (236.44 µm) and subepithelial (72.91 µm) damage zones (p < 0.001). Cutting gaps were significantly narrower for CO2 (878.72 µm) compared to Er:YAG (1090.78 µm; p = 0.027) laser. ESEM revealed intact collagen fibres along Er:YAG laser cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 laser incisions. IRT demonstrated absolute temperature rise below 70 °C for Er:YAG laser incisions. This study has demonstrated significantly reduced lateral thermal damage zones with wider basal cutting gaps for vocal fold incisions made using Er:YAG laser in comparison to those made using CO2 laser.

A novel tool in laryngeal surgery: preliminary results of the picosecond infrared laser.

OBJECTIVES/HYPOTHESIS: Conventional lasers ablate tissue through photothermal, photomechanical, and/or photoionizing effects, which may result in collateral tissue damage. The novel nonionizing picosecond infrared laser (PIRL) selectively energizes tissue water molecules using ultrafast pulses to drive ablation on timescales faster than energy transport to minimize collateral damage to adjacent cells. STUDY DESIGN: Animal cadaver study. METHODS: Cuts in porcine laryngeal epithelium, lamina propria, and cartilage were made using PIRL and carbon dioxide (CO2) laser. Lateral damage zones and cutting gaps were histologically compared. RESULTS: The mean widths of epithelial (8.5 µm), subepithelial (10.9 µm), and cartilage damage zones (8.1 µm) were significantly lower for cuts made by PIRL compared with CO2 laser (p < 0.001). Mean cutting gaps in vocal fold (174.7 µm) and epiglottic cartilage (56.3 µm) were significantly narrower for cuts made by PIRL compared with CO2 laser (P < 0.01, P < 0.05). CONCLUSION: PIRL ablation demonstrates superiority over CO2 laser in cutting precision with less collateral tissue damage.