Tissue tearing caused by pulsed laser-induced ablation pressure

Area of Science:

• Biomedical Engineering
• Laser Physics
• Tissue Mechanics

Background:

• Laser ablation is a key technique in various medical procedures.
• Understanding the physical forces during laser-tissue interaction is crucial for safety and efficacy.
• Previous studies have explored laser effects, but precise pressure-tissue strength correlations require further investigation.

Purpose of the Study:

• To quantify the ablation pressure generated during Er:YSGG laser irradiation of biological tissues.
• To correlate measured ablation pressures with the observed mechanical disruption of skin, liver, and aorta.
• To elucidate the mechanism of tissue damage based on pressure thresholds.

Main Methods:

• Utilized a ballistic pendulum to measure recoil momentum and calculate ablation pressure during Er:YSGG laser irradiation.
• Irradiated samples of skin, liver, and aorta.
• Performed gross and microscopic examination of ejected material and ablation craters.
• Employed a gas-dynamic model to interpret laser-induced vaporization and pressure generation.

Main Results:

• Ablation pressure was successfully calculated for Er:YSGG laser irradiation of skin, liver, and aorta.
• Direct correlation observed between laser-induced ablation pressure and the extent of mechanical tissue disruption.
• Mechanical disruption was consistently observed when ablation pressure exceeded the intrinsic strength of the tissue at specific weak points.

Conclusions:

• Laser ablation pressure is a critical factor in the mechanical disruption of biological tissues.
• The findings provide a quantitative basis for understanding laser-tissue interactions and predicting tissue damage.
• This research informs the safe and effective application of Er:YSGG lasers in surgical and therapeutic settings.