Laser operator duty cycle effect on temperature and thermal dose: in-vitro study.

Area of Science:

• Urology
• Medical Devices
• Biomedical Engineering

Background:

• High-power laser lithotripsy poses a risk of thermal injury to the urinary tract.
• Temperature elevation during laser lithotripsy is influenced by power settings and operator duty cycle (ODC).
• Understanding the relationship between ODC and thermal effects is critical for patient safety.

Purpose of the Study:

• To quantify temperature and thermal dose in an in-vitro model during laser activation at varying ODCs.
• To assess the impact of ODC on thermal injury thresholds and maximal allowable energy.

Main Methods:

• Holmium laser energy (1800 J at 30 W) was delivered to a fluid-filled glass bulb.
• Irrigation was maintained at 8 ml/min, with ODC tested in 10% increments (50-100%).
• Fluid temperature, thermal dose, time to thermal injury threshold, and maximal allowable energy were recorded.

Main Results:

• Higher ODCs led to increased fluid temperature and thermal dose.
• ODCs of 70% and above exceeded the threshold for thermal injury.
• A decrease from 60% to 50% ODC resulted in a tenfold increase in time to reach thermal injury threshold and an eightfold increase in maximal allowable energy.

Conclusions:

• Higher operator duty cycles during laser lithotripsy significantly increase fluid temperature and thermal dose.
• Reducing ODC dramatically enhances the time to thermal injury threshold and maximal allowable energy.
• Optimizing ODC management is essential for improving patient safety and treatment efficacy in laser lithotripsy.