Evaluation of Temperature Changes in an Ex Vivo Model of Holmium Laser Enucleation for Prostate Surgery
Overview
This study investigated temperature changes during holmium laser enucleation of the prostate (HoLEP) using ex vivo models. Temperature measurements were taken in simulated prostate cavities with varying irrigation flow rates, and coagulation effects were assessed on bovine tissue. Findings demonstrated that irrigation flow significantly influences temperature elevation, and coagulation depth correlates with power settings.
Background
HoLEP is a minimally invasive surgical technique increasingly favored for treating benign prostatic hyperplasia due to its efficacy and safety profile compared to TURP and open prostatectomy. The holmium:YAG laser used in HoLEP has a wavelength of 2140 nm, resulting in shallow tissue penetration and targeted energy delivery. Despite its clinical adoption, temperature dynamics during HoLEP have not been thoroughly studied, prompting this ex vivo investigation to better understand thermal effects and safety.
Data Highlights
Parameter
Condition
Temperature Change (K)
Cavity Volume
10 to 100 cc
Varied by volume and irrigation flow
Irrigation Flow Rate
0, 300, 400, 500 ml/min
Higher flow rates reduced temperature rise
Laser Power
80 W, 4 J pulse energy, 400 µs pulse duration
Consistent across experiments
Coagulation Power
6.5 sprayCOAG® (~78 W), 10 sprayCOAG® (~144 W)
Depth of necrosis measured histopathologically
Key Findings
Temperature increases during HoLEP are inversely related to irrigation flow rates; higher irrigation reduces heat accumulation.
Smaller enucleation cavity volumes tend to show higher temperature elevations under low irrigation conditions.
At irrigation flow rates approximating clinical practice (~400 ml/min), temperature elevations remain within safe limits.
Thermal imaging confirmed localized heating near the laser tip without excessive spread to surrounding simulated tissue.
Coagulation depth in bovine tissue increases with higher electrosurgical power settings, indicating controlled tissue necrosis.
Ex vivo models effectively simulate clinical HoLEP conditions for assessing thermal safety parameters.
Clinical Implications
Maintaining adequate irrigation flow during HoLEP is critical to prevent excessive temperature rises and potential thermal injury. Surgeons should monitor irrigation parameters to ensure effective cooling. Additionally, electrosurgical coagulation settings should be optimized to achieve hemostasis while minimizing collateral tissue damage.
Conclusion
This ex vivo study demonstrates that irrigation flow rate is a key factor in controlling temperature elevation during HoLEP, supporting its safety profile. Controlled coagulation parameters further contribute to effective and safe surgical outcomes.
References
Department of Urology, University Medical Centre Freiburg -- Evaluation of Temperature Changes in an Ex Vivo Model of Holmium Laser Enucleation for Prostate Surgery
