Giglio Nicholas C, Fried Nathaniel M
Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, NC 28223 USA.
IEEE J Sel Top Quantum Electron. 2021 Jul-Aug;27(4):1-8. doi: 10.1109/jstqe.2020.3045912. Epub 2020 Dec 18.
Blood vessel burst pressures were simulated and predicted for sealing and cutting of vessels in a two-step process, using low (<25 W), medium (~100 W), and high (200 W) power lasers at a wavelength of 1470 nm. Monte Carlo optical transport, heat transfer, Arrhenius integral tissue damage simulations, and vessel pressure equations were utilized. The purpose of these studies was to first validate the numerical model by comparison with experimental results (for low and medium power) and then to use the model to simulate parameters that could not be experimentally tested (for high power). The goal was to reduce the large range of parameters (power, irradiation time, and linear beam dimensions) to be tested in future experiments, for achieving short vessel sealing/cutting times, minimal bifurcated seal zones (BSZ), and high vessel burst pressures. Blood vessels were compressed to 400 μm thickness. A wide range of linear beam profiles (1-5 mm widths and 8-9.5 mm lengths), incident powers (20-200 W) and clinically relevant irradiation times (0.5-5.0 s) were simulated and peak seal and cut temperatures as well as thermal seal zones, ablation zones, and BSZ computed. A simplistic mathematical expression was used to estimate vessel burst pressures based on seal width. Optimal low-power parameters were: 24W/5s/8×2mm (sealing) and 24W/5s/8×1mm (cutting), yielding a BSZ of 0.4 mm, corresponding to experimental burst pressures of ~450 mmHg. Optimal medium-power parameters were: 90W/1s/9.5×3mm (sealing) and 90W/1s/9.5×1mm (cutting), yielding a BSZ of 0.9 mm for burst pressures of ~1300 mmHg. Simulated only optimal high-power parameters were: 200W/0.5s/9×3 mm (sealing) and 200W/0.5s/9×1mm (cutting), yielding a BSZ of 0.9 mm and extrapolated to predict a seal strength of ~1300 mmHg. All lasers produced seal zones between 0.4-1.5 mm, corresponding to high vessel burst pressures of 300-1300 mmHg (well above normal systolic blood pressure of 120 mmHg). Higher laser powers enable shorter sealing/cutting times and higher vessel strengths.
使用波长为1470nm的低（<25W）、中（~100W）和高（200W）功率激光，在两步过程中模拟和预测血管的破裂压力，以实现血管的密封和切割。利用了蒙特卡洛光学传输、热传递、阿伦尼乌斯积分组织损伤模拟和血管压力方程。这些研究的目的是首先通过与实验结果（低功率和中功率）比较来验证数值模型，然后使用该模型模拟无法通过实验测试的参数（高功率）。目标是减少未来实验中需要测试的参数范围（功率、照射时间和线性光束尺寸），以实现短的血管密封/切割时间、最小的分叉密封区（BSZ）和高的血管破裂压力。血管被压缩至400μm厚度。模拟了广泛的线性光束轮廓（宽度为1 - 5mm，长度为8 - 9.5mm）、入射功率（20 - 200W）和临床相关的照射时间（0.5 - 5.0s），并计算了峰值密封和切割温度以及热密封区、消融区和BSZ。使用一个简单的数学表达式根据密封宽度来估计血管破裂压力。最佳低功率参数为：24W/5s/8×2mm（密封）和24W/5s/8×1mm（切割），产生的BSZ为0.4mm，对应实验破裂压力约为450mmHg。最佳中功率参数为：90W/1s/9.5×3mm（密封）和90W/1s/9.5×1mm（切割），产生的BSZ为0.9mm，破裂压力约为1300mmHg。仅模拟的最佳高功率参数为：200W/0.5s/9×3mm（密封）和200W/0.5s/9×1mm（切割），产生的BSZ为0.9mm，并外推预测密封强度约为1300mmHg。所有激光产生的密封区在0.4 - 1.5mm之间，对应300 - 1300mmHg的高血管破裂压力（远高于正常收缩压120mmHg）。更高的激光功率可实现更短的密封/切割时间和更高的血管强度。
