A theoretical model of the application of RF energy to the airway wall and its experimental validation
A theoretical model of the application of RF energy to the airway wall and its experimental validation
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DOI：
10.1186/1475-925x-9-81
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发表时间：
2010-11-27
影响因子：
3.9
通讯作者：
Mitzner, Wayne
中科院分区：
文献类型：
--
作者：
Jarrard, Jerry;Wizeman, Bill;Mitzner, Wayne
工作背景：支气管热成形术是一种新型技术，旨在通过控制气道壁的加热减少气道平滑肌的量来降低气道收缩的能力。这种方法已经在动物模型中进行了检查，并作为人类受试者哮喘的治疗方法。目前，关于在支气管热成形术过程中射频（RF）能量和热量如何转移到肺气道的研究很少。在这篇手稿中，我们描述了一个计算，理论模型的RF能量的输送到气道wall.Methods：电热有限元分析模型的目的是模拟输送的温度控制的RF能量的气道壁在体内肺。该模型包括由于RF焦耳加热和由于热传导在气道壁内的热传递而产生的热量的预测。为了实现该模型，我们使用气道和肺组织的已知物理特性和尺寸。模型预测进行了测试与测量的温度，阻抗，能量，和功率在实验犬model.Results：电极温度，电压，电流，沿着与组织阻抗和输送能量的模型预测进行了比较，实验测量和实验平均值的+/- 5%内采取超过157个样本激活。实验结果显示显着的协议与模型的预测，从而验证了使用该模型来预测气道壁内的热产生和转移支气管thermoplasty.Conclusions：该模型还表明，作为一个损失项，影响电气测量和热分布的蒸发的重要性。模型预测结果与经验结果非常吻合，因此支持使用该模型开发下一代支气管热成形术器械。我们的研究结果表明，将模型结果与射频发生器电气测量结果进行比较可能是模型早期评估的有用工具。
Background: Bronchial thermoplasty is a novel technique designed to reduce an airway's ability to contract by reducing the amount of airway smooth muscle through controlled heating of the airway wall. This method has been examined in animal models and as a treatment for asthma in human subjects. At the present time, there has been little research published about how radiofrequency (RF) energy and heat is transferred to the airways of the lung during bronchial thermoplasty procedures. In this manuscript we describe a computational, theoretical model of the delivery of RF energy to the airway wall.Methods: An electro-thermal finite-element-analysis model was designed to simulate the delivery of temperature controlled RF energy to airway walls of the in vivo lung. The model includes predictions of heat generation due to RF joule heating and transfer of heat within an airway wall due to thermal conduction. To implement the model, we use known physical characteristics and dimensions of the airway and lung tissues. The model predictions were tested with measurements of temperature, impedance, energy, and power in an experimental canine model.Results: Model predictions of electrode temperature, voltage, and current, along with tissue impedance and delivered energy were compared to experiment measurements and were within +/- 5% of experimental averages taken over 157 sample activations. The experimental results show remarkable agreement with the model predictions, and thus validate the use of this model to predict the heat generation and transfer within the airway wall following bronchial thermoplasty.Conclusions: The model also demonstrated the importance of evaporation as a loss term that affected both electrical measurements and heat distribution. The model predictions showed excellent agreement with the empirical results, and thus support using the model to develop the next generation of devices for bronchial thermoplasty. Our results suggest that comparing model results to RF generator electrical measurements may be a useful tool in the early evaluation of a model.