In vitro assessment of tissue heating near metallic medical implants by exposure to pulsed radio frequency diathermy
In vitro assessment of tissue heating near metallic medical implants by exposure to pulsed radio frequency diathermy
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DOI：
10.1088/0031-9155/48/17/312
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发表时间：
2003-09-07
影响因子：
3.5
通讯作者：
Bassen, HI
中科院分区：
文献类型：
--
作者：
Ruggera, PS;Witters, DM;Bassen, HI
一名双侧植入神经刺激器的患者在接受透热疗法治疗以加速拔牙后的恢复后，遭受了严重的脑组织损伤，随后死亡。随后的MRI检查显示，脑深部刺激器（DBS）电极导线电极附近的组织严重恶化，这是由于透热治疗引起的组织过度发热造成的。尽管未在公开文献中发表，但报告了一例植入神经刺激器治疗帕金森病的患者的第二起事件。在对严重脊柱后凸进行透热疗法治疗期间，患者的精神状态和神经功能缺损突然发生变化。透热疗法与造成病人脑组织损伤有关。为了研究透热疗法是否可能导致其他类型的植入式电极导线系统或一般金属植入物过度发热，我们进行了一系列体外实验室测试。我们获得了一个透热治疗装置，并组装了一个可控的实验室暴露系统。在植入物附近使用光纤测温法进行比吸收率（SAR）测量，以确定使用典型透热治疗功率水平的温升率。比较了脊髓刺激器（SCS）电极导线、起搏器电极导线和三种类型骨假体（螺钉、棒和接骨板）的SAR测量值。结果表明，SCS和起搏器电极附近的温度变化为2.54和4.88 ℃ s（-1），相应的SAR值为9129和17563 W kg（-1），显著高于其他金属植入物附近的温度变化，其范围为0.04至0.69 ℃ s（-1）（129至2471 W kg（-1））。由于在所报告的人体事件中植入的DBS电极导线的电极表面积是受试SCS电极导线的一半，因此这些结果意味着DBS电极导线的组织产热率至少等于或高达此处报告的SCS电极导线的两倍。
A patient with bilateral implanted neurostimulators suffered significant brain tissue damage, and subsequently died, following diathermy treatment to hasten recovery from teeth extraction. Subsequent MRI examinations showed acute deterioration of the tissue near the deep brain stimulator (DBS) lead's electrodes which was attributed to excessive tissue heating induced by the diathermy treatment. Though not published in the open literature, a second incident was reported for a patient with implanted neurostimulators for the treatment of Parkinson's disease. During a diathermy treatment for severe kyphosis, the patient had a sudden change in mental status and neurological deficits. The diathermy was implicated in causing damage to the patient's brain tissue. To investigate if diathermy induced excessive heating was possible with other types of implantable lead systems, or metallic implants in general, we conducted a series of in vitro laboratory tests. We obtained a diathermy unit and also assembled a controllable laboratory exposure system. Specific absorption rate (SAR) measurements were performed using fibre optic thermometry in proximity to the implants to determine the rate of temperature rise using typical diathermy treatment power levels. Comparisons were made of the SAR measurements for a spinal cord stimulator (SCS) lead, a pacemaker lead and three types of bone prosthesis (screws, rods and a plate). Findings indicate that temperature changes of 2.54 and 4.88 degreesC s(-1) with corresponding SAR values of 9129 and 17 563 W kg(-1) near the SCS and pacemaker electrodes are significantly higher than those found in the proximity of the other metallic implants which ranged from 0.04 to 0.69 degreesC s(-1) (129 to 2471 W kg(-1)). Since the DBS leads that were implanted in the reported human incidents have one-half the electrode surface area of the tested SCS lead, these results imply that tissue heating at rates at least equal to or up to twice as much as those reported here for the SCS lead could occur for the DBS leads.