Adaptation of tissue to a chronic heat load.
Adaptation of tissue to a chronic heat load.
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DOI：
10.1097/00002480-199407000-00053
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发表时间：
1994-07-01
期刊：
影响因子：
--
通讯作者：
Harasaki, H
中科院分区：
文献类型：
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作者：
Davies, C R;Fukumura, F;Harasaki, H
确定热对组织的慢性影响是机械驱动全人工心脏(TAH)发展面临的重要问题之一。为了描述这种效应，在11头小牛(H系列)上植入了恒定热流密度为0.04瓦/厘米~2、0.06瓦/厘米~2和0.08瓦/厘米~2的加热装置。将加热的圆盘植入肺和肌肉组织附近，为期7周。温度传感器放置在表面，作为加热器组件的一部分。结果表明，在0.08、0.06和0.04W/cm2条件下，肌肉加热器表面高于体温(T)的温度升高分别为6.4+/-0.6℃、4.5+/-0.2℃和1.8+/-0.5℃。在植入后2周，Delta T值分别变为5.5+/-0.6℃、3.4+/-0.2℃和1.8+/-0.2℃。植入后7周，植入0.08、0.06和0.04W/cm2的Delta T值分别降至3.7+/-1.2℃、2.8+/-0.1℃和0.8℃。作者认为，这种变化归因于组织通过血管生成增加热量散失的适应性反应。来自三个TAH病例的结果表明，在两个测量的组织界面上，增量T在15天内下降了1摄氏度。与此同时，在此期间，废热(伏特x流入血液的电流x后负荷)保持在11.1+/-0.5W不变。在较高热流密度下，增量T的下降与H系列实验中所观察到的结果相一致。因此，在H系列实验中观察到的适应性似乎也适用于热源周围的组织，如TAH。
Determination of the chronic effect of heat on tissue is one of the important issues facing mechanically actuated total artificial heart (TAH) development. In an effort to characterize this effect, implantations of heating devices producing constant heat fluxes of 0.04 watts/cm2, 0.06 W/cm2, and 0.08 W/cm2 were performed in 11 calves (H-series). Heated disks were implanted adjacent to lung and muscle tissue for a period of 7 weeks. Temperature sensors were placed at the surface as part of the heater assemblies. The results showed that initially, temperature elevations above body temperature (delta T) were 6.4 +/- 0.6 degrees C, 4.5 +/- 0.2 degrees C, and 1.8 +/- 0.5 degrees C at the muscle heater surface for 0.08, 0.06, and 0.04 W/cm2, respectively. At 2 weeks after implant delta T values changed to 5.5 +/- 0.6 degrees C, 3.4 +/- 0.2 degrees C, and 1.8 +/- 0.2 degrees C, respectively. Seven weeks after implant, delta T values decreased to 3.7 +/- 1.2 degrees C, 2.8 +/- 0.1 degrees C, and 0.8 degrees C for 0.08, 0.06, and 0.04 W/cm2, respectively. The authors think this change is attributable to an adaptive response of the tissue to increase heat dissipation through angiogenesis. Results from three TAH cases indicated that at two measured tissue interfaces, delta T decreased by 1 degrees C during a 15 day period. At the same time, the waste heat (volts x current in-flow x afterload to the blood) remained constant at 11.1 +/- 0.5 W during this period. This decrease in delta T corresponded to that observed for the H-series experiments at the higher heat fluxes. Thus, it appears that adaptation observed in the H-series experiments also is seen for tissues surrounding heat sources such as the TAH.