Center for Sensory-Motor Interaction, Aalborg University, Fredrik Bajers vej 7D-3, DK 9220 Aalborg, Denmark.
Biomed Eng Online. 2010 Nov 8;9:69. doi: 10.1186/1475-925X-9-69.
CO2 lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial to deeper skin layers.
In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO2 laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were compared to the subjective pain intensity ratings from 16 subjects and to the surface skin temperature distributions measured by an infrared camera.
The stimulations were sensed significantly slower and less intense in glabrous skin than they were in hairy skin (MANOVA, p < 0.001). The model simulations of superficial temperature correlated with the measured skin surface temperature (r > 0.90, p < 0.001). Of the 16 subjects tested; eight subjects reported pricking pain in the hairy skin following a stimulus of 0.6 J/cm2 (5 W, 0.12 s, d1/e2 = 11.4 mm) only two reported pain to glabrous skin stimulation using the same stimulus intensity. The temperature at the epidermal-dermal junction (depth 50 μm in hairy and depth 133 μm in glabrous skin) was estimated to 46°C for hairy skin stimulation and 39°C for glabrous skin stimulation.
As compared to previous one dimensional heat distribution models, the current two dimensional model provides new possibilities for detailed studies regarding CO2 laser stimulation intensity, temperature levels and nociceptor activation.
几十年来，二氧化碳激光器一直被用作实验性的非接触式疼痛刺激器。激光能量被皮肤最表层的水分吸收。更深层的伤害感受器通过热从表层到深层皮肤的被动传导而被激活。
在目前的研究中，开发并验证了一个二维轴向有限元模型，以描述红外 CO2 激光刺激后皮肤内的空间温度分布。模型的几何形状基于高分辨率超声扫描。将模拟结果与 16 名受试者的主观疼痛强度评分和红外摄像机测量的表面皮肤温度分布进行了比较。
与有毛皮肤相比，无毛皮肤的刺激感觉速度更慢，强度更低（MANOVA，p<0.001）。与测量的皮肤表面温度相关的浅层温度模型模拟（r>0.90，p<0.001）。在 16 名受试者中；有 8 名受试者在 0.6 J/cm2（5 W，0.12 s，d1/e2 = 11.4 mm）的刺激下报告有毛发皮肤的刺痛感，只有 2 名报告在相同刺激强度下有毛发皮肤的刺痛感。在有毛皮肤刺激时，表皮-真皮交界处（有毛皮肤深度 50 μm，无毛皮肤深度 133 μm）的温度估计为 46°C，而在无毛皮肤刺激时为 39°C。
与以前的一维热分布模型相比，当前的二维模型为 CO2 激光刺激强度、温度水平和伤害感受器激活的详细研究提供了新的可能性。
