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Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation.

Frahm KS, Andersen OK, Arendt-Nielsen L, Mørch CD - Biomed Eng Online (2010)

Bottom Line: The laser energy is absorbed by the water content in the most superficial layers of the skin.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 model simulations of superficial temperature correlated with the measured skin surface temperature (r > 0.90, p < 0.001).

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Sensory-Motor Interaction, Aalborg University, Fredrik Bajers vej 7D-3, DK 9220 Aalborg, Denmark. ksf@hst.aau.dk

ABSTRACT

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

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Related in: MedlinePlus

The figure illustrates the surface and subsurface temporal maximum temperature profiles calculated by the finite element model during laser heating and subsequent cooling (pulse duration listed). The surface temperature profile and six different depths are displayed (100, 200, 300, 400, 500 μm and the depth of the epidermal ridge (ER), which is 130 μm in glabrous skin and 50 μm in hairy skin). It is seen that the delay to reach the maximum temperature after stimulus termination increased with depth, as the heat energy took longer time to diffuse into the skin. Comparing the temperature profile at the ER in hairy and glabrous skin, it is seen that following 5 W stimulations the maximum temperature was almost twice as high in hairy skin as it was in glabrous skin. For the 1 W data the differences were not as pronounced, because the slower heating allows better time for the heat time to diffuse into the skin. A) glabrous skin, 1 W, 0.6 s, 0.6 J/cm2 B) hairy skin, 1 W, 0.6 s, 0.6 J/cm2 C) glabrous skin, 5 W, 0.12 s, 0.6 J/cm2 D) hairy skin, 5 W, 0.12 s, 0.6 J/cm2.
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Figure 5: The figure illustrates the surface and subsurface temporal maximum temperature profiles calculated by the finite element model during laser heating and subsequent cooling (pulse duration listed). The surface temperature profile and six different depths are displayed (100, 200, 300, 400, 500 μm and the depth of the epidermal ridge (ER), which is 130 μm in glabrous skin and 50 μm in hairy skin). It is seen that the delay to reach the maximum temperature after stimulus termination increased with depth, as the heat energy took longer time to diffuse into the skin. Comparing the temperature profile at the ER in hairy and glabrous skin, it is seen that following 5 W stimulations the maximum temperature was almost twice as high in hairy skin as it was in glabrous skin. For the 1 W data the differences were not as pronounced, because the slower heating allows better time for the heat time to diffuse into the skin. A) glabrous skin, 1 W, 0.6 s, 0.6 J/cm2 B) hairy skin, 1 W, 0.6 s, 0.6 J/cm2 C) glabrous skin, 5 W, 0.12 s, 0.6 J/cm2 D) hairy skin, 5 W, 0.12 s, 0.6 J/cm2.

Mentions: The temperature development at the surface and at six different depths was extracted from the FEM (Figure 5). It is evident, that sub-surface temperatures were shifted both in time and magnitude meaning that lower maximum temperatures were observed for increasing skin depth and the delay of the peak temperature also increased with skin depth. The maximum sub-surface temperatures reached for all 1 W stimulations are depicted in Figure 6. The delays after stimulus end to reach maximum subsurface temperature for all 1 W stimulations are depicted in Figure 7. For all but one stimulation the subsurface temperatures in hairy skin were generally higher than in glabrous skin (Figures 6 &8). The delay after stimulus end to reach maximum temperature in glabrous skin was for all but two stimulations higher than the delay in hairy skin (Figure 7). Both the maximum temperature reached and the delay to the peak temperature showed a significant differences between skin type, skin depth and stimulation duration (3-way MANOVA, p < 0.001). For both dependent variables (maximum temperature reached and delay to peak temperature) a 2-way interaction was seen between all factors. A Tukeys post-hoc test showed significant differences both between all 1 W stimulation durations, and between all tested depths. Furthermore, the post-hoc test showed that between hairy and glabrous skin there were no interaction for 100 μm and 500 μm, but for all other depths.


Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation.

Frahm KS, Andersen OK, Arendt-Nielsen L, Mørch CD - Biomed Eng Online (2010)

The figure illustrates the surface and subsurface temporal maximum temperature profiles calculated by the finite element model during laser heating and subsequent cooling (pulse duration listed). The surface temperature profile and six different depths are displayed (100, 200, 300, 400, 500 μm and the depth of the epidermal ridge (ER), which is 130 μm in glabrous skin and 50 μm in hairy skin). It is seen that the delay to reach the maximum temperature after stimulus termination increased with depth, as the heat energy took longer time to diffuse into the skin. Comparing the temperature profile at the ER in hairy and glabrous skin, it is seen that following 5 W stimulations the maximum temperature was almost twice as high in hairy skin as it was in glabrous skin. For the 1 W data the differences were not as pronounced, because the slower heating allows better time for the heat time to diffuse into the skin. A) glabrous skin, 1 W, 0.6 s, 0.6 J/cm2 B) hairy skin, 1 W, 0.6 s, 0.6 J/cm2 C) glabrous skin, 5 W, 0.12 s, 0.6 J/cm2 D) hairy skin, 5 W, 0.12 s, 0.6 J/cm2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2991325&req=5

Figure 5: The figure illustrates the surface and subsurface temporal maximum temperature profiles calculated by the finite element model during laser heating and subsequent cooling (pulse duration listed). The surface temperature profile and six different depths are displayed (100, 200, 300, 400, 500 μm and the depth of the epidermal ridge (ER), which is 130 μm in glabrous skin and 50 μm in hairy skin). It is seen that the delay to reach the maximum temperature after stimulus termination increased with depth, as the heat energy took longer time to diffuse into the skin. Comparing the temperature profile at the ER in hairy and glabrous skin, it is seen that following 5 W stimulations the maximum temperature was almost twice as high in hairy skin as it was in glabrous skin. For the 1 W data the differences were not as pronounced, because the slower heating allows better time for the heat time to diffuse into the skin. A) glabrous skin, 1 W, 0.6 s, 0.6 J/cm2 B) hairy skin, 1 W, 0.6 s, 0.6 J/cm2 C) glabrous skin, 5 W, 0.12 s, 0.6 J/cm2 D) hairy skin, 5 W, 0.12 s, 0.6 J/cm2.
Mentions: The temperature development at the surface and at six different depths was extracted from the FEM (Figure 5). It is evident, that sub-surface temperatures were shifted both in time and magnitude meaning that lower maximum temperatures were observed for increasing skin depth and the delay of the peak temperature also increased with skin depth. The maximum sub-surface temperatures reached for all 1 W stimulations are depicted in Figure 6. The delays after stimulus end to reach maximum subsurface temperature for all 1 W stimulations are depicted in Figure 7. For all but one stimulation the subsurface temperatures in hairy skin were generally higher than in glabrous skin (Figures 6 &8). The delay after stimulus end to reach maximum temperature in glabrous skin was for all but two stimulations higher than the delay in hairy skin (Figure 7). Both the maximum temperature reached and the delay to the peak temperature showed a significant differences between skin type, skin depth and stimulation duration (3-way MANOVA, p < 0.001). For both dependent variables (maximum temperature reached and delay to peak temperature) a 2-way interaction was seen between all factors. A Tukeys post-hoc test showed significant differences both between all 1 W stimulation durations, and between all tested depths. Furthermore, the post-hoc test showed that between hairy and glabrous skin there were no interaction for 100 μm and 500 μm, but for all other depths.

Bottom Line: The laser energy is absorbed by the water content in the most superficial layers of the skin.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 model simulations of superficial temperature correlated with the measured skin surface temperature (r > 0.90, p < 0.001).

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Sensory-Motor Interaction, Aalborg University, Fredrik Bajers vej 7D-3, DK 9220 Aalborg, Denmark. ksf@hst.aau.dk

ABSTRACT

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Show MeSH
Related in: MedlinePlus