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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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The figure illustrates the spatial surface temperature profile at stimulus end (maximum surface temperature) for both mean experimental data (Exp. data) and modeled temperatures based on a finite element model (FEM). 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. In all plots, it is seen that the temperature change 0.6 cm from the beam center at stimulus termination was less than 5°C. Even though the maximum temperature (at the beam center, 0 cm) for the 5 W power setting was approximately the double of the 1 W power setting, the measured and simulated temperature changes more than 0.5 cm from the beam center was identical.
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Figure 4: The figure illustrates the spatial surface temperature profile at stimulus end (maximum surface temperature) for both mean experimental data (Exp. data) and modeled temperatures based on a finite element model (FEM). 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. In all plots, it is seen that the temperature change 0.6 cm from the beam center at stimulus termination was less than 5°C. Even though the maximum temperature (at the beam center, 0 cm) for the 5 W power setting was approximately the double of the 1 W power setting, the measured and simulated temperature changes more than 0.5 cm from the beam center was identical.

Mentions: The spatial temperature profiles of the model were similar to the infrared recordings (Figure 4). The spatial profiles for the three other 1 W stimulus energies were also found close to the infrared recordings (not displayed). The maximum temperature reached at the end of the stimulus (at the beam center, 0 cm) was approximately doubled when using the 5 W (0.12 s, 0.6 J/cm2) stimulation compared to the 1 W (0.6 s, 0.6 J/cm2) stimulation (Figure 4). However, the evoked temperature change more than 5 mm from the beam center was comparable (Figure 4).


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 spatial surface temperature profile at stimulus end (maximum surface temperature) for both mean experimental data (Exp. data) and modeled temperatures based on a finite element model (FEM). 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. In all plots, it is seen that the temperature change 0.6 cm from the beam center at stimulus termination was less than 5°C. Even though the maximum temperature (at the beam center, 0 cm) for the 5 W power setting was approximately the double of the 1 W power setting, the measured and simulated temperature changes more than 0.5 cm from the beam center was identical.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: The figure illustrates the spatial surface temperature profile at stimulus end (maximum surface temperature) for both mean experimental data (Exp. data) and modeled temperatures based on a finite element model (FEM). 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. In all plots, it is seen that the temperature change 0.6 cm from the beam center at stimulus termination was less than 5°C. Even though the maximum temperature (at the beam center, 0 cm) for the 5 W power setting was approximately the double of the 1 W power setting, the measured and simulated temperature changes more than 0.5 cm from the beam center was identical.
Mentions: The spatial temperature profiles of the model were similar to the infrared recordings (Figure 4). The spatial profiles for the three other 1 W stimulus energies were also found close to the infrared recordings (not displayed). The maximum temperature reached at the end of the stimulus (at the beam center, 0 cm) was approximately doubled when using the 5 W (0.12 s, 0.6 J/cm2) stimulation compared to the 1 W (0.6 s, 0.6 J/cm2) stimulation (Figure 4). However, the evoked temperature change more than 5 mm from the beam center was comparable (Figure 4).

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