Page 206 - Blog Posts v1

Temperature
Skin
Blood
Collagen
100
0.0035
0.69
0.29
90
0.06
39.3
13.5
80
1.4
2.8 sec
763
70
35
258 sec
54.7 sec
60
1.1 sec
8.6 hr
1.4 hr
Time required to reach 100% denaturation points depending on temperature (all times are in milliseconds unless otherwise stated)
The data in the table clearly shows how the temperature of a tissue strongly determines the time required to reach 100% cellular denaturation. Clearly, ‘skin’ reacts to heat mush more quickly than collagen, which itself reacts more quickly than blood.
The Arrhenius Damage Integral
For example, ‘skin’ will become fully denatured (this means it is irreversible – the tissue is ‘dead’) after about 1.1 seconds if it is maintained at a temperature of 60°C. But, the same skin will fully denature after only 1.4 ms if the temperature is 80°C, and only after 0.06 milliseconds at 90°C.
Clearly, there is a huge difference in how long it takes the various tissues to reach 100% denaturation, which is highly dependent on the temperature. This is because the time required to denature the proteins is exponentially dependent on the local temperature. So, even a small rise in temperature can have a significant effect on the time required to induce denaturation.
This can be applied to laser/IPL treatments of skin and its components. The temperature rise in the skin depends on the applied energy at the skin surface and the amount of energy that is ultimately absorbed by the target.
Knowing the above, it is now clear that an increase in the skin surface energy density (fluence) can have a hugely significant effect on the timing of the denaturation process inside the skin.
This is why we must always be very careful when increasing the fluence applied, for all treatments. The time required to induce the desired reaction is very strongly linked to the applied fluence (and subsequent temperature rise).
Mike’s Blog Posts 206