Page 239 - Blog Posts v1

The importance of fluence
Let’s go back to basics. What are we trying to do with these laser/IPL treatments?
In essence, we are trying to ‘cook’ something - usually proteins in the hair or blood vessels or pigmentation. This requires heating them. We do this by firing light energy at them, which is preferentially absorbed, thereby generating heat energy. This translates into a rise in temperature in the targets.
However, calculations show that less than 10% of the energy we fire at the skin actually does the job!! More than 90% of it is excess to requirements. But that energy has to ‘go somewhere’. If left unattended, this excess heat energy will remain in the skin (which is 70% water and very conductive, unlike the air) and will potentially start ‘cooking’ other proteins like collagen.
So the trick is to encourage the heat energy to leave the skin as quickly as possible. We can do this by applying anything cold at the skin surface. This can be cool air, ice packs, cold compresses or IPL tips.
I now train IPL users to ‘pre-cool’ the skin for about 1 to 2 seconds to protect the epidermis and reduce the thermal pain sensation. After firing the energy pulse, I train them to keep the cold IPL tip on the skin for at least 2 or 3 seconds - this cold (often icy) tip will suck much of the excess heat energy out of the skin, before it has a chance to damage the dermis, or epidermis.
After the treatment area has been covered, I suggest applying cold ice packs to it, to keep drawing as much heat from the skin as possible.
Bu using this technique, it is possible to apply higher fluences without damaging the skin. It also feels much more comfortable, since the thermal pain receptors are pre-cooled before the light is delivered.
Mike’s Blog Posts 239