Page 21 - Blog Posts v1

range from 0.5 seconds up to 3 minutes, if a lot of cooling is required (for example, when very high fluences are about to be applied, or darker skin tones are to be treated).
Lasers do not employ glass tips. Instead, many systems use cooled-air devices to cool the skin. This method is not as thermodynamically efficient as the contact cooling used in IPL systems – but it can still help to reduce the epidermal temperature. Air cooling devices can make the skin surface very cold, but I wonder if they apply sufficient cooling over an extended period of time.
Post-Cooling
If the treatment area is large, then a high number of laser/IPL shots may need to be used. As pointed out above, most of the light energy will simply raise the temperature of the bulk dermis. This may be only a few degrees, but it may feel uncomfortable to some people. Most of the painful sensations will come from the hot basal layer.
Applying sufficient post-cooling will help those people. Ice-packs are a good method of cooling. Allow them to sit with ice-packs for as long as they require, to draw any excess heat out of the skin.
It should be noted that the air is a poor heat conductor. This means that any heat in the skin (which is full of water) trying to escape into the surrounding air will ‘prefer’ to stay in the skin, since water conducts almost four times better than air. This is why ice-packs are so good at sucking out the heat energy from the skin, especially if the skin surface is wet or has a water-based gel on it.
(The vast majority of people who died in the Titanic sinking died from hypothermia because they were in the very cold water. The comparatively high heat conductivity of the water cooled their bodies rapidly, whereas the people in the lifeboats survived because they were in the poorly-conducting air!!)
Poor practice
We are aware that some laser/IPL users employ a strange practice when treating hair – they set their devices at some fluence and fire a couple of shots. If their patient complains about the pain level, they reduce the fluence until the patient can tolerate it.
This is completely wrong!
This approach determines the treatment fluence by the patient’s pain response. This will inevitably lead to poor results.
Mike’s Blog Posts 21