Depth of vaporization with the UltraPulse CO2 laser

Basic histological data involving the UltraPulse CO2 laser has shown that layers of tissue measuring 50-100 mu may be ablated per pass, for passes one to three, leaving a similar layer (< 100 mu) of tissue necrosis. Clinical usage has suggested a decreasing level of ablation per pass with the maximum depth of ablation achieved with the first pass involving the epidermis. Each subsequent dermal pass appears to ablate successively less tissue with little visible tissue effects occurring after 3 or 4 passes total. At this point in treatment if instead of using single pulse tissue impacts, pulses are stacked one on top of another, a new threshold is reached whereby deeper dermal ablation is achieved. It is not known how many pulses (at 10 Hz) must be accumulated to reach this threshold of deeper ablation, nor is it known what happens to the layer of thermal necrosis associated with this pulse-stacking technique. A study was devised to evaluate the effects of 10 consecutive passes of single pulse vaporization regarding depth of vaporization as well as thickness of residual thermal necrosis. The same study was repeated regarding the tissue effects of 2 pulses at 10 Hz and 3 pulses at 10 Hz per pass for 10 passes.