Effect of mechanical tissue properties on thermal damage in skin after IR-laser ablation

Abstract

The damage created instantaneously in dorsal skin and in the subjacent skeletal muscle layer after CO2 and Er3+ laser incisions is histologically and ultrastructurally investigated. Light microscopical examinations show an up to three times larger damage zone in the subcutaneous layer of skeletal muscle than in the connective tissue above. The extent of thermally altered muscle tissue is classified by different zones and characterized by comparison to long time heating injuries. The unexpectedly large damage is a result of the change of elastic properties occurring abruptly at the transition between different materials. This leads to a discontinuity of the cutting dynamics that reduces the ejection of tissue material. We show that the degree of thermal damage originates from the amount of hot material that is not ejected out of the crater acting as a secondary heat source.