The use of laser radiation as a surgical “light knife”

Abstract

An investigation into the effects of continuous wave (CW) infrared laser radiation on skin, muscle, skull, brain, liver, and small bowel was carried out on 24 dogs. A unique articulating arm was utilized by the surgeon to conveniently direct the energy to the exposed target. About 30 watts of power focused to a 2-mm. diameter spot size readily cut through skin and muscle without significant bleeding. When vessels more than 1 mm. in diameter were encountered, bleeding usually occurred since the energy caused vaporization of the vessel wall without sealing off the opening. Such bleeding was troublesome in attempting to cut through brain and liver. As soon as a film of blood covered the surgical field the laser energy was absorbed by the blood, preventing deeper penetration. The skull bone could be incised down to a depth of about 3 mm. at which point charring occurred and further penetration was not practical since the deeper layers could not be exposed to the energy by retraction of superficial layers (unlike soft tissue). Healing of canine abdominal skin wound incisions deteriorated during the sixth to tenth day after laser radiation causing wound edge separation. Healing by secondary intention then rapidly ensued. Gross and histologic examination of knife and laser wounds during the first week and during the third through the sixth week failed to reveal significant differences. Use of laser radiation as a “light knife” by the clinical surgeon has some practical hazards which include accidental radiation of unintentional targets. At present, except for some select applications, the disadvantages to the use of laser radiation in surgery outweigh any advantages.