Soft tissue studies with 805 nm diode laser radiation: Thermal effects with contact tips and comparison with effects of 1064 nm Nd:YAG laser radiation

This study compares the perioperative depths of thermal coagulation, charring, and incision in rabbit liver, internal anterior abdominal wall skeletal muscle, and abdominal skin and in swine liver and abdominal skin obtained with 805 nm diode laser and 1,064 nm Nd:YAG laser radiation using 300‐μm‐diameter conicaltip and 1,200‐μm‐diameter spherical‐tip contact fibers by hand. Additionally, the total depth of tissue necrosis surrounding incisions made with both lasers and contact tips is determined 48 hours postoperatively in the three tissues, and healing of the liver and abdominal wall muscle 21 and 35 days postoperatively is assessed histologically. Perioperatively determined charring, coagulation, and incision depth obtained in all tissues with either 805 nm or 1,064 nm laser radiation were sensibly equivalent at equal laser power values for each of the two contact tip shapes tested. At equal laser power values, coagulation depths obtained in rabbit abdominal skin using the 300‐μm‐diameter conical tip differed significantly (P ⩽ 0.01) from those values obtained with the 1,200‐μm‐diameter spherical tip. Incision depths obtained with the two different contact tip shapes at equal laser power settings in the different tissues studied differed in a few instances with no apparent pattern relating to tissue type or laser power. Depth of incisions obtained with both laser and tip types increases in the range of 6–12 w, but plateaus in the range 12–18 w in the tissues studied. Incisions obtained with both diode and Nd:YAG laser contact were essentially hemostatic, with self‐limiting oozing at most. Tissue necrosis examined at 48 hours showed invasion of inflammatory cells in liver, abdominal skeletal muscle, and skin; 21 and 35 days postoperatively, histology samples of liver and skeletal muscle showed healing with normal fibrous tissue deposition. Results of this study support the essential equivalency of tissue thermal effects obtained with the 805 nm diode and Nd:YAG lasers in the contact mode and support the use of the diode laser as an alternative medical laser. © 1993 Wiley‐Liss, Inc.