ABSTRACT
We report on a pulse-stacking technique in which a Cr, Nd:GSGG laser pumped by a high-pulse-rate (25 kHz) source is Q switched at lower pulse rates (submultiples of the pump rate) to achieve higher-output pulse energies and shorter pulse durations. For six pump pulses stacked, the output peak power increased by a factor of 10 compared with gain-switched output.
ABSTRACT
BACKGROUND: This study investigated the potential of sutureless nerve repair using two promising laser fusion methods: direct 2 microns irradiation of the epineurium, and protein solder assisted epineurial fusion using a 800 nm laser. MATERIALS AND METHODS: Laser anastomosis of the rat sciatic nerve was performed in vitro without stay sutures in two groups of six animals. In the first group, direct laser fusion used a pulsed Cr, Tm: YAG laser. In the second group an albumin-based fluid solder containing the dye indocyanine green was applied to the epineurium, then irradiated with a diode laser. These two techniques were compared with regards to coaptation success and axonal damage. RESULTS: Direct laser welding produced weak bonds despite microscopic investigation of the irradiated nerves showing fusion of the epineurium. The unsatisfactory bonding can be attributed to poor tissue overlap and insufficient protein in the thin epineurium denaturation of underlying axons was also observed. In contrast, the laser solder method produced successful welds with greatly reduced axonal damage, and significantly improved the tensile strength. CONCLUSIONS: This study confirmed the technical possibilities of sutureless nerve anastomosis. Laser activated solders enable stronger bonds, by the addition of protein to the anastomosis site, and less thermal damage to underlying tissue through selective absorption of laser energy by dye in the solder. Further in vivo studies are required before drawing final conclusions.
Subject(s)
Laser Therapy/methods , Nerve Tissue Proteins/radiation effects , Sciatic Nerve/surgery , Anastomosis, Surgical/methods , Animals , Axons/radiation effects , Male , Protein Denaturation , Rats , Rats, Wistar , Sciatic Nerve/pathology , Sciatic Nerve/radiation effectsABSTRACT
A compact, pulsed Ti:sapphire laser producing 320 mW of average power at a 24-kHz repetition rate has been demonstrated, with the output pulses having 50-ns-width and 440-W peak power. Use of a novel small-scale copper laser as the pump source results in high-efficiency, short-pulse operation without a Q switch, with excellent pulse-to-pulse amplitude stability.
