Tissue effects of a new laparoscopic carbon dioxide laser probe

The effects of CO2 laser beam delivered through a new laparoscopic probe on rabbit uteri is presented. This device has an outer diameter of 4.9 mm and can be delivered through most of the standard operative laparoscopic accessories. Two probes with miniature zinc selenide lenses of 6.5 mm and 17 mm back focal length attached at the distal end were tested. Through each probe, constant 0.5-second pulses and power levels of 5, 10, and 15 W were applied in three different lens-to-target distances. Measurements of beam spot diameters and microscopic crater characteristics revealed significant differences as a result of minor shifting of lens-target distance. From 7 to 9 mm beyond the focal plane and at power levels of 5 to 10 W, negligible tissue effects could be detected. This was defined as an "optical back-stop" effect. A new application mode using an easily maneuverable probe for cutting and coagulating [focusing/defocusing] effects increases the options available for operative laparoscopy.