Development and Initial Trial of the Minilaparoscopic Argon Coagulator

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Abstract
A major limitation of minilaparoscopic or needlescopic instrumentation is the lack of a proficient mechanism by which to effect coagulation and hemostasis. Our purpose was to test the feasibility of the first minilaparoscopic argon coagulator (MAC). Performance requirements insist on a system that ensures noncontact ignition and coagulation, a low argon gas flow rate, and safety and efficacy at a variety of wattages. The first MAC was formulated and produced in the laboratory. Among its unique properties was that it contained a corona ignition system. The efficacy of the system was measured in the laboratory by advancing the prototype instrument, while under power and with the argon flowing, toward a brass screen connected to the electrosurgical generator return. The distances at which an arc formed at various wattages were measured via a micrometer translation stage and recorded as the ignition gap. After the successful laboratory trials, an experiment was conducted in four 30-kg pigs. A gastroscope was introduced for vision and insufflation, and transcutaneous, transgastric placement of needlescopic instruments and the MAC was performed. Areas of mucosa 1 x 2 cm were coagulated at 15, 25, 35 and 40 W in each animal. Ulcers of 1 cm were created and coagulated with the MAC. Two animals were sacrificed immediately and one each at 12 and 14 days, and the coagulated areas were examined histologically. In the laboratory, ignition of the beam was induced without surface contact, and the desired 5-mm ignition gap was seen at power as low as 15 W. The argon gas flow rates were limited to 1.5 L/min. At each wattage, the mucosa was entirely ablated. The depth of injury varied (submucosa to 2.2 mm) according to the wattage applied. Ulcerative hemorrhage was controlled in each instance. There were no complications attributable to coagulation effects. Surviving animals tolerated a regular diet on postoperative day 1. Histologic examination of tissue from surviving animals revealed growth of normal mucosa in the superficially coagulated areas and mixed normal mucosa and fibrosis in the more deeply injured regions. Both in the laboratory and in animal experiments, the first MAC demonstrated noncontact ignition and operation, a low flow rate, and safety and efficacy at all wattage settings applied. It arrested ulcerative bleeding and ablated the mucosal surface at various depths according to the applied power. The MAC may be a solution to the lack of a consistent and reliable means for coagulation in needlescopic or minilaparoscopic surgery.

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