THE TISSUE COMPRESSION OPTIMIZATION AS THE CONDITION OF CONTROLLED IMPEDANCE CHANGE DURING ELECTRIC WELDING INTESTINAL ANASTOMOSIS CREATING

Abstract

Introduction. The intestinal wall' structural unevenness determines uneven structure of the electric welding compound, and, accordingly, needs for increased compression to homogenize the density and electrical conductivity for better connection result. But at the same time, the required compression amount is close to destructive for intestine wall, since smaller quantities are ineffective.

Aim: was to create the optimum method for balancing and distributing the compression effort on intestinal tissue in the model of electro-welded anastomosis in order to achieve by this way the high frequency welding process stability during the gut walls connecting.

Material and methods. We performed 348 studies of programmed influence to pig organ complex the radio frequency electric voltage up to 200 V, with controlled change of impedance, after a pressure of 2.0 N/mm2 to 3.9 N/mm2 have applied on electrodes. The intestines were doubled in the instrument prototype, simulating an anastomosis. Electrode types were changed: smooth 247 mm2 (group 1); relief 280 mm2 (group 2); smooth 254 mm2 included limiters of their approach (group 3).

Results. In group 1 we tried to find by the steps of 0.1 N/mm2, the pressure value as a point of equilibrium of mechanical and electrical properties. In 7.5% studies the failure of basic impedance parameters achieving was observed, in 42.5% — significant deviation of growth rate, in 7.5% — its critical decrease. In group 2, the prevention of possible electrodes displacement was investigated by applying that's different relief configurations. In this series, the basic impedance reduction parameters achieving increased to 82.5%, but in the next phase its sudden drop was observed in 30% probes. Also in 32.5% the significant impedance fluctuations were observed. In group 3, the electrodes approaching limitations in the range of 0.03 mm to 0.3 mm were studied. The limiters usage proved to be most effective at the ratio: limiter height to tissues thickness between the electrodes in anastomosis model — as 1:40. A critical impedance drop was observed in only 2.5% of studies.

Conclusions. The electrodes pressure reducing increases the tissues impedance deviation from the target. The relief electrodes increases electrical conductivity and improves the starting part of electric welding, but increases the unevenness in its end part due to the impedance fluctuation. The limiters of electrodes approach usage provide the effect of full-time electric welding algorithm elaboration, regardless the values of optimal or subcritical intestinal compression.

Discussion. The obtained data are intended to serve as the technological solutions basis in creating the elements of the specialized electric weld anastomosis making tool. Their technological introduction will provide the further increase of yet established benefits of electric-welded anastomosis over sewn and stapled. This technological device could be also effective in other biological tissues welding.