The Study Of Characteristic Changes Of Small Intestine Based On Cole_Y Model

With the continuous improvement of surgical technique and application of stapling devices,safety of reconstruction of digestive tract has been greatly improved.However,serious complications such as staple-line leakage following anastomosis with a stapler remain one of the problems that trouble the surgeons.This topic combines the present research actuality of home and abroad to explore the characteristic changes of small intestine and investigate the effects of precompression time and strength on tissue characteristic changes by employing the method of multifrequency bioimpedance analysis based on Coley model.The purpose of this study is to provide a basis for compression parameters optimization of stapler and to achieve more safety stapling.The main researches of this paper are as follows.1.Experimental system development for research of characteristic changes of small intestine First,a portable tissue thickness measurement instrument was developed to select samples with uniform thickness.Second,the stapler was modified by replacing the stapler cartridge with an in-house built measurement cartridge,which can collect the multifrequency bioimpedance data during the compression and relaxation of the stapler.Third,a pressure measurement set-up was developed,and as a result the pressure signal could be processed,visualized,and stored on the personal computer by using Labview.At last,a graphical user interface was designed to fit the multifrequency bioimpedance data.2.Preliminary study on the characteristic changes of small intestine This study investigated the characteristic changes of small intestine,that is,the expulsion of extracellular and intracellular fluid with time.In experiment,pressure and multifrequency bioimpedance data were collected to observe the change of pressure exerted on the tissue and the change of extracellular and intracellular fluid conductance with time.At the same time,the Pearson correlation analysis to G0 and ?G,with pressure respectively was conducted,and finally the characteristic changes of small intestine were preliminarily concluded.3.Effects of precompression time and strength on the characteristic changes of small intestine In this experiment,the precompression time and strength were selected as the independent variables on the basis of preliminary study of the tissue characteristic changes.In detail,the precompression time was set to 5 different levels:5s,10s,15s,20s and 30s.As well as the compression strength was set to 3 different levels by 3 different thickness of spacer:0mm(i.e.,no spacer),0.39mm and 0.78mm.Then,the effects of these two independent variables on the expulsion of the extracellular and intracellular fluid and the amount of tissue rebound,from before clamping the tissue with the stapler until the release of the tissue after precompression without firing,were researched.The study results showed that the expulsion of extracellular fluid increases rapidly with measuring time,while intracellular fluid fluctuates.The correlation between expulsion of extracellular fluid and pressure are highly significant for all samples,but correlation between expulsion of extracellular fluid and pressure are highly significant only for 40%and significant for 20%of all samples.This paper concluded that the expulsion of extracellular and intracellular fluid increase with the precompression time and strength during the compression of the stapler.Thus increasing the precompression time and strength appropriately can make the tissue clamped by the stapler becomes thinner and more uniform,which will benefit the staple formation.During the relaxation process of the stapler,Tissue resilience which can cause the tissue to exhibit rapid volume resilience and may produce unwanted pressure on the staples,possibly leading to staple malformation.But it can be weakened by increasing the precompression time and strength.However,an excessive increase in the precompression strength does not lead to improved results.