| Part 1 Establishment of lung recruitment model by implanting and removing a plugged, bullet-shaped, angled Stent.Objective To discuss the technology of stent implantation in rabbit's trachea and make a base for animal experiment. To evaluate the feasibility of a lung recruitment animal model by implanting and removing a plugged, bullet-shaped angled stent with the aim to improve the repeatability and controllability of the model and to lay the foundation for clinical research.Methods Fifty-two Japanese White rabbits, weighing 2.75kg,were randomly divided into four groups:group 1w,2w,3w,4w(n=13).We implanted plugged, bullet-shaped, angled stent in 52 rabbit's chest by the guiding of DSA in the light anesthesia condition and then removed the stent in lw,2w,3w,4w respectively. The weight,temperature and MSCT were performed in every group preoperative and at specified time to determine whether obstructive atelectasis formed or reexpansion occurred.Result We put 52 stents successfully and 40 stents were correct located. The successful rate is 76.9%; 26 out of 40 rabbits with a stent survived and 14 were dead postoperatively.All rabbits who survived formed atelectasis. The successful rate of atelectasis formation is 76.9%.25 out of 26 stents were removed successfully. The rate is 96.2%.Lung recruitment did not occur in two rabbits. So the rate of reexpantion is 92%.Conclusion It is a good technology to implant a plugged, bullet-shaped angled stent then remove it by the guiding of DSA in light anesthesia condition to make a model of lung recruitment in rabbits. The method is simple and easy. Either the successful rate of stent implantation and removal or the successful rate of atelectasi and lung recruitment is higher.Part 2 The correlation study of MSCT imaging and pathologic in lung recruitment and reexpansion pulmonary edema(RPE) by animal experimental modelObjective By now, it reachs a consensus in clinic that obstructive atelectasis should be treated as fast as possible to make lung recruit. But, the possibility and time when lungs could recruit are still not comes to an agreement. The mechanism that RPE occurs is also undercover. Our experiment aimed the relevance of MSCT and pathology in the field of lung recruitment and RPE. It will do a lot of help to diagnose and treat these illnesses.Methods Fifty-two healthy adult rabbits were randomly divided into four groups, each group contains thirteen of them. Firstly, we implant a plugged, bullet-shaped angled stent in the rabbit to form atelectasis. Then we remove the stent at specified time and measured MSCT value and executed the rabbit to get lung tissue that reexpanded. Then we did pathology. At last we analyze the correlation of MSCT and pathology in each group.Results Longer a lung cllapse, higher the MSCT value is when lung reexpanded. Correlation of MSCT images and pathological changes is as follow:lung collapse for one week, alveolar epithelial cells have not been ruined, Pulmonary telangiectasia are congestive. Pulmonary interstitial thicken slightly. Lung reexpand well in 2h.The density is close to-1000HU which is the density of gas.When RPE occur, the density increase. That is between-400HU and-500HU,lower than the density of water but higher than that of gas. Lung collapse two weeks, Pulmonary interstitial thicken obviously and form fibrosis initiatively. Lung reexpand worse than one week group. The density is between-600HU and-700HU in the first 2h, then between-450HU and-650HU because RPE is not serious. Lung collapse three weeks or four, alveolar epithelial cells degenerate, Pulmonary interstitial fibrosis (PIF) become more serious. A great quantity of lymphocyte gather in pulmonary interstitial. All these above make pulmonary interstitial less elastic that lung barely reexpand in the first 2h, and the density is between-200HU and-400HU.It goes a bit better in 48h and lung reexpand a little more. The extent of RPE is too low to count, the density is between-400HU and-600HU, depended on how much air goes into pulmonary alveoli.Conclusion Longer a lung collapse, harder it reexpand without any artificial intervention. However, the rate of RPE occurrence is lower. Longer a lung reexpand, better it reexpand. Lung recuritmeng should be taken as soon as possible in clinic and RPE should be prevented. |
