Temporary Pancreatic Duct Occlusion To Prevent Postoperative Pancreatic Leakage In A Porcine Model Of Pancreatojejunostomy

Pancreatoduodenectomy is the first choice for cases with resectable tumor in pancreatic head and periampullary region.But itself carried great risk both intraoperatively and postoperatively.In the early age of this procedure, postoperative motality was around 32%. Recently, alone with the improvement of the technic and appearing of new drugs,postoperative motality can be 5% or less in big centres. Motality postoperation is tightly correlated to the incidence of pancreatic leakage of the anastomosis between the remnant of the pancreas stump and jejunal loop or stomach .Once pancreatic leakage ocuurs,there would be prolonged hospital stay and much higher costs,Motality rate would elevate as 20%-40% according to the reports. Now days, the incidence of pancreatic leakage after pancreatoduodenectomy is about 10% in sophisticated centres.Many perioperative factors attribute to the incidence of pancreatic leakage, including the primary disease of the patient,texture of the pancreatic parenchyma,diameter of the main pancreatic duct etc,but the most important factors are the experience of the operator and the method used in processing the pancreatic stump.Traditional methods used in managing the pancreatic stump are as follows: pancreatojejunostomy which could be further categorized intoduct-mucosa anastomosis and imagination of the pancreatic stump to the jejunum; pancreaticogastrostomy; ligation ofthe pancreatic duct without anastomosis; permanent occlusion ofthe pancreatic duct using undegradable gels. In comparison ofthe efficacy within different methods in preventing the pancreatic leakage,there was no difference between the duct-mucosa and the invagination, pancreaticogastrostomy was deemed as superior than the pancreatojejunostomy in leakage rate but it results in other complications postoperatively such as stenosis ofthe anastomosis due to the overgrowth the gastric mucosa as well as atrophy of the exocrine pancreas owing to the ineffective activation ofthe pancreatic enzyme by the acid environment in the stomach. Pancreatic duct ligation was once thought effective in preventing the leakage, but further study showed the continous secreting of the pancreas following ligation would increase the pressure of the pancreatic duct thus produce a higher leakage rate. Besides those above,some scholars have propagated permanent pancreatic duct occlusion using undegradable gels which did brought a lower leakage rate but in the long run, exocrine and endocrine function ofthe patients were greatly compromised.Our concept of temporary pancreatic duct occlusion came about with the idea that fibrin can be degraded by the proteinase in the pancreatic juice, withing the use of aprotinin, an antagonist of the the proteinase ,the degradation time of the fibrin and thus the recanalization of the pancreatic duct can be well controlled,further more to preserve the exocrine and endocrine function ofthe pancreas.The major objective of our study is to construct a temporary pancreatic duct occlusion model on juvenile pigs underwent partial pancreatectomy andpancreatoduodenostomy, thus to investigate the feasibility of pancreatic duct recanalization after the occluding in vivo.the histological influence of the occluding on pancreatic parenchyma as well as endocrine and exocrine function of pancreas after the procedure are evaluated.Part 1: ex vivo research on the degradational characteristics offibrin-aprotinin mixture under porcine pancreatic juiceObjective:To investigate the degradational velocity of fibrin gel mixed with different concentration of aprotinin ex vivo under the effect of porcine pancreatic juice,hence to control the time of degradation of fibrin and recanalization of the pancreatic duct at optimal time in an pancratoduodenostomy animal model of temporary pancreatic duct occlusion. Methods: Pancreatic juice was prepared in a pig being performed duodenotomy,A tube was inserted through the papilla to the main pancreatic duct for draining of pancreatic juice. 8 groups of 6cm length fibirin mixed with aprotinin of different concentration were injected to erected silica gel tubes and solidicated.14 cm porcine pancreatic juice was then added through the top of the tubes to simulate the pressure of pancreatic duct.Fresh pancreatic juice collected from the drainage of animal model was added daily following evacuating of the former.The time of recanalization within the tubes were recorded and a regression curve of recanalization time-aprotinin concentration was made.then we used the mothod above again to test the influence of the fibrin gel length to the time of tube recanalization.a curve of recanalization time-gel length was made. Result: Pancreatic juice was drained from the inserted tube in the animalpancreatic duct uneventfully.Mixture of fibrin-aprotinin can be degraded bythe porcine pancreatic juice thus the obstructed tube can recanalize.The tubeoccluded with 6cm length of fibrin mixed with aprotinin at a concentration of28600KIU/ml recanalized at day 6.1cm length increasing of fibrin gel makesa 24.143 hours delay in recanalization time under aprotinin at concentrationof28600KIU/ml.Conclusion: In the ex vivo experiment,mixed aprotinin concentration andlength of fibrin gel are positively correlated to the time of recanlization oftube occluded with fibrin under 14cm pressure of pancreatic juice.Therecanalization time of the tube occluded with fibrin can be controlled withladdered concentration of aprotinin when being digested by the pancreaticjuice.Part 2 Construction of the porcine model ofpancreatoenterostomyObjective: To construct animal model of pancreatoenterostomy thus to investigate the feasibility of temporary pancreatic duct occlusion using fibrin-aprotinin mixture in preventing pancreatic leakage after pancreatoenterostomy in vivo.Method: Fifteen healthy juvenile pigs were assigned into 3 groups randomly. Pancreaticoduodenostomy following partial resection of the pancreatic head was applied to all the groups. Group 1 was anastomosed with in situ intraductal stenting,occlusion of the pancreatic duct was not adopted.Occlusion of the pancreatic duct was used in Group 2 and 3.Group 2 was with a ex situ intraductal stenting while Group 3 a in situ one. Serum amylase and glucose level before and after operation was surveilled. 1 animal of every group was executed in the postoperative day 20,25,30,35,40 to observe the intraabdominal complications and to examing the recanalization of the obstructed pancreatic duct, specimens from the pancreatic remnant were also obtained for pathological and immunohistochemical examing. Result: There was 1 case of pancreatic leakage in goup 1 within all the fifteen animals. Basical preoperative amylase level of the pigs is 678.4± 126.6IU/ml. Amylase level of the 3 groups on the postoperative day 1 , 5, 10, 20 are: group 1: 2061 ± 261.6IU/ml,2807.6 + 3351.6IU/ml,2777.3 + 4479.3IU/ml,712 + 36.6IU/ml;group 2: 5344.8 ± 1549.3rU/ml,8213.4 + 2067.5IU/ml,8790 + 942.5IU/ml,2174.8 + 1089.8IU/ml;group 3: 3983 ± 1247.1IU/ml,8260 ± 1297.8IU/ml, 7170.4 ± 1853.2IU/ml,1402.6 ± 731.9IU/ml.Difference with statistical significance was found in the postoperative day 1,5,10 among the groups using One-Way ANOVA Test(P=0.003,P=0.004,P=0.016) .On the postoperative day 20,the difference of amylse level among the groups did not hold statistical significance any longer(P=0.752) .The difference of postoperative serum glucose level among groups did not appear to be statistical significant. Median time of juice draining out in group 2 with ex situ intraductal stenting is 10 days. Intraabdominal inflammation in the group 2 and 3 are similar which is more intense than group 1 in the postoperative day 25.Examing after the postoperative day 30 found no difference within groups regarding the severity of intraabdominal inflammation. Recanalization of the pancreaticduct in group 3 was observed in all the cases. Pancreatic duct dilated in all the cases ,but the extent of dilation did not correlate to the modality of pancreatic stump reconstruction. Microscopic examing of the H-E stained section as well as immunohistochemical assay of TNF- a reveal no difference within groups.Conclusion: The main pancreatic duct occluded with fibrin in animal model of pancreatoenterostomy can be recanalized,the time of recanalization can be controlled by adding aprotinin in the fibrin.amylase level will transiently elevate after this procedure postoperatively but it can be well tolerated by the animal. Temporary occlusion of the pancreatic duct during pancreatoenterostomy does not increase the risk of postoperative pancreatic leakage and motality. Inflammation result from occlusion will fade gradually postoperatively. Invaginated pancreatoenterostomy results in dilation of the pancreatic duct.Part 3:Compact of temporary pancreatic duct occlusion on pancreatic endocrine and exocrine function as well aspancreatic fibrosisObjective:To investigate the functional alteration of pancreas and whether there is a tendency of fibrosis of it after recanalization of the temporary fibrin-occluded main pancreatic duct. Method: Specimens were collected from the animal model of part 2.Amylase, trypsinogen and hisulin are indicators for pancreatic endocrine and exocrine function while EGF, EGFR and TGF-/3 are for pancreatic fibrosis.Total tissue mRNA was extracted for semi-quantitative RT-PCR analysis of the amylase, trypsinogen, Insulin ffl EGF, EGFR, TGF-/3 expression level.the expression level of /3-actin in every independent sample was used as control. The related expression level of every indicator was compared.Result:The difference on expression level of amylase, trypsinogen and Insulin were with no statistical significance (Amylase, P = 0.433 ; trypsinogen, P=0.163; hisulin, P=0.398) as well as the indicators for pancreatic fibrosis (EGF, P=0.372; EGFR, P = 0.335; TGF-0, P=0.323). Conclusion: Temporary occlusion using fibrin gel in pancreatoenterostomy does no harm to endocrine and exocrine function to pancreas remnant. There is no sign of elevation regarding the growth factors and its receptor deemed as attributors to chronic pancreatic fibrosis in previous studies therefor we concluded that this procedure possibly do not evoke a tendency of pancreatic fibrosis after recannalization.