Experimental Study Of Poloxamer 407 Temperaturesensitive In Situ Gel-assisted End-to-end Anastomosis Of Rabbit Femoral Vein

Objective: To establish a rabbit model of end-to-end anastomosis of femoral veins.To prepare thermosensitive in situ gel(P407 gel)using thermosensitive material poloxamer 407 as small vessel dilator,and open the anastomotic stoma of small vessels for suture anastomosis(P407 method).To investigate the feasibility and validity of P407 method in clinical application through an experimental study of rabbits.Methods: 1.Preparation of a specific temperature-sensitive in-situ P407 gel,which is liquid at room temperature,converted to a gel when heated to a phase transition temperature(30?),and rapidly dissolved at normal temperature.2.Thirty-two healthy adult New Zealand rabbits were selected and randomly divided into treatment group and control group,with 16 rabbits in each group.A left femoral vein model was established(internal diameter,1.79~2.13 mm;mean,1.92 mm).End-to-end microvascular anastomosis was carried out.The treatment group received anastomosis using the P407 method,while the control group underwent traditional suture anastomosis.3.The duration of microvascular anastomosis in each rabbit was recorded during the experiment,and the patency rate of anastomotic stoma was detected by burst test.The patency rate and internal diameter of blood vessels after vascular anastomosis were detected using color Doppler ultrasonography and CT venography(CTV)at the 6th week after surgery.The patency rate of anastomotic blood flow was observed with naked eyes.Then,the rabbits were killed painlessly and corresponding specimens were prepared.The inflammatory response and tissue repair of vascular wall were observed by HE staining.Result: 1.Specific P407 gel was prepared successfully.In the living rabbit model of end-to-end anastomosis of femoral veins,P407 gel was used as small vessel dilator to open the anastomotic stoma for successful suture anastomosis.2.The duration of vascular anastomosis in the two groups was recorded during the experiment.The average duration of the P407 method for each anastomotic stoma was(1,250 ± 91)s.In traditional suture anastomosis,the average duration for each anastomotic stoma was(1,876± 144)s.The velocity of vascular anastomosis by the P407 method was higher than that by traditional suture anastomosis,with a statistically significant difference(P < 0.01).3.In the operation,16 vascular anastomoses were observed in the P407 group,and the overall success rate of vascular anastomosis was 100%.Among them,15 one-time anastomosis was successful,accounting for 93.75%,and the second revision was successful,accounting for 6.25%;the traditional suture anastomosis group was anastomotic with 16 vessels,and the overall vascular anastomosis was successful,accounting for 100%,of which one-time anastomosis was successful.Twelve,accounting for 75%,four successful revisions,accounting for 25%.The success rate of one-time anastomosis of P407 group was higher than that of traditional suture anastomosis group.According to the chi-square test results of the paired fourtable(P<0.01),it was statistically significant.4.Color Doppler,CTV examination At the 6th week after surgery,color Doppler ultrasound results showed that the blood flow of the two groups of vascular anastomosis was good.The statistical results of the inner diameter of the P407 group were 1.97 ± 0.13 mm on the healthy side and 1.87 ± 0.11 mm on the anastomosis side.The anastomotic side vessels were slightly narrower than the healthy side,and there was no statistical significance(P>0.05).The results of the inner diameter of the suture anastomosis group were 1.99 ± 0.15 mm on the healthy side and 1.86 ± 0.11 mm on the anastomosis side.The anastomotic side vessels were slightly narrower than the healthy side(P>0.05).There was no significant difference in the inner diameter of the vascular anastomosis between the two groups(P>0.05).At the 6th week after operation,the results of CTV examination showed that there was no obvious stenosis in the anastomotic stoma of the two groups,and the blood flow was good.5.Visual observation and histological examination At the 6th week after operation,the rabbits underwent anesthesia with naked eyes.The blood vessels of the two groups were well flowed,and the blood vessels were slightly adhered to the surrounding tissues.Then,the rabbits were sacrificed without pain,and the anastomotic vascular specimens were made.The healing of the anastomotic vascular anastomosis was observed by HE staining.The results suggest that there are endothelial cell proliferation,a small amount of inflammatory cell infiltration and scar formation around the anastomotic stoma of rabbits.There was no significant difference between the two groups,indicating that P407 gel had no obvious toxicity to vascular tissue.Conclusion: The P407 method has certain advantages in reducing the difficulty of venous anastomosis,reducing the time of vascular anastomosis,and improving the success rate of one-time anastomosis.