Effect Of The Vacuum Drainage With Different Positions On Microcirculation Of Venous Congestion Flap

Objective: To study the effect of the vacuum drainage with differentpositions on microcirculation of the venous congestion flap through the rabbitabdominal venous congested flap model. This study was expected to provideclinical evidence for treating venous congested flap.Methods:1Experimental animal:30adult New Zealand white rabbits with cleanhealth level were selected. The body weight was from2.5to3.0kilograms andthe female rabbits were not pregnant. They were provided by HEBEI medicaluniversity and license number was SCXK(HEBEI)2008-2-001.2Animal groups:60abdominal skin flaps were made and randomlydivided into four groups: A (control group), B (proximal group) and C (distalgroup). In each group,10flaps were for monitoring microcirculation by laserDoppler imaging and the other10flaps were used for sampling to measureVEGF, CD34and histological observation.3Animal model: The ketamine and sumianxin at the rate of1:1(0.2ml/kg)were given to the rabbits. They were fixed in the supine position afteranesthetization and then molted in the double sides of abdomen. Two axialpattern flaps were made at the center of superficial vein in under the abdomenand each flap was4cm×12cm. The vein combined by Iliac groin vein andinferior epigastric vein were separated and then cut off. Mucosa and skin wassutured in A group. Drainage tube with four bye holes were located toproximal in B group and distal in C group. The tubes were perpendicular tothe axis of the flap. The tubes were removed after3days.4Laser Doppler imaging in scan group: Each flap was divided into threeparts along with the long axis of the flap. Perfuse unit in each part wasrecorded before2hours, after2hours,4hours,6hours,8hours,24hours,3 days and7days in B and C group by laser Doppler imaging.5Deal with the sample group: There were30flaps and they were handled asfollows:5.1The samples were collected in the middle part after4hours,24hours,3days,5days and7days. The samples were fixed in10%formalin, alcoholdehydration, hyaline, paraffin-embedded and then cut into4μm pieces.5.2The samples were collected in distal part at2hours before operation, after4hours,8hours,24hours and3days. The samples were kept at minus20Celsius degree and used to measure the activity of SOD.6Main Outcome Measures and methods:6.1General observation: general condition, the color, texture and edema.6.2Drainage volume: Record drainage volume in B and C group after4hours,24hours,2days and3days.6.3The survival proportion: Survival proportion was measured by standardgrid test paper. Necrotic tissue was blackened, hardened and no blood.6.4Flap blood perfusion: blood perfusion was measured by LPI and PU wasrecorded for each flap.6.5Histology observation: The alterations of the flap were observed underlight microscope after HE-dye.6.6Immunohistochemical observation: The volume of VEGF and MVD ineach flap by immunocytochemistry and computer image analysis system.6.7Measure the activity of SOD.7Statistical analyses were conducted using SPSS13.0statistical package.The results were presented as mean±SD(x±s) and P＜0.05was considered assignificant difference.Results:1General observation: Edema emerged after four hours. The scope anddegree in A group was more obvious than that in B and C group.The edemareached peak after2days and gradually subsided after3days in B and Cgroup. While edema in A group was still worse. Necrosis emerged after7daysin all groups. 2Drainage volume: The blood volume in C groups was more than that inB group after4hours,24hours,2days and3days. The difference wasstatistically significant (P <0.01).3Survival proportion: The survival proportions in A, B and C groupswere51.7%±9.2%,67.5%±8.9%and82.5%±8.2%after14days. The differencewas statistically significant and comparison with each other was alsostatistically significant (P <0.01).4Blood perfusion:Blood volume started to drop after2hours in three groups. It began torise after4hours in B and C groups and after8hours in A group.The rate of increased began to emerge difference. Blood volume washigher in B and C groups than that in A group(P <0.01). This difference lasteduntil7days after operation.In distal part of flaps, Blood volume in C group was more than that in Bgroup and this difference last until7days after operation(P <0.01).5Histology observation: Erythrocyte gathered after1day anddegenerated after7days in vessel in A group. Neovascularization emerged inB and C groups and this phenomenon was especially obvious in C group.6Microvessel density: Microvessel density began to increase after4hours in three groups. The density is maximum in C group, fewer in B group,and minimum in A group. The density reached peak after5days and then keepthe level for some time. The rate of increase was low in A group. The densityreached peak after3days and then gradually decrease. The density is higher inB and C group than that in A group(P <0.01).7VEGF expression: VEGF expression began to increase in A, B and Cgroups. VEGF expression is maximum in C group, fewer in B group, andminimum in A group. Comparison with each other was statistically significant(P <0.05). The volume reached a peak at5days in B and C groups and3daysin A group.8The activity of SOD: The activity of SOD started to drop after2hoursin three groups and reached a low point after24hours. The comparison among the three groups was statistically significant (P <0.01). Then it began to riseand there was no statistically significant after3days.Conclusion:1The vacuum drainage could reduce the blood clot scope and degree ofthe venous congestion flaps. Distal discharge is more advantageous and theeffect is better than that proximal discharge.2The vacuum drainage could significantly improve blood perfusion,distal drainage can effectively maintain microcirculation and improve the curerate of venous congestion flap.3The vacuum drainage could promote VEGF expression in venouscongestion flaps. It was conducive to the formation of new blood vessels andincreased microvascular density in venous congestion flaps.4The vacuum drainage could enhance the vitality of SOD in tissue andantioxidant capacity in early.