Clinical And Experimental Studies Of Vacuum Drainage In Ear Reconstruction Using Skin Expander Combined With Autogenous Costal Cartilage Transplantation

Part one The Principles and Effects of Vacuum Drainage on blood circulation of expanded skin flap in Ear reconstruction using skin expander combined with autogenous costal cartilage transplantationObjectives:To investigate(1) The principles and negative pressure change styles of two different Vacuum Drainage systems;(2) The effects on blood circulation of expanded skin flap and appropriate intensity of negative pressure caused by Vacuum Drainage in Ear reconstruction using skin expander combined with autogenous costal cartilage transplantation,for correct and efficient use of Vacuum Drainage in clinic.Methods:(1) 40 patients(Auricular Reconstructive Center of Plastic Surgery Hospital, PUMC,Beijing,PR.China) were divided into two groups randomly using different Vacuum Drainage system.Set the initial intensity of Vacuum Drainage -60kPa.Measure the volume of two Vacuum Drainage systems and record the numerical value of negative pressure,quantity of leakage,0,2,4,8,24 hours postoperatively.Draft the volume-pressure curve diagram.(2) Using infrared thermography post-operational instantly to detect the temperature of proximal(concha) and distal(helix) part of the expanded flaps—represent the arterial blood supply of flaps—of 21 reconstructed ears while 0,-20,-40 and -60kPa Vacuum Drainage were applied.3 groups were divided randomly of 21 patients,-20,-40 and -60kPa Vacuum Drainage were gave separately.The length and width of reconstructed ears—represent the swelling degree—were measured instantly and 5,10days postoperatively.The differences were calculated and stand for venous return of flaps.Results:(1) The volume difference of two Vacuum Drainage systems were significant(P＜0.01);The intensity of Vacuum Drainage was lower according to the decrease of Vacuum Drainage volume,accompanying with the increase of leakage quantity.The Vacuum intensity lower speed of small volume drainage system was significant fast than the big volume Drainage system(P＜0.01);The leakage quantity of big volume drainage system was significant high than small volume drainage system at the 8,24 hours postoperatively(P＜0.01).(2) 0 to -60kPa,following the strengthen of intensity of Vacuum Drainage,the flap temperature of reconstructed ears increased(P＜0.01),the increase in value of proximal(concha) part was significant high than distal(helix) part (P＜0.01);but the swelling degree of reconstructed ears firstly decreased,and then increased(P＜0.01).Conclusions:(1) The volume of drainage system affects the endurance period and actual using result of Vacuum Drainage.In clinical,the intensity of Vacuum Drainage of big volume drainage system was less influenced by the leakage quantity and contributed to the endurance period and actual using result of Vacuum Drainage.(2) Vacuum Drainage influenced both arterial blood supply and venous return of flaps in Ear reconstruction. The effects of Vacuum Drainage were presented both proximal and distal part of the flap. -40kPa Vacuum Drainage was benefited to both arterial blood supply and venous return. It can be consulted by clinical use. Part two The mechanism and histological studys of Vacuum Drainage on blood circulation of expanded skin flap in Rabbit Ear reconstruction ModelObjectives:Vacuum Drainage was used in Rabbit Ear reconstruction Model to investigate(1) The mechanism and relations and flap blood circulation change accompanying with the pressure change under the expanded skin flap;(2) The histological and ultramicro structure and tissue water content changes of the expanded skin flap;(3) The histological and structure changes between the expanded skin flap and the cartilage framework.Discuss the possible mechanism of blood supply improvement and the efficient period of the Vacuum Drainage.Methods:2 kidney-shaped skin expanders,with a 50ml potential volume,were implanted into the subcutaneous pocket dissected at symmetrical part of rabbit back separately.The total expansion volume was 80ml each and took about 15 days.After additional 15 days static expansion phase,the expanders were removed.A "C"-shaped skin flap,pedicled anteriorly,was elevated and a carved silicon gel ear framework was inserted under the flap.The rabbit ear reconstruction model was established.(1) While 0, -10,-20 and -40kPa Vacuum Drainage were applied separately,mini-pressure detectors were applied to measure the pressure of the helix(Group A) and the concha(Group B) part of reconstructed ear under the flap.Laser Doppler Flowmetry was used on same place of the flap surface to measure the perfuse unit(PU).(2) Same experimental model, -15kPa Vacuum Drainage was applied to treated group,no negative pressure was applied to control group.Histological specimen of both two groups were harvested 1,3,5 days postoperatively and observed under the optical microscope and the transmission electron microscope.Total tissue water content was measured by the method of wet-dry subtraction for both treated and control groups.(3) 2 circular shaped skin expanders,with a 30ml potential volume,were implanted into the subcutaneous pocket dissected at symmetrical part of rabbit back separately.Each expander was injected 50ml normal saline.After additional 15 days static expansion phase,the expanders were removed.A "C"-shaped skin flap,pedicled anteriorly,was elevated and an autogenous lamellar rabbit auricular cartilage was inserted under the flap.-15kPa Vacuum Drainage was applied to treated group,no negative pressure was applied to control group.Histological specimen of both two groups were harvested 2,4,6 days postoperatively and observed under naked eye and the optical microscope and the scanning electronic microscope.Results:(1) 0 to -40kPa Vacuum Drainage,The positive pressures unde flap was increased according to the increase of Vacuum Drainage,no significant difference was found in two groups(P＞0.05).The PU of flap firstly increased,and then decreased(P＜0.01).The PU of Group B was significant high than Group A(P＜0.01).(2) There is significant difference between all specimen of treated and control groups in the blood capillary antilinear and the tissue water content(P＜0.01).The microvessel density in 5 days postoperatively specimen of two group was approximately(P＞0.05).Treated group:expanded capillaries were observed and cell space was narrowed at 1 day after treatment;more significant expansion and the budding of capillaries was found at 3 days postoperatively;the expansion and budding of capillaries were still significant on the 5th day postoperatively,while cell junction was compacted.Control group:no significant morphological changes in capillaries;capillary budding was observed on the 5th day, while cell junction was still loose.(3) The skin flap and cartilage takes good,no rejection was observed.2 days after operation:skin flap and the cartilage were sticking tightly in treated group,while there were transudate accumulated under flap and blocked the attachment of flap and cartilage in control group.In treated group,plenty of fibrous tissues between skin flap and cartilage were observed on the 4th day postoperatively.6 days after operation,the fibrous tissues around the cartilage and the fibrous tissues under the skin flap were mixed together and hardly to discern.No visible interspace can be found between flap and cartilage.There is no apparent fibrous tissues were detected 4th day postoperatively in control group,the fibrous tissues were thick but the interspace between flap and cartilage still significant on the 6th day postoperatively.Conclusions:Vacuum Drainage was used in Rabbit Ear reconstruction Model(1) Negative and positive pressure was both existed under the skin flap.The pressures were well-distributed and bring two adverse effects to blood supply of expanded skin flap. Improving effect took the superiority while the intensity of Vacuum Drainage was lower than -20kPa,but the blood supply of expanded skin flap would be compromised when the intensity of Vacuum Drainage exceeded -20kPa.The concha part was located at pedicle of the flap and was less influenced by Vacuum Drainage than helix part which was located at distal of the flap.(2) The capillaries expansion,the compacted vascular endothelial cell junction,less tissue edema and more efficient microcirculation can be obtained by using proper Vacuum Drainage.The improving of microcirculation of skin flap was mainly come from capillaries expansion instead of the budding and proliferation of capillaries in the early stage.(3) Vacuum Drainage can efficient reduce the transudate, improve the attachment and the fibrous tissues proliferation,induce the formation of organismic-bind between flap and cartilage early and improve the survival of the cartilage grafts.The efficacious period of Vacuum Drainage would be 4-6 days.That was indicated the appropriate time for removing Vacuum Drainage to avoid the complications caused by excess drainage time.