The Effect of Fondaparinux Versus Enoxaparin in the Survival of a Congested Skin Flap in a Rabbit Model

Management of venous flap insufficiency: the role of low molecular weight heparin in salvage

Flap loss resulting from venous insufficiency is a difficult issue, both with pedicled or free flaps. We examined the efficiency of low molecular weight heparin administration in various forms and dressing methods in venous insufficiency. Forty-five Sprague Dawley rats were included and inferior epigastric artery perforated island flaps were obtained from the abdominal skin of the animals. Nine animals were randomly allocated to each of five experimental groups: sham-control (Group 1), venous occlusion only (Group 2), occlusion with systemic enoxaparin (Group 3), occlusion with systemic enoxaparin + local enoxaparin infusion to the punctiform incisions (Group 4), and occlusion with systemic enoxaparin + local enoxaparin infusion to the punctiform incisions and enoxaparin-impregnated sponge dressing (Group 5). Group 5 had higher flap survival rates than the other groups. Groups 3 and 4 had numerically better vitality than the control group, but the difference was not significant. Low molecular weight heparin administration, with or without punctiform incisions, is not efficient in rescuing flaps with venous insufficiency. Specialised dressing methods are necessary to maintain bleeding.

Non-microvascular Successful Management of Near-total Ear Avulsion

Traumatic ear avulsion represents a difficult challenge for all reconstructive surgeons; hence, replantation and reattachment will provide the best aesthetic outcome. However, when microsurgery is not possible, the surgeon must choose the most appropriate alternative method to address the concern. We are reporting a case of a near-total right ear external auricle amputation attached only by small skin bridge. The patient was admitted to our institute 22 hours after sustaining an injury during a motor vehicle collision. He was successfully managed by reattaching the external auricle into the anatomical place, with the repair of cartilage. This was followed by applying a daily protocol for venous congestion with the use of subcutaneous and intradermal injection of low-molecular-weight heparin daily for 10 days with gradual tapering of the dose. The external auricle survived with no complications or morbidity. Subcutaneous and intradermal low-molecular-weight heparin can be used effectively in cases of severe venous congestion of avulsed ear with adequate arterial inflow without causing any morbidity.

Impact of different antithrombotics on the microcirculation and viability of perforator-based ischaemic skin flaps in a small animal model

The effects of antithrombotic drugs on random and free flap survival have been investigated in the past, but the experimental and clinical results are not in agreement. A perforator-based critical ischaemia model was used to evaluate the effects of different perioperatively administered pharmaceutical agents on tissue ischaemia and to assess the potential additional haemorheological or vasodilative effects of antithrombotics on flap microcirculation. Combined laser Doppler flowmetry and remission spectroscopy revealed an increase in certain microcirculation parameters in most groups in comparison with saline controls, and these changes correlated with flap survival. Clopidogrel and hirudin significantly improved the amount of viable flap tissue in comparison with controls, while unfractioned heparin had a negative effect on flap survival. Low molecular weight heparin, aspirin, pentoxifylline, and hydroxyethyl starch had no impact on the amount of viable flap tissue. A higher complication rate was observed in all experimental groups, but only clopidogrel had a negative impact on the flap viability. Our results add to the body of evidence supporting the conclusion that perioperative antithrombotic treatment improves flap survival. Clopidogrel and hirudin are effective pharmacological agents that significantly increased the viability of perforator-based skin flaps in rats, but at a higher risk of postoperative bleeding.

Transplantation of adipose tissue-derived stromal cells promotes the survival of venous-congested skin flaps in rabbit ear

Venous congestion after skin flap transplantation usually slows blood flow velocity and induces skin flap necrosis and surgical failure. Adipose tissue-derived stromal cells (ADSCs) can promote neovascularization and have been extensively applied in cell transplantation therapy and tissue regeneration. However, their function has not been reported in venous-congested skin flaps. In this study, rabbit ADSCs were isolated and identified. We established a rabbit ear venous-congested skin flap model and injected ADSCs into points along the midlines of skin flaps. The survival conditions of venous-congested skin flaps on postoperative day 7 showed that there was obvious swelling, hemorrhage, or necrosis in skin flaps of the control group, while the skin flap survival rate in the ADSC treatment group significantly increased. Hematoxylin and eosin (HE) staining results indicated that compared with the control group, thrombosis was significantly relieved and neovascularization was observed in the ADSC treatment group. Immunofluorescence revealed that the CD34 expression level and the number of capillaries significantly increased in the ADSC treatment group. In summary, ADSC transplantation promotes neovascularization in venous-congested skin flaps and skin flap survival. Therefore, ADSC transplantation may be an effective measure for promoting the survival of venous-congested skin flaps.

Multiphoton microscopic imaging of rabbit dorsal skin

Rabbits are often preferred to be experimental animals during the skin research. The visualizing and understanding the full-thickness structure of rabbit skin has significance in biology, medicine, and animal husbandry. In this study, multiphoton microscopy (MPM) was employed to examine the rabbit skin on the back, which was based on second harmonic generation and two-photon excited fluorescence. High-resolution images were achieved from the fresh, unfixed, and unstained tissues, showing detailed microstructure of the skin without the administration of exogenous contrast agents. The morphology and distribution of the main components of epidermis and dermis, such as keratin, collagen fibers, elastic fibers, and hair follicles, can be distinctly identified in MPM images. Since the changes in these components are tightly related to skin diseases and wound healing, the noninvasive nature of MPM enables it become a valuable tool in skin research for detecting and monitoring.

The time-dependent expressions of IL-1β, COX-2, MCP-1 mRNA in skin wounds of rabbits

In this study, we investigated the time-dependent expression of IL-1beta, COX-2, MCP-1 mRNA after incised wounds in rabbit skin using real-time fluorescent quantitative PCR. The tested wound ages were distributed as following: <0.5h, 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 8h, 12h, 24h, 2d, 3d, and 7d. The expressions of three markers in postmortem wounds were determined. Comparison of each wound age with control group, expression of IL-1beta mRNA showed that the significant increase occurred at <0.5h (p<0.01), and the peak level at 2h. The expression was almost normalized at 2d. But for COX-2 and MCP-1 mRNA, the significant increase occurred at 1h for COX-2 mRNA, and 3h for MCP-1 mRNA. The expression peak levels were at 3h and 5h, and were almost normalized at 3d and 7d, respectively. There was no significant increase in all postmortem samples for IL-1beta, COX-2, MCP-1 mRNA compared with control group. Thus, the results of these cytokines and enzyme significant increase at different early wound ages implied that the combined investigation could make wound age determination more objective and accurate. Moreover, the three markers could also be used to distinguish the supravital injuries.