Improved skin flap survival with nicotinic acid and nicotinamide in rats

The effects of some components of the coenzyme nicotinamide adenine dinucleotide (NAD) on tissue viability were investigated in acute island skin flaps which were constructed to exceed the blood supply provided by a unilateral pedicle of inferior epigastric vessels. Control flaps undergo significant necrosis. Treatment with nicotinamide or nicotinic acid, precursors of NAD, prior to flap elevation significantly improved the area of viability in the random portion of the flap from 44 +/- 9% (mean +/- SD) to 67 +/- 12 and 65 +/- 5%, respectively. Similarly, NAD improved viability to 68 +/- 10% (P less than 0.001). Treatment with other components, adenosine diphosphoribose or quinolinic acid, had no effect on flap survival. The results suggest that nicotinic acid and nicotinamide deserve therapeutic consideration with regard to the treatment of ischemia/reperfusion injury in skin.     

Complications of free flap transfers

Review of 72 cases of free flap transfer showed that flap failure was associated with thrombocytosis and open wounds and that complications were associated with open wounds. Specific biologic variables, therefore, may underlie flap failure and complications, and investigation of these variables could lead to reduced morbidity.     

Vascularized free flap transfers.

The success of a free flap transfer depends entirely on the suture of a paired artery and vein between the donor and recipient sites. The interrupted suturing method with biangulation or successive interrupted suturing is the method of choice. The size of the site, small or large, does not effect either the resulting patency or the process of intimal healing. When occlusion of the anastomosed site is encountered, the transferred free flap can be saved by exploration within 6 hours after surgery. Reapplication of the clamp proximally or distally to the anastomosed site does not change the patency rate. Free groin flaps can be successfully transferred in 2 orthopedic cases.     

Sulfatide elongates dorsal skin flap survival in rats

Monoclonal antibodies to adhesive molecules have been used in many trials to decrease ischemia-reperfusion injury, which is considered to occur in areas such as the distal region of the random pattern flap. The monoclonal antibody to the primary neutrophil adherence-mediating glycoprotein CD18 improves the survival length of the random pattern flap. Sulfatide binds strongly with L- and P-selectin. We found that sulfatide has a protective effect against ischemia-reperfusion injury. The purpose of this study was to evaluate the effect of sulfatide on the survival length of the random pattern flap in rats. Sulfatide was administered intravenously just before elevation of the cranially based dorsal skin flap. Administration of sulfatide significantly augmented flap survival length (49.5 +/- 1.7 mm vs control 41.5 +/- 2.1 mm, P = 0. 01). Flap survival length was significantly longer than dye distance (49.1 +/- 2.0 mm vs 39.7 +/- 1.1 mm, P = 0.01). In the control flap, no significant difference between survival length and dye distance was detected. Histological examination 48 h after flap elevation showed leukocyte invasion in the dermal layer of control flaps, whereas little leukocyte invasion was observed in the flaps of rats administered sulfatide.     

Improved skin flap survival after local heat preconditioning in pigs

BACKGROUND: Preconditioning induces the expression of heat shock proteins (HSPs), which can help a cell survive an acute episode of stress. Similar to the induction of HSP expression, the cell protection is independent of the type of stress. The aim of this study was to test in a large, randomized animal model, if skin flap survival may be improved by local heat preconditioning and induction of HSP 70. MATERIALS AND METHODS: Twenty-four hours before surgery, a heating blanket was laid on the buttocks of large white pigs. In the preconditioned group (n = 6), the blanket was warmed up to 43 degrees C for 3 x 30 min, whereas it was kept at room temperature in between the heating episodes as well as in the control animals (n = 6). A random pattern skin flap was raised on both sides of the buttocks. Flap survival was measured clinically. Induction of HSP and apoptosis were assessed quantitatively by immunohistochemistry and TUNEL assay, respectively. RESULTS: Preconditioning reduced flap necrosis from 40 +/- 8% of the total flap surface to 7 +/- 14% (P < 0.01). Induction of HSP was significantly higher in the experimental group (79 +/- 12% versus 42 +/- 13%, P < 0.01), whereas apoptosis in healthy flap tissue was reduced from 30 +/- 11 to 11 +/- 6 cells/visual field (P < 0.01). CONCLUSION: In the present study, necrosis and apoptosis rate of skin flaps could be reduced significantly due to local heat preconditioning. Our results suggest that ischemia-related wound healing complications could be diminished with local heat application, a most simple and least invasive method of preconditioning.     

Acute difluoromethylornithine treatment increases skin flap survival in rats

Difluoromethylornithine (DFMO) pretreatment for 7 days improved survival of rat abdominal skin flaps in previous studies. The purpose of this study was to determine if acute administration of DFMO enhances survival. Each rat had a 7 x 7-cm abdominal skin flap raised on a single epigastric neurovascular pedicle. Within 1 minute of pedicle ligation, the rats were given 0, 1, or 4 gm/kg of body weight of DFMO intraperitoneally. Putrescine was administered to additional rats alone or with DFMO. After 48 hours, the percentage of flap survival was estimated using fluorescein injection and planimetry to quantify the perfused and unperfused areas. Flap survival increased from 71 +/- 3% in controls to 83 +/- 2% and 92 +/- 3% in rats treated with 1 and 4 gm/kg of DFMO, respectively (p less than 0.005). Putrescine reversed the protective effect of DFMO, suggesting a specific polyamine-related mechanism. This study indicates that there may be both short- and long-term polyamine pools through which DFMO acts. In summary, DFMO may prove to be important in preventing cell death following acute ischemia.     

Experimental study of ischemia time influencing free skin flap survival

Summary The relationship between the ischemia time of the isolated skin flap and its survival after transfer by microvascular anastomosis was studied in rat. Our result would confirm that warm ischemia of under 9 h will not adversely affect survival of transplanted skin flap while cool ischemia of under 48 h also will not have an adverse effect. Based on our histological findings, the degeneration of vessels and fatty tissue were the most important change in skin flaps resulting from ischemia.Paper presented at the Second Congress of the Asian Pacific Section, International Confederation for Plastic and Reconstructive Surgery, in Tokyo August 22, 1977     

Experimental cutaneous free flap transfers in the horse

Equine limb wounds often heal slowly by epithelialization, and large scars are a frequent end result. In some ways, they resemble the wound associated with human tibial injuries. The literature indicates that previous investigators have failed to transfer free skin flaps successfully in the horse. In this paper, we review our experimental work with the deep circumflex iliac flap in the horse. Dissections of 20 cadavers confirmed the anatomical consistency of the flap. Four flaps survived well when elevated as island flaps, but five orthotopic and nine heterotopic free flap transfers all failed. The cause of failure is still unknown, but our experiments suggested that the horse must be highly susceptible to ischemic reperfusion injury.     

Impedance monitoring for subcutaneous free flap transfers

The assessment of thoracic blood flow by electrical impedance is a well-established technique. In an application of this a small electrode array has been developed in which an alternating electric current is passed through a subcutaneous free flap and the induced voltage across a small volume measured. A graphical display of this changing voltage illustrates the pulsatile flow through the flap, allowing continuous assessment of perfusion on a beat by beat basis. The electrode array is such that it can be placed in close contact with muscle without interface problems and can assess its viability. It is non-invasive and easily removed. We have found this accurate, easily interpreted by inexperienced staff, and a considerable reassurance in the postoperative period.     

水蛭素对大鼠随意型皮瓣存活的影响

目的 研究水蛭素对大鼠背部超长随意型皮瓣存活的影响.方法 采用改良大鼠"McFarlane flap"模型,将实验动物随机分为水蛭素实验组(水蛭素组)和生理盐水对照组(生理盐水组),水蛭素组局部注射3 ml(30 ATU)水蛭素,生理盐水组则注射3 ml生理盐水,连续注射7 d后分别检测两组皮瓣的存活面积百分比,并取皮瓣近、中、远段(即Ⅰ、Ⅱ、Ⅲ区)组织做光镜观察,免疫组化法检测血管内皮生长因子(VEGF)和碱性成纤维细胞因子(bFGF)的表达.结果 术后7 d,水蛭素组皮瓣的存活面积百分比为(69.52±3.23)%,生理盐水组为(50.36±2.37)%,水蛭素组显著高于生理盐水组,差异有统计学意义(P＜0.01);水蛭素组皮瓣坏死与存活并存的Ⅱ区,组织水肿、炎性细胞浸润情况明显比生理盐水组轻.水蛭素和生理盐水组皮瓣Ⅱ区的新生血管计数分别为(28.24±4.23)个/mm2和(17.45±5.43)个/mm2,两组比较差异有统计学意义(P＜0.05).通过计算累积吸光度A值(IA),得到水蛭素和生理盐水组VEGF阳性量分别为9262.23±896.99和4938.05±1623.67,bFGF阳性量分别为5122.83±1176.12和2779.45±472.00,水蛭组VEGF及bFGF的表达均高于生理盐水组,差异均有统计学意义(P＜0.01).结论 水蛭素可能通过体内一系列复杂的调控通路,最终增加VEGF、bFGF表达,促进皮瓣新生血管增生,改善皮瓣血供,减轻炎性反应,降低缺血皮瓣的坏死率,从而提高大鼠随意型皮瓣的存活.

Abstract：

Objective To investigate the effect of Hirudin on random skin flap survival in rats.Methods 24 SD rats were randomly divided into control group and experimental group. The "McFarlane flap(3 cm ×9 cm)" rat models were established on the rat dorsum. 3 ml Hirudin (30 ATU) was injected into the flap in the experimental group, while 3 ml saline in the control group. The injection was performed for 7 days. The flap survival area in the two groups was measured. The tissue samples were taken from proximal( Ⅰ ), middle( Ⅱ ) and distal( Ⅲ ) portions of flaps for histologic study. The VEGF and bFGF expression was also detected with immunohistochemistry method. Results 7 days after operation, the flap survival rate was ( 69.52 + 3.23 )% in the experimental group, while ( 50.36 ± 2.37 )% in control group,showing a significant difference between the two groups ( P ＜ 0.01 ). In the middle portion, tissue edema and infiltration of neutrophils in experimental group was markedly slighter than that in control group. The VEGF and bFGF expression and neovascularization was enhanced markedly in experimental group.Conclusions Hirudin can increase the survival of random pattern skin flaps. It may increase the VEGF,bFGF expression through a series of complex regulatory pathway. Then flap neovascularization is promoted and the flap blood supply is increased.     

Thirty-eight free fasciocutaneous flap transfers in acute burned-hand injuries

The benefits of free flap transfers in the acute burn injury are early wound closure, early mobility, reduced hospitalization, and possibly limb salvage. This retrospective study will attempt to provide principles to the use of free fasciocutaneous flap for the reconstruction of acute burned-hand injuries. Between 1995 and 2004, 5521 patients were admitted to the burn unit at Linkou Chang Gung Memorial Hospital. Of these, 38 patients (0.7%) patients received free fasciocutaneous flap transfers. Each patient's chart was reviewed the following data: age, gender, burn injury type, percentage of the burned area to total body surface area, flap type, operations prior to free flap coverage, the size and location of recipient area, timing of free flap coverage, operative time, duration of hospital stay, complications, flap survival and returning to work. All 38 free flaps survived and healed well. Three flaps with partial necrosis due to wound infections required subsequent debridement and skin grafting. Arterial thrombosis occurred in one patient and was salvaged successfully. Minimal donor-site morbidity with no intraoperative mortality was observed. Free fasciocutaneous flap transfer is a safe, efficacious one-stage reconstruction for acute burned-hands with satisfactory aesthetic and functional outcomes. Flap survival is not affected neither by the etiologies of burn nor the timing of free flap coverage.     

Deferoxamine increases skin flap survival: additional evidence of free radical involvement in ischaemic flap surgery

This study presents further evidence of free radical involvement in skin flap necrosis in a dorsal rat flap model. Rats receiving deferoxamine, a free radical scavenger and iron chelator had significantly less necrosis (p less than 0.001) than saline treated rats. In a separate experiment, tissue determinations for malonyldialdehyde (MDA) were consistent with the survival results in showing a significant decrease in MDA in all biopsy sites (p less than 0.05 or less), indicative of reduced lipoperoxidation in the deferoxamine treated rats.     

Efficacy of postoperative steroids on ischemic skin flap survival in rats

Necrosis of skin flaps remains a significant clinical problem. This study examined whether steroids improve skin flap survival in rats. Random skin flaps were raised in 30 male Sprague-Dawley rats. Intramuscular methylprednisolone (n=15) or saline solution (n=15) were administered 1, 24, and 48 h after flap elevation. Surviving flap areas were measured after 7 days. The mean surviving flap area in the methylprednisolone group was greater than that in controls (916 vs. 675 mm). These results suggest that postoperative methylprednisolone improves skin flap viability in the ischemic rat flap model.     

The effect of basic fibroblast growth factor on the neovascularisation process: skin flap survival and staged flap transfers.

Forty-two male Sprague-Dawley rats were utilised to determine whether the angiogenic property of basic fibroblast growth factor (bFGF) could be applied to improve the survival of the ischaemic portion of a random skin flap and to accelerate the process of staged flap transfer. In the ischaemic flap model, bFGF enhanced the development of vascular connections between the bed and the flap and prevented marginally perfused areas from undergoing necrosis. No effect was observed in the staged reconstruction model using the same dosage of bFGF. A speculative explanation is given for the differential effect of BFGF in these two models. The application of angiogenic factors may improve the survival of the random portion of skin flaps. Further investigations are needed to determine whether exogenously applied angiogenic factors can have a beneficial effect in staged flap reconstructions.     

Nicotinamide enhances skin flap survival

The effects of nicotinamide in an abdominal island pedicle skin flap were examined. A 7 x 7 cm island pedicle skin flap ligating the left inferior neurovascular pedicle was created on 50 male Sprague Dawley rats (250-275 grams) that were divided into five groups. Animals received either 0.6 cc of saline or doses of nicotinamide for 16 days (14 days preoperatively and 2 days postoperatively): 25 mg b.i.d., 50 mg b.i.d., 100 mg b.i.d. or 200 mg b.i.d. Forty-eight hours postoperatively each animal received 25 mg of Fluorescein via the tail vein. The area of necrosis was visualized and quantified and is presented as % survival. A one factor Fisher PLSD test was performed with a statistical significance of p less than 0.05 with the results as follows: saline 58.8%, 25 mg 68.6%, 50 mg 82%, 100 mg 80.8%, and 200 mg 86%. From this data it would appear that the angiogenic factor nicotinamide may increase random flap survival.     

The effect of botulinum toxin A on skin flap survival in rats

This study examines the role of botulinum toxin type A (BoTA) in preventing the collapse of the peripheral vessels in the cutaneous flap and in increasing the survival of the flap. Because BoTA cleaves the SNAP-25 protein, the release of vasoconstriction cotransmitters as well as acetylcholine would be blocked. Dorsal skin flaps in rats were elevated and returned to the original position. In the BoTA and the control group, either BoTA or saline was injected into the entire flap. The flap survival rate measurement and a histopathological examination were performed 1 week after flap elevation. The cutaneous blood flow was measured in three different areas of each flap, serially. In BoTA group, there was a significant increase in the survival rate (93.79 ± 6.06%, p =0.042). In the control group, the blood flow was decreased significantly immediately after flap elevation. The blood flow was high in all areas in the BoTA group in a week, and also most of the vessels maintained their shape without collapsing. In conclusion, pretreatment with BoTA increases the dorsal skin flap survival in rats by increased perfusion, and further studies should be performed to determine the possible mechanism by which BoTA attenuates the sympathetic vasoconstriction effect in skin flaps.     

Immediate skin grafting on microvascular free tissue transfers

Clinical reports of pedicled muscle flaps and microvascular tissue transfers include two distinctly different strategies for skin grafting. Some authors describe immediate grafting, whereas others recommend a three- to 5-day interval between flap transfer and grafting. No systematic analysis of either strategy has been reported. We reviewed 51 consecutive successful free tissue transfers that involved immediate skin grafting. Ninety-six percent of the grafts survived without complication. Bot muscle and fascial flaps supported skin grafts. Skin grafts survived infected recipient sites, pedicle revisions, partial flap necrosis, and secondary operation. We conclude that immediate skin grafting on free tissue transfers is reliable.     

疏血通注射液对大鼠随意型皮瓣存活的影响

目的研究疏血通注射液对大鼠背部随意型皮瓣存活的影响。方法采用改良的大鼠McFarlane皮瓣制作方法,将Sprague Dawley大鼠随机分为疏血通实验组和生理盐水对照组,实验组每只每天腹腔注射疏血通注射液1．5mL／kg,对照组每只每天腹腔注射生理盐水1．5mL／kg。术后第7天处死大鼠分别进行皮瓣存活面积比的检测,并取皮瓣近、中、远区组织切片光镜下观察,免疫组化法检测血管内皮生长因子（VEGF）的表达。结果术后7d,实验组皮瓣的存活面积比为（72．52±2．23）％,对照组皮瓣的存活面积比为（50．36±2．37）％,实验组存活面积比显著高于对照组（P〈0．01）。实验组中区皮瓣的组织水肿、炎症细胞浸润情况明显比对照组减轻,并且出现大量的新生血管,中区新生血管密度（27．42±4．21）个／mm^2,与对照组（17．45±5．43）个／mm^2差异有统计学意义（P〈0．05）。实验组VEGF表达量为4731．24±448．99,对照组为2466．01±801．67,差异有统计学意义（P〈0．01）。结论疏血通注射液可能通过增加VEGF表达等途径,促进皮瓣新生血管增生,改善皮瓣血供,减轻炎症反应,从而改善大鼠随意型皮瓣的存活。     

Subdermal nitrous oxide delivery increases skin microcirculation and random flap survival in rats

Random skin flaps are essential tools in reconstructive surgery. In this study, we investigated the effect of subdermal nitrous oxide (N₂O) application on random flap survival. In this experimental study, we used 21 female rats in three groups. In the N₂O and air groups, gases were administrated under the proposed dorsal flap areas daily for seven days. Following the treatment period, flaps were raised and inserted back into their place from the dorsal skin. In the control group, the flaps were elevated and inserted back to their place without any pretreatment. Calculation of necrotic flap areas, histological examination and microangiography was performed to evaluate the results 7 days after the flap surgery. The average of necrotic flap area in the N₂O, air and control group was 13.45%, 37.67% and 46.43%, respectively. (N₂O vs air p?=?.044; N₂O vs control p?=?.003). The average number of capillary formations identified in the histological analysis was 7.0?±?1.58, 3.75?±?2.36 and 4.4?±?0.54 in the N₂O, air and control group, respectively. (N₂O vs air p?=?.017; N₂O vs control p?=?.037). The average number of capillary structures identified in the angiography images were 6.3?±?1.52, 1.6?±?1.15 and 1.3?±?0.57 in the N₂O, air and control group, respectively. (N₂O vs air p?=?.04; N₂O vs control p?=?.02). We conclude that subdermal N₂O application increases random flap survival through an increase in the skin microcirculation and could be promising for future clinical applications.     

Effects of low-power laser irradiation on survival of random skin flap in rats

This research was designed to study the effects of low-power helium–neon (He–Ne) laser irradiation on random skin flap survival in rat. Fifty 50 male rats were randomly divided into five groups. On the dorsum of each rat, one full thickness random skin flap which contained no specific vessel was elevated. Groups 1 to 4 were exposed to different models of a low-power He–Ne laser. Group 5 rats received no laser treatment and were considered as the control group. The energy density of the He–Ne laser used was 0.2 J/cm². Immediately after surgery and at day 7, the surface area of all flaps was determined. Histological and tensiometrical studies on the surviving part of the flaps were also performed. The data obtained were analyzed by ANOVA. The results showed a significant difference in the surface area of survival parts of flaps and density of blood vessels on day 7 between group 3 rats and the other groups (P=0.0188, P=0.0455). Low-power He–Ne laser irradiation of flaps without recognized blood vessels in rats, reduced vasospasm, produced vasodilation, and caused a significant increase in the surviving surface area.Presented at the 14th World Congress of the International Society for Laser Surgery and Medicine, India, 27–30th August, 2001