Efficacy of steroids and hyperbaric oxygen on survival of dorsal skin flaps in rats

This study was designed to determine if steroids improved skin flap survival in rats, and if steroids and hyperbaric oxygen (HBO) showed an additive beneficial effect. Cranially based, 3 x 9 cm dorsal skin flaps were raised in 60 adult rats. All animals received either intramuscular methylprednisolone (30 mg/kg) or an equal volume of intramuscular saline solution placebo 24 hours and 1 hour before, and 24 hours and 48 hours after, flap elevation. Treatment for animals receiving HBO was begun within 5 hours after flap elevation. The regimen consisted of two 90-minute treatments of 100% oxygen at 2.4 atm separated by 5-hour intervals or room air per day for 3 consecutive days. The 60 rats were divided equally into four treatment groups, as follows: group A, flap elevation alone (control); group B, flap plus steroids; group C, flap plus HBO; and group D, flap plus steroids plus HBO. Surviving flap length was measured by visual inspection 7 days after flap elevation. The mean surviving flap length for group A was 4.9 cm, for group B it was 6.4 cm, for group C it was 6.7 cm, and for group D it was 6.5 cm. The approximately 30% to 36% improvement in surviving flap length was highly statistically significant (p less than 0.006) when compared with controls. However, no statistically significant difference was found between the three treatment modalities. These findings indicate that in a rat dorsal skin flap model, perioperative steroids improve skin flap viability, and that steroids alone are as efficacious as HBO and as steroids combined with HBO.     

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.     

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 survival in free skin flap transfers in rats

We have demonstrated previously that oxygen-derived free radicals are important mediators of tissue injury in experimental island skin flaps that have been subjected to prolonged ischemia (vascular occlusion) followed by reperfusion. In this study the role of oxygen free radicals in ischemia/reperfusion injury has been investigated in free flap transfers. Groin skin flaps were harvested, stored at room temperature for 21 to 24 hours, and transplanted to the contralateral groin. These free flap transfers normally exhibit a high incidence of complete necrosis. Treatment before the onset of reperfusion with a single dose of superoxide dismutase (SOD), a scavenger of superoxide radicals, increased the survival rate of these skin flaps from 38% in the control group to 76% (p less than 0.025). Tissue levels of SOD were measured before ischemia, after ischemia but before reperfusion, and 30 minutes after reperfusion: untreated flap tissues, which were destined to undergo necrosis, exhibited a significant decrease in SOD activity after reperfusion, whereas SOD-treated flap tissues, destined to survive, demonstrated increased enzyme activity. High levels of tissue SOD activity thus appeared to be associated with improved flap survival. The results have significant clinical implications with regard to organ preservation and transplantation.     

Augmentation of experimental skin flap survival via postoperative phosphocreatine replacement

Despite improvements in our understanding of cutaneous vascular territories, clinical skin flap necrosis resulting from ischemic compromise is still a reality. Therapy with vasodilators has been generally unsuccessful, but replacement of high-energy phosphometabolites through the use of ATP-MgCl2 and fructose 1,6-diphosphate has been effective. Recently we reported that phosphocreatine is the major high-energy phosphometabolite in mammalian skin and that ATP levels and cellular well-being in skin flaps are dependent on adequate supply of this phosphometabolite. We report herein the successful augmentation of survival of ischemically compromised skin flaps through postoperative phosphocreatine infusion. This metabolite effectively circumvents the nonfunctioning mitochondrial creatine-phosphocreatine energy shuttle without disturbing the delicate [ATP]/[ADP] balance in the cytosol. In addition, phosphocreatine may favorably redistribute blood flow from muscle to the ischemically compromised skin.     

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.     

氨氯地平经皮肤渗透给药对缺血随意型皮瓣成活的影响

目的 探讨氨氯地平水凝胶(amlodipine gel)经皮肤渗透给药及其对大鼠缺血随意型皮瓣成活的影响.方法 制备0.5％、1.0％、1.5％、2.0％和2.5％氨氯地平水凝胶.用改良的Franz扩散池测定氨氯地平经大鼠皮肤的累积渗透量.在大鼠缺血随意型皮瓣外用氨氯地平水凝胶7d后,测定皮瓣的成活面积和给药后第2、6小时皮瓣组织中氨氯地平的含量.结果 氨氯地平的累积渗透量随氨氯地平浓度和渗透时间增加而增加(P＜0.05).0.5％、1.0％氨氯地平水凝胶中的氨氯地平的累积渗透量＜1.5％、2.0％、2.5％氨氯地平水凝胶(P＜0.05).1.5％氨氯地平水凝胶组皮瓣组织内氨氯地平的含量均＞0.5％氨氯地平水凝胶组(P＜0.05).0.5％氨氯地平水凝胶组皮瓣的成活面积为(391.4±65.4) mm2,高于凝胶基质对照组的(192.9±56.8) mm2及空白对照组的(191.0±50.2)mm2(P＜0.05),但1.5％氨氯地平水凝胶组皮瓣(265.7±88.3)mm2与两对照组间差异无显著统计学意义(P＞0.05).结论 氨氯地平可渗透进入皮肤组织;0.5％氨氯地平水凝胶可显著提高缺血随意型皮瓣的成活面积.     

Dual preconditioning: effects of pharmacological plus ischemic preconditioning on skin flap survival

To enhance skin flap viability, pharmacological and ischemic preconditioning methods were investigated intensively. This study was designed to determine whether combined local dexamethasone administration and pedicle clamping would result in an additive enhancement of skin flap survival in the rat model. Twenty-eight male Sprague-Dawley rats were included in dexamethasone injection, clamping, clamping plus dexamethasone injection, and control groups. A rectangular random skin flap (3 x 11 cm) was outlined as bipedicled on the back of the animals. The dexamethasone or saline injection points in the flap were standardized. In the dexamethasone injection group, after raising the flaps, a total of 2.5 mg/kg dexamethasone was injected into the flaps. In the ischemic preconditioning group, 1 hour after saline injection, the cranial pedicle was clamped for 20 minutes and then 40 minutes reperfusion was performed. The clamping-plus-dexamethasone injection group was the same as the clamping group except dexamethasone was injected instead of the saline. In the control group, saline was injected instead of dexamethasone. Regardless of the group, all flaps were cut at the cranial side at the end of the 2 hours and were sutured back. On day 7, the surviving area was significantly greater in all experimental groups compared with the control group (p<0.05). Furthermore, the clamping-plus-dexamethasone group demonstrated the highest flap viability.     

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.     

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     

Effect of Fluosol-DA (20%) on skin flap survival in rats

This study evaluates the effect of increased oxygen-carrying capacity of blood with the oxygen-carrying blood substitute Fluosol-DA (20%) on skin flap survival in rats. A skin flap model as described by Finseth was used in male Sprague-Dawley rats. We found that Fluosol-DA (20%) alone or in conjunction with O2 does not augment survival of skin flaps in rats, while hemodilution enhances and hemoconcentration deteriorates skin flap survival. Systemic O2 does not enhance survival of skin flaps in rats.     

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.     

pcD2/hVEGF对缺血皮瓣存活的影响

目的 观察并探讨pcD2/hVEGF对缺血皮瓣血循环重建和皮瓣存活率的影响.方法 SD大鼠24只,分2组,每组12只.在鼠背部制作蒂位于尾侧的缺血皮瓣(7cm×1cm).实验组皮下注射pcD2/hVEGF,对照组皮下注射生理盐水,术后7天观察皮瓣存活面积比、单位面积微血管计数和及VEGF基因表达水平.结果 2组中pcD2VEGF组皮瓣存活面积比、单位面积微血管密度与对照组有显著性差异.结论 pcD2VEGF能促进缺血皮瓣存活.     

苦碟子注射液对大鼠随意皮瓣存活的影响

目的：观察苦碟子注射液研究苦碟子注射液对大鼠随意型皮瓣存活的影响对大鼠随意皮瓣成活的影响。方法：将2～3月龄重SD大鼠24只,采用随机抽签法分为2组（实验组和对照组,每组12只）。采用改良的大鼠随意型皮瓣制作方法造模,实验组每天腹腔注射苦碟子注射液5 ml/kg ,对照组每天腹腔注射生理盐水5 ml/kg。术后第7天颈椎脱臼处死大鼠分别进行皮瓣存活面积比的检测,同时取皮瓣近中远端组织经组织染色切片后光镜下观察,免疫组化法检测血管内皮生长因子（VEGF）的表达。结果：术后7 d,实验组皮瓣存活面积比为（70．432±3．867）％,显著高于对照组的（50．498±2．346）％（P＜0．01）;实验组皮瓣组织水肿、炎症细胞浸润情况比对照组明显减轻;切片观察出现较多新生血管,Ⅱ区新生血管密度（（30．11±5．53）/mm2,与对照组（20．13±4．11））/mm2比较,差异有统计学意义（P＜0．01）,Ⅲ区坏死严重。实验组VEGF表达量为（4867．31±452．36）,与对照组的VEGF表达量（2387．45±768．46）比较,差异有统计学意义（P＜0．01）。结论：苦碟子注射液可以提高VEGF的表达量、促进毛细血管新生,减轻皮瓣炎性浸润,还可以明显提高大鼠随意型皮瓣的成活率,为临床皮瓣移植研究提供了新的思路。     

An experimental study on the effect of nifedipine on ischaemic skin flap survival in rats

Vasodilators have been employed previously in an attempt to improve survival of ischaemic rat skin flaps. The effect of nifedipine, a calcium channel blocker, on skin flap survival was studied using a standard experimental rat model. The control group had a mean flap necrosis of 37.009%. Rats treated by nifedipine starting 1 day preoperatively and continued for 1 week postoperatively had a mean necrosis of 10.0953%. Rats treated by nifedipine started postoperatively and continued for 1 week had a mean flap necrosis of 12.289%. Treated groups had significantly lower flap necrosis in comparison to untreated controls. There was no significant difference in flap necrosis between the two treated groups. This study shows that nifedipine improves survival in standard ischaemic rat skin flaps.     

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.     

Deleterious mechanical factors on skin flap survival

Summary In a comparative experimental work, the deleterious effect of tension, kinking and rotation, were studied using undelayed cutaneous cranially based dorsal flaps, in 105 albino-rats (sabra). The results showed a significant reduction in flap survival length. This is consistently diminished by kinking and rotation as compared to minimal changes produced by tension.The authors dedicate this paper to the dear memory of their teacher, the late Prof. Zvi Neuman, who passed away untimely on March 22, 1977     

Gene transfer of bFGF to recipient bed improves survival of ischemic skin flap.

BACKGROUND: The recipient bed is a promising target of angiogenic therapy to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) gene to the recipient bed by a plasmid-based method with electroporation, and assessed the effects on flap viability in a rat dorsal skin flap model. METHODS: A 25 x 90 mm(2) axial skin flap was elevated on the back of male Sprague-Dawley rats. Two days before flap elevation, an expression plasmid vector containing the bFGF gene with the signal sequence was injected into the dorsal muscles beneath the skin flap, and then electroporation was delivered (FGF-E(+) group). As control, rats were injected with a plasmid vector containing LacZ gene (LacZ-E(+) group), instead of bFGF gene. Other groups of animals received plasmid vector containing bFGF (FGF-E(-) group) or LacZ (LacZ-E(-) group) gene without electroporation. Seven days later, the area of necrosis and neovascularisation of the skin flap were evaluated. RESULTS: The bFGF gene was successfully transferred to the dorsal muscles, and bFGF was expressed in muscle tissue. The area of flap necrosis (%) in the FGF-E(+) group (21.7+/-5.3%) was significantly smaller than that in the LacZ-E(+) (28.3+/-4.1%), FGF-E(-) (29.7+/-3.3%), and LacZ-E(-) (28.1+/-2.5%) groups. Postmortem angiograms and histological analyses showed that vascularisation in the distal part of the skin flap was significantly increased in the FGF-E(+) group compared with the other groups. CONCLUSION: These findings suggested that gene delivery of bFGF to the recipient bed muscles enhanced vascularity and viability of an ischemic skin flap, and that plasmid-based gene delivery with electroporation was a suitable delivery method.     

The effect of bovine basic fibroblast growth factor on skin flap survival in rats.

Basic fibroblast growth factor (bFGF) was prepared from bovine pituitary glands and evaluated for its effect on the viability of pedicle skin flaps in rats. Pedicle flaps measuring 3 x 7.5 cm and based cephalad were created on the backs of animals. The treatment group received bFGF in saline solution intradermally by Dermo-jet injection 30 minutes before flap elevation. Skin flaps treated with a single application of 80 U of bFGF demonstrated a significant increase in viability from 40.8% to 69.7% of the flap area (p less than 0.001); the flaps treated with 16 U of bFGF exhibited little improvement. Intradermal administration of bFGF to pedicle skin flaps produced an increase in viability that approximates the increase obtained by a surgical delay procedure; treatment of flaps with exogenous bFGF may offer advantages over surgical delay procedures.