Response of random skin flaps to rapid expansion

We studied the physiologic accommodation of tissues to 5-day expansion in a porcine random flap model to assess the time taken to expand skin to provide early coverage of traumatic defects. Three 6 X 20 cm random flaps were outlined but not elevated on the backs of 12 small (20-kg) pigs. One flap was not manipulated (control). A 450-ml expander was inserted at the base of the second flap and left in place (sham). At the base of the third flap a 450-ml expander was inserted and sequentially filled to the limits of skin viability each day for 5 days (expanded). Skin tension produced by the pressure of expansion and tissue oxygen (TpO2) in each flap were measured before and after each manipulation. Flaps were raised on day 8, and survival determined on day 15. Creation of the pocket reduced TpO2 to 55% of control values, expansion to 17.5% of control. Within 24 hours both sham and expanded had recovered to 80% of control values. After the second expansion, recovery from hypoxia was again almost complete after 24 hours. Recovery after subsequent expansions was less complete, but 3 days after the final expansion there was no statistical difference between TpO2 values in expanded, sham, and control groups. High pressures generated in the flap by expansion also returned to near normal within 24 hours. Flaps utilizing expanded skin survived to greater length (14.2 cm) than did sham (11.6 cm) or control (7.2 cm) flaps (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Resistance of rapidly expanded random skin flaps to bacterial invasion

This study tested the hypothesis that rapidly expanded random pattern skin flaps demonstrate enhanced resistance to bacterial invasion from intradermal injection of Staphylococcus aureus in a porcine model. Sites for a 6 X 12 cm expanded, a 6 X 9 cm sham-expanded, and a 6 X 6 cm acute random pattern skin flap were outlined, but not elevated, on the backs of 14 white pigs. A 450-cc tissue expander inserted beneath the panniculus carnosus at the site for expansion was sequentially filled to the limits of skin viability each day for 5 days. At the sham site a tissue expander was similarly inserted but left unexpanded; the acute flap site was left undisturbed. On day 8, flaps were elevated, immediately sutured in place, and 0.1 ml of saline solution containing 10(7) Staphylococcus aureus inoculated intradermally at four corresponding sites in each flap and at three sites in normal skin. In seven animals these sites were at the proximal base of the flaps; in seven others the sites were distal. The resulting areas of erythema and skin ulceration were measured on each of the next 3 days and the measurements compared. At corresponding proximal sites, the mean area of erythema and ulceration measured over the next 3 days in expanded flaps (31.2 mm2) and in sham-expanded flaps (33.8 mm2) was significantly less than in acute flaps and control skin (47.5 mm2, 43.4 mm2, p less than 0.05). Measurements in the rapidly expanded flaps were not significantly different than those in the sham-operated expanded flaps.(ABSTRACT TRUNCATED AT 250 WORDS)     

皮肤扩张术机理探讨

目的 探讨皮肤扩张术（Ｓｋｉｎ ｅｘｐａｎｓｉｏｎ ｔｅｃｈｎｉｑｕｄｅ,ＳＥＴ）的机理。方法 以家犬为动物模型,应用显微分光光度计及放射微球技术,对扩张后皮肤表皮有丝分裂及皮瓣微循环进行了测定。结果 （１）被扩皮肤表皮明显增厚;（２）基底细胞有丝分裂较对照组显著增强;（３）皮瓣微循环较即刻皮瓣显著增强。结论 （１）ＳＥＴ并非仅以代偿为基础,而复制了新的“剩余”皮肤。（２）增强了皮瓣微循环,增大皮     

Hemodynamics in skin and tissue expansion]

The capillary blood flow (CBF) of the random flaps constructed on expanded and unexpanded skin of dogs was determined by radioactive microsphere technique. The CBF was significantly higher (P < 0.001) in the skin flaps of the expanded group (387 +/- 23 microliters/min/flap) than that of the acute group (127 +/- 16 microliters/min/flap). There were no significant differences in the expanded group, the delayed group (374 +/- 35 microliters/min/flap) and the control group (389 +/- 48 microliters/min/flap). Even at the pedicle site, the CBF of the acute group was already significantly lower than that of other three groups (P < 0.001). The general tendency of gradual CBF reduction from the pedicle to the distal end of all the flaps was observed. The CBF at the point 8cm from the pedicle of the acute group was 12 microliters/min/g, whereas in other three groups, at point 13 cm from the pedicle the CBF was 12 microliters/min/g. The results suggested that during skin expansion the area of skin is enlarged, and its CBF and survival length may be increased. The problem of capsulectomy during flap construction was discussed.     

Augmentation of acute random pattern skin flap viability in the pig.

Three experiments were conducted to study the effect of ketanserin and LY53857, S2-serotonergic receptor antagonists, on skin blood flow and viability in acute random pattern skin flaps (4 x 10 cm) in the pig. In experiment 1, the dose-response effect of intravenous ketanserin (0, 0.15, 0.25, 0.35, and 0.50 mg/kg) on skin flap capillary blood flow was studied 6 hr after skin flap surgery, using the radioactive microsphere (15 microns) technique and under pentobarbital anesthesia. Significant (P less than 0.05) increase in skin flap blood flow was seen at the dosages of 0.25 and 0.35 mg/kg compared with the saline-treated control. In experiment 2, the effect of five-day intramuscular ketanserin and LY53857 treatment (0.30 mg/kg/day; in divided doses) on skin flap viability was studied. The drug treatments were started two days preoperatively. It was observed that the length of skin flap viability in ketanserin (6.6 +/- 0.2 cm; n = 40 flaps) and LY53857 (6.8 +/- 0.3 cm; n = 40 flaps) treated flaps were significantly (P less than 0.05) higher than the saline-treated control (5.5 +/- 0.1 cm; n = 48 flaps). Ketanserin treatment started 30 min after flap surgery also significantly (P less than 0.05) increased the length of skin flap viability (6.1 +/- 0.1 cm) compared with the control. There was no significant difference in skin viability between ketanserin and LY53857 treated skin flaps. The preceding study on the effect of ketanserin treatment on random pattern skin flap viability was repeated in experiment 3. Again, it was observed that intramuscular ketanserin treatment significantly (P less than 0.05) increased the skin flap viability. It was concluded that ketanserin and LY53857 treatment resulted in significant augmentation of porcine acute random pattern skin flap viability. This is the first experimental evidence to indicate that S2-serotonergic receptors participate in the pathogenesis of skin flap ischemia.     

持续扩张后任意皮瓣的活力及回缩的动态观察

目的　观察持续扩张后皮瓣的活力及近期修复效果。方法　用小家猪和恒压灌注仪制作持续扩张动物模型 ,A组动物用 180ml扩张器 ,B组动物用 2 10ml扩张器。完成扩张后 3d制作扩张区皮瓣和正常区任意皮瓣 (对照组 )。结果　A组和B组皮瓣的存活长度比正常任意皮瓣分别增加 92 60 %和 91 96% ,A、B两组差别不明显 (P >0 0 5 )。术后早期扩张后皮瓣有明显回缩 ,术后两个月皮瓣的宽度恢复到正常任意皮瓣水平 (P >0 0 5 )。结论　持续快速扩张后皮瓣的存活能力和修复效果可靠 ,可在临床使用。利用大容量扩张器不能进一步增加皮瓣的存活能力。     

超量扩张皮肤血流量改变的初步临床观察

目的 探讨超量扩张时皮肤血流量的变化与皮瓣存活的关系。方法 对临床10例患者21个扩张器在扩张器置入前、满量、超量注水时，应用激光多谱勒血流测定仪测定扩张皮肤微循环血流量及其波幅，并与最终临床效果进行观察比较。结果 正常皮肤血流量及血管的运动波较小且较稳定，扩张后尤其是超量扩张后其血流量明显增加。与正常皮肤相比差异有统计学意义（P〈0．05），血管的运动波与正常皮肤相比差异亦有统计学意义（P（0．05），与超量注水扩张皮肤相比差异有显著的统计学意义（P（0．01）。结论 扩张皮肤血流量的增加，主要表现为血管数量的增加和增粗，当扩张皮瓣的长宽比例较大时，尤其在过度扩张时，扩张皮肤的血供不像延迟皮瓣具有方向性，加上微血管括约肌的功能异常，更易出现皮瓣远端血供的不足，并为皮瓣转移时带来风险。     

兔股动脉和静脉预构轴型扩张皮瓣的实验观察

目的 通过兔股动脉、静脉预构轴型扩张皮瓣的微循环血流晕动态变化、光镜下结构的改变及其成活面积,为预构轴型扩张皮瓣的临床应用提供依据.方法 选择新西兰白兔40只,随机分为4组:预构轴型扩张皮瓣组、预构轴型不扩张皮瓣组、单纯预构轴型皮瓣组及无蒂游离皮瓣组,每组4只,前2组股动脉、静脉移位后,预构轴型扩张皮瓣组、预构轴型不扩张皮瓣组分别在肉膜深面置入容量为50 ml长方形皮肤软组织扩张器,预构轴型扩张皮瓣组7 d后开始注水;无蒂游离皮瓣组为对照组,未采取预构及扩张处理.定期对4组皮肤进行微循环血流量检测,并取样进行光镜观察.预构术后52 d,前3组形成以预构股动静脉血管束为蒂的岛状皮瓣,游离皮瓣组则形成无蒂游离皮瓣后均原位缝合,观察其成活面积.结果 预构轴型扩张皮瓣组较其他组微循环血流量增加,成活面积大[(97.54±2.73)%],光镜下改变显著(P<0.05).结论 扩张术能促进预构轴型皮瓣的血管化进程,明显增大预构轴型皮瓣成活面积,增加其移植的安全性.     

Neovascularization in prefabricated flaps using a tissue expander and an implanted arteriovenous pedicle

Creating prefabricated flaps using tissue expanders in combination with the implantation of maximal blood flow vascular pedicles into suitable tissue areas represents a new tendency in the reconstruction of large skin defects. In 42 Chinchilla Bastard female rabbits weighing 3,700-4,600 g, skeletonized arteriovenous pedicles with maximal blood flow, dissected from the femoral and saphena magna bundles, were implanted underneath abdominal fasciocutaneous flaps. Oval tissue expanders of 250 ml were placed and fixed on the abdominal wall to expand these prefabricated flaps. The evaluation parameters were macroscopic observation, blood analysis, selective microangiography, histology, and scintigraphy. The study results showed that neovascularization in expanded prefabricated flaps was established from newly formed vessels generated from the implanted pedicles and their vascular connections with the originally available vasculature in the flap. After 20 days of prefabrication, the entirety of the expanded prefabricated flaps was perfused by blood flow supplied from newly implanted arteriovenous pedicles. The study indicated that an expanded prefabricated flap can be successfully created by the simultaneous implantation of a maximal blood flow pedicle in combination with flap expansion.     

海普林对大鼠皮瓣成活影响的实验研究

目的 探讨外用药海普林软膏对皮瓣血液循环的影响，以期为挽救临床已出现循环危象的皮瓣提供一种新方法。方法 采用随机对照的方法将80只大鼠随机分为实验组和对照组，分别观察其背部随意型皮瓣成活与坏死面积，并进行组织学检查,记数断面毛细血管数。结果 组织学观察术后5，7d皮瓣远端两组均为全层坏死，术后5d皮瓣中断面毛细血管记数经统计学处理两组无显著性差异（P＞0．05），术后7d皮瓣中段断面毛细血管记数实验组明显多于对照组，统计学处理两组有显著性差异（P＜0．05）。结论 海普林软膏可明显改善皮瓣血循环。     

The action of piracetam in ischaemic flaps

The effects of piracetam on skin flap viability, capillary blood flow and temperature were studied in abdominal cutaneous flaps in rats. The drug significantly increased the viability of the distal (random) portion of the flap and this response was dose-related. Compared with controls, the area of skin necrosis was 12.4% less in the piracetam-treated animals and extended necrosis was not observed. Piracetam appeared to act by increasing the capillary blood flow, mainly in the distal portion of the flap. The improved perfusion was reflected as a smaller drop in the recorded temperature compared with controls. Blood levels of this drug in animals receiving the maximum effective dose corresponded to the active drug concentration in human rheology.     

人脂肪干细胞对兔任意型皮瓣成活的影响

目的 探索人脂肪干细胞(adipose-derived stem cells,ADSCs)对兔任意型皮瓣成活能力的影响.方法 获得健康成人的脂肪,经体外分离、培养及传代至第5代,进行流式细胞术检测和三系分化能力的鉴定.于大白兔背部对称地设计2个蒂部在头侧的任意型皮瓣(长6 cm、宽2 cm),左、右侧分别为对照组和实验组.应用DiO荧光标记ADSCs,实验组(n=10)分5点注射2×106悬浮于0.5 ml无血清的DMEM培养基中的ADSCs,对照组(n=10)同样分5点注入无血清的DMEM0.5 ml,于术后7 d分别测量皮瓣成活面积;随机作冰冻切片,在激光扫描共聚焦显微镜下观察切片荧光显影情况;随机作常规切片HE染色,光镜下观察皮瓣组织毛细血管分布密度.统计学分析ADSCs在促进任意型皮瓣成活过程中的作用.结果 与对照组相比,实验组皮瓣成活率明显提高(P<0.01),组织学检测证明实验组毛细血管增生明显增多.结论 人ADSCs具有较好的免疫相容性,局部应用可明显提高皮瓣的成活率.

Abstract：

Objective To explore the effect of the adipose derived stem cells (ADSCs)on the survival of random pattern skin flap in rabbits. Methods ADSCs were isolated from fresh human fat and expanded in vitro for five passages. Then the characterization of ADSCs were determined by their CD marker profile and their ability to differentiate into osteogenic, adipogenic and chondrogenic lineages. On the back of the rabbits, two symmetric cephalic-based random pattern skin flaps were designed (6 cm × 2cm). The right flaps were used as experimental groups with the contra-side flaps as control group. Human ADSCs were pre-labeled before seeding with fluorescent 3, 30-dioctadecyloxacarbocyanine perchlorate (DiO) dye. The experimental flaps evenly received 5-point injection of 2 × 106Dio-labeled ADSCs resuspended in 0.5 ml of serum-free DMEM, while only 0. 5 ml medium was injected into the control flaps.Seven days later, the survival rate of flaps was evaluated. The flaps underwent frozen section and were observed under the laser scanning confocal microscope to detect the fluorescence imaging. Flaps also underwent HE staining and were observed under light microscope to detect the vascular density. Results Compared with control group, there was a significant increase of flap survival rate in the experimental group(P <0.01). Histological analysis also demonstrated a statistically significant increase in capillary density in the experimental group. Conclusions It suggests that ADSCs have a better immune compatibility and potential for enhancing the blood supply of random pattern skin flaps.     

LED (660 nm) and laser (670 nm) use on skin flap viability: angiogenesis and mast cells on transition line

Skin flap procedures are commonly used in plastic surgery. Failures can follow, leading to the necrosis of the flap. Therefore, many studies use LLLT to improve flap viability. Currently, the LED has been introduced as an alternative to LLLT. The objective of this study was to evaluate the effect of LLLT and LED on the viability of random skin flaps in rats. Forty-eight rats were divided into four groups, and a random skin flap (10?×?4 cm) was performed in all animals. Group 1 was the sham group; group 2 was submitted to LLLT 660 nm, 0.14 J; group 3 with LED 630 nm, 2.49 J, and group 4 with LLLT 660 nm, with 2.49 J. Irradiation was applied after surgery and repeated on the four subsequent days. On the 7th postoperative day, the percentage of flap necrosis was calculated and skin samples were collected from the viable area and from the transition line of the flap to evaluate blood vessels and mast cells. The percentage of necrosis was significantly lower in groups 3 and 4 compared to groups 1 and 2. Concerning blood vessels and mast cell numbers, only the animals in group 3 showed significant increase compared to group 1 in the skin sample of the transition line. LED and LLLT with the same total energies were effective in increasing viability of random skin flaps. LED was more effective in increasing the number of mast cells and blood vessels in the transition line of random skin flaps.     

Comparative viability of expanded and unexpanded axial pattern skin flaps in pigs

A comparison of viable areas of axial pattern flaps post inset was made between expanded and non-expanded pig buttock island flaps. The deep circumflex iliac artery and vein supply approximately the proximal 14 x 10 cm area of this flap. Larger flaps were raised on expanded and control sides of eight pigs to determine if expansion increased the area of survival. In six of eight pigs whose initial tissue expansion did not create more than approximately a 50% increase in skin area, the expanded flaps had a statistically significant increase in viable skin area (proportionally) 10 days post inset than their control flaps (p less than 0.05). Two other pigs did not conform to this pattern. Their initial tissue expansion was greater than 50%, and the resulting area of flap viability was proportionally less in expanded flaps than the control flaps.     

Pharmacologic manipulation of the microcirculation in cutaneous and myocutaneous flaps in pigs

The vascular effects of isoxsuprine, diazoxide, and isoproterenol were studied in arterial buttock flaps and latissimus dorsi myocutaneous flaps in pigs. Capillary blood flow to the skin and muscle of these flaps was measured by the radioactive microsphere (15-mu diameter) technique 6 hours postoperatively under pentobarbital anesthesia. It was observed that isoproterenol, a beta-adrenergic receptor agonist, was not effective in augmentation of skin blood flow in the arterial buttock flaps. However, isoproterenol significantly increased capillary blood flow to the arterialized portion of latissimus dorsi myocutaneous flaps compared with controls. Isoxsuprine and diazoxide (vascular smooth muscle relaxants) significantly (p less than 0.05) increased total capillary blood flow to the skin of arterial buttock flaps and to the skin and muscle of the latissimus dorsi myocutaneous flaps. However, the increase in capillary blood flow occurred mainly in the arterialized portion of these flaps. The capillary blood flow, which was supplied by the small arteries in the distal portion of the arterial buttock and latissimus dorsi flaps, was not increased by treatment with isoxsuprine or diazoxide. Therefore, there was also no increase in the maximum distance of capillary blood flow from the pedicle to the distal end of the flaps. These observations led us to hypothesize that different sizes (diameters) of arteries in the skin and muscle have different reactivity (or sensitivity) to vasodilatory drugs. In the present experiment, the large dominant artery of the arterial buttock and latissimus dorsi flaps responded to isoxsuprine or diazoxide (vascular smooth-muscle relaxants), resulting in an increase in blood supply to the capillaries in the proximal portion of the flaps. On the other hand, the small arteries in the distal portion (random portion) of these flaps were not sensitive to isoxsuprine or diazoxide. Therefore vasodilation did not occur, and there was no increase in blood supply to the capillaries in the distal portion of arterial buttock and latissimus dorsi flaps. This explanation also lent support to our previous report that treatment with isoxsuprine did not augment skin viability in the distal portion of arterial buttock and latissimus dorsi flaps. It is suggested that research in pharmacologic manipulation of skin blood flow and viability in skin flap surgery should emphasize the sensitivity of small arteries to various drug actions.(ABSTRACT TRUNCATED AT 400 WORDS)     

Dose and time effects of nicotine treatment on the capillary blood flow and viability of random pattern skin flaps in the rat

The deleterious effects of nicotine treatment on skin haemodynamics and survival of 4 X 10 cm acute random pattern skin flaps constructed on the dorsum of the rat were studied. Rats were injected subcutaneously with 0.2 ml of saline containing varying doses (0, 1, 2, 4 or 8 mg kg-1; bid) of nicotine for 5 weeks, starting 4 weeks before flap surgery. It was observed that nicotine treatment at the dose of 2 mg kg-1 (bid), or higher, significantly (p less than 0.05) decreased the length and area of skin flap survival compared with the control. This dose of nicotine treatment also significantly (p less than 0.05) decreased the capillary blood flow and distal perfusion in the skin flaps compared with the control. However, the detrimental effect of nicotine treatment on the survival of acute random pattern skin flaps was not seen if the treatment was started 2 instead of 4 weeks preoperatively. It is concluded that nicotine may cause hypoperfusion and necrosis in acute random pattern skin flap surgery, and the deleterious effects are time-dependent.     

Evaluation of the Effect of Sildenafil and Vascular Endothelium Growth Factor Combination Treatment on Skin Flap Survival in Rats

BACKGROUND: Distal ischemic necrosis of surgical flaps remains a challenging problem for the reconstructive surgeon. Recent studies have shown that either sildenafil or vascular endothelium growth factor (VEGF) treatment significantly improves ischemic skin flap viability. In this study, the effect of the combination of sildenafil and VEGF165 was evaluated on a rat skin flap model using orthogonal polarization spectral imaging and histologic analysis. METHODS: Rats were assigned to either a sham (n = 31), vehicle (n = 24), sildenafil (n = 24), VEGF (n = 23), or sildenafil and VEGF combination treatment (n = 21) groups. Distances from the distal end of the flap to avascular, stasis, and normal capillary blood flow zones were determined using orthogonal polarization spectral imaging on a skin flap model. Vessel density assessment was done at 7 days post surgery. RESULTS: Imaging analysis showed significant reduction in avascular and stasis areas in sildenafil and VEGF combination-treated groups at 7 days post surgery (p < 0.05). The combination-treated group, however, was not significantly different when compared to the group treated with sildenafil only. The sildenafil-treated group showed a significant (p < 0.05) reduction in both areas at day 7 compared to the VEGF and control groups. Histologic analysis showed no significant differences in vessel density between the groups. CONCLUSION: The combination of sildenafil and VEGF decreases the extent of avascular and stasis zones in skin flaps. The skin flap improvement seen with the combination treatment was similar to the sildenafil treatment alone suggesting that enhanced flap survival was due solely to the effect of sildenafil.     

Comparative analysis of tissue fluorescence as related to capillary perfusion in random pattern skin flaps.

In random pattern skin flaps of mice, tissue fluorescence measured by means of videodensitometry at 24 h after flap elevation significantly correlates with intravital microscopically measured functional vessel density and viability of skin tissue as assessed by transmission light and electron microscopy. The correlation was found reproducible in non-ischaemic flaps (r = 0.86) and flaps being rendered ischaemic for 6 h after elevation (r = 0.98), indicating that increased microvascular permeability as a result of ischaemia/reperfusion does neither affect tissue fluorescence nor the accuracy of the fluorescein dye test. In addition, tissue fluorescence at 24 h after flap elevation accurately predicts ultimate flap survival on the 7th postoperative day with a sensitivity of 0.89 and a specificity of 0.85. These results suggest that in non-ischaemic as well as in ischaemic random pattern skin flaps tissue fluorescence can be used for assessment of nutritive blood flow, viability of skin tissue and ultimate tissue survival in these flaps.     

组织扩张对预构轴型皮瓣血供影响的实验研究

目的　研究组织扩张对预构轴型皮瓣血供范围的影响 ,为临床上获取更大面积的预构轴型皮瓣提供理论指导。方法　在同一只兔子腹部的左右侧分别设计、完成以股动、静脉为轴型血管的预构皮瓣 ,右侧腹部仅预构皮瓣未埋置扩张器 (未扩张组 ) ,左侧预构皮瓣下埋置扩张器进行扩张 (扩张组 ) ,分别于预构术后 1、3、5、7、10、14、2 1、2 8、5 6天对扩张组与未扩张组预构皮瓣血供范围进行相关检测。结果　预构皮瓣经扩张后其轴型血管供血范围明显大于未经扩张的预构皮瓣 (P <0 .0 5 )。结论　扩张术可加速皮瓣预构进程 ,增加预构轴型皮瓣的存活面积     

包膜对猪扩张后动脉筋膜皮瓣血供影响的研究

目的：探讨包膜切除与包膜保留,对猪扩张后超长动脉筋膜皮瓣血流动力学、氧代谢及皮瓣活力的影响,为临床处理皮瓣包膜提供参考。方法：9～12个月龄成年小型香猪8只,每只猪对称各设计1个以胸背动脉穿支血管为蒂、面积为5cm×20cm的扩张后动脉筋膜皮瓣。实验组扩张后动脉筋膜皮瓣包膜切除,对照组皮瓣包膜保留。比较二组皮瓣的血氧饱和度、MDA含量和成活长度的变化。结果：实验组扩张后动脉筋膜皮瓣的血氧饱和度低于对照组;MDA含量高于对照组;成活长度小于对照组。结论：包膜增加了扩张后动脉筋膜皮瓣的血供,应该予以保留。