The influence of sildenafil on random skin flap survival in rats: an experimental study.

Sildenafil (Viagra), a selective and specific inhibitor of cyclic guanosine monophosphate (cGMP) phosphodiesterases (PDEs), is currently marketed for the treatment of erectile dysfunction. Sildenafil is a potent and highly selective PDE-V inhibitor and enhances smooth muscle relaxation in human. Systemic arterial and venous smooth muscle cells contain PDE-V and nitric oxide (NO) which is a major mediator of relaxation of the smooth muscle cell. The aim of the present study is to investigate, in a rat model, the potential effect of sildenafil on survival of random pattern skin flaps. For this purpose, 32 Sprague-Dawley rats were used and a McFarlane-type caudally based skin flap was designed on the dorsum of the rat (2.5 x 8 cm). Rats were divided into four groups: One control (Group D), and three treatment groups (Groups A, B, C). Sildenafil was administered orally to the experiment groups; Group A: 3 mg/kg/single dose a day, Group B: 10 mg/kg/single dose a day and Group C: 10 mg/kg/twice dose a day. The areas of flap necrosis were measured in each group. The extent of viable flap areas were expressed as a percentage of total flap area, and differences were studied by Completely Randomised Experimental design. The areas of necrosis of skin flaps decreased depending on sildenafil dose, but viability of the flaps treated with 3 mg/kg/day was not different than the control group. The flaps receiving 2 x 10 mg/kg/day sildenafil gave the highest (P < 0.01) survival rate. As a conclusion, sildenafil may have a dose dependent effect to increase flap survival in random skin flaps.     

张力对扩张皮瓣血运影响的实验研究

目的研究张力对扩张皮瓣血运的影响.方法在23只兔的背部脊柱旁肉膜和深筋膜之间,各置入一个150 ml的长方形扩张器,每周注水一次,共注水400 ml.其中10只兔子,以胸背动脉为轴心,形成一个5.0 cm×15.0 cm 的轴型皮瓣,另外13只兔避开胸背动脉,形成一个5.0 cm×15.0 cm 的随意皮瓣.分别在距扩张皮瓣蒂部3.0、7.5、10.5、13.5 cm的位置上,用双面胶固定两排激光多普勒血流仪探头座(分别命名腹侧为A1、A2、A3、A4,背侧为B1、B2、B3、B4).分别在0、15、35、55、75、95、115、135 g张力下,测量皮瓣的血流值.结果随意皮瓣中60.2%的位点血流峰值出现在0张力或15 g张力时,血流峰值在中等张力的位点占24.2%.62.5%的A1、41.6%的A2、70.8%的A3、70.8%的A4血流峰值在0张力或15 g.B1血流峰值在前的位点占62.5%,B2占50%,B3占45.8%,B4占75%.轴型皮瓣中血流峰值在0张力或15 g张力位点占44.2%,血流峰值在中等张力的位点占22.1%.A1血流峰值0张力或15 g张力的位点占所有A1的40%,A2占40%,A3占50%,A4占50%.B1血流峰值在前的位点占40%,B2占40%,B3占40%,B4占50%.结论随意皮瓣、轴型皮瓣的位点多数情况下,在张力较小时血流最好,皮瓣的末端尤其如此.轴型皮瓣可耐受较大张力,而血流值仍保持较高水平.     

张力对扩张皮瓣血运影响的实验研究

目的研究张力对扩张皮瓣血运的影响。方法在23只兔的背部脊柱旁肉膜和深筋膜之间,各置入一个150ml的长方形扩张器,每周注水一次,共注水400ml。其中10只兔子,以胸背动脉为轴心,形成一个5.0cm×15.0cm的轴型皮瓣,另外13只兔避开胸背动脉,形成一个5.0cm×15.0cm的随意皮瓣。分别在距扩张皮瓣蒂部3.0、7.5、10.5、13.5cm的位置上,用双面胶固定两排激光多普勒血流仪探头座(分别命名腹侧为A1、A2、A3、A4,背侧为B1、B2、B3、B4)。分别在0、15、35、55、75、95、115、135g张力下,测量皮瓣的血流值。结果随意皮瓣中60.2%的位点血流峰值出现在0张力或15g张力时,血流峰值在中等张力的位点占24.2%。62.5%的A1、41.6%的A2、70.8%的A3、70.8%的A4血流峰值在0张力或15g。B1血流峰值在前的位点占62.5%,B2占50%,B3占45.8%,B4占75%。轴型皮瓣中血流峰值在0张力或15g张力位点占44.2%,血流峰值在中等张力的位点占22.1%。A1血流峰值0张力或15g张力的位点占所有A1的40%,A2占40%,A3占50%,A4占50%。B1血流峰值在前的位点占40%,B2占40%,B3占40%,B4占50%。结论随意皮瓣、轴型皮瓣的位点多数情况下,在张力较小时血流最好,皮瓣的末端尤其如此。轴型皮瓣可耐受较大张力,而血流值仍保持较高水平。     

The effect of ultrasound on flap survival: an experimental study in rats

BACKGROUND: Ultrasound is commonly used by physical therapists, but there is no consensus regarding the most effective therapeutic dose for accelerating healing of open or closed wounds. Now, the effect of therapeutic ultrasound on the formation of new blood vessels in full-thickness excised lesions in the flank skin of adult rats has been assessed quantitatively using microfocal X-ray techniques. METHODS: To investigate this, 30 rats were divided into three groups of 10 animals: a control group and two treated with ultrasound groups. Random dorsal skin flaps were elevated on the rats. In the control group, no operative procedures agents were used. Of the two treated groups, group 1 were exposed to pulsed ultrasound (2 ms on, 8 ms off) at an intensity of 0.1 W cm(-2) SATA (frequency either 0.75 MHz or 3.0 MHz). Group 2 exposed to pulsed ultrasound (2 ms on, 8 ms off) at an intensity of 0.18 W cm(-2) SATA (frequency either 0.75 MHz or 3.0 MHz), respectively. RESULTS: The areas of flap necrosis were measured in each group. The median lengths of flap necrosis of the groups were 79.3, 57.0, and 35.3 mm, respectively. There was a statistically significant improvement of flap necrosis in ultrasound-treated groups compared with the control group (group 2, p=0.001; group 3, p=0.001). Furthermore, there was less necrosis in the high intensity ultrasound-treated group than the low intensity-treated group. CONCLUSION: Ultrasound may have an intensity-dependent effect to increase flap survival in random skin flaps.     

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.     

The effect of twisting on perforator flap viability: an experimental study in rats

Perforator flaps increasingly find acceptance and use in the field of reconstructive surgery due to their decreased donor-site morbidity and increased like-tissue coverage. Nevertheless, they are more prone to vascular compromise, especially when the meticulous technique they require is not employed. Pedicle twisting is a condition occasionally encountered in flap procedures, sometimes inadvertently, sometimes inevitably. In this study, circulatory comprise induced by twisting of the pedicle on a true perforator flap in a rat model is investigated.Thirty-eight Wistar-Albino rats were randomized into 4 groups, and cranial epigastric artery true perforator flaps were elevated on a single perforator. The flaps were returned as they were in the control group (n = 9), and with 90 degrees , 180 degrees , and 270 degrees of torsion in groups 2 (n = 9), 3 (n = 10), and 4 (n = 10), respectively. The flaps were evaluated by their flap survival area, weight, and histopathological appearance by the end of the first week.The mean flap survival ratios for groups 1, 2, 3, and 4 were 97.78 +/- 4.41%, 72.22 +/- 44.10%, 73.50 +/- 30.46%, and 30 +/- 30.18% (mean +/- SD), respectively. The degree of degenerative changes in group 4 was found to be statistically significant (P < 0.016).Our histopathological examinations indicate that vascular compromise was moderate in group 3 and severe in group 4. Our findings suggest that under normal conditions, the pedicle of a true perforator flap must not be twisted more than 180 degrees .     

A neurocutaneous island flap model: an experimental study in rats

Neurocutaneous flaps have been popularized recently in clinical reconstructive surgery. However, controversies exist concerning their anatomy and physiology. The particular role of neural vasculature in the survival of these skin flaps is also quite undefined in the experimental setting, and additional studies on this subject are necessary. The goal of this study was to describe a neurocutaneous flap in a rat model and to investigate its blood supply. Thirty male Sprague-Dawley rats weighing 300 to 350 g were used in this study, which was conducted in two stages. During the first stage, the lower extremities of 10 rats were dissected for the anatomic study of the neurocutaneous flap. A constant cutaneous nerve innervating the anterolateral thigh skin was exposed. It arose either from the saphenous nerve or the superficial epigastric nerve and was accompanied by a constant longitudinal arterial plexus. The tiny neural vessels were conveyed by the superficial fascia along their course. A 30 x 30-mm cutaneous island flap, which was based only on the cutaneous nerve with its accompanying vessels and a strip of superficial fascia, was raised on the anterolateral thigh skin using an operating microscope. The well-perfused skin territory was marked after sodium fluorescein injection. The stained skin territory was located centrally and medially on the whole island flap, and it was approximately 10 x 20 mm. This finding was confirmed by the qualitative assessment of the vascularity for this skin territory in microangiography. After studying the pedicle anatomy and determining the optimal viable skin island, the second stage of the study was performed. The remaining 20 rats were divided into two groups. In the experimental group (N = 10), a neurocutaneous island flap (10 x 20 mm) was outlined on the anterolateral aspect of the thigh at its middle third. It was designed in such a way that its short and long axes lay in the center of the distance between the anterior superior iliac spine and the anterior aspect of the knee joint. After identification and dissection of the neurovascular pedicle, the flap was raised in a lateral-to-medial direction without including the deep fascia. At this point the flap remained connected only by the pedicle and a strip of superficial fascia surrounding it. It was sutured in the same place. In the control group (N = 10), the pedicle of the flap was severed and the skin island was sutured back as a composite graft. All the experimental flaps survived well. In the control group, none of the flaps survived except one that was partially viable. The flaps in the experimental group were reelevated as neurocutaneous island flaps on day 7 for microangiographic study, and specimens were processed for histologic staining. Microangiography revealed the extent of neural vasculature and vascularization of the skin through cutaneous perforators. Histologic investigation demonstrated the neural vessels that were related closely to the superficial fascia. The authors propose a neurocutaneous island flap model in the lower extremity of the rat in which the survival of the flap depended mainly on the neural arterial supply. It was also demonstrated that the superficial fascia played a role as a connective tissue framework for conveying tiny neural blood vessels to reach the skin. This model may serve as a reproducible and reliable neurocutaneous island flap model for additional studies in this field.     

The effects of radiofrequency on skin: experimental study

BACKGROUND AND OBJECTIVE: Radiofrequency represents the most recent skin-rejuvenation treatment. The aim of this study was to study the changes in tissues and cells, as well as in the thickness and structure of the skin of guinea pigs following several sessions of radiofrequency. MATERIALS AND METHODS: Six sessions (1 session/week) of radiofrequency (Thermafine Lift device, Grupo Soliláser, S.L., Girona, Spain) were applied to the skin of guinea pigs. Biopsies were taken following each session and 2 months following the last application. The resultant samples were included in paraffin via the usual method, sectioned at 5 microm and stained with Haematoxylin-Eosin, Alcian blue, Toluidine blue, van Gieson's and Verhoeff's stains. These techniques were used in order to observe possible changes in the thickness and structures of the skin: mucopolysaccharides and collagen and elastic fibres. RESULTS: The most relevant changes were found in the papillary dermis which underwent an expansion due to oedema and vascular congestion (first half of the experiment), followed by an increase in cellularity and the accumulation of intercellular substance. An increase in collagen, elastic fibres and mucopolysaccharides was observed. CONCLUSION: The Thermafine Lift device caused no significant macroscopic or microscopic alterations in the skin of guinea pigs, yet increased both the thickness, as well as the mucopolysaccharide, collagen and elastic-fibre content.     

Relationship between serum fibronectin levels and carnitine administration: an experimental study in rats

We aimed to investigate the relationship between dorsal flap viability and serum fibronectin levels in carnitine‐administered rats. A total of 24 rats were equally divided into three groups and operated on. Group 1 (sham group n = 8): following surgery, no agent was given. Group 2 (control group, n = 8): following surgery, sterile saline solution at 0·9% with a dose of 100 mg/kg per day for 7 days was administered intraperitoneally. Group 3 (study group, n = 8): following surgery, carnitine with a dose of 100 mg/kg per day for 7 days was administered intraperitoneally. The flap model used was a 10 × 3 cm dorsal flap extending from the tip of the scapula to the hip joint. This was elevated, and then sutured back to its original site. At the end of postoperative day 8, the animals were anaesthetised and blood samples were collected from intracardiac space. Then, the animals were euthanised. Flap viability was then evaluated measuring the surviving area, using a transparent graph paper. Finally, excised tissue was examined histopathologically. The percentages of viable areas in groups 1, 2 and 3 were 64·68 ± 3·37%, 67·35 ± 5·82% and 75·15 ± 3·56%, respectively. The mean value of fibronectin levels in groups 1, 2 and 3 were 22·3 ± 3·5, 23·1 ± 3·5 and 31 ± 6·8 mg/dl, respectively. The results of this study demonstrated that 100 mg/kg carnitine administration led to an increase in flap viability, and increased serum fibronectin levels might have a role in this process.     

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.     

机能代偿性皮瓣--快速预制随意皮瓣的实验研究

目的　探讨在 2 4h内使随意皮瓣超范围扩大长宽比例 ,增加皮瓣成活面积的可能性及其限度。方法　选择SD大白鼠 2 0只 ,随机分为实验组 (n =10 )和对照组 (n =10 ) ,按一定方式预制皮瓣 ;实验组行快速预制皮瓣成形训练 ,对照组不训练 ;监控皮瓣微血流灌注值变化过程 ,根据皮瓣微循环参数判断皮瓣血液循环网建立是否成熟。结果　预制皮瓣训练第 18小时皮瓣微循环血流灌注值基本稳定 ,2 4h可完成皮瓣成形术。对照组皮瓣平均成活面积百分率为 (6 8 2 5± 0 18) % ,实验组为 (97 2 5± 0 2 4 ) % ,两组比较差异有显著意义 (P <0 0 1)。结论　在较短的时间里能够建立起超出传统理论极限的随意皮瓣 ,通过数字化判断及监控 ,证明该方法可靠 ,提高了随意皮瓣成活几率     

Bare dorsal thoracic fascial flap for esophageal defects: an experimental study with dogs

Background

Reconstruction of esophageal defects has challenged reconstructive surgeons for a long time. Problems that affect the continuity of the orogastic tract influence the patient’s quality of life and general health. Bare free fascial flaps are used to restore soft tissue defects of the oral cavity because they provide thin, pliable tissues with a high capacity for epithelialization to preserve the local anatomy. An experimental study was planned to investigate reconstruction of anterior cervical esophageal defects using a pedicled dorsal thoracic fascial flap.

Methods

Eight hybrid dogs were used in the study. All operations were planned in three steps and performed with the animals under general anesthesia. For the two-layered reconstruction, the bare dorsal thoracic fascial flap was harvested and adapted like a patch to the defect.

Results

No partial or total flap loss was observed. On postoperative day 20 surgery, a complete epithelial lining on the same plane as the esophageal mucosa was observed over the flap tissue. A 4- to 5-mm longitudinal scar that did not form even a minimal stricture in any dog also was observed. No significant changes from postoperative day 20 to postoperative days 40 and 60 were observed.

Conclusion

Bare fascial flaps in the oral cavity heal with spontaneous epithelialization and with no need for skin and mucosal grafts. Fascial flaps are easy to harvest and do not cause any functional loss because they are nonfunctional units. Their thin constitution helps the surgeon to shape the tissue and even form tubed flaps.     

Free transplantation of venous network pattern skin flap: an experimental study in rabbits

Free skin flaps using rabbit ear to replace rabbit scalp have been accomplished using only arteriovenous and venous-venous anastomosis, without arterio-arterial anastomosis. The technique produced excellent graft survival in 30 of 33 rabbits. Without the vascular anastomosis control grafts did poorly. The mechanism of flow reversed revascularization is discussed.     

前臂背侧皮瓣的临床应用

本组病人共１２例，其中肘部外伤性皮肤缺损之例，腕部皮肤缺损４例，面部外伤性皮肤缺损和恶性肿瘤各１例，手背及虎口外伤３例，拇指再造１例，２例顺行设计，１０例逆行岛状转移。皮瓣切取最大范围１２．０ｃｍ×１０．０ｃｍ，最小６．０ｃｍ×５．０ｃｍ，平均７．８ｃｍ×６５ｃｍ。经２～４年随访，皮瓣均生长良好，供瓣区功能无任何异常。在解剖和手术中发现骨间前动脉背侧穿支穿骨间膜部位有２６％稍靠上，设计皮瓣时应稍向上一点，防止蒂部过短转移不到位。在分离蒂部血管时要注意保护好骨间背侧神经。以骨间后动脉和骨间前动脉背侧穿支为血管蒂的前臂背侧皮瓣既可以顺行设计修复前臂和肘部的皮肤缺损，也可以逆行转移修复远端的手部和腕部的皮肤缺损。设计灵活、供皮区损伤小，且血管位置表浅，手术操作简单，是小面积皮肤缺损较为理想的皮瓣。     

The ideal rotation flap: an experimental study.

BACKGROUND/PURPOSE: Numerous modifications exist and opinions vary between surgeons with regard to the design of the ideal rotation flap. A literature review revealed inconsistencies as well as three different designs of rotation flap (standard rotation flap, Ahuja's modified rotation flap, divine rotation flap) based on entirely different concepts. It is not clear which of these designs serves its purpose best in wound reconstruction since they have not been previously examined experimentally and directly compared. The aim of this study is to determine the optimal rotation flap design in wound reconstruction. Several modifications of the standard rotation flap are examined and the three different rotation flap designs are directly compared. METHODS: This study tests the ability of various rotation flaps to close triangulated defects on sheets of neoprene, a synthetic rubber compound. Section A examines four important features in the design of the standard rotation flap: triangulation of a lesion, rotation flap circumference, pivot point and the back cut. Section B compares the standard rotation flap, Ahuja's modified rotation flap and the divine rotation flap. Tension resulting from wound closure is measured and the length of scar calculated. RESULTS/CONCLUSION: The standard rotation flap remains superior in comparison to the modified rotation flap and the divine rotation flap. Triangulation of a lesion should be performed with care and, in particular, the apex of the triangle should coincide with the geometrical pivot point. A flap circumference more than five times the width of the defect is of minimal benefit. The back cut is an effective modification and should be used if necessary.     

The beneficial effect of chlorpromazine on dorsal skin flap survival

A 3 x 10-cm dorsal rat skin flap contains a distal portion that is poorly perfused. The dorsal flap served as a useful model to test hemodynamic properties of the vasodilatory drug chlorpromazine. A control group of flaps were treated with saline and the test group with chlorpromazine (15 mg/kg intraperitoneally). Eight days postoperatively, the surface area of the flaps that necrosed was 27.3% for the treated group and 36.5% for the controls. Using Student's t-test this difference was significant (p less than 0.001). Nutrient blood flow determined by the penetration of fluorescein dye into the flap was consistently greater in the chlorpromazine-treated group compared with the control group in the first 24 hours postoperatively. The adenosine triphosphate (ATP) levels measured at 0 and 24 hours postoperatively were consistently lower in the distal parts of the flap, treated or control, compared with proximal parts of the flap (p less than 0.001, analysis of variance). However, there were no significant differences in ATP levels between treated and control biopsies at any one site on the flap. In conclusion, chlorpromazine had a beneficial effect on rat skin survival, and increased blood flow appears to be one of the major reasons.