Improved dorsal random-pattern skin flap survival in rats with a topically applied combination of nonivamide and nicoboxil

The effects of a topically applied combination of nonivamide and nicoboxil in improving skin perfusion and preventing distal flap necrosis were tested in a random-pattern dorsal skin flap model. Forty male Wistar rats were randomized into two groups (n = 20), and a standardized dorsal random-pattern skin flap was raised on each rat. Animals in the experimental group were treated with the topically applied drug combination four times per day for 6 days, whereas in the control group only a placebo ointment was applied each time. Skin flap viability was evaluated on day 7, and the extent of skin flap necrosis was compared between the two groups. The topically applied combination of nonivamide and nicoboxil resulted in a statistically significant decrease in skin flap necrosis, compared with the control group (mean percentage of skin flap necrosis in the nonivamide/nicoboxil-treated group, 22.6 +/- 6.0 percent; control group, 36.8 +/- 4.3 percent; p< 0.05). The topical combination of nonivamide and nicoboxil was effective in reducing ischemic necrosis in failing random-pattern skin flaps in this rat model. The results of this study suggest that such a topical drug application might have significant effects in the reduction of ischemic necrosis in the distal parts of skin flaps, and this treatment might also have applications as prophylactic therapy for risky skin flaps.     

The effect of low-energy laser on skin-flap survival in the rat and porcine animal models.

Low-energy lasers are currently being used in the therapy of rheumatoid arthritis, chronic pain, muscle strain, and the promotion of wound healing in human and veterinary medicine. This study examined the effects of low-energy laser on skin-flap survival in a controlled interspecies study using the rat and porcine models. Twenty dorsal skin flaps based caudally were performed in 20 rats (10 laser-treated and 10 control flaps). The wounds were closed, and the flaps were sutured over the skin. Forty dorsal pig skin flaps based medially were raised in five pigs. The flaps were treated once per day for 10 days: 4 days preoperatively, the day of surgery, and 5 days postoperatively (30 s/cm3 per day). The average surviving rat flap surface area for the laser-treated flaps was 653 +/- 112 mm (mean +/- SD) and 580 +/- 60 mm in the control flaps, which was not significant (p greater than 0.05). In the porcine model, the average surviving area for the 20 laser-treated flaps was 949 +/- 174 mm, and the control average (n = 20) was 969 +/- 147 mm, also not significant. No beneficial effect was seen with low-energy laser preoperative and postoperative treatment of skin flaps in the rat and porcine models.     

Effect of radiation on skin expansion and skin flap viability in pigs

The aim of the present study was to investigate the effect of radiation treatment both on skin tissue expansion with the chronic inflation of subcutaneous expanders and on skin flap viability in surgically delayed and expanded skin in the pig. One flank in each of six pigs (initially weighing 17 +/- 1.8 kg) was randomly assigned for radiation treatment, and the contralateral flank served as a nonirradiated control. Three mirror-image, 8 x 10 cm, rectangular templates were marked on each flank; these templates were randomly assigned to the construction of a delayed skin flap (group A), a skin flap raised on expanded skin (group B), or a skin flap raised on expanded skin with a capsulectomy before flap surgery (group C). Radiation treatment was performed using sequential radiation with three fractions per week (810 cGy/fraction) for 2 weeks, with a total dose of 4,860 cGy. Twelve weeks after radiation treatment, skin expanders (8 x 10 cm) were installed subcutaneously in the locations assigned for skin expansion. Skin expansion by the inflation of subcutaneous skin expanders with saline twice weekly was started 8 weeks later and lasted for 3 weeks. Two weeks after surgical delay and the last skin expansion, 8 x 20 cm skin flaps were raised on the locations assigned for delayed skin flaps, expanded skin flaps, and expanded skin flaps with a capsulectomy. Skin flap viability was assessed 24 hours later using a fluorescein dye-staining technique. Skin expansion by the inflation of subcutaneous expanders with saline was slower (p < 0.05) in the radiated skin (39 +/- 6 ml/filling) than in the nonirradiated control skin (51 +/- 6 ml/filling). Radiation reduced the overall area of expanded skin by 23 percent (p < 0.05) compared with the control. Radiation treatment also reduced skin viability by 36 percent (p < 0.05) in the delayed skin flaps, 27 percent (p = 0.10) in the expanded skin flaps, and 36 percent (p < 0.05) in the expanded skin flaps with a capsulectomy when compared with their contralateral, nonirradiated controls. There were no significant differences in skin viability among these three types of skin flaps within the radiated and nonirradiated groups. Taken together, these observations indicate that radiation treatment reduced the effectiveness of the surgical delay procedure, the amount of subcutaneous skin expansion (by an increase in skin area), and skin flap viability. However, a capsulectomy alone did not affect the viability of skin flaps raised on expanded skin.     

Effect of capsulectomy on the hemodynamics and viability of random-pattern skin flaps raised on expanded skin in the pig

Skin flaps constructed on expanded skin usually include the underlying capsular tissue. It has been hypothesized that capsulectomy may jeopardize the viability of the expanded skin flap. The experiments reported herein were designed to test this hypothesis. Specifically, we studied the hemodynamics and viability of random-pattern skin flaps (8 X 20 cm) raised on delayed bipedicle flaps (group A) and on expanded skin pockets with capsulectomy at the time of flap elevation (group B) or with intact underlying capsular tissue (group C). Each group was randomly assigned to each flank in 16 pigs. Skin pockets were expanded by inflation of subcutaneous silicone tissue expanders with sterile saline (299 +/- 7 ml; X +/- SEM) over a period of 3 weeks. At the end of this period, the bipedicle flaps were constructed. Eight days later, random-pattern skin flaps were raised on bipedicle flaps and skin pockets. The length and area of skin flap viability, judged by the fluorescein dye test performed 1 day postoperatively, were not significantly different (p greater than 0.05) among groups A, B, and C (n = 31 to 32). There also were no significant differences (p greater than 0.05) in total skin capillary blood flow measured 1 day postoperatively (A = 2.6 +/- 0.4, B = 2.4 +/- 0.4, and C = 2.7 +/- 0.6 ml/min per flap; n = 15 to 16) and in skin viability assessed 7 days postoperatively (A = 74 +/- 2, B = 75 +/- 2, and C = 76 +/- 2 percent; n = 16) among delayed skin flaps and skin flaps raised on expanded skin pockets with or without capsulectomy. The results of this flap viability study were confirmed in 5 minipigs in a separate experiment. We conclude that capsulectomy did not have a detrimental effect on the hemodynamics and viability of random-pattern skin flaps raised on expanded skin. Furthermore, we hypothesize that skin flaps raised on expanded skin are similar to delayed skin flaps in that the skin blood flow is optimally augmented; therefore, the capsular tissue does not add significant blood supply to the overlying skin.     

The microcirculation of myocutaneous island flaps in pigs studied with radioactive blood volume tracers and microspheres of different sizes.

In order to further improve the understanding of hemodynamic changes in the immediate postoperative phase after elevation of myocutaneous flaps, regional blood flow and arteriovenous (A-V) shunting were measured in rectus abdominis island flaps in 8 pigs. Radioactive microspheres of two sizes (15 and 50 micron) were used. Approximately half (53.4 +/- 6 percent) of the 15-micron microspheres and one-fourth (24.1 +/- 6 percent) of the 50-micron microspheres entering the flap appeared in the venous outflow. Compared with the control area, A-V shunting was significantly increased in muscle and substantially more pronounced in skin. Nutritional blood flow, total blood flow, and vascular volume were increased in muscle and unchanged in skin and subcutis. The lowest tissue hematocrit of 7 +/- 1 percent was found in skin as compared with a central hematocrit of 35 +/- 2 percent. Tissue hematocrit in flap muscle was decreased to 17 +/- 2 percent when compared with control muscle (22 +/- 3 percent), and the mean transit time for blood was correspondingly decreased. Thus vasodilation provided increased perfusion through muscular capillaries and through A-V shunts. Shunting of 15-micron microspheres appeared to take place not only in skin, but also in subcutis and muscle, which challenges the widespread belief that A-V shunting does not occur in muscle.     

Prevention of ischemia-reperfusion injury in a rat skin flap model: the role of mast cells, cromolyn sodium, and histamine receptor blockade

The objective of this study was to examine the role of mast cells and their principal product, histamine, in ischemia/reperfusion injury. Cromolyn sodium, diphenhydramine, and cimetidine were administered to ischemic flaps just before reperfusion and evaluated for flap survival, mast cell count, neutrophil count, and myeloperoxidase levels. Epigastric island skin flaps were elevated in 49 rats; they were rendered ischemic by clamping the artery for 10 hours. Thirty minutes before reperfusion, the rats were treated with intraperitoneal saline (n = 11), cimetidine (n = 11), diphenhydramine (n = 11), or cromolyn sodium (n = 10). Flap survival was evaluated at 7 days. Neutrophil counts, mast cell counts, and myeloperoxidase levels were evaluated 12 hours after reperfusion. Flap necrosis in the sham group of animals (n = 6) was 0.0 percent, as expected, whereas the control group (saline-treated animals) had 47.3+/-33.4 percent necrosis. Animals treated with diphenhydramine and cimetidine demonstrated a significant decrease in flap necrosis to 17.7+/-8.8 percent and 19.4+/-14.7 percent, respectively. This protective effect was not seen with cromolyn sodium (44.3+/-35.6 percent). Both neutrophil and mast cell counts were significantly decreased in flaps from antihistamine-treated and sham animals versus both saline- and cromolyn sodium-treated groups. The administration of diphenhydramine and cimetidine before reperfusion can significantly reduce the extent of flap necrosis and the neutrophil and mast cell counts caused by ischemia/reperfusion. This protective effect is not seen with cromolyn sodium. The protective effect of antihistamines on flap necrosis might be related to the decrease in neutrophils and, possibly, mast cells within the flap.     

Fasciocutaneous flaps: an experimental model in the pig

No experimental studies have substantiated the claim that fasciocutaneous flaps are superior to skin flaps. Using fasciocutaneous flaps designed in the pig, both flap survival and blood flow were assessed. The forelimb and hindlimb fasciocutaneous flaps survived to 8.2 +/- 0.3 cm and 7.9 +/- 0.3 cm, respectively, compared with 7.3 +/- 0.3 cm and 6.7 +/- 0.3 cm for the comparable cutaneous flaps, a statistically significant finding (p less than 0.01). Random fasciocutaneous flaps survive 12 to 18 percent longer than skin flaps. Using the radioactive microsphere technique, blood flow was measured after flap elevation, and flap survival was estimated using fluorescein. Again, a significant difference in flap survival was found, but there was no significant difference in measured blood flow. This can be explained by the relatively large interval between blood flow measurements (2 cm) compared with the observed difference in survival length (1.0 +/- 0.3 cm).     

The effect of low-molecular-weight heparin in the survival of a rabbit congested skin flap

Swelling and congestion of flaps are frequently seen postoperatively and can cause unexpected necrosis. According to previous reports, venous thrombosis seems to be a more frequent problem than arterial occlusion in both experimental and clinical surgery. Few satisfactory venous trauma models exist, and reports on experimental venous thrombosis are rare. The object of this study was to create a rabbit venous occlusion flap model and to evaluate the effect of low-molecular-weight heparin on this flap. Eight New Zealand rabbits were used in the pilot study, in which the ideal congested flap was investigated using a flap pedicle based on the central auricular artery with a skin pedicle 0, 1, 2, or 3 cm wide. The flap (3 x 6 cm) was designed on the central part of the left ear, and the central auricular vein and nerve, the former for venous return, were cut out at the base of the flap. The flaps with skin pedicles 0, 1, 2, or 3 cm wide showed mean necrosis length of 60.0, 9.3, 4.2, and 0.0 mm, respectively. The flaps with skin pedicles 0, 1, 2, or 3 cm wide showed mean necrosis of 100, 15.5, 7, and 0 percent, respectively. Therefore, the flap, based on a 1-cm-wide skin pedicle and the central auricular artery, was selected as an optimal congested flap model showing 15.5 percent necrosis. The congested flap was then elevated on the left ear of another 10 rabbits. Subcutaneous low-molecular-weight heparin (320 IU/kg) was administered immediately after surgery to five of the rabbits (the low-molecular-weight heparin group), and the remaining five were used as a control group. Fluorescein was injected 15 minutes after surgery to evaluate the circulatory territory of the flap, and the circulatory territory was measured 5 minutes after injection. The flaps were assessed 7 days after surgery by angiography, histology, and clinical findings. The circulatory territory was significantly greater in the low-molecular-weight heparin group (mean +/- SD, 39.2 +/- 3.0 mm) than the control group (mean +/- SD, 48.0 +/- 1.0 mm) (p < 0.001) assessed 7 days after surgery. The longest flap survival length in group A and group B ranged from 40 to 55 mm (mean +/- SD. 49.4 +/- 5.6 mm) and complete survival (mean +/- SD, 60.0 +/- 0.0 mm). The improvement in survival was statistically significant for group B compared with group A (p < 0.015). Histologic evaluation revealed moderate to severe venous congestion and inflammation in the control group, whereas there were minimal changes in the low-molecular-weight heparin group. Angiography of the flap revealed obvious venous occlusion in the periphery in the control group compared with the low-molecular-weight heparin group. The authors conclude that subcutaneous administration of low-molecular-weight heparin has a great potential to improve the survival length of a congested flap without major complications.     

Comparison of three different supercharging procedures in a rat skin flap model

A significant clinical problem in reconstructive surgery is partial loss of a pedicled flap. To resolve this problem, various methods of vascular augmentation have been developed; "supercharging" is one of those techniques. A new rat flap model was developed for investigation of the supercharging procedure, and the efficacy of the arterial supercharging method was examined. The purpose of this study was to investigate how an arterial supercharging procedure could generate large flap survival areas with different supercharging positions in rats. On the basis of the vascular anatomical features of rats, a circumferential skin flap from the lower abdomen to the back, measuring 4 x 12 cm, was marked. The flap was divided along the dorsal midline. Forty rats were divided into four experimental groups, as follows: group 1 (control), flaps based only on the deep circumflex iliac artery and vein; group 2, flaps supercharged with the ipsilateral superficial inferior epigastric artery; group 3, flaps supercharged with the contralateral superficial inferior epigastric artery; group 4, flaps supercharged with the contralateral deep circumflex iliac artery. On the fourth postoperative day, the flaps were evaluated with measurements of necrosis and survival areas. Microfil (Flow Tech, Inc., Carver, Mass.) was then injected manually throughout the body, and the vascular changes produced by supercharging were angiographically evaluated. Compared with group 1 (control), the flap survival areas were significantly greater in distally supercharged flaps in groups 3 and 4 (mean flap survival, 91.2 +/- 5.2 percent and 90.5 +/- 10.6 percent, respectively; p < 0.001) and in proximally supercharged flaps in group 2 (45.9 +/- 4.1 percent, p < 0.05). Angiographic assessment of the flaps that survived completely revealed marked dilation of the choke veins among the territories and reorientation of dilated veins along the axes of the flaps. This study suggests that distal arterial supercharging (contralateral superficial inferior epigastric artery or contralateral deep circumflex iliac artery) is more effective than proximal arterial supercharging (ipsilateral superficial inferior epigastric artery) in increasing flap survival. Although the rat skin flap may not be analogous to human flaps, distal arterial supercharging might have useful therapeutic potential in increasing flap survival in clinical practice.     

The effects of a topical PGE2 analogue on global flap ischemia in rats

The present study evaluated the ability of DHV-PGE2ME, a topically effective 16-vinyl prostaglandin E2 analogue, to improve the tolerance of skin flaps to a period of ischemia. DHV-PGE2ME and placebo were applied to bilateral island flaps on 70 anesthetized rats; then the vascular pedicle of each flap was clamped for 10 hours. Treated flaps evidenced significantly better reperfusion, as documented by quantification of fluorescein dye delivery at 90 minutes after clamp release, and they had significantly greater ultimate viability (p less than 0.05, by ANOVA). While less than 3 percent of untreated flaps survived, those treated with 1.75 and 17.5 microgram/cm2 of drug evidenced 76 and 86 percent survival, respectively. Treatment of a given flap did not affect its contralateral mate, since there was no evidence of a systemic effect. Especially since its effect can be limited to the site of application, DHV-PGE2ME should be valuable for the treatment of compromised perfusion in a variety of settings.     

Perforator-based flap in rats: a new experimental model.

A new type of flap, the perforator-based flap, has been described in the last decade. It has been used successfully as a pedicle or free flap by many plastic surgeons. There is no animal model for research, although these flaps have gained popularity in clinical use. We created a perforator-based flap model in the rat (a perforator-based flap group and two control groups; 10 rats in each group) and evaluated the survival characteristics of the new flap. The abdominal skin flap was elevated based on the second perforator of the right superior deep epigastric artery and then sutured to its original bed. In the first control group, the same flap was elevated with a subcutaneous pedicle without any perforator; in the second control group, a right-sided, random-pattern pedicle abdominal skin flap with the same dimensions and location was elevated and sutured to its original bed. Flap survival was studied, and microangiography and histologic studies were performed. The amount of viable skin in the three groups was compared 1 week later. The area of surviving skin paddles in the experimental group ranged from 74 to 83 percent; in the first control group, it was 0 percent; and in the second control group, it ranged from 29 to 44 percent (p < 0.001 and p < 0.001, respectively). There was a predictable and constant area of necrosis in the model.The results of this study demonstrate that most of the abdominal skin of the rat can survive on the basis of a single musculocutaneous perforator vessel. This flap can be easily elevated, and it can be used as a reliable model for flap research.     

Comparison of TRAM and DIEP flap physiology in a rat model

Dynamic and physiologic studies objectively comparing the attributes of the transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric perforator (DIEP) flaps would be most practical in an animal model. This has now been accomplished using the ventral abdomen of the Sprague-Dawley rat. A conventional TRAM flap, a multiple perforator DIEP flap, and a solitary perforator DIEP flap were raised in three equal groups of five rats each. Flow studies using laser Doppler flowmetry demonstrated the highest flow in zone I in the TRAM flap group (87.6 +/- 15.4 percent), which was a statistically significant difference from the multiple perforator DIEP flap group (45.4 +/- 13.3 percent) and the solitary perforator DIEP flap group (43.4 +/- 26.4 percent) (p = 0.005). Flow in zone IV was proportionately lower for all groups, with no significant difference noted between TRAM and DIEP flaps (p = 0.736). Although ultimate flap survival was greatest for the TRAM flap group (96.1 +/- 6.7 percent) when compared with the multiple perforator DIEP flap (79.8 +/- 15.2 percent) or the solitary perforator DIEP flap groups (77.1 +/- 23.0 percent), this difference was not statistically significant (p = 0.183). In summary, relative flow to these rat ventral abdomen models was directly proportional to the number of retained musculocutaneous perforators, but a single perforator only could routinely allow near-total survival.     

Enhanced neovascularization of rat tubed pedicle flaps with low perfusion of the wound margin

To study the role of ischemia due to low perfusion as the inciter of neovascularization, caudally based 3 X 9 cm skin flaps were created on the dorsum of 50 Sprague-Dawley rats. After injection of 0.2 ml 10% fluorescein, the animals were divided into two groups. In group I (n = 25), the distal margin of the flap tip was 1 cm proximal to the border of the fluorescence (good perfusion). In group II (n = 25), the flap was cut 1 cm distally in the nonfluorescent part (poor perfusion). The tips of the tubed flaps were transferred to a wound bed on the right flank. After 10 days, the pedicles were ligated, so that flap survival depended totally on the new vascular supply from the inset area of the flap. The flaps in group I showed a significantly higher rate of necrosis of 52.4 +/- 15.1 percent versus 1.7 +/- 1.4 percent in group II (p less than 0.0001), although the flap length in group I (5.85 +/- 1.16 cm) was less than in group II (7.15 +/- 0.95 cm; p = 0.0001). A nearly three times larger amount of tissue based on the new blood supply survived in group II compared to group I. Xerograms after injection of PbO2-gelatine on day 10 showed an increased ingrowth of blood vessels in group II. After excluding the delay phenomenon as the cause for the difference in necrosis rate, it is concluded that the only possible explanation is an enhancement of neovascularization by a perfusion gradient between the wound margins.     

The use of free groin flaps in children

The free groin flap is a well-established method of skin coverage. Although its use in children has been reported, there have been no published series specifically in such cases. The authors report 33 consecutive cases of free groin flaps in children in their unit over a period of 9 years (1992 to 2001). Tissue transfer was performed to provide soft-tissue coverage during reconstruction of congenital defects and tumor resection and following trauma. Twenty-six cases (79 percent) involved the upper limb, six cases (18 percent) involved the lower limb, and one case involved the head. The complication rate compares favorably with similar series published for adults, with only two complete failures (6 percent), three (9 percent) minor donor-site complications (superficial wound infection, hypertrophic scarring, and dog-ears), and nine flaps requiring debulking. The reexploration rate was 24 percent, with seven of the eight flaps undergoing reexploration surviving. The groin flap is a reliable flap that can be used safely in children, with minimal morbidity.     

Enhancement of epigastric skin flap survival by adenovirus-mediated VEGF gene therapy

A novel approach to treat ischemic tissues by using gene therapy has recently been introduced on the basis of the angiogenic potential of certain growth factors. The authors investigated the effect of adenovirus-mediated gene therapy with vascular endothelial growth factor (VEGF) delivered into the subdermal space to treat compromised skin flaps. For this purpose, the epigastric skin flap model in rats, based solely on the right inferior epigastric vessels, was used. Thirty male Sprague-Dawley rats were divided into five groups of six rats each. Viral transfection with 108 plaque-forming units was performed 2 days before the epigastric flap elevation. Rats received subdermal injections of adenovirus encoding VEGF (Ad-VEGF) or green fluorescent protein (Ad-GFP) as treatment control. Another set of animals (n = 6) received no injections and were designated as control. To determine whether site of injection had an impact on flap viability, injections were given into the predicted local ischemic area (Ad-VEGF local, n = 6; Ad-GFP local, n = 6) and into the midline of the flap (Ad-VEGF midline, n = 6; Ad-GFP midline, n = 6). A flap measuring 8 x 8 cm was outlined on the abdominal skin extending from the xiphoid process proximally and the pubic region distally, to the anterior axillary lines bilaterally. Then, the epigastric flap was elevated as an island on the right inferior epigastric vessels and sutured back to its bed. Flap viability was evaluated at 7 and 14 days after the first operation. The epigastric flaps were scanned to the computer and areas of hypoxic and/or necrotic zones relative to total flap surface area were measured and expressed as percentages by using Image Pro Plus software. Specimens were taken for histologic evaluation at day 14 before the animals were killed. Combined area of necrotic and hypoxic zones as well as necrotic zone were decreased to 9.7 +/- 1.4 percent and 1.4 +/- 0.9 percent in Ad-VEGF local, and 11.8 +/- 1.9 percent and 3.5 +/- 1.64 percent in Ad-VEGF midline compared with the control and Ad-GFP treatment groups (control, 23 +/- 3.6 percent and 20.1 +/- 3.3 percent; Ad-GFP local, 24.8 +/- 4.8 percent and 16.2 +/- 5.9 percent; and Ad-GFP midline, 23.4 +/- 6.9 percent and 19.5 +/- 7.7 percent; p < 0.05). Histologic evaluation by light microscopy failed to demonstrate any quantitative difference in vascularity of skin flaps between the treatment groups. In this study, the authors demonstrated that adenovirus-mediated gene therapy using VEGF enhanced epigastric skin flap survival, as confirmed by the significant reduction in combined area of necrotic and hypoxic zones of the flap. Compared with the control, both local and midline subdermal injections of Ad-VEGF showed improvement in overall flap survival by 57.9 and 48.7 percent, respectively. The results of this study raise the possibility of using adenovirus-mediated therapeutic angiogenesis for safer flap surgery in high-risk patients.     

Effect of vascular delay on viability, vasculature, and perfusion of muscle flaps in the rabbit

The delay procedure is known to augment pedicled skin or muscle flap survival. In this study, we set out to investigate the effectiveness of vascular delay in two rabbit muscle flap models. In each of the muscle flap models, a delay procedure was carried out on one side of each rabbit (n = 20), and the contralateral muscle was the control. In the latissimus dorsi flap model, two perforators of the posterior intercostal vessels were ligated. In the biceps femoris flap model, a dominant vascular pedicle from the popliteal artery was ligated. After the 7-day delay period, the bilateral latissimus dorsi flaps (based on the thoracodorsal vessels) and the bilateral biceps femoris flaps (based on the sciatic vessels) were elevated. Animals were divided into three groups: part A, assessment of muscle flap viability at 7 days using the tetrazolium dye staining technique (n = 7); part B, assessment of vascular anatomy using lead oxide injection technique (n = 7); and part C, assessment of total and regional capillary blood flow using the radioactive microsphere technique (n = 6). The results in part A show that the average viable area of the latissimus dorsi flap was 96 +/- 0.4 percent (mean +/- SEM) in the delayed group and 84 +/- 0.7 percent (mean +/- SEM) in the control group (p < 0.05, n = 7), and the mean viable area of the biceps femoris flap was 95 +/- 2 percent in the delayed group and 78 +/- 5 percent in the control group (p < 0.05, n = 7). In part B, it was found that the line of necrosis in the latissimus dorsi flap usually appeared at the junction between the second and third vascular territory in the flap. Necrosis of the biceps femoris flap usually occurred in the third territory, and occasionally in both the second and the third territories. In Part C, total capillary blood flow in delayed flaps (both the latissimus dorsi and biceps femoris) was significantly higher than that in the control flaps (p < 0.05). Increased regional capillary blood flow was found in the middle and distal regions, compared with the control (p < 0.05, n = 6). In conclusion, ligation of either the dominant vascular pedicle in the biceps femoris muscle flap or the nondominant pedicle in the latissimus dorsi muscle flap in a delay procedure 1 week before flap elevation improves capillary blood flow and muscle viability. Vascular delay prevents distal flap necrosis in two rabbit muscle flap models.     

Have we found an ideal soft-tissue flap? An experience with 672 anterolateral thigh flaps

The free anterolateral thigh flap is becoming one of the most preferred options for soft-tissue reconstruction. Between June of 1996 and August of 2000, 672 anterolateral thigh flaps were used in 660 patients at Chang Gung Memorial Hospital. Four hundred eighty-four anterolateral thigh flaps were used for head and neck region recontruction in 475 patients, 58 flaps were used for upper extremity reconstruction in 58 patients, 121 flaps were used for lower extremity reconstruction in 119 patients, and nine flaps were used for trunk reconstruction in nine patients. Of the 672 flaps used in total, a majority (439) were musculocutaneous perforator flaps. Sixty-five were septocutaneous vessel flaps. Of these 504 flaps, 350 were fasciocutaneous and 154 were cutaneous flaps. Of the remaining 168 flaps, 95 were musculocutaneous flaps, 63 were chimeric flaps, and the remaining ten were composite musculocutaneous perforator flaps with the tensor fasciae latae. Total flap failure occurred in 12 patients (1.79 percent of the flaps) and partial failure occurred in 17 patients (2.53 percent of the flaps). Of the 12 flaps that failed completely, five were reconstructed with second anterolateral thigh flaps, four with pedicled flaps, one with a free radial forearm flap, one with skin grafting, and one with primary closure. Of the 17 flaps that failed partially, three were reconstructed with anterolateral thigh flaps, one with a free radial forearm flap, five with pedicled flaps, and eight with primary suture, skin grafting, and conservative methods.In this large series, a consistent anatomy of the main pedicle of the anterolateral thigh flap was observed. In cutaneous and fasciocutaneous flaps, the skin vessels (musculocutaneous perforators or septocutaneous vessels) were found and followed until they reached the main pedicle, regardless of the anatomic position. There were only six cases in this series in which no skin vessels were identified during the harvesting of cutaneous or fasciocutaneous anterolateral thigh flaps. In 87.1 percent of the cutaneous or fasciocutaneous flaps, the skin vessels were found to be musculocutaneous perforators; in 12.9 percent, they were found as septocutaneous vessels. The anterolateral thigh flap is a reliable flap that supplies a large area of skin. This flap can be harvested irrespective of whether the skin vessels are septocutaneous or musculocutaneous. It is a versatile soft-tissue flap in which thickness and volume can be adjusted for the extent of the defect, and it can replace most soft-tissue free flaps in most clinical situations.     

Acute local subcutaneous VEGF165 injection for augmentation of skin flap viability: efficacy and mechanism

Distal skin ischemic necrosis is a common complication in skin flap surgery. The pathogenesis of skin flap ischemic necrosis is unclear, and there is no clinical treatment available. Here, we used the 4 x 10 cm rat dorsal skin flap model to test our hypothesis that subcutaneous injection of vascular endothelial growth factor 165 (VEGF165) in skin flaps at the time of surgery is effective in augmentation of skin flap viability, which is associated with an increase in nitric oxide (NO) production, and the mechanism involves 1) an increase in skin flap blood flow in the early stage after surgery and 2) enhanced angiogenesis subsequently to sustain increased skin flap blood flow and viability. We observed that subcutaneous injection of VEGF165 in skin flaps at the time of surgery increased skin flap viability in a dose-dependent manner. Subcutaneous injection of VEGF165 at the dose of 2 microg/flap increased skin flap viability by 28% (P < 0.05; n = 8). Over 80% of this effect was blocked by intramuscular injection of the NO synthase (NOS) inhibitor Nomega-nitro-L-arginine (13 mg/kg) 45 min before surgery (P < 0.05; n = 8). The VEGF165 treatment also increased skin flap blood flow (2.68 +/- 0.63 ml x min(-1) x 100 g(-1)) compared with the control (1.26 +/- 0.10 ml x min(-1) x 100 g(-1); P < 0.05, n = 6) assessed 6 h postoperatively. There was no change in skin flap capillary density at this time point. VEGF165-induced increase in capillary density (32.2 +/- 1.1 capillaries/mm2; P < 0.05, n = 7) compared with control (24.6 +/- 1.4 capillaries/mm2) was seen 7 days postoperatively. There was also evidence to indicate that VEGF165-induced NO production in skin flaps was stimulated by activation of NOS activity followed by upregulation of NOS protein expression. These observations support our hypothesis and for the first time provide an important insight into the mechanism of acute local VEGF165 protein therapy in mitigation of skin flap ischemic necrosis.     

Autologous breast reconstruction with the extended latissimus dorsi flap

The extended latissimus dorsi myocutaneous flap can provide autogenous tissue replacement of breast volume without an implant. Nevertheless, experience with the extended latissimus dorsi flap for breast reconstruction is relatively limited. In this study, the authors evaluated their experience with the extended latissimus dorsi flap for breast reconstruction to better understand its indications, limitations, complications, and clinical outcomes. All patients who underwent breast reconstruction with extended latissimus dorsi flaps at the authors' institution between January of 1990 and December of 2000 were reviewed. During the study period, 75 extended latissimus dorsi flap breast reconstructions were performed in 67 patients. Bilateral breast reconstructions were performed in eight patients, and 59 patients underwent unilateral breast reconstruction. There were 45 immediate and 30 delayed reconstructions. Mean patient age was 51.5 years. Mean body mass index was 31.8 kg/m2. Flap complications developed in 21 of 75 flaps (28.0 percent), and donor-site complications developed in 29 of 75 donor sites (38.7 percent). Mastectomy skin flap necrosis (17.3 percent) and donor-site seroma (25.3 percent) were found to be the most common complications. There were no flap losses. Patients aged 65 years or older had higher odds of developing flap complications compared with those 45 years or younger (p = 0.03). Patients with size D reconstructed breasts had significantly higher odds of flap complications compared with those with size A or B reconstructed breasts (p = 0.05). Obesity (body mass index greater than or equal to 30 kg/m2) was associated with a 2.15-fold increase in the odds of developing donor-site complications compared with patients with a body mass index less than 30 kg/m2 (p = 0.01). No other studied factors had a significant relationship with flap or donor-site complications. In most patients, the extended latissimus dorsi flap alone, without an implant, can provide good to excellent autologous reconstruction of small to medium sized breasts. In selected patients, larger breasts may be reconstructed with the extended latissimus dorsi flap alone. This flap's main disadvantage is donor-site morbidity with prolonged drainage and risk of seroma. Patients who are obese are at higher risk of developing these donor-site complications. In conclusion, the extended latissimus dorsi flap is a reliable method for total autologous breast reconstruction in most patients and should be considered more often as a primary choice for breast reconstruction.     

Increase in skin-flap survival by the vasoactive drug buflomedil

The effect of buflomedil to protect skin tissue from ischemia and necrosis was studied in random cutaneous flaps. Measurements were performed by intravital microscopy on the microcirculatory level of capillary perfusion in a flap model in the hairless mouse. In 30 hairless mice, single-pedicle flaps measuring 6 x 16 mm were raised perpendicular to the spine of the animal. This flap develops a reliable amount of necrosis at its distal edge over a period of 7 days. A group of 10 mice received intravenous injections of buflomedil in doses of 3 mg/kg per day diluted in 0.1 ml normal saline beginning 4 hours before flap elevation and for 6 consecutive days postoperatively. In addition, 10 further animals received the same treatment except that it was started 5 minutes after flap elevation. In 10 mice serving as controls, normal saline in equal volumes as in the experimental groups was applied. By means of intravital microscopy, functional vessel density (FVD) was determined in 2.5-mm increments from the flap's base to its distal edge at 1, 6, and 24 hours after elevation. Skin-flap survival was quantified by measuring the necrotic area on day 7 by means of digital planimetry. Functional vessel density was preserved in the distal flap of animals pretreated with buflomedil, revealing a higher functional vessel density at 10.0 mm (p less than 0.01), 12.5 mm (p less than 0.05), and 15.0 mm (p less than 0.001) from the flap's base as compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)