Random Flap Survival Research Articles

Effect of aspirin on random pattern flap survival in rats

Aspirin is known to increase dermal perfusion and is commonly used to enhance anastomotic patency in microvascular surgery. However, we were unable to find any reports of an effect of aspirin on simple flap survival. In order to determine its effect on flap survival, a controlled experiment was designed using random pattern flaps in rats. The results indicate a statistically significant increase in flap survival in rats receiving aspirin. It is suggested that aspirin’s anti-aggregation effect, in combination with its vasodilatational and anti-inflammatory effect, increases the perfusion in the initial critical hours and thus secondarily decreases the reperfusion injury.

Augmentation of Random-Flap Survival by Implantation of Vascularized Fascia Allografts and Temporary Immunosuppression: Implications for Flap Fabrication

The purpose of this study was to explore the possible use of an allogeneic vascular source for flap fabrication. Epigastric fascia with its superficial epigastric vessel pedicle was harvested from the donor rat and microsurgically revascularized in the recipient rat across a major histocompatibility barrier. ACI rats (Rtl-a) served as donors, and Lewis rats (Rtl-1) served as recipients. The recipient rat was immunosuppressed with a daily dose of 2 mg/kg cyclosporin A plus 5 mg/kg prednisone for 4 weeks. Three experiments were performed for skin, muscle, and bone studies. In experiment 1 (20 Lewis rats), placement of the allotransplanted fascia underneath the epigastric skin significantly improved the survival of a random epigastric skin flap raised 3 weeks later (7.35 +/- 0.65 cm2 versus 6.09 +/- 0.90 cm2, p < 0.05). Immunosuppression was discontinued 10 days after flap elevation with no observable additional skin necrosis. In experiment 2 (13 Lewis rats) and experiment 3 (14 Lewis rats), segments of isogeneic muscle and bone were grafted successfully on the allotransplanted fascia, respectively. The survival of these grafts was confirmed by metabolic bone activity, bone labeling, microangiography, and histologic studies and further confirmed 2 weeks after cessation of immunosuppression. An allotransplanted fascia as a vascular source proved in this model its capability to improve the survival of a random skin flap and to accept a free bone or muscle graft with temporary immunosuppression. These findings hold promise for possible use of an allogeneic vascular source in flap fabrication.

Transforming growth factor beta 1 improves wound healing and random flap survival in normal and irradiated rats.

To evaluate the effect of chronic irradiation on wound healing and random flap survival (FV), and the effect of transforming growth factor beta 1 (TGF-beta 1) in this setting using an animal model. A randomized, controlled study with four groups of rats to study the effect of irradiation 4 months before surgical intervention. The effect of TGF-beta 1 on FV and wound healing also was evaluated in the irradiated and nonirradiated groups. Ninety-five rats were available for evaluation. Group 1 (n = 10) was the control; group 2 (n = 28) received TGF-beta 1; group 3 (n = 28) received radiation therapy; and group 4 (n = 29) received radiation therapy and TGF-beta 1. The irradiated groups received 15 Gy to their dorsal skin. Four months later all received McFarlane skin flaps. Groups 2 and 4 received topical TGF-beta 1, 4 micrograms, to the bed of the flap; groups 1 and 3 received saline. On postoperative day 7 all rats were evaluated for tensile strength and FV, and histologic staining with hematoxylin-eosin for collagen and TGF-beta 1 was done. The slides were evaluated in a "blinded" fashion. Irradiation decreased tensile strength and FV, but not to a notable degree. Transforming growth factor beta 1 improved tensile strength in the irradiated (P = .04, Student's t test) and nonirradiated groups (P = .05, Student's t test). Transforming growth factor beta 1 also improved FV in all groups, but significantly in the irradiation plus TGF-beta 1 group (P = .001, Student's t test). The TGF-beta 1 group had the most mature collagen present at the wound edge. No qualitative difference was seen in the immunohistochemical staining for the four groups. Transforming growth factor beta 1 improves wound healing and random FV in radiated and nonirradiated rat skin. Further study is needed to determine the radiation dose necessary to create an "impaired wound-healing model" in rats, and the optimum dose of TGF-beta 1 in this setting.

Improved Survival Rates of Random Flaps in Rabbits with a Monoclonal Antibody That Blocks Leukocyte Adherence

To examine the role of neutrophil adhesiveness in the tissue injury involving the ischemic "at risk" area of random flaps, we used the monoclonal antibody 60.3, which binds selectively to the primary neutrophil adherence-mediating glycoprotein CD18 in a random cutaneous flap model. Control animals that had flaps elevated and replaced (n = 12) had a mean distal necrosis of 31.9 +/- 9.3 percent of the total flap surface area. Treatment with monoclonal antibody 60.3 (n = 12) reduced distal necrosis to 10.6 +/- 7.5 percent (p < 0.005). Inhibiting inosculation by interposing a thin silicone sheet decreased distal flap survival; however, the protective effect of monoclonal antibody 60.3 on improving flap survival was unchanged. Control isolated flaps (n = 13) had a mean distal necrosis of 49.0 +/- 15.5 percent compared with 22.2 +/- 5.6 percent for the antibody-treated (n = 8) isolated flaps (p < 0.05). We conclude that increased neutrophil adhesiveness plays an important role in the tissue injury involving the ischemic "at risk" area of random flaps and the transient, specific inhibition of leukocyte adherence by monoclonal antibody 60.3 improves the distal survival of random flaps in this model. Moreover, we conclude that "graft inosculation" contributes to "flap" survival in this model; however, conclusions regarding the effect of treatment are not altered by blocking inosculation.

Long-term Pretreatment With Pentoxifylline Increases Random Skin Flap Survival

Optimizing survival of random skin flaps is essential to ensure successful rehabilitation of patients in whom flap reconstruction is necessary. This study tested the hypothesis that pentoxifylline improves random skin flap survival in porcine dorsal flank flaps when administered for at least 2 weeks preoperatively. Specific aims included establishing the mechanisms by which pentoxifylline enhanced survival. Treatment with pentoxifylline (25 mg/kg per day) for 14 days before surgery and for 7 days thereafter significantly increased mean flap survival to 73.2% +/- 4.5% compared with mean flap survival of 49.6% +/- 2.2% in untreated pigs. Increased flap survival was associated with a parallel increase in red blood cell flexibility. Plasma concentration of pentoxifylline ranged from 92.9 to 122.7 ng/mL but did not correlate directly with the improved flap survival. Likewise, pentoxifylline decreased platelet aggregation; there was a trend toward increased flap survival in those pigs with the least amount of aggregation. Thus, pentoxifylline improves random flap survival but only after a sufficient pretreatment period of at least 14 days.

Increased Skin Flap Survival and Arterial Dilation by Calcitonin Gene-Related Peptide: A Study in the Pig

Calcitonin gene-related peptide (CGRP), a recently discovered neuropeptide, is a potent vasodilator and increases blood flow in many vascular beds. The effect of CGRP treatment was investigated in critical pig pedicle and island flaps. Prior to pharmacological treatment the peroperative circulation border was estimated with fluorescein. Intradermal or intraarterial flap treatment with CGRP was given. Control flaps were untreated or injected with saline. Increased or decreased survival was calculated as the difference between the peroperative fluorescein penetration border and the survival border one week after surgery. CGRP treatment significantly increased the survival of both random pedicle and island flaps. CGRP doses as low as 3 ml x 10(-14) M (equal to 0.03 fmoles) increased the survival of random pedicle flaps. In 4 untreated pigs the deep circumflex iliac arteries were excised and artery ring preparations were studied in vitro. A dose-dependent relaxation of artery rings was noted between 10(-9) M and 10(-7) M CGRP.

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.

Improved ischemic island skin flap survival with continuous intraarterial infusion of adenosine triphosphate--magnesium chloride and superoxide dismutase: a rat model.

Neurovascular island skin flaps are still hampered by occasional necrosis of their most distal aspect. Cells subjected to prolonged hypoxic conditions become intracellularly depleted of needed metabolic substrates and eventually die. Once hypoxic conditions are improved, ischemic tissue suffers further injury from the rapid accumulation of oxygen free radicals. This study showed 53% survival of a standard random flap constructed on the inferior epigastric neurovascular bundle of a rat. Random flap survival increased to 65% after intraarterial infusion of adenosine triphosphate--magnesium chloride (ATP-MgCl2); to 75% after superoxide dismutase infusion; and to 98% after combined ATP-MgCl2 and superoxide dismutase infusion. Neither substrate appeared to act by increasing blood flow to the ischemic tissue.

The effect of Prostacyclin on experimental random pattern flaps in the rat.

Abstract In a controlled experimental study of the survival of random pattern flaps in rats it has been found that pre-treatment with prostacylin prior to raising the skin flaps did not improve flap survival. However, if treatment was begun at the commencement of the operation and continued afterwards, there was a significant improvement in flap survival compared with the viability predicted by intravital dye injection. Possible explanations of these findings are discussed and the suggestion put forward that in addition to reducing platelet adherence and vasoconstriction PGI 2 may also stimulate the formation of new capillaries in ischaemic areas. This hypothesis requires further investigation.

Survival of skin random flaps by the use of a platelet antiaggregate. (Spanish)

Survival of skin random flaps by the use of a platelet antiaggregate. (Spanish)

The effect of prostacyclin on experimental random pattern flaps in the rat

In a controlled experimental study of the survival of random pattern flaps in rats it has been found that pre-treatment with prostacylin prior to raising the skin flaps did not improve flap survival. However, if treatment was begun at the commencement of the operation and continued afterwards, there was a significant improvement in flap survival compared with the viability predicted by intravital dye injection. Possible explanations of these findings are discussed and the suggestion put forward that in addition to reducing platelet adherence and vasoconstriction PGI 2 may also stimulate the formation of new capillaries in ischaemic areas. This hypothesis requires further investigation.

Lack of effect of isoxsuprine on experimental random flaps in the rat.

Using 1.5 x 6 cm caudally based rat dorsal pedicled flaps, the effect of isoxsuprine on skin flap survival was studied. The results showed isoxsuprine to have no augmentation effect on the survival of random pattern flaps.