Correlation between blood flow, tissue volume and microvessel density in the flap.

The purpose of this study was to assess the correlation between tissue volume and blood flow of the flap in an animal model. Using animal model, tissue volume can be attenuated, and precise change of blood flow could be evaluated. We further investigate the relationship between blood flow and vascular density in the tissue. In this study, we assessed flap conductance (ml/min/mm Hg) as to evaluate the conductivity of blood flow into the flap. Japanese white rabbit was used (n = 7) for this study. The amount of blood flow of jejunal and latissimus dorsi muscle (LD) flaps was measured while removing the distal portion of the flap sequentially. Conductance at each time was calculated from blood pressure and blood flow volume. The tissue volume at each time was also measured. The correlation between conductance and volume was analyzed using a linear mixed model. Immunohistochemical evaluation of microvessel densities (MVD) in these tissues was also performed for CD31/PECAM1 positive area. Conductance and tissue volume were significantly correlated in both jejunal and LD flaps. As the volume increases by 1 cm3, the conductance increased significantly by 0.012 ml/min/mm Hg in jejunum, and by 0.0047 ml/min/mm Hg in LD. Mean MVD was 1.15 ± 0.52% in the jejunum and 0.37 ± 0.29% in the LD muscle. In this study, we revealed that flap conductance is proportional to volume and proportional constant is different between the type of tissue. It suggests that the difference of MVD creates the unique conductance of each tissue.

Increased Defect Size is Associated with Increased Complication Rate after Free Tissue Transfer for Midanterior Skull-Base Reconstruction.

Objective Complications after skull-base reconstruction are often problematic. We consider that local factors, for example, localization of defect areas are possible risk factors. This study aimed to investigate our case series of skull-base reconstructions in our institution and to identify local risk factors that predispose to wound complications. Design This study is presented as a retrospective study. Setting Research work was took place at Nagoya University Hospital. Participants Forty-eight patients who had undergone reconstruction after midanterior skull-base resection between January 2004 and December 2015 were included in this study. Defects apart from the skull-base were categorized into nasal and paranasal cavity (N), orbit (O), palate (P), and facial skin (S). Postoperative local complications including cerebrospinal fluid (CSF) leakage, local infection, wound dehiscence (fistula in face or palate), and flap necrosis (partial or total) were investigated. Main Outcome Measures Main outcome measures were postoperative complications in patients with each defect. Results Apart from the skull-base, defects included 28 ONP (58.3%), 10 ONPS (20.8%), 3 ON (6.3%), 3 ONS (6.3%), 1 NP (2.1%), and 1 OS (2.1%). Comparison based on numbers of resected regions revealed that a significantly higher complication rate was seen in patients with four resected regions than in those with three regions (90.0% vs. 45.2%, p < 0.05). Conclusion There was a trend suggesting that more resected regions corresponded to a greater risk of complications in midanterior skull-base reconstruction. Reconstructive surgeons need to carefully consider the reconstruction of such complicated defects.

Erratum: Increased Defect Size is Associated with Increased Complication Rate after Free Tissue Transfer for Midanterior Skull-Base Reconstruction.

[This corrects the article DOI: 10.1055/s-0038-1676777.].

＜Editors' Choice＞ Effect of postoperative doxorubicin administration on ischemic wound healing.

Some patients undergo postoperative chemotherapy despite showing impaired wound healing after a major surgery. We speculated that postoperative chemotherapy further delays wound healing in these patients. This study aimed to compare the effects of doxorubicin (DXR) in ischemic skin flap and normal incisional wound models after surgery. A 2-cm incisional wound was made in group 1 rats, and saline was injected intravenously, following surgery on the same day. Incisional wound was made in group 2-5 rats, and 8 mg/kg DXR was injected intravenously, following surgery on the same day and after 7, 14, and 21 days respectively. H-shaped double flaps were made in group 6 rats, and saline was injected intravenously, following surgery on the same day. Flaps were made in group 7-10 rats, and 8 mg/kg DXR was injected intravenously, following surgery on the same day and after 7, 14, and 21 days respectively. On days 7, 14, 21, and 28 after surgery, the suture wounds were removed, tensile wound strengths were measured, and tissue samples were collected for histopathological evaluation. The tensile strength was significantly lower in the DXR-treated groups than in the control groups for both ischemic skin flaps and incision wounds. Additionally, the cross effect between DXR and ischemia was not significant. On pathological examination, DXR showed atrophic skin changes and degeneration of skin appendages on days 14-21 after the surgery in both the models. DXR decreased the wound tensile strength and caused an atrophic change in the ischemic wound.

Does a muscle flap accelerate wound healing of gastric wall defects compared with an omental flap?

INTRODUCTION: Most often used for reconstruction at superficial sites, a muscle flap recently was reported to promote clinical wound healing in a duodenal defect. We therefore examined whether a muscle flap could promote wound healing comparably to an omental flap in rats with gastric wall defects. METHODS: After perforation of the centre of the anterior gastric wall, rats were divided into 2 groups. In the muscle group, a muscle flap was fixed to the defect; in the omentum group, an omental flap was placed over the defect. We histopathologically compared tissue responses during gastric wall healing. RESULTS: While stratified villi had completely covered the defect by day 7 in both groups, scar maturation differed. Scar tissue persisted in the muscle group, but was gradually replaced by adipose tissue in the omentum group. DISCUSSION: Both muscle and omental flaps accelerated gastric wall wound healing. CONCLUSION: A muscle flap is an excellent alternative for repair of gastric defects when no omental flap is available.

Free calvarial periosteum graft vascularized by an omental flap in a rat model.

Because omental flaps are useful for flap prefabrication and the cambium layer of the periosteum can be osteogenic, we examined whether calvarial periosteum grafted onto greater omentum of rats was osteogenic and suitable for a flap. Distal omentum was wrapped with calvarial periosteum and so the cambium faced the omentum. Grafted omentum was harvested at 1 to 9 days. In other rats, grafted omentum was elevated as a pedicled flap and moved to the abdominal subcutis, to be harvested later at 1 to 5 months after the initial surgery. Bone formation was evaluated histologically, histochemically, and radiographically. On day 3, osteoid had formed. From day 4, calvarial periosteum was revascularized by omentum and bone was forming. New bone was maintained after grafting to subcutis for 5 months. Thus, bone formed by periosteum on the omentum could be used to reconstruct defects of the bone.

Omental flap closure of refractory wounds: rat model.

Omental flaps, with their associated rich and pliable vascular arcades, are frequently used in clinical practice for the reconstruction of complex and irregular defects. There is little experimental evidence, however, to prove that omental flaps can be a useful tool for the defects. Using a gastric-wall defect model, we performed histological and immunocytochemical examinations. We created an omental flap lining a 2.0-mm defect perforating the center of the anterior wall of a rat stomach. We examined the tissue response during gastric wall regeneration by H&E and Masson trichrome stains. We also performed immunocytochemical studies for the detection of proliferating cell nuclear antigen (PCNA), factor VIII-related antigen, fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF). One day after the operation, the omental flap was found to firmly adhere to the gastric serosa surrounding the defect. An extensive inflammatory response occurred from Day 1 to 3 with dilated vessels in the omentum. From Days 3 to 7, a significant number of PCNA-positive cells, FGF-2-positive cells and VEGF-positive cells were observed at the edge of the mucosa and within the granulation tissue. On Day 4, in place of extensive inflammation, an exuberant granulation tissue response was observed from the omentum. The defect had been covered by stratified villi by Day 7. This study demonstrated that an omental flap came to rapidly adhere to the defect serving as a source of extensive inflammation and granulation for the rich and pliable vascular arcades.