Noninvasive Flap Preconditioning by Foam-Mediated External Suction Improves the Survival of Fasciocutaneous Axial-Pattern Flaps in a Type 2 Diabetic Murine Model:

[Cytosteatonecrosis after breast reconstruction by fat flap with or without ischemic preconditioning]

INTRODUCTION

Cytosteatonecrosis (CTN) is a frequent postoperative complication after breast autologous reconstruction using DIEP (deep inferior epigastric perforator) flap. CTN radiological diagnostic reveals different types of lesions, as nodes or extended fat necrosis, which become in some cases infected, or pass for tumor recurrence after breast cancer treatment. CTN is caused by intraoperative ischemia of the flap, and no current method can prevent postoperative CTN development after DIEP breast reconstruction. Mechanical ischemic preconditioning, consisting in intraoperative briefs consecutive cycles of ischemia reperfusion using vascular clamp upon the graft pedicle, is used in transplantation surgery. This procedure improves the graft tolerance towards ischemic surgical lesions. The aim of this retrospective observational study was to assess PCIM effects on CTN development after DIEP surgery, comparing CTN occurrence after breast reconstruction using DIEP flap with or without intraoperative PCIM.

MATERIAL AND METHODS

All patients breats reconstructed using DIEP flap between novembre 2020 and may 2022, presenting 6 months postoperative breast echography were retrospectively included. Primary outcome was the ultrasonic existence of CTN, according to the Wagner classification. Clinical data, postoperative outcomes such as infection, hematoma or surgical revision, and length of stay in hospital were also recorded.

RESULTS

Twenty nine patients among which 8 PCIM were included. CTN occurrence rate after PCIM (25%) was quite lower than CTN rate without PCIM (71,4%), although the difference was not significant (P=0,088). Other postoperative complications rates were not significantly different with or without PCIM.

CONCLUSION

PCIM seems to improve CTN occurrence after DIEP breast reconstruction, improving fat flap tolerance to ischemic perioperative lesions. Those preliminary results need to be confirmed with clinical prospective study.

High-pressure infusion improves multi-territory perforator flap viability via choke artery dilation: A preliminary study in a rat model

BACKGROUND

Multi-territory perforator flaps have become the preferred option for the repair and reconstruction of large soft tissue defects. Although methods (e.g., pharmacological agents, mechanical stimulation, and thermal stimulation) were developed to open choke vessels to improve flap survival, the flap necrosis rate is still as high as 28.8%. The authors hypothesized that high-pressure infusion might enhance flap viability by dilating choke arteries intraoperatively in a rat model of multi-territory perforator flap.

METHODS

Two-month-old male Sprague-Dawley rats were randomized into two groups (n = 32 each). During the multi-territory perforator flap elevation based on the right superficial epigastric angiosome, one group received continuous high-pressure infusion (mean pressure, 250 mmHg; duration, 1 min) of an isotonic heparin sodium solution (12,500 U/L) via the artery in the pedicle, whereas the other group received no infusion. At 7 days postoperatively, arteriography was performed; endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF) expression and microvascular density were evaluated by western blot and histology, respectively; and flap survival was compared. Moreover, intraluminal diameters were examined at 1 day and 7 days postoperatively using hematoxylin and eosin staining, and coagulation function was assessed immediately postoperatively.

RESULTS

High-pressure infusion significantly promoted the dilation of choke arteries at 1 day and 7 days postoperatively. It also increased eNOS and VEGF expression, flap survival, and microvascular density. The coagulation function remained unaffected.

CONCLUSIONS

High-pressure infusion allowed intraoperative and postoperative dilation of the choke arteries that enhanced the viability of multi-territory perforator flaps in rats.

Determination of Flap Survival Isolated From Wound Bed Vasculature Using a Murine Axial Flap Model

Background: Axial pattern flaps are a common reconstructive option following resection of soft tissue malignancies. We determine the early dependence of an axial flap on wound bed vasculature by isolating the underlying wound bed and depriving contact with the overlying flap. Materials and Methods: Mice were divided into 5 groups: No silicone (n = 7), silicone in the proximal 50% of the wound bed (n = 8), silicone in the distal 50% of the wound bed (n = 5), silicone over the full length of the wound bed with pedicle preservation (n = 5), and silicone over the full length of the wound bed with pedicle sacrifice (n = 5). The pedicle was the lateral thoracic artery. Daily photographs were taken, and the percent of viable flap was determined using ImageJ© software (public domain JAVA image processing program, National Institute of Health, Bethesda, MA). Percent flap viability for each group was compared to the no silicone group, which acted as the reference. Results: Mean differences in percent flap necrotic area (with 95% confidence interval) compared to the no silicone group were -0.15% (-15.09 to 14.09), 2.07% (-5.26 to 9.39), 2.98% (-10.98 to 16.94), and 14.21% (0.48 to 27.94) for the full-length silicone with preserved pedicle, proximal silicone, distal silicone, and full-length silicone with sacrificed pedicle groups, respectively. The full-length silicone with sacrificed pedicle group had a significant difference in flap viability (P = .045) compared to the no silicone group. Conclusion: We investigate the role of the wound bed vasculature in a murine axial flap model and demonstrate that the wound bed vasculature is not essential for early distal flap survival.

Applied Usage and Tips of High Stretch Fixation NPWTi-d for Sternal Osteomyelitis

Sternal osteomyelitis is a rare but devastating complication of median sternotomy. To achieve good outcomes, it should be diagnosed early and treated appropriately. Standard treatment involves antibiotics, debridement, and reconstruction with flaps. To prevent flap complications and recurrence, the wound bed must be prepared carefully. One approach, a recent development, is negative pressure wound therapy with instillation and dwell time (NPWTi-d), where suction cycles are interspersed with wound instillation with solutions. NPWTi-d is currently cautioned against for large trunk wounds and cavities because it might alter core body temperature. Here, we report a new NPWTi-d dressing technique that is associated with successful reconstruction in two severe sternal osteomyelitis cases with wound sizes of 29 × 10 and 28 × 8 cm. This "delay-dressing technique" involves manually pulling the wound edges together; inserting a thin strip of dressing foam; applying dressing film strips from one side of the chest wall to the other, thus placing strong stretching tension on the normal skin around the wound; and then applying NPWTi-d. In our cases, we used the V.A.C. Ulta system for 20 and 17 days. The successful reconstruction in both cases may reflect good wound bed preparation and flap preconditioning due to the mechanical stress imposed by NPWTi-d. Thus, this dressing technique with the V.A.C. Ulta system may be an effective treatment option for sternal osteomyelitis cases.

Negative-Pressure Wound Therapy: What We Know and What We Need to Know

Negative-pressure wound therapy (NPWT) promotes wound healing by applying negative pressure to the wound surface. A quarter of a century after its introduction, NPWT has been used in various clinical conditions, although molecular biological evidence is insufficient due to delay in basic research. Here, we have summarized the history of NPWT, its mechanism of action, what is currently known about it, and what is expected to be known in the future. Particularly, attention has shifted from the four main mechanisms of NPWT to the accompanying secondary effects, such as effects on various cells, bacteria, and surgical wounds. This chapter will help the reader to understand the current status and shortcomings of NPWT-related research, which could aid in the development of basic research and, eventually, clinical use with stronger scientific evidence.

An Innovative and Economical Device for Ischemic Preconditioning of the Forehead Flap Prior to Pedicle Division: A Comparative Study

BACKGROUND

 Ischemic preconditioning of the forehead flap prior to pedicle division helps to improve angiogenesis. Clamping the pedicle by a clamped rubber band with vessel forceps is often clinically applied. However, the severe pain and unstable blocking effect influenced the preconditioning process. In this study, we described an innovative device designed for ischemic preconditioning and compared its efficacy with the clamped rubber band.

METHODS

 The device consists of a self-locking nylon cable tie with a buckle and a rubber tube. The rubber tube is fed over the cable tie to act as a soft outer lining and the cable tie is tightened across the pedicle to block the perfusion for ischemic preconditioning. This device and the standard clamped rubber band were applied respectively before division surgery. The constriction effect, reliability, reproducibility, and the patients' pain tolerance were compared.

RESULTS

 A total of 20 forehead flaps were included. The cable tie had less incidence of loosening (7.7% vs. 16.6%, p < 0.05) and maintained the pressure more effectively. The pain score for the nylon cable tie was significantly lower than the clamped rubber band (4.25 ± 1.02 vs. 6.75 ± 1.12, p < 0.05), especially for 10 pediatric patients (4.50 ± 0.85 vs. 8.10 ± 1.20, p < 0.01). All 20 pedicles were successfully divided at 19 to 22 days with no surgical complications.

CONCLUSION

 Compared with the clamped rubber band, the cable tie produces a more reliable and reproducible ischemic preconditioning effect. It is also better tolerated by the patients. Therefore, we recommend using the nylon cable tie as the preferred device for ischemic preconditioning of the forehead flap.

[Research progress of external volume expansion assisted autologous fat grafting for breast reconstruction]

OBJECTIVE

To review the application progress, mechanism, application points, limitations, and oncological safety of external volume expansion (EVE) assisted autologous fat grafting for breast reconstruction and provide a reference for optimizing the design of EVE.

METHODS

Based on the latest relevant articles, the basic experiments and clinical applications of EVE were summarized.

RESULTS

EVE can reduce interstitial fluid pressure, increase blood supply, and promote adipogenic differentiation, thereby benefiting the survival of transplanted fat. EVE assisted autologous fat grafting in clinical practice can improve the retention rate of breast volume and the outcome of breast reconstruction, meanwhile it doesn't increase the risk of local recurrence. But there is no standard parameters for application, and there are many complications and limitations.

CONCLUSION

EVE improves the survival of transplanted fat, but its complications and poor compliance are obvious, so it is urgent to further investigate customized products for breast reconstruction after breast cancer and establish relevant application guidelines.

Early Experience with External Negative Pressure Delay in Free Anterolateral Thigh Perforator Flap Reconstruction

Negative pressure therapy has been utilized in the treatment of open and closed wounds to increase blood flow and improve wound healing. More recently, external negative pressure has been shown to induce a noninvasive delay phenomenon in animal models by increasing vessel size and density within a planned flap, leading to improvement in flap survival. Although successful in animal models, this new method of delay has not been demonstrated in clinical practice. We present our initial experience with preoperative external negative pressure delay of free anterolateral thigh flaps in upper extremity reconstruction to detail the technique and safety profile of this innovative new technique. External negative pressure delay has the potential to provide results similar to those of traditional surgical delay, while being cost effective, safer, and more convenient for patients. More research is needed to investigate the clinical benefit and cost effectiveness of external negative pressure delay.

Distal Arterialized Venous Supercharging Improves Perfusion and Survival in an Extended Dorsal Three-Perforasome Perforator Flap Rat Model

BACKGROUND

Perforator flaps are commonly applied for a variety of skin defects. Many strategies (e.g., hyperbaric oxygen and preconditioning) have been investigated to improve flap survival, but a postoperative 2.03 to 18.2 percent flap necrosis frequency remains a major complication. The authors hypothesized that a distal arterialized venous supercharged (DAVS) flap procedure might improve perfusion and survival in an extended three-perforasome perforator flap rat model and rescue flap ischemia intraoperatively.

METHODS

One hundred twenty male Sprague-Dawley rats (200 to 300 g) were divided into the thoracodorsal artery (TDA) flap group and the DAVS flap group (n = 60 per group). An approximately 11 × 2.5-cm2 flap based on the TDA perforasome was designed in the TDA flap. A DAVS flap was designed based on the TDA flap and supercharged by anastomosing the rat caudal artery with the deep circumflex iliac vein. At postoperative times 1, 3, 6, and 12 hours and 1, 3, 5, and 7 days, perfusion and angiography were compared. On day 7, flap viability and angiogenesis were assessed using histology and Western blotting.

RESULTS

The DAVS flap showed a higher survival rate compared with the TDA flap (100 percent versus 81.93 ± 5.38 percent; p < 0.001). All blood flow ratios of deep circumflex iliac artery to TDA perforasome and of choke zone II to choke zone I were higher in the DAVS flap (all p < 0.05). Angiography qualitatively revealed that choke vessels in choke zone II dilated earlier and extensively in the DAVS flap group. CD34+ vessels (68.66 ± 12.53/mm2 versus 36.82 ± 8.99/mm2; p < 0.001) and vascular endothelial growth factor protein level (0.22 ± 0.03 versus 0.11 ± 0.03; p < 0.001) were significantly increased in the DAVS flap group.

CONCLUSIONS

The DAVS procedure improves three-perforasome perforator flap survival and can be used for rescuing flap ischemia intraoperatively. Further study is needed before possible clinical adoption for reconstructive operations.

Preconditioning with Foam-mediated External Suction on Flap Microvasculature and Perfusion in a Rodent Model

Foam-mediated external suction (FMES) has previously shown to improve tissue microcirculation. We hypothesized that preconditioning fasciocutaneous perforator flaps with FMES would augment perfusion and demonstrate greater capillary recruitment.

Larger free flap size is associated with increased complications in lower extremity trauma reconstruction

BACKGROUND

Free flap reconstruction after lower extremity trauma remains challenging with various factors affecting overall success. Increasing defect and flap size have been demonstrated to be a surrogate for overall injury severity and correlated with complications. In addition, larger free flaps that encompass more tissue theoretically possess high metabolic demand, and may be more susceptible to ischemic insult. Therefore, the purpose of our study was to determine how flap size affects microsurgical outcomes in the setting of lower extremity trauma reconstruction.

METHODS

Retrospective review of 806 lower extremity free flap reconstructions performed from 1979 to 2016 among three affiliated hospitals: a private university hospital, Veterans Health Administration Hospital (VA), and a large, public hospital serving as a level 1 trauma center for the city. Soft tissue free flaps used for below the knee reconstructions of traumatic injuries were included. A receiver operating curve (ROC) was generated and Youden index was used to determine the optimal flap size for predicting flap success. Based on this, flaps were divided into those smaller than 250 cm² and larger than 250 cm² . Partial flap failure, total flap failure, takebacks, and overall major complications (defined as events involving flap compromise) were compared between these two groups. Multivariate logistic regression was performed to determine whether flap size independently predicts complications and flap failures, controlling for injury-related and operative factors.

RESULTS

A total of 393 patients underwent lower extremity free tissue transfer. There were 229 flaps (58.2%) with size <250 cm² and 164 flaps (41.7%) ≥ 250 cm² . ROC analysis and Youden index calculation demonstrated 250 cm² (AUC 0.651) to be the cutoff free flap for predicting increasing flap failure. Compared to flaps with less than 250 cm² , larger flaps were associated with increased major complications (33.6% vs. 50.0%, p = .001), any flap failure (11.8% vs. 25.0%, p = .001) and partial flap failure (4.8% vs. 14.6%, p = .001). Logistic regression analysis controlling for age, flap type, era of reconstruction, number of venous anastomoses, presence of associated injuries, presence of a bone gap, vessel runoff, and flap size identified increasing flap size to be independently predictive of major complications (p = .05), any flap failure (p = .001), partial flap failure (p < .001), and takebacks (p = .03). Subset analysis by flap type demonstrated that when flap size exceeded 250 cm² , use of muscle flaps was associated with significantly increased flap failure rates (p = .008) while for smaller flap size, there was no significant difference in complications between muscle and fasciocutaneous flaps.

CONCLUSION

Increasing flap size is independently predictive of flap complications. In particular, a flap size cutoff value of 250 cm² was associated with significantly increased flap failure and complications particularly among muscle-based flaps. Therefore, we suggest that fasciocutaneous flaps be utilized for injuries requiring large surface area of soft tissue reconstruction.

Tissue-Engineered Soft-Tissue Reconstruction Using Noninvasive Mechanical Preconditioning and a Shelf-Ready Allograft Adipose Matrix

BACKGROUND

Adipose tissue defects leading to severe functional (disability) and morphologic (disfigurement) morbidity are often treated in plastic surgery with fat grafting, which can be limited by resorption, necrosis, and cyst formation. This study aimed to assess whether adipose scaffolds could provide an environment for in situ autologous fat grafting, and to study whether adipose cell migration and proliferation (adipogenesis) within scaffolds could be enhanced by preliminarily increasing the vascularity (preconditioning) of the surrounding tissue receiving the scaffolds.

METHODS

Using an established rodent model of subcutaneous tissue/scaffold grafting, the authors tested the potential of a human-derived, shelf-ready, injectable, decellularized allograft adipose matrix to reconstruct soft-tissue defects when used in combination with noninvasive mechanical (suction-induced) skin preconditioning.

RESULTS

Combined use of the allograft adipose matrix and noninvasive skin preconditioning significantly improved long-term volume retention (50 to 80 percent higher at a 12-week follow-up) and histologic quality of reconstructed tissues compared with standard of care (autologous adipose grafts). The components of the allograft adipose matrix supported adipogenesis and angiogenesis. Combining the allograft adipose matrix with living adipose grafts mitigated negative outcomes (lower long-term volume retention, higher presence of cystic-like areas).

CONCLUSIONS

This study suggests that the synergistic use of the allograft adipose matrix and noninvasive tissue preconditioning provides an effective solution for improving fat grafting. These strategies can easily be tested in clinical trials and could establish the basis for a novel therapeutic paradigm in reconstructive surgery.

Efficacy of an external volume expansion device and autologous fat grafting for breast reconstruction following breast conserving surgery and total mastectomy: Small improvements in quality of life found in a prospective cohort study

BACKGROUND

Although autologous fat grafting (AFG) for breast reconstruction is feasible, the best methods have yet to be established. This study aimed to assess the efficacy of fat grafting using an external expansion device for complete breast reconstruction post breast cancer surgery hypothesizing that it would improve quality of life.

METHODS

A prospective cohort study was conducted in women who had undergone breast cancer surgery and complete reconstruction using AFG. An external expansion device was used previously (as per Miami protocol) to a single-stage AFG. Quality of life outcomes were determined using the validated BREAST-Q questionnaire, and 3D laser and magnetic resonance imaging scan were used to measure fat graft retention.

RESULTS

Twenty-six participants were recruited, with seven withdrawing. The remaining 19 women were compliant with external expander use. The mean volume of AFG was 270.4 mL (98-490 mL) with a mean of 48.8% retained at 12 months following injection. Symmetry improved but did not meet the acceptable symmetry ratio of 0.8. Nine patients (47.3%) noted increased skin elasticity and softening of areas of scarring. Skin irritation occurred in 11 out of 19 patients. Mean BREAST-Q scores improved significantly in the domains of satisfaction with breast (40 vs. 49, p < 0.001), psychosocial well-being (55 vs. 68, p < 0.001), physical well-being abdomen (73 vs. 87, p < 0.001), and sexual well-being (41 vs, 48, p < 0.001).

CONCLUSION

Improved quality of life and breast volume increase were achieved following external expansion and AFG. However, breast fat engraftment retention was similar to that reported in previous studies using fat grafting alone.

Allogenic endothelial progenitor cell transplantation increases flap survival through an upregulation of eNOs and VEGF on venous flap survival in rabbits

BACKGROUND

Endothelial progenitor cells (EPCs) are one type of bone marrow hematopoietic stromal cells which play a vital role in neovascularization and tissue repair. In this study, we investigated whether EPCs promote flap survival in a rabbit venous model.

MATERIALS AND METHODS

EPCs were customized from CHI Scientific, Inc, China. Thirty-six rabbits were randomly assigned to either the sham group (n = 12), the control group (n = 12) or the EPC transplantation group (n = 12). A 10 × 6 cm venous flap was created on the rabbit abdomen. Both the EPC transplantation and control groups had the same volume of EPCs-PBS (phosphate buffered saline) and PBS on postoperative day 1. Flap survival, blood flow, histopathology, expression of endothelial nitric oxide synthase (eNOs) and Vascular Endothelial Growth Factor (VEGF) were detected on postoperative day 10.

RESULTS

Cellular immunofluorescence assay positively confirmed that the EPCs were undergoing differentiation. The survival rate of the flap in the EPC transplantation group was 58.4 ± 7.1%, which was significantly higher than that of the control group (4.8 ± 3.4%) (p<0.01). Histological examination revealed that the EPC transplantation group had higher microvessel density, fewer inflammatory cells, and a higher expression of eNOs and VEGF. Significantly increased blood flow perfusion was seen in the EPC transplantation group using laser Doppler imaging. The Western Blot technique revealed that the expression of eNOs and VEGF in the EPC transplantation group were both significantly higher than those in the control group.

CONCLUSION

This study demonstrated that EPC transplantation improved venous flap survival in rabbits. The present findings may provide insight into the promotion of venous flap survival in clinical practice in the future.