The Application of a Synthetic Biodegradable Temporizing Matrix in Extensive Burn Injury: A Unicenter Experience of 175 Cases.

Objectives: Addressing extensive and deep burn wounds poses considerable challenges for both patients and surgeons. The NovoSorb® Biodegradable Temporizing Matrix (BTM) emerged as a novel dermal substitute and has been subjected to evaluation in large burn wound cases, with a specific focus on identifying risk factors associated with suboptimal take rates. Methods: All patients with burn wounds greater than 10% body surface that underwent BTM treatment between March 2020 and November 2023 were eligible for inclusion. Univariate analyses and linear regression models were employed to discern risk factors and predictors influencing the take rates of both the BTM and split-thickness skin grafts (STSGs). Results: A total of 175 patients (mean age 56.2 ± 19.8 years, 70.3% male) were evaluated. The mean take rates of the BTM and STSGs were 82.0 ± 24.7% and 87.3 ± 19.0%, respectively. There were significant negative correlations between BTM take and the number of surgeries before BTM application (r = -0.19, p = 0.01), %TBSA and STSG take (r = -0.36, p = <0.001) and significant positive correlations between BTM and STSG take (r = 0.41, p ≤ 0.001) in addition to NPWT and STSG take (r = 0.21, p = 0.01). Multivariate regression analyses showed that a larger number of surgeries prior to BTM application (OR -3.41, 95% CI -6.82, -0.03, p = 0.04) was associated with poorer BTM take. Allograft treatment before BTM application (OR -14.7, 95% CI -23.0, -6.43,p = 0.01) and failed treatment with STSG before BTM application (OR -20.8, 95% CI -36.3, -5.23, p ≤ 0.01) were associated with poorer STSG take, whereas higher BTM take rates were associated with overall higher STSG take (OR -0.15, 95% 0.05, 0.26, p = 0.01). The Meek technique was used in 24 patients and showed similar take rates (BTM: 76.3 ± 28.0%, p = 0.22; STSG: 80.7 ± 21.1, p = 0.07). Conclusions: This study summarizes our findings on the application of a BTM in the context of large burn wounds. The results demonstrate that successful treatment can be achieved even in patients with extensive burns, resulting in satisfying take rates for both the BTM and STSG. The data underscore the importance of promptly applying a BTM to debrided wounds and indicate good results when using Meek.

Gynecomastia Surgery in 4996 Male Patients Over 14 Years: A Retrospective Analysis of Surgical Trends, Predictive Risk Factors, and Short-Term Outcomes.

BACKGROUND: The high prevalence of benign male breast tissue enlargement (gynecomastia) has resulted in a marked increase of gynecomastia cases. While about one third of male adults experience some form of gynecomastia, gynecomastia surgery (GS) outcome research is limited to small study populations and single-center/-surgeon databases. In this study, we aimed to access the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database to identify preoperative risk factors for complications and investigate postoperative outcomes of GS. METHODS: In this retrospective study, we queried the ACS-NSQIP database from 2008 to 2021 to identify male adult patients who underwent GS. Postoperative outcomes involved the occurrence of any, surgical and medical complications, as well as reoperation, readmission, and mortality within a 30-day postoperative time period. Univariable and multivariable assessment were performed to identify risk factors for complications while adjusting for possible confounders. RESULTS: The study included 4,996 GS patients with a mean age of 33.7 ± 15 years and BMI of 28.2 ± 5.1 kg/m2. White patients constituted 54% (n = 2713) of the cohort, and 27% (n = 1346) were obese. Except for 2020, there was a steady increase in GS cases over the study period. Outpatient surgeries were most common at 95% (n = 4730), while general surgeons performed the majority of GS (n = 3580; 72%). Postoperatively, 91% (n = 4538) of patients were discharged home; 4.4% (n = 222) experienced any complications. Multivariable analysis identified inpatient setting (p < 0.001), BMI (p = 0.023), prior sepsis (p = 0.018), and bleeding disorders (p = 0.047) as independent risk factors for complications. CONCLUSION: In this study, we analyzed 4996 male adult GS patients from the ACS-NSQIP database, revealing an increased caseload and significant general surgeon involvement. Risk factors like bleeding disorders, inpatient status, and prior sepsis were linked to postoperative complications, while BMI was crucial for predicting adverse events. Overall, our findings may aid in enhancing patient care through advanced preoperative screening and closer perioperative management. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

NovoSorb® Biodegradable Temporising Matrix (BTM): What we learned from the first 300 consecutive cases.

INTRODUCTION: Extensive full-thickness soft-tissue defects remain a challenge in reconstructive surgery. NovoSorb® Biodegradable Temporising Matrix (BTM) represents a novel dermal substitute and was evaluated in wounds deriving from different aetiologies and to highlight risk factors for poor take rates. METHODS: All patients treated with BTM at our department between March 2020 and October 2022 were included. Differences in univariate and linear regression models identified predictors and risk factors for take rates of BTM and split-thickness skin grafts (STSG). RESULTS: Three hundred patients (mean age 54.2 ± 20.1 years, 66.3% male, 59.7% burns, 19.7% trauma and 20.6% others) were evaluated. Mean take rates of BTM and STSG after BTM delamination were 82.7 ± 25.2% and 86.0 ± 22.6%, respectively. Multiple regression analyses showed that higher body mass index (BMI, OR 0.43, 95% CI 0.86, -0.01, p = 0.44), prior allograft transplantation (OR 15.12, 95% CI 26.98, -3.31, p = 0.041), longer trauma-to-BTM-application intervals (OR 0.01, 95% CI 0.001, -0.001, p = 0.038), positive wound swabs before BTM (OR 7.15, 95% CI 13.50, -0.80, p = 0.028) and peripheral artery disease (OR 10.80, 95% CI 18.63, -2.96, p = 0.007) were associated with poorer BTM take. Higher BMI (OR 0.40, 95% CI 0.76, -0.08, p = 0.026), increasing BTM graft surface areas (OR 0.58, 95% CI -1.00, -0.17, p = 0.005), prior allograft (OR 12.20, 95% CI -21.99, -2.41, p = 0.015) or autograft transplantations (OR 22.42, 95% CI 38.69, -6.14, p = 0.001), tumour as the aetiology of the wound (OR 37.42, 95% CI 57.41, -17.83, p = 0.001), diabetes (OR 6.64, 95% CI 12.80, -0.48, p = 0.035) and impaired kidney function (OR 5.90, 95% CI 10.94, -0.86, p = 0.021) were associated with poorer STSG take after delamination of BTM, whereas higher BTM take rates were associated with better STSG take (OR 0.40, 95% CI 0.31,0.50, p < 0.001). CONCLUSION: Extensive complex wounds of different aetiologies unsuitable for immediate STSG can be successfully reconstructed by means of two-staged BTM application and subsequent skin grafting. Importantly, presence of wound contamination or infection and prior allograft coverage appear to jeopardise good BTM and STSG take.

[Robot-assisted Microsurgery in Lower Extremity Reconstruction]. / Roboter-assistierte Mikrochirurgie in der Rekonstruktion der unteren Extremität.

BACKGROUND: In recent years, various robotic systems specifically designed for microsurgical tasks have been developed and approved. There is not much evidence for these systems to date. In our study, we examined the use of robot-assisted microsurgery in the reconstruction of the lower extremity. PATIENTS/MATERIAL AND METHODS: Data was prospectively collected between February and November 2023. The Symani robotic system was used in 42 robot-assisted microsurgical procedures on the lower extremity, and the results were evaluated and documented. RESULTS: The average age of the patients was 57±18 years. A total of 39 free flap reconstructions (95%), one lymphatic surgical procedure (3%) and two nerve transfers (5%) were performed. In total, 46 anastomoses and coaptations were carried out. This included six arterial end-to-end anastomoses (11%), seven arterial end-to-side anastomoses (13%), 36 venous end-to-end anastomoses (65%), two lymphovenous anastomoses (4%), and five epineural coaptations in the context of nerve transfers (9%). Arterial end-to-end anastomoses took an average of 26±12 minutes, and arterial end-to-side anastomoses took 42±21 minutes. The venous anastomoses took an average of 33±12 minutes. Epineural coaptations took an average of 24±13 minutes. In no procedure was there a need for a conversion to conventional hand suturing. There were two arterial thromboses (5%), one of which was successfully revised to save the flap. One total flap loss occurred, but there were no partial flap losses. CONCLUSION: Using the Symani robotic system for microsurgical reconstruction of the lower extremity, we were able to demonstrate results that are comparable to conventional microsurgery.

Using a Microsurgical Robotic Platform for In-flap Anastomosis in Autologous Bipedicular Breast Reconstruction.

Autologous microsurgical breast reconstruction has become a standard of care. As techniques become more individualized and aim for less-invasive approaches, vessels ever smaller in diameter are considered for flap anastomosis. Robot-assisted surgery has great potential to reduce tremor and enhance precise motion. The Symani Surgical System (Medical Microinstruments, Inc., Wilmington, Del.) is a robotic platform designed for microsurgery. It was used for a microsurgical in-flap anastomosis of a bipedicular deep inferior epigastric artery flap for unilateral breast reconstruction. The procedure included fully robot-assisted anastomoses with significant size mismatches using a 3D-exoscope for magnification. Arterial and venous anastomoses were entirely robot-assisted completed in 23 minutes (seven stitches) and 28 minutes (eight stitches) using 9/0 nylon sutures. The intra- and postoperative course was uneventful. This robotic platform facilitates in-flap anastomoses of small vessels by increasing the precision of instrument handling and eliminating tremor. The combination of robotic platforms and exoscopes provides superior ergonomics in comparison with conventional (super)microsurgery. We expect robotic platforms to play a significant role in modern microsurgical breast reconstruction.

The transverse myocutaneous gracilis flap (TMG) for breast reconstruction: ipsi vs. contralateral harvest-aesthetic outcome and refinement procedures.

BACKGROUND: The TMG flap is a popular choice for breast reconstruction. However, it remains unclear whether the side of flap harvest, subsequent flap shaping and inset impacts breast appearance and volume dispersion. This study compares the aesthetic outcome of the reconstructed breast following TMG flap harvest from the ipsilateral or contralateral thigh. PATIENT AND METHODS: A retrospective matched-pair multi-center study was conducted. Patients were grouped according to the side of flap harvest (ipsilateral vs. contralateral) and matched for age, BMI and mastectomy type. Between 01/2013 and 03/2020, 384 TMG breast reconstructions were performed, of which 86 were included (43 ipsilateral vs. 43 contralateral). Standardized pre- and postoperative photographs were evaluated using a modified assessment scale comprising of a symmetry score (SymS, max. 20 points), a volume discrepancy score (VDS, max. 8 points) and an aesthetic appearance score (AS, max. 10 points). Autologous fat grafting (AFG) procedures for breast refinement were compared. RESULTS: Pleasing breast symmetry (SymS Ipsi: 14.5/20; Contra: 14.9/20), volume (VDS Ipsi: 3.3/8; Contra: 2.4/8) and aesthetic appearance (AS Ipsi: 6.7/10; Contra: 6.7/10) were achieved with both surgical methods. No significant changes were present regarding the VDS (F(1.82) = 2.848, p = 0.095) or the SymS (F(1.82) = 1.031, p = 0.313) pre- to postoperatively. Significantly more autologous fat grafting was done in the contralateral group (p < 0.001). CONCLUSION: The side of the TMG flap harvest, different shaping and inset techniques do not impact the aesthetic breast outcome. Both surgical methods result in pleasing breast symmetry and volume. Secondary procedures are common and should be entailed in the reconstructive strategy.

Reconstruction of Hand and Foot Defects with Free Serratus Carpaccio Flap and Free Serratus Fascia Flap: A Comparative Retrospective Study of Surgical Outcomes.

BACKGROUND: Defects of the hand and foot often require an individualized reconstructive approach, due to their unique functional and aesthetic characteristics. Transferred tissues should be thin, pliable, and durable, with free fascial flaps meeting these requirements. This study aimed to evaluate the serratus fascia flap and the serratus carpaccio flap, which is a modification of the fascia flap, by including a thin muscle layer, with the goal of enhancing flap resilience and lowering morbidity rates. METHODS: Between January 2000 and December 2017, 31 patients underwent microsurgical reconstruction of the hand or foot either by serratus fascia flap (fascia group) or serratus carpaccio flap (carpaccio group). The serratus fascia flaps were mainly harvested between 2000 and 2012, and the serratus carpaccio flaps between 2013 and 2017. Patient records were reviewed retrospectively, regarding demographics, complications, overall flap survival, additional revision surgeries, and surgical outcome. Categorical variables were compared using Fisher's exact test and continuous data with the Mann-Whitney tests. Logistic regression was used to examine the correlation between comorbidities and postoperative complication rates. Differences were considered significant when p < 0.05. RESULTS: The fascia group consisted of 17 patients and the carpaccio group of 14 patients. The average patient age in the fascia group was 39.2 ± 10.5 years, and it was 39.1 ± 14.7 years in the carpaccio group. Overall complication rates were significantly lower in the carpaccio group than in the fascia group (28.6% vs. 70.6%, p = 0.03). The rates of overall flap survival (85.7% in the carpaccio group vs. 74.5% in the fascia group, p = 0.66) and partial flap loss (14.3% in the carpaccio group vs. 47.1% in the fascia group, p = 0.07) did not differ significantly among both groups. One postoperative hematoma of the donor site requiring revision surgery was reported in the carpaccio group (7.1%, p = 0.45) while no donor-site morbidity was reported in the fascia group. CONCLUSIONS: Our findings indicate that the serratus carpaccio flap presents a promising alternative to the serratus fascia flap. This modification has proven to be effective in substantially reducing postoperative complications requiring additional surgical interventions. Therefore, the serratus carpaccio flap can be considered a dependable reconstructive option for addressing complex soft tissue defects of the hand and foot, with complication rates that are within an acceptable range.

Scalp Reconstruction Using the Latissimus Dorsi Free Flap: A 12-Year Experience.

BACKGROUND: Complex scalp defects are regularly reconstructed using microvascular tissue transfer. The latissimus dorsi free flap is one of the workhorse flaps used in scalp reconstruction. These cases necessitate, particularly in the elderly, a close cooperation between plastic surgeons and neurosurgeons. The purpose of this study was to evaluate the suitability of the latissimus dorsi free flap for complex scalp reconstructions and to analyze potential risk factors. METHODS: A retrospective study identified 43 patients undergoing complex scalp reconstruction using a latissimus dorsi free flap at our department between 2010 and 2022. RESULTS: The mean patient age was 61 ± 18 years. Defects were mostly caused by oncologic tumor resections (n = 23; 55%), exposure to a cranioplasty (n = 10; 23%) or infection (n = 4; 9%). The most frequent recipient vessels were the superficial temporal artery (n = 28; 65%), external carotid artery (n = 12; 28%) and the venae comitantes (n = 28; 65%), external jugular vein (n = 6; 14%). The reconstructive success rate was 97.7%. There was one total flap loss (2%). Partial flap loss occurred in five cases (12%). Follow-up was 8 ± 12 months. Major complications were seen in 13 cases, resulting in a revision rate of 26%. Multivariate logistic regression identified active tobacco use as the only risk factor for major complications (odds ratio 8.9; p = 0.04). CONCLUSION: Reconstruction of complex scalp defects using the latissimus dorsi free flap yielded high success rates. Among the potential risk factors, active tobacco use seems to affect the outcome of complex scalp reconstructions.

Development of a mathematical formula and online tool to calculate the potential maximum flap width to allow for primary anterolateral thigh donor-site closure in Caucasians.

BACKGROUND: Primary anterolateral thigh (ALT) flap donor-site closure is crucial to achieve patient satisfaction, avoid burdensome secondary surgeries, and avert poor outcomes. Only vague maximum flap width recommendations have been suggested, which fall short of acknowledging individual patient habitus and thigh morphology. Therefore, we aimed at identifying a user-friendly preoperative calculation of maximum flap width for primary closure. METHODS: A total of 429 ALT free flaps performed between 2009 and 2020 were analyzed. A total of 350 donor-sites were closed primarily (82%) and 79 (18%) were split-thickness skin-grafted (STSG). Patient demographics including sex, age, and BMI, operative details, and flap characteristics were compared to assess their impact on the outcome variable. Receiver operating characteristic (ROC) curves were plotted for all significant predictors discriminating between closure and STSG. Areas under the curve (AUCs) were calculated for each parameter combination and optimal cutoffs were determined using Youden's Index. RESULTS: Sex, age, BMI, and flap width alone were poor discriminators. Dividing flap width by BMI and logarithmized BMI yielded AUCs of 0.91 and 0.94, respectively. Including patient sex yielded the best fitting regression model (χ2  = 251.939, p < .0001) increasing the AUC to 0.96 (95% CI: 0.93-0.98, p < .0001). The optimal cutoff value discriminated between primary closure and STSG with 90% sensitivity and 89% specificity. An online calculator of patient-individual maximum ALT width was then programmed. CONCLUSIONS: Sex and BMI are reliable predictors of successful primary ALT donor-site closure in Caucasians. We devised a novel formula for calculating patient-individual maximum ALT widths preoperatively, predicting failure of primary closure with 90% sensitivity in our cohort, available at: https://kitteltaschenbuch.com/altwidth/calculate.htm.

Identification of Independent Risk Factors for Skin Complications in a Multifactorial Logistic Regression Analysis of Simultaneous Immediate Autologous Breast Reconstruction and Skin Reduction Mastectomy in Large and Ptotic Breasts Using an Inferiorly Based Deepithelialized Dermal Breast Flap.

Autologous immediate breast reconstruction in large and ptotic breasts remains challenging. We aimed to identify independent risk factors for impaired wound healing and nipple necrosis after skin reducing wise pattern mastectomy in autologous reconstruction with an auxiliary deepithelialized inferiorly based dermal flap (IBDF). METHODS: This retrospective study examined patients with wise pattern mastectomy with autologous immediate breast reconstruction (IBR) between 2017 and 2019. All cases of large and ptotic breasts were included. Demographic, oncologic, reconstructive, and surgical data were compiled, and multifactorial binary logistic regression models identified independent predictors for skin complications and nipple areolar complex (NAC) necrosis. RESULTS: Of 591 autologous breast reconstructions, 62 (11%) met the inclusion criteria. Overall wound complication rate was 32% (n = 20, DIEP 11, thigh 9, p = 0.99), including 26% minor (n = 16, non-surgically treated) and 7% major complications (n = 4, surgically treated). Complete NAC necrosis occurred in one case. Nipple sparing mastectomy (NSM) (p = 0.003), high BMI (p = 0.019), longer operation time (p = 0.044) and higher patient age (p = 0.045) were independent risk factors for skin complications. Using internal mammary artery perforators (IMAP) as recipient vessels did not result in increased complication rates (p = 0.59). CONCLUSION: Higher patient age, BMI, and operation time (OT) significantly increase the risk for skin complications in combined reduction wise pattern mastectomies with autologous IBR. In this context, IBDFs help preserve the inframammary fold, providing vasculature to the T-junction and the mastectomy skin flaps. Acceptable complication rates can be achieved in large and ptotic breasts, regardless of preoperative chemotherapy or radiation. Gentle tissue handling with minimal thermal trauma preserves internal mammary artery perforators (IMAPs) as recipient vessels. In cases of flap failure and alloplastic conversion, the IBDF can serve as an autoderm, protecting the implant from exposure.

A Retrospective Comparative Functional and Aesthetic Outcome Study of Muscle versus Cutaneous Free Flaps for Distal Upper Extremity Reconstruction.

BACKGROUND: Function and cosmesis are crucial in upper extremity reconstruction. Yet, there persists a lack of outcome evaluations, particularly regarding differences between free flap types. METHODS: In a single-center retrospective analysis, outcomes were compared between patients with cutaneous or muscle free flaps for distal upper extremity reconstruction between 2008 and 2018. The Disabilities of Arm, Shoulder and Hand -Score, Michigan-Hand (MHQ), and Short Form 36 Health Survey (SF-36) Questionnaires were assessed, motor function was quantified, and self-reported measures of cosmesis were compared, including the Vancouver Scar-Scale (VSS), MHQ aesthetics-subscale (MAS), and Moscona's cosmetic validation-score (CVS). RESULTS: One-hundred forty-one cases were identified, with a shift toward cutaneous flaps over the study period. Muscle flaps were used for larger defects (251 vs. 142 cm2, p = 0.008). Losses, thromboses, and donor-site complications were equally distributed. Partial necroses were more frequent in muscle flaps (11 vs. 1%, p = 0.015). Seventy patients with 53 cutaneous versus 17 muscle flaps were reexamined. There was no difference in the timing of flap coverage (after 16 vs. 15 days, p = 0.79), number of preceding (2 vs. 1.7, p = 0.95), or subsequent operations (19/53 vs. 5/17, p = 0.77). Patients with cutaneous flaps showed higher grip strength (25 vs. 17 kg, p = 0.046) and reported better hand function (MHQ: 58 vs. 47, p = 0.044) and general health (SF-36: 70 vs. 61, p = 0.040), as well as more favorable appearance (MAS: 71 vs. 57, p = 0.044, CVS: 77 vs. 72, p = 0.048), and scar burden (VSS: 0 vs. 3, p < 0.001). CONCLUSION: Cutaneous flaps yielded better motor function, self-perceived cosmesis, patient satisfaction, and quality of life in our cohort of distal upper extremity reconstructions.

Comparison of pedicled versus free flaps for reconstruction of extensive deep sternal wound defects following cardiac surgery: A retrospective study.

BACKGROUND: Myocutaneous pedicled flaps are the method of choice for sternal reconstruction after deep sternal wound infection (DSWI) following cardiac surgery. We set out to investigate whether free flaps provide a superior alternative for particularly extended sternal defects. METHODS: Between October 2008 and February 2020, 86 patients with DSWI underwent sternal reconstruction with myocutaneous flaps at our institution. Patients were retrospectively grouped into pedicled (A; n = 42) and free flaps (B, n = 44). The objective was to compare operative details, outcome variables, surgical as well as medical complication rates between both groups, retrospectively. Binary logistic regression analysis was applied to determine the effect of increasing defect size on flap necrosis. RESULTS: Rates of partial flap necrosis (>5% of the skin island) were significant higher in pedicled flaps (n = 14), when compared to free flaps (n = 4) (OR: 5.0; 33 vs. 9%; p = .008). Increasing defect size was a significant risk factor for the incidence of partial flap necrosis of pedicled flaps (p = .012), resulting in a significant higher rate of additional surgeries (p = .036). Binary regression model revealed that the relative likelihood of pedicled flap necrosis increased by 2.7% with every extra square-centimeter of defect size. CONCLUSION: To avoid an increased risk of partial flap necrosis, free flaps expand the limits of extensive sternal defect reconstruction with encouragingly low complication rates and proved to be a superior alternative to pedicled flaps in selected patients.

An Appraisal of Internal Mammary Artery Perforators as Recipient Vessels in Microvascular Breast Reconstruction-An Analysis of 515 Consecutive Cases.

BACKGROUND: The usage of internal mammary artery perforators (IMAPs) has been described in autologous breast reconstruction although IMAPS are not yet considered standard recipient vessels. It remains unclear if these vessels can be safely used in large flaps after radiation therapy or in delayed breast reconstruction. METHODS: Over a 2-year period, 515 free flaps for autologous breast reconstruction were performed on 419 patients by 2 surgeons (S1 and S2). In a retrospective analysis, time of reconstruction, ischemia time, flap weight, diameter of couplers, and complications were analyzed. All 515 flaps were compared in a subset with regard to the 2 surgeons: S1 who always used the IMA as a recipient vessel and S2 who attempted IMAP use if possible. RESULTS: Of all 515 flaps, 424 were abdominal flaps and 91 flaps were from the upper thigh. Three hundred six cases were immediate reconstructions, and 112 were delayed reconstructions. In 97 cases, implants were converted to autologous tissue. In 112 cases, the IMAPs were used; of these, 82 were immediate and 17 were delayed reconstructions, and in 13 cases, implants were removed. Thirty-five percent of all anastomoses to IMAPs had previous radiation therapy. The flap failure rate was 1.9%. In none of these cases, the IMAPs were used. S1 never used the IMAP, and S2 used the IMAP in 37% of all of his flaps. CONCLUSIONS: IMAPs were safely used in all kinds of reconstructions and after radiation therapy, with no flap failure or negative effects on mastectomy skin flap perfusion. Using the IMAPs as recipient vessels is a further step toward simplifying microsurgical breast reconstruction.

Ischemia/reperfusion injury of porcine limbs after extracorporeal perfusion.

BACKGROUND: Revascularization of amputated extremities after prolonged ischemia is complicated by reperfusion injury. We assessed ischemia/reperfusion (I/R) injury of porcine extremities after prolonged preservation using extracorporeal circulation (ECC). METHODS: Forelimbs of 32 pigs were divided into four groups based on ischemia times: group I: 6 h, group II: 12 h, group III: 0 h plus replantation, and group IV: 6 h plus replantation. Limbs were perfused with autologous blood using ECC for 12 h except group II with only 5 h perfusion. Limbs from groups III and IV were heterotopically replanted with a 7-d follow-up. Contralateral limbs served as controls in all groups. Tissue, plasma, and serum were analyzed for the extent of I/R injury. RESULTS: No significant differences in tissue wet/dry ratios were found within or between groups. This finding was confirmed by histology, except for an increased damage in group IV muscles compared with baseline (P = 0.016). Complement C3 deposition was only increased in group IV muscle (P = 0.031), group II nerves (P = 0.046), and group II vessels (P = 0.037). Group IV muscle and nerve tissues were the only ones with significant IgM antibody deposition (P = 0.031) at end of perfusion. Values were normal again after replantation. Reduced complement activity and elevated IL-6, IL-8, MCP-1, VEGF, PDGF-bb, bFGF, and complement split products were found during perfusion but were normal again after replantation. Staining for heparin sulfate proteoglycans and von Willebrand factor confirmed minimal activation of endothelial cells. CONCLUSION: The results demonstrate that prolonged limb preservation using ECC has minimal impact on I/R-induced tissue injury. Extracorporeal perfusion is a potential limb-preserving technique encouraging further studies for use in limb revascularization.

Solder doped polycaprolactone scaffold enables reproducible laser tissue soldering.

BACKGROUND AND OBJECTIVES: In this in vitro feasibility study we analyzed tissue fusion using bovine serum albumin (BSA) and Indocyanine green (ICG) doped polycaprolactone (PCL) scaffolds in combination with a diode laser as energy source while focusing on the influence of irradiation power and albumin concentration on the resulting tensile strength and induced tissue damage. MATERIALS AND METHODS: A porous PCL scaffold doped with either 25% or 40% (w/w) of BSA in combination with 0.1% (w/w) ICG was used to fuse rabbit aortas. Soldering energy was delivered through the vessel from the endoluminal side using a continuous wave diode laser at 808 nm via a 400 microm core fiber. Scaffold surface temperatures were analyzed with an infrared camera. Optimum parameters such as irradiation time, radiation power and temperature were determined in view of maximum tensile strength but simultaneously minimum thermally induced tissue damage. Differential scanning calorimetry (DSC) was performed to measure the influence of PCL on the denaturation temperature of BSA. RESULTS: Optimum parameter settings were found to be 60 seconds irradiation time and 1.5 W irradiation power resulting in tensile strengths of around 2,000 mN. Corresponding scaffold surface temperature was 117.4+/- 12 degrees C. Comparison of the two BSA concentration revealed that 40% BSA scaffold resulted in significant higher tensile strength compared to the 25%. At optimum parameter settings, thermal damage was restricted to the adventitia and its interface with the outermost layer of the tunica media. The DSC showed two endothermic peaks in BSA containing samples, both strongly depending on the water content and the presence of PCL and/or ICG. CONCLUSIONS: Diode laser soldering of vascular tissue using BSA-ICG-PCL-scaffolds leads to strong and reproducible tissue bonds, with vessel damage limited to the adventitia. Higher BSA content results in higher tensile strengths. The DSC-measurements showed that BSA denaturation temperature is lowered by addition of water and/or ICG-PCL.