Large Burns Research Articles

758 Correlation between initial and diagnostic bronchoalveolar lavage isolates among patients with inhalation injury and pneumonia

Abstract Introduction Inhalation injury is associated with increased risk of pneumonia. Bronchoscopy with bronchoalveolar lavage (BAL) is commonly used to diagnose and grade inhalation injury while obtaining a microbiological sample. It has been shown that a quarter of patients with inhalation injury have a single bacteria isolated from initial BAL within 12-48 hours of injury. The clinical significance of this and role of antibiotics in this setting are unknown. We investigated the incidence that bacteria isolated during a pneumonia episode were previously isolated on surveillance BAL among patients with inhalation injury. Methods Among patients with inhalation injury admitted to a large ABA-verified burn center from 2009-2022, microbiological isolates from initial BAL and subsequent culture obtained during a pneumonia episode (BAL, sputum), were extracted from medical records. Abbreviated injury severity score (AIS) was used to grade inhalation injury. Hospital-acquired pneumonia (HAP) was defined using CDC PNU1 criteria, and ventilator-associated pneumonia (VAP) was defined using PNU2 criteria with BAL cutoff >10,000 colony forming units (CFU). Results Two-hundred forty-eight patients with inhalation injury who underwent bronchoscopy for airway inspection and surveillance BAL within 48 hours of injury were included in the analysis. Of the 111 who had a bacterial isolate from initial BAL, 23 (21%) subsequently developed HAP or VAP during the hospitalization. Median (IQR) days between bronchoscopy and pneumonia diagnosis was six (2-8.5). In three of the 11 VAP cases (27%), the organisms identified at pneumonia diagnosis matched the organisms identified on initial BAL. Antibiotic use on admission was not associated with re-culture of initial BAL organism during a subsequent pneumonia episode (p=0.071). Conclusions Among patients with inhalation injury and bacteria isolated on surveillance BAL, 21% developed pneumonia during their hospital stay, usually with different bacteria than those isolated at initial bronchoscopy. There was no association between empiric antibiotic use and incidence of initial BAL organisms re-cultured during subsequent pneumonia episode. Applicability of Research to Practice Findings suggest initial BAL isolates cannot guide empiric coverage of pneumonia for patients with inhalation injury. This remains an important area of future research.

78 Improvement of Cell Viability in Temporary Storage of Split Thickness Skin Grafts

Abstract Introduction Autologous split thickness skin grafts (STSGs) are the preferred donor tissue for restoration of large tissue deficits. Although grafting should be done at the time of donor harvest, various factors necessitate tissue storage, traditionally in saline solution (SS) at 4oC. However, STSGs often expire before grafting in these conditions. Patients then require further excision procedures or die due to inadequate skin coverage. For patients’ wellbeing, establishing a new storage protocol is imperative. This study sought to determine an effective storage media for prolongation of graft viability for subsequent incorporation into excision and grafting practice. Methods Following patient consent, excess tissue >1cm2 was collected after grafting procedures. Tissue was stored at 4oC in RPMI, DMEM, and SS with penicillin/streptomycin. Samples were evaluated at 2, 5, 7, and 14 days. Cell viability was measured by Trypan blue dye exclusion test in an automated cell counter yielding percentage of viable keratinocytes (PVK). An unbiased pathologist assessed tissue integrity by epidermal-dermal junction, perinuclear keratinocyte halos, and collagen organization with higher scores denoting deterioration. Data were evaluated by ANOVA and Effect size. Results A total of 155 sets of two specimens each were collected from 13 patients. Mean PVK values at day 2, 5, 7, and 14: SS (57.38, 36.96, 38.38, 27.50), RPMI (69.46, 69.92, 70.33, 62.67), DMEM (63.17, 53.50, 54.83, 37.92). By pairwise comparison, RPMI preserved PVK better than SS at days 5, 7, and 14 (p = 0.001 for each day). DMEM preserved PVK better than SS when comparing all days (p = 0.011) but failed to produce a statistically significant difference at any specific day. RPMI preserved PVK greater than DMEM each day. However, statistically significant differences were only revealed at day 14 (p = 0.017) and when comparing all days (p < 0.001). Effect size was large for overall group differences of PVK at day 5, 7, and 14 (Cohen’s f = 0.72, 0.73, and 0.75). Tissue integrity scores at day 2, 5, 7, and 14: SS (0.69, 1.0, 1.38, 2.0), RPMI (0.54, 0.92, 0.85, 1.54), DMEM (0.77, 0.92, 0.77, 1.15). Although culture media preserved tissue integrity greater than SS, no statistically significant differences were found. Conclusions RPMI preserved cell viability better than DMEM and SS. This suggests that STSGs stored in RPMI may prolong the time of which tissue could be stored and successfully amalgamated with skin. Applicability of Research to Practice Storing tissue in RPMI could benefit burn patients by decreasing tissue disposal therefore reducing future donor site area or eliminating repetitious excision procedures entirely. These effects decrease inpatient days and healthcare costs. Most importantly, successful tissue storage will save patients’ lives, especially those of large surface area burns who lack sufficient donor sites.

96 A Quality Improvement Study of Routine Mattress Exchange to Reduce Microbial Recontamination

Abstract Introduction It is industry standard for a patient to maintain a single mattress throughout admission, which may be problematic with burn injuries. Significant burn injuries are high exudate wounds which provide challenging care, including frequent dressing changes and environmental contamination. As part of an infection prevention process improvement (PI) including routine air mattress (AM) exchanges throughout admission, the purpose of this study was to examine microbial contamination of mattresses before and after utilization. Methods This single center, retrospective study was conducted in an ABA-verified burn center. Routine AM exchanges began in November 8, 2020, including logging serial numbers of incoming/outgoing AM and periodic environmental cultures. Pre- and post-occupation AM environmental cultures (EC) (outside and inside the top cover and baffles) were compared with patient culture data. All patients were admitted to the Burn Center. Results During the 91 weeks, a total of 635 AM were exchanged. A total of 34 AM were cultured with 20 (59%) being post- and 14 being the pre-occupation. For the pre-occupation AM cultures, all 14 outer and inner surfaces cultured sterile. Regarding post-occupation AM, 80% had a positive EC of the outside surface, while 58% had positive environmental culture from inside the sealed AM. The median time of AM utilization prior to culturing was 6 (6, 7) days. All microbes isolated from post-occupation AM matched culture data from each patient’s hospital course. There were a total of 42 microbes isolated from environmental swabs taken from the outside cover with the most common: S.epidermidis 38%, S.aureus 14%, and P.aeruginosa 12%. A total of 40 microbes were isolated from inside the sealed AM with the most common: S.epidermidis 25%, Acinetobacter spp. 13%, Enterobacter spp. 10%, and Pseudomonas spp. 10%. There were 5 different EC taken from inside the sealed AM resulting in fungal growth. The 34 EC were taken from AM of 9 patients during the 91 week period. The median age was 48 (22, 66) years with 42 (21.25, 44) %TBSA burned. The median weight was 92 (76, 98) kg with body mass index of 27.47 (23.72, 37.11) kg/m2. Two of the 9 patients were below 20 % TBSA burned (9 and 19.5%) while the remaining 7 patients had greater that 20% TBSA burns. There was an inverse signals between size of burn and amount of wound closure and contamination. Conclusions AM are not impervious to the heavy exudate of patients with large burn injuries. Over time, the mattress becomes contaminated with microorganisms specific to the patient. This study justifies the infection prevention practice of routine mattress exchanges during admission for patients with large, open burn wounds. We do not send patients back from the operatory theater or hydrotherapy with reused dressing. Given these findings mattresses should be no different. Applicability of Research to Practice First study to analyze infectious mitigation potential of routine AM exchanges in burn patients.

752 Burn Rehab Guidelines Following Application of Cultured Epithelial Autografts For Closure of Large Burn Wounds

Abstract Introduction As the use of CEA by burn surgeons becomes more widespread, the existence of an experienced and dedicated burn therapy team, educated in post-operative care and treatment of CEA, is essential to short and long-term success of patients post-CEA, and their ability to achieve and maintain maximum functional status. Early mobilization of patients is an important aspect of treatment in the BICU, and has demonstrated a positive effect on patient outcomes throughout the continuum of care. However, postoperative treatment practices following application of CEA vary across burn centers, depending on experience and perceptions of CEA fragility and expense. The objective of this case series is to review one burn center’s therapy treatment plan before and after CEA application, and short and long-term outcomes in response to early implementation of therapy interventions. The hypothesis is early mobilization of patients after CEA can be achieved without negative consequence of graft loss. Methods This single-center, retrospective case series utilized electronic chart review to assess patients admitted between Apr '15 and Apr '20 who received CEA. Demographics, injury characteristics, surgical procedures collected. Therapy interventions and outcomes also collected, including postoperative therapy treatment plans, functional status at and following discharge, and occurrence of graft loss and contracture formation. Data collected analyzed with descriptive statistics. Results 8 patients met inclusion criteria for the case series. Median post-operative day for initiating positioning techniques post CEA application was POD0 (0,0); POD6.5 (3.75,7) for active, passive elongation; POD12 (11,15) for out of bed mobilization, functional mobility training; POD25 (17.75,25) for return to treatment in therapy clinic. All 8 patients demonstrated 0% occurence of graft loss and 0% contracture formation; none of the patients required reconstructive surgical procedures as a result of decreased joint mobility. In addition, 6 out of the 8 patients were admitted to the burn-specific inpatient rehab program, and all achieved a functional status of independent community locomotor upon discharge, including return to work and leisure activity. Conclusions Early implementation of therapy interventions by burn therapists trained in post-op treatment of CEA resulted in optimal short and long-term functional patient outcomes following closure with CEA. Early mobilization of patients in the BICU post-CEA did not result in any graft loss related to therapy treatment, despite the increased risk for shearing due to the physiological structure of CEA. 75% of patients reviewed in this case series achieved functional mobility skills required for independent living upon discharge, as well as return to work or leisure activities, after receiving treatment in a burn-specific inpatient rehabilitation facility within the burn center. Applicability of Research to Practice n/a

99 Retrospective Review of Pediatric Fluid Resuscitation at a Large Burn Center

Abstract Introduction Foundational approaches to burn fluid resuscitation were largely developed with the adult patient in mind. Experience has shown, however, that physiologic nuances between adults and children necessitate an adjusted approach to resuscitation for pediatric patients. As practice has advanced to account for these differences, our burn center sought to evaluate efficacy of resuscitation for our pediatric patient population. The purpose of this study was to examine pediatric fluid resuscitation including trends and complications, and to establish a baseline for future quality improvement initiatives. Methods This was a retrospective review of pediatric patients <14 years of age treated with resuscitation in a burn center between 2017 and 2021. Descriptive statistics were calculated. Results Over a five-year period, 42 pediatric patients were admitted with a burn total body surface area (TBSA) >20%, of which 23 met inclusion/exclusion criteria. Average admission weight was 31.8 kg and average TBSA of 39%. Contributing mechanisms of injury were flame (61%), scald (35%) and chemical (4%). Concomitant inhalation injury was diagnosed in 17% of patients. Average hourly fluid resuscitation volume was 6.9 mL/kg/TBSA with a mean resuscitation duration of 25.7 hours. Total volume administered throughout resuscitation exceeded recommendations per the Parkland formula for 83% of the sample. Continuous albumin was administered for 74% of patients and was initiated on average at 10 hours post-injury. Boluses of lactated ringer’s and albumin were administered for 30% and 9% of patients, respectively. Urine output for the pediatric patients averaged 60 mL/hr with a mean low optimal urine output of 15.9mL/hr and high optimal output of 25.5 mL/hr. Adverse events occurring during fluid resuscitation included temperature < 36◦C (35%), vasopressor administration (9%), intra-abdominal pressure >12 (13%) and/or >19 (9%), and peripheral vascular pulses < +1 (61%). Prophylactic escharotomy was performed for 35%. Of note, none of the patients were diagnosed with compartment syndrome nor abdominal compartment syndrome and none required abdominal laparotomy. One patient (4%) was diagnosed with acute respiratory distress syndrome. Continuous renal replacement therapy (CRRT) was not utilized for any pediatric patients during or post-resuscitation, compared to 34% of adults resuscitated at the same center. No patients expired in the initial 48 hours post-burn. The overall survival rate for this population was 91.3%, with 87% discharged direct to home. Conclusions Resuscitation volumes for pediatric patients in a large burn center have exceeded historically accepted rates for resuscitation. Despite the divergence from traditional practice, associated complications remain low, and outcomes have been favorable. Applicability of Research to Practice Further research is needed to establish benchmarks for pediatric fluid resuscitation.

295 Topical Tranexamic Acid in Burn Surgery – A Randomized Controlled Trial

Abstract Introduction Early excision and grafting of large burn wounds can result in considerable bleeding. Systemic use of tranexamic acid (TXA) generally reduces surgical bleeding by 30-40%, but its safety in burn surgery has not been studied. Topical use may provide a sufficient wound concentration with negligible risk of systemic adverse events. However, it is unclear whether topical use may delay wound re-epithelialization. This pilot double-blinded randomized controlled trial aimed to evaluate the therapeutic potential of topical TXA for reducing blood loss and the effect on wound re-epithelialization in burn surgery. Methods Between Jan 2021 – April 2022, burn patients at a single national burn center who needed at least two separate donor sites for split-thickness skin grafting were included. In total, 36 wound pairs in similar anatomical areas were made in 23 patients. Donor sites were infiltrated with tumescence containing epinephrine before harvesting. Paired wounds were randomized to topical application of standard epinephrine solution, with or without added TXA 25 mg/ml, before coverage with vaseline and dry gauze. Endpoints were time to re-epithelialization and surrogate bleeding estimates defined as net weight gain of dressings per cm2 wound area, bloodstain area per wound area, and visual rating of the amount of blood in dressings on the first postoperative day. Results There was no difference in healing time between wounds. The results trended towards less increase in dressing weight gain per cm2 of wound area in the TXA group, though not significant (p=0.12). However, when dividing the results in two at the median bleeding volume, there was a significant reduction in bleeding in the high-bleed group (p=0.012). Similar observations were made for the other two bleeding endpoints, but the differences did not reach statistical significance. Conclusions Moistening a superficial wound surface with TXA 25 mg/ml does not impair wound re-epithelialization. Topical TXA may reduce bleeding from graft donor sites with low risk of systemic complications. Applicability of Research to Practice This pilot study suggests that topical TXA is of value in reducing bleeding in burn surgery without delaying donor site healing. The effect may be larger in wounds not prepared with epinephrine infiltration. More research is warranted regarding the optimal mode of topical drug delivery and systemic concentrations after topical application in burns. Furthermore, it remains to investigate whether topical TXA affects graft take.

550 Retrospective Review of Fluid Resuscitation and Associated Complications for Adults in a Large Burn Center

Abstract Introduction The foundation for burn fluid resuscitation is well established, however an opportunity exists to improve outcomes for patients requiring such intervention. Resuscitation is influenced by a variety of factors, including associated complications. The purpose of this study was to establish a baseline at our center using historical performance and outcomes to drive quality improvement initiatives. Methods This was a retrospective chart review of patients admitted over a five-year period requiring resuscitation. Due to factors, such as early enactment of comfort care, patients who expired < 48 hours of injury were excluded. Results Charts were reviewed for 346 patients with a total body surface area (TBSA) >20%, 297 were adults. Of these, 32 died < 48-hours post-injury and 127 did not undergo fluid resuscitation or complete records were not available. Thus 138 were evaluable. Averages at admission were age 44.9, weight 86.4 kg and TBSA 39%. Most patients were male (71%). Mechanism was predominantly flame (86%), followed by 7% scald, 3% contact, 2% electrical, and 1% chemical. Concomitant inhalation injury was diagnosed for 34%. Average hourly fluid resuscitation volume was 6.5mL/kg/TBSA with a duration of 31.8 hours. Total volume exceeded Parkland formula calculations for 80%. Continuous albumin was administered for 97%, initiated on average at 8 hours post-injury. Boluses of lactated ringer’s and albumin were administered for 43% and 36% of patients, respectively. Urine output averaged 91 mL/hr and we identified a mean low optimal urine output of 43.2 mL/hr and mean high optimal output of 69.1 mL/hr. Associated complications during fluid resuscitation included temperature < 36◦C (58%), vasopressor administration (12%), intra-abdominal pressure >12 (59%) and/or >19 (14%), and peripheral vascular pulses < +1 (70%). Escharotomy was performed for 42%; 32% preventative, 2% required subsequent fasciotomy. Laparotomy/open abdomen was performed for 7.9%. Diagnosed complications were low for compartment syndrome (9.5%), abdominal compartment syndrome (6.5%), and acute respiratory distress syndrome (1.4%). Continuous renal replacement therapy was initiated for 11.5% of patients < 48 hours post-burn and for 22.4% >48 hours; 25% requiring CRRT had a dialysis or renal history. The overall survival rate for this population was 76.1%. Patients were discharged most often to rehab (37%), home (19%), or skilled nursing facility (12%). Conclusions A baseline for resuscitation in our center revealed a rate double historically accepted rates. Despite nonconformity with tradition, complications remain low. Outcomes have been favorable, yet opportunity for improvement endures. Applicability of Research to Practice Further research is needed to evaluate the predictive value of assessment measures to forecast associated complications.

Development and Characterization of Novel Anisotropic Skin Graft Simulants

Split-thickness skin grafting is a well-known procedure for the treatment of small- and medium-sized burns. However, its effectiveness has been reported to be limited in the case of large and severe burns due to much lower real expansion offered by the grafts than the claimed expansion by graft mesh manufacturers. Recent computational studies have indicated that the collagen fiber orientation within the skin layers have a significant effect on the skin graft expansion. In this study, biofidelic anisotropic synthetic skin with one and two layers and all possible fiber orientations were developed, and incision patterns used in traditional graft meshing techniques were projected to fabricate novel synthetic skin grafts with a theoretical meshing ratio of 3:1. A biaxial tensile testing device was designed to simulate skin graft stretching in clinical settings, and a wide range of synthetic skin graft variants were mechanically tested. The measured quantities included induced nonlinear stress–strain, void area, and meshing ratio. In addition, the stress–strain responses were characterized using nonlinear hyperelastic models. The key observations include the generation of higher induced stresses in two-layer grafts. In the one-layer graft models, a 15° fiber orientation produced the highest expansion at a minimal stress value of 0.21 MPa. In the two-layer graft models, the 45°–15° fiber orientation generated the maximum expansion with minimum stress. A range of such findings were analyzed to determine the graft orientations that may allow enhanced expansion without generating much stress. This information would be indispensable not only for understanding the expansion potential of skin grafts, but also for further research and the development of skin grafts with enhanced expansion for severe burn injury treatment.

Clinical Indications of Cultured Epithelial Autografts.

Cultured epithelial autografts (CEAs) have been used for decades as a treatment for massive burn injuries. Cultured epithelial autografts allow for wounds to heal by taking a small sample and growing a patient's own epithelium in culture to create large, graftable sheets. This technique is especially useful in large wounds where donor sites are limited compared with conventional skin grafting. However, CEAs have a variety of uses in wound healing and reconstruction and have the potential to aid in the closure of several types of defects. Cultured epithelial autografts have shown applicability in large burns, chronic nonhealing wounds, ulcerating wounds of various etiologies, congenital defects, wounds requiring specialized epithelium to replace like by like, and wounds in critically ill patients. Several factors must be considered when using CEAs, such as time, cost, and outcomes. In this article, we detail the various clinical applications of CEAs and how they can be situationally advantageous outside of their original purpose.

Effect of boundary layer thickness on supersonic combustion in a scramjet combustor

In this study, the effect of boundary layer thickness on supersonic combustion in an ethylene-fueled scramjet combustor under Mach 5.5 flight conditions is studied by employing experiments, numerical simulations, and theoretical modeling. The plate flow quantitative results show that the absolute thickness of the boundary layer is higher for a larger combustor. But the relative thickness is thin. Although boundary layer thickness changes greatly as the combustion chamber scale enlarges, the influence on the transverse jet and cavity flow is limited. In contrast, the combustion chamber scale change has a great impact on the combustion. More violent flames exist in large-scale combustion chambers. A theoretical model demonstrated that a large subsonic region led to a long fuel residence time, resulting in larger Damköhler numbers. This indicated that a large combustor could maintain large combustion. Based on the above analysis, although the relative thickness of the boundary layer is thinner, the absolute subsonic region of the boundary layer full of combustion is increased, which is conducive to intense combustion. In addition, a verification calculation of the 50 mm shortening isolation section is carried out. It is found from the flame cloud diagram and the quantitative wall pressure data that the combustion is significantly weakened.

Surface topography characterization using a simple optical device and artificial neural networks

State-of-the-art methods for quantifying wear in cylinder liners of large internal combustion engines for stationary power generation require disassembly and cutting of the examined liner. This is followed by laboratory-based high-resolution microscopic surface depth measurement that quantitatively evaluates wear based on bearing load curves (also known as Abbott-Firestone curves). Such reference methods are destructive, time-consuming and costly. The goal of the research presented here is to develop nondestructive yet reliable methods for quantifying the surface topography. A novel machine learning framework is proposed that allows prediction of the bearing load curves representing the depth profiles from reflection RGB images of the liner surface. These images can be collected with a simple handheld microscope. A joint deep learning approach involving two neural network modules optimizes the prediction quality of surface roughness parameters as well. The network stack is trained using a custom-built database containing 422 perfectly aligned depth profile and reflection image pairs of liner surfaces of large gas engines. The observed success of the method suggests its great potential for on-site wear assessment of engines during service.

Core temperature responses in well-healed burn survivors during exercise heat stress: effect of cooling modalities

Introduction: Every year, ~150,000 patients are treated in the United States with burn-related injuries. Previously, our group has shown that ~75% of burn survivors have a maximal aerobic capacity in the lowest 20th percentile rankings, relative to sex and age-adjusted non-burned individuals. This level of impairment is strongly associated with cardiovascular-specific, as well as all cause, morbidity, and mortality. Moreover, burn injuries that require grafting impair thermoregulation, and the subsequent increases in skin and core temperature may dissuade these individuals from engaging in exercise and/or physical activity. Low-energy cooling strategies have potential to attenuate increases in core temperature in burn survivors, which may promote regular physical activity. Thus, the purpose of this study was to evaluate the efficacy of low-energy cooling modalities on thermoregulatory responses during physical activity in the heat. Methods: Twenty-four adults with NO-BURN (n = 9), MODERATE burns (20-40% body surface area burned, n = 7), or LARGE burns (> 40% body surface area burned, n = 8) walked for one hour at a moderate intensity (rate of metabolic heat production of 4.5 W/kg body mass) in an environmental chamber (39°C, 40% RH). Burn survivors were at least 2 years post-injury. Participants performed this activity four times, with the following modalities randomly applied throughout each trial on separate days: no cooling (i.e., control), fan at 4 m/s (FAN), water spray (WS, minimum 10-50 g every 5 min, scaled to burn area size), or WS+FAN. Core temperature (Tcore) was recorded throughout each trial via a telemetric pill. Final Tcore values for each cooling modality were compared against the no cooling condition. Results: For the LARGE burn group, WS reduced end-exercise Tcore by 0.37°C (range 0.09 to 0.66°C) compared with no cooling ( p = 0.01). FAN and WS+FAN did not impact end-exercise Tcore for the LARGE burn group ( p ≥ 0.48). No cooling modality affected Tcore for the MODERATE burn group ( p ≥ 0.12) or the NO-BURN group (p ≥ 0.55). Conclusion: At the assessed workload and environmental condition, the efficacy of the applied cooling modalities on Tcore responses for burn survivors appears to be dependent on both the selected modality and the size of the burn surface area. Namely, WS attenuated the increases in Tcore in participants with LARGE burn injuries, but FAN and WS+FAN did not attenuate Tcore responses in any group. Supported by NIHGrant R01GM068865 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Predicting blood loss in burn excisional surgery.

Blood loss during burn excisional surgery remains an important factor as it is associated with significant comorbidity, mortality and longer length of stay. Blood loss is, among others, influenced by length of surgery, burn size, excision size and age. Most literature available is aimed at large burns and little research is available for small burns. Therefore, the goal of this study is to investigate blood loss and develop a prediction model to identify patient at risk for blood loss during burn excisional surgery ≤10% body surface area. This retrospective study included adult patients who underwent burn excisional surgery of ≤10% body surface area in the period 2013-2018. Duplicates, patients with missing data and delayed surgeries were excluded. Primary outcome was blood loss. A prediction model for per-operative blood loss (>250ml) was built using a multivariable logistic regression analysis with stepwise backward elimination. Discriminative ability was assessed by the area under the ROC-curve in conjunction with optimism and calibration. In total 269 patients were included for analysis. Median blood loss was 50ml (0-150) / % body surface area (BSA) excised and 0.28 (0-0.81) ml / cm2. Median burn size was 4% BSA and median excision size was 2% BSA. Blood loss of>250ml was present in 39% of patients. The model can predict blood loss>250ml based on %BSA excised, length of surgery and ASA-score with an AUC of 0.922 (95% CI 0.883 - 0.949) and an AUC after optimism correction of 0.915. The calibration curve showed an intercept of 0.0 (95% CI -0.36 to 0.36) with a slope of 1.0 (95% CI 0.78-1.22). Median blood loss during burn excisional surgery of ≤10% BSA is 50ml / % BSA excised and 0.28ml / cm2 excised. However, a substantial part of patients is at risk for higher blood loss. The prediction model can predict P(blood loss>250ml) with an AUC of 0.922, based on expected length of surgery, ASA-score and size of excision. The model can be used to identify patients at risk for significant blood loss (>250ml).

Development of hierarchical auxetic skin graft simulants with high expansion potential

Skin grafting is a surgical procedure to treat extensive burn injuries, and the design of skin grafts plays an essential role in burn surgery. In skin grafting, parallel incisions are projected onto a small section of healthy skin that has been removed for maximum expansions and coverage of a larger burn area. Currently, in the traditional method, skin graft expansions are insufficient to cover large burn areas. This work studied the hierarchy of alternating slit (AS) shaped and rotating rectangle (RR) shaped auxetic skin graft patterns. The 3D models of hierarchical structures were designed and developed using SolidWorks and additive manufacturing methods, respectively. These moulds were used to fabricate the hierarchical skin graft simulants. Statistical analysis was performed to calculate the significance among the groups. These hierarchical skin graft simulants were tested uniaxially and calculated the effective Poisson's ratio, meshing ratio, and induced stress up to 300% strain. From the results, all the auxetic skin graft simulants showed very high expansion. The first-order AS-shaped skin graft simulant showed the maximum expansion among all the hierarchical models. Till now, skin grafts have not achieved such high expansion experimentally. This research will be useful to the doctors to improve burn surgery outcomes and guide the manufacturers to develop new mesher with higher expansion potential.

Factor XIII: More than just a fibrin stabilizer for the burn patient? A matched-pair analysis

Acquired factor XIII deficiency is an underestimated risk in patients with large surface burns, which potentially exposes these patients to prolonged bleeding and delayed wound healing if undetected. A retrospective matched-pair analysis of the burn registry of the Department of Plastic, Aesthetic, Hand, and Reconstructive Surgery of Hannover Medical School was performed from 2018 to 2023. A total of 18 patients were included. Acquired factor XIII deficiency was not statistically significant correlated with age, sex, or body mass index. Patients who developed acquired factor XIII deficiency had a significantly longer hospital stay (72.8 days) compared with those in the matched group (46.4 days), although burn depths, total body surface area, and Abbreviated Burn Severity Index were not statistically correlated with factor XIII deficiency. Little is known about acquired factor XIII deficiency in patients with burns. Factor XIII supplementation may improve hemostasis, wound healing, and general outcome while reducing the patient's exposure to blood products.

Weighted Network Degree Screening Method for Low-Temperature Combustion Mechanism Reduction.

A new method is proposed for the reduction mechanism used in the low-temperature negative temperature coefficient region on the basis of the statistical degree screening (SDS) method. Dynamic information is used to redefine network structure and exclude the influence of very weak interactions on node degree according to the statistics character of their distribution as edge weight. Representative low-temperature conditions are used to set weight thresholds to redefine the network structure so that an effective low-temperature oxidation mechanism is covered while negligible interactions are overlooked. Then, the reduction mechanism is obtained by the SDS method through screening out the redundant species and corresponding reactions according to the scale-free character of the degree distribution. This weighted network degree screening (WNDS) method is demonstrated in the n-heptane system. The performance of the reduced mechanism is evaluated in a closed homogeneous reactor for the fuel over T = 600-1000 K, P = 1-30 atm, and φ = 0.5-2. Results show WNDS yields a skeletal mechanism with comparable or even better prediction ability over a wide parameter range than those generated by directed relation graph. WNDS is a novel statistical property-based reduction method that is suitable for low-temperature oxidation reduction. Its good reduction application indicates a brand-new angle for large combustion mechanism reduction.

Bilayered skin substitute incorporating rutin nanoparticles for antioxidant, anti-inflammatory, and anti-fibrotic effect

Hypertrophic scarring in large burns and delayed healing in chronic wounds are consequences of prolonged and aggravated inflammation, sustained infiltration of immune cells, free radical generation, and abundance of inflammatory mediators. Therefore, it is imperative to curb hyperinflammation to expedite wound healing. In this study, rutin nanoparticles (RNPs) were synthesized without an encapsulant and incorporated into eggshell membrane powder-crosslinked gelatin-chitosan cryogels to impart antioxidant and anti-inflammatory properties for treating hyperinflammation. The resultant nanoparticles were found to be 17.53 ± 4.03 nm in size and were stable at room temperature for a month with no visible sedimentation. RNPs were found to be non-cytotoxic and exhibited anti-inflammatory (by increasing IL-10 levels) and antioxidant properties (by controlling the generation of reactive oxygen species and enhancing catalase production in human macrophages). Additionally, RNPs were found to reduce α-SMA expression in fibroblasts, thereby demonstrating their anti-scarring effect. In vivo studies with a bilayered skin substitute constituting an RNP-incorporated cryogel proved that it is biocompatible, does not induce renal toxicity, aids wound healing, and induces better re-epithelialization than the control groups at the initial stages. Thus, RNP-incorporated cryogels containing bilayered skin substitutes are an advanced and novel alternative to commercial dermo-epidermal substitutes that lack anti-inflammatory or anti-scarring properties.

Data-Driven Prediction of Key Combustion Parameters Based on an Intelligent Diesel Fuel Injector for Large Engine Applications

<div class="section abstract"><div class="htmlview paragraph">Digital technologies are capable of making a significant contribution to improving large internal combustion engine technology. In particular, methods from the field of artificial intelligence are opening up new avenues. So-called “intelligent” engine components rely on advanced instrumentation and data analytics to create value-added data, which in turn can serve as the basis for applications such as condition monitoring, predictive maintenance and controls. For related components and systems, these data may also allow for novel condition monitoring approaches. This paper describes the use of value-added data from an intelligent diesel fuel injection valve that give detailed information about the injection process for real-time prediction of key combustion parameters such as indicated mean effective pressure, maximum cylinder pressure and combustion phasing. These parameters are usually involved in combustion controls and power unit condition monitoring and normally acquired using in-cylinder pressure indication systems, which are costly and prone to wear. On the one hand, a data-driven model for key combustion parameters based on an intelligent fuel injection valve could replace an indication system. On the other hand, such a model may enable backup functionality and mutual condition monitoring of the fuel injection valve and the indication system. The data required for model building were acquired from a medium-speed four-stroke single-cylinder research engine with a displacement of approximately 15.7 dm<sup>3</sup>. Different machine learning methods are compared to obtain an accurate yet reliable model for each of the desired combustion parameters. In addition to the value-added injection data, readily available parameters on production engines serve as model inputs (e.g., engine speed, charge air and exhaust gas pressures). Based on the results, the quality of the model predictions is evaluated, and it is assessed whether the approach might be useful for series engine applications.</div></div>

Development of novel hierarchical designs for skin graft simulants with high expansion potential

Skin graft designs play an essential role in healing severe burn injuries. Split-thickness skin grafting (STSG) is one of the commonly used techniques for treating large burn injuries. In STSG, parallel cuts are projected onto a small portion of excised healthy skin for expansion and covering a larger burn area. To date, expansions reported for STSG are very low and insufficient to cover large burn areas. In this work, novel traditional and auxetic hierarchical cuts were designed on skin graft simulants, which were mechanically tested to study their expansion potential. Additive manufacturing and a two-part polymeric material were employed to fabricate the skin graft simulants. The nonlinear mechanical behavior of the hierarchical skin graft simulants was characterized using hyperelastic models. The effective Poisson’s ratio, meshing ratios, and induced stresses in first and second-order hierarchical cut patterns were estimated across all skin graft simulants for up to 300% strain. Also, Statistical analysis was performed to calculate the significance among the groups. From the analysis, the skin graft simulants with second-order auxetic incision patterns were found to exhibit the lowest induced stresses and maximum expansion of approximately four times, at 300% strain. To date, traditional skin grafts have only been able to achieve up to three times expansion. Therefore, the expansions realized with the novel hierarchical skin graft simulants is unprecedented, with the potential to generate ground-breaking advances in burn injury treatment.

A Pilot Randomised Controlled Trial Evaluating a Regenerative Epithelial Suspension for Medium-Size Partial-Thickness Burns in Children: The BRACS Trial.

There is little evidence regarding the efficacy of Regenerative Epidermal Suspension (RES™) management for paediatric partial-thickness burns. The Biobrane® RECELL® Autologous skin Cell suspension and Silver dressings (BRACS) Trial evaluated three dressings for the re-epithelialisation of partial-thickness burns in children. Eligible children (age ≤ 16 years; ≥5% TBSA; ≤48 h of injury) were randomised to silver dressings, RES™/Biobrane® or Biobrane®. The measured outcomes were the time to re-epithelialisation (primary outcome), pain, itch, intervention fidelity, treatment satisfaction, health-related quality of life, health resource utilisation and adverse effects. The median time to re-epithelialisation in days was no different for RES™/Biobrane® at 12 (IQR: 5.6-18.4; n = 7) and slower by two days for Biobrane® at 14 (IQR: 6.3-21.7; n = 7) when compared to silver dressings 12 (IQR: 3.7-20.3; n = 8). Reduced pain, fewer infections, no sepsis, no skin graft, and the lowest impact on health-related quality of life were reported in the RES™/Biobrane® group compared to other groups. Due to the COVID-19 pandemic, recruitment suspension resulted in a smaller cohort than expected and an underpowered study. The pilot trial findings should be interpreted cautiously; however, they indicate that a fully powered randomised controlled trial is warranted to substantiate the role of RES™ for medium to large paediatric partial-thickness burn management.