Early abnormal fibrinolysis and mortality in patients with thermal injury: a prospective cohort study.

INTRODUCTION: Abnormal fibrinolysis early after injury has been associated with increased mortality in trauma patients, but no studies have addressed patients with burn injury. This prospective cohort study aimed to characterize fibrinolytic phenotypes in burn patients and to see if they were associated with mortality. METHODS: Patients presenting to a regional burn centre within 4 h of thermal injury were included. Blood was collected for sequential viscoelastic measurements using thromboelastography (RapidTEG™) over 12 h. The percentage decrease in clot strength 30 min after the time of maximal clot strength (LY30) was used to categorize patients into hypofibrinolytic/fibrinolytic shutdown (SD), physiological (PHYS) and hyperfibrinolytic (HF) phenotypes. Injury characteristics, demographics and outcomes were compared. RESULTS: Of 115 included patients, just over two thirds were male. Overall median age was 40 (i.q.r. 28-57) years and median total body surface area (TBSA) burn was 13 (i.q.r. 6-30) per cent. Some 42 (36.5 per cent) patients had severe burns affecting over 20 per cent TBSA. Overall mortality was 18.3 per cent. At admission 60.0 per cent were PHYS, 30.4 per cent were SD and 9.6 per cent HF. HF was associated with increased risk of mortality on admission (odds ratio 12.61 (95 per cent c.i. 1.12 to 142.57); P = 0.041) but not later during the admission when its incidence also decreased. Admission SD was not associated with mortality, but incidence increased and by 4 h and beyond, SD was associated with increased mortality, compared with PHYS (odds ratio 8.27 (95 per cent c.i. 1.16 to 58.95); P = 0.034). DISCUSSION: Early abnormal fibrinolytic function is associated with mortality in burn patients.

Shedding of the endothelial glycocalyx is quantitatively proportional to burn injury severity.

Limited information exists regarding endothelial dysfunction following burn injury. This project aims to evaluate whether thermal injury results in shedding of the endothelial glycocalyx in a manner quantitatively proportional to injury severity, and whether theloss of intact glycocalyx is measurable in end organs. C57BL/6 mice were grouped as uninjured controls, 10% or 25% Total Body Surface Area (TBSA) scald burns. Blood and tissue sampling was performed over a specific time course. Plasma levels of shed syndecan-1, a marker of glycocalyx damage, were quantified by ELISA. Lung and spleen sections were stained with immunofluorescent anti-syndecan-1 antibodies to evaluate intact glycocalyx. Plasma syndecan-1 levels were higher in injured versus uninjured animals. Normalized levels of syndecan-1 in burned mice were significantly increased compared to hour 0 (p<0.05) at hours 4 and 8 post-injury in the 10% TBSA, and at hour 4 in the 25% TBSA group. Levels in the 10% and 25% TBSA groups peaked at hour 4 with fold change of 2.3 and 2.4 respectively. There was less pulmonary syndecan-1 immunostaining in burned animals compared to controls, and the levels inversely correlated with systemic shed syndecan- 1, beginning at hour 4 in the 10% TBSA injury group and at all time points in the 25% TBSA injury group, (0.27±0.06 and 0.14±0.04 respectively for hour 4). Similarly, there was less spleen syndecan-1 immunostaining in burned animals compared to controls at all time points. Burn injury causes shedding of syndecan-1 in a murine model, with levels correlated to injury severity and loss of the glycocalyx in lung and spleen. This work provides further insight into quantification and temporality of glycocalyx damage and systemic response to burn.

Les données concernant la dysfonction endothéliale après brûlure sont parcellaires. Les buts de cette étude étaient d'établir une corrélation entre la perte de glycocalyx et la gravité de la brûlure et si cette perte était mesurable au niveau des organes. Des souris C57BL/6 ont été réparties en groupes contrôle, brûlure 10% et brûlure 25% de SCT. Des prélèvements de sang et de tissus ont été réalisés à intervalles prédéterminés. Les taux plasmatiques de syndecan 1 (S1), marqueur de lésion du glycocalyx, ont été mesuré par méthode ELISA. Des échantillons de poumon et de rate ont été mis en présence d'anticorps anti S1, afin d'évaluer le glycocalyx intact. Les taux plasmatiques de S1 étaient plus élevés que ceux du groupe contrôle. Chez les souris brûlées sur 10% de SCT, les taux de S1 à 4h et 8 h étaient supérieurs au taux avant brûlure, ceci n'étant observé qu'à h4 chez les souris brûlées sur 25% de SCT. Le pic de S1 se produisait à h4, avec un rapport de x2,3 (10%) et x2,4 (25%) par rapport à la valeur de base. A partir de h4, on observait une baisse de complexes S1-antiS1 dans les poumons des souris brûlées sur 10% (0,27 +/- 0,06), inversement corrélée aux taux plasmatiques de S1. Cette observation se répétait lors de tous les dosages chez les 25% (0,14 +/- 0,04 à h4). Les mêmes constatations étaient faites sur les échantillons de rate. La brûlure cause des lésions du glycocalyx, parallèles à sa gravité. Ces travaux ouvrent le champ à des recherches futures sur les lésions du glycocalyx et la réponse inflammatoire aux brûlures.

Hydroconductive and silver-impregnated foam dressings: a comparison.

OBJECTIVE: As the number of commercially available wound dressings is increasing rapidly, it is important for clinicians to understand the strengths and limitations of each and to recognise relationships between wound type and dressing properties to obtain optimal healing results. Our aim is to test the antimicrobial activity of two dressings. METHOD: A hydroconductive (HC) dressing and a silver-impregnated foam (SIF) dressing were compared for their potential to reduce the levels meticillin-resistant Staphylococcus aureus (MRSA). We also assessed MRSA-derived biologically active components in liquid or agar matrices, simplified models for heavily exuding or dry wounds respectively, and in an in vivo animal model with MRSA infected wounds. RESULTS: In the agar model (dry wounds) both dressings showed a strong reduction in MRSA activities within 24 hours post-application. The antibacterial effects of the SIF dressing were more pronounced in the liquid model, however, at an increasing cytotoxic cost. In agreement with these in vitro results, assessment of dressings using an MRSA-infected wound in an rat model showed a decrease in MRSA which was significant 7 days post-burn and inoculation, with more compromised viability of MRSA. Dressings showed a similar capability to reduced and eliminate toxic shock syndrome toxin (TSST-1) at day 7 post-burn in the animal model but not at day 4, where the SIF dressing was more potent Conclusion: These results confirm the advantages of using silver in reducing bacterial load in wound treatment, except for conditions of highly exuding wounds where the cytotoxic properties of silver may offset these advantages and HC dressing use is more suitable.

A Translational Animal Model for Scar Compression Therapy Using an Automated Pressure Delivery System.

BACKGROUND: Pressure therapy has been used to prevent and treat hypertrophic scars following cutaneous injury despite the limited understanding of its mechanism of action and lack of established animal model to optimize its usage. OBJECTIVES: The aim of this work was to test and characterize a novel automated pressure delivery system designed to deliver steady and controllable pressure in a red Duroc swine hypertrophic scar model. METHODS: Excisional wounds were created by dermatome on 6 red Duroc pigs and allowed to scar while assessed weekly via gross visual inspection, laser Doppler imaging, and biopsy. A portable novel automated pressure delivery system was mounted on developing scars (n = 6) for 2 weeks. RESULTS: The device maintained a pressure range of 30 ± 4 mm Hg for more than 90% of the 2-week treatment period. Pressure readings outside this designated range were attributed to normal animal behavior and responses to healing progression. Gross scar examination by the Vancouver Scar Scale showed significant and sustained (>4 weeks) improvement in pressure-treated scars (P < .05). Histological examination of pressure-treated scars showed a significant decrease in dermal thickness compared with other groups (P < .05). Pressure-treated scars also showed increased perfusion by laser Doppler imaging during the treatment period compared with sham-treated and untreated scars (P < .05). Cellular quantification showed differential changes among treatment groups. CONCLUSION: These results illustrate the applications of this technology in hypertrophic scar Duroc swine model and the evaluation and optimization of pressure therapy in wound-healing and hypertrophic scar management.