Enteral resuscitation with oral rehydration solution to reduce acute kidney injury in burn victims: Evidence from a porcine model

Consumer focus group testing with stakeholders to generate an enteral resuscitation training flipbook for primary health center and first-level hospital providers in Nepal

INTRODUCTION

Enteral resuscitation (EResus) is operationally advantageous to intravenous resuscitation for burn-injured patients in some low-resource settings. However, there is minimal guidance and no training materials for EResus tailored to non-burn care providers. We aimed to develop and consumer-test a training flipbook with doctors and nurses in Nepal to aid broader dissemination of this life-saving technique.

MATERIALS AND METHODS

We used individual cognitive interviews with Nepali (n = 12) and international (n = 4) burn care experts to define key elements of EResus and specific concepts for its operationalization at primary health centers and first-level hospitals in Nepal. Content, prototype illustrations, and wireframe layouts were developed and revised with the burn care experts. Subsequently, eight consumer testing focus groups with Nepali stakeholders (5-10 people each) were facilitated. Prompts were generated using the Questionnaire Appraisal System (QAS) framework. The flipbook was iteratively revised and tested based on consumer feedback organized according to the domains of clarity, assumptions, knowledge/memory, and sensitivity/bias.

RESULTS AND DISCUSSION

The flipbook elements were iterated until consumers made no additional requests for changes. Examples of consumer inputs included: clarity-minimize medical jargon, add shrunken organs and wilted plants to represent burn shock; assumptions-use locally representative figures, depict oral rehydration salts sachet instead of a graduated bottle; knowledge/memory-clarify complex topics, use Rule-of-9 s and depict approximately 20% total body surface area to indicate the threshold for resuscitation; sensitivity/bias-reduce anatomic illustration details (e.g. urinary catheter placement, body contours).

CONCLUSION

Stakeholder engagement, consumer testing, and iterative revision can generate knowledge translation products that reflect contextually appropriate education materials for inexperienced burn providers. The EResus Training Flipbook can be used in Nepal and adapted to other contexts to facilitate the implementation of EResus globally.

Research progress and considerations on oral rehydration therapy for the prevention and treatment of severe burn shock: A narrative review

Severe burns are a significant cause of life-threatening conditions in both peacetime and wartime. Shock is a critical complication during the early stages of burn injury, contributing substantially to mortality and long-term disability. Effective fluid resuscitation is crucial for preventing and treating shock, with prompt administration being vital. However, timely intravenous fluid resuscitation is often challenging, and errors in resuscitation significantly contribute to mortality. Therefore, exploring a more rapid and effective non-invasive method of fluid resuscitation is necessary. Oral rehydration therapy (ORT) has shown considerable potential in this regard. This paper reviews ORT's historical development and current research progress, discussing its application in early anti-shock treatment for burns. While ORT is generally safe, potential complications like diarrhoea, vomiting, and abdominal discomfort must be noted, particularly if the rehydration rate is too rapid or if gastrointestinal issues exist. Careful patient assessment and monitoring are essential during ORT administration. Based on a comprehensive review of relevant research, we present provisional guidelines for ORT in burn patients. These guidelines aim to inform clinical practice but should be applied cautiously due to limited clinical evidence. Implementation must be tailored to the patient's condition under healthcare supervision, with adjustments according to evolving circumstances: ① Initiation timing: Start as soon as possible, and the ideal start time is usually within 6 h after injury. ② Rate of application: Employing a fractional administration approach, wherein small quantities of approximately 150-250 millilitres are provided for each instance and the initial fluid rate of oral rehydration can be simplified to 100 mL/kg/24 h. ③ Composition combination: In addition to essential salts and glucose, the oral rehydration solution can incorporate various anti-inflammatory and cellular protection constituents.

Kinetics of Inflammatory Mediators in the Immune Response to Burn Injury: Systematic Review and Meta-Analysis of Animal Studies

Burns are often accompanied by a dysfunctional immune response, which can lead to systemic inflammation, shock, and excessive scarring. The objective of this study was to provide insight into inflammatory pathways associated with burn-related complications. Because detailed information on the various inflammatory mediators is scattered over individual studies, we systematically reviewed animal experimental data for all reported inflammatory mediators. Meta-analyses of 352 studies revealed a strong increase in cytokines, chemokines, and growth factors, particularly 19 mediators in blood and 12 in burn tissue. Temporal kinetics showed long-lasting surges of proinflammatory cytokines in blood and burn tissue. Significant time-dependent effects were seen for IL-1β, IL-6, TGF-β1, and CCL2. The response of anti-inflammatory mediators was limited. Burn technique had a profound impact on systemic response levels. Large burn size and scalds further increased systemic, but not local inflammation. Animal characteristics greatly affected inflammation, for example, IL-1β, IL-6, and TNF-α levels were highest in young, male rats. Time-dependent effects and dissimilarities in response demonstrate the importance of appropriate study design. Collectively, this review presents a general overview of the burn-induced immune response exposing inflammatory pathways that could be targeted through immunotherapy for burn patients and provides guidance for experimental set-ups to advance burn research.

Burn Care in Low-Resource and Austere Settings

More than 95% of the 11 million burns that occur annually happen in low-resource settings, and 70% of those occur among children. Although some low- and middle-income countries have well-organized emergency care systems, many have not prioritized care for the injured and experience unsatisfactory outcomes after burn injury. This chapter outlines key considerations for burn care in low-resource settings.

Advantages of pyruvate-based fluids in preclinical shock resuscitation-A narrative review

This review focuses on the innate beneficial effects of sodium pyruvate-based fluids, including pyruvate in intravenous solutions, oral rehydration solutions, and peritoneal dialysis solutions, on shock resuscitation with various animal models relative to current commercial fluids over the last two decades. Due to its superior pharmacological properties, pyruvate effectively sustains cytosolic glycolytic pathways and mitochondrial oxidative phosphorylation by restoration of redox potentials and reactivation of pyruvate dehydrogenase in hypoxia, even anoxia, and diabetes, reversing the Warburg effect and diabetic glucometabolic aberration. Pyruvate has been demonstrated to protect against multiorgan dysfunction and metabolic disturbance in numerous preclinical studies with various pathogenic injuries. The unique features of pyruvate potential clinical benefits encompass to efficiently correct lethal lactic acidosis via metabolically rapid consumption of intracellular [H⁺] and robustly protect multiorgan metabolism and function, particularly visceral organs in addition to the heart and brain, significantly prolonging survival in various animal models. Pyruvate protection of red blood cell function and preservation of the partial pressure of arterial oxygen should be highly concerned in further studies. Pyruvate is much advantageous over existing anions such as acetate, bicarbonate, chloride, and lactate in commercial fluids. Pyruvate-based fluids act as a therapeutic agent without causing iatrogenic resuscitation injury in addition to being a volume expander, indicating a potential novel generation of resuscitation fluids, including crystalloids and colloids. Pyruvate-based fluids have an enormous potential appeal for clinicians who face the ongoing fluid debate to readily select as the first resuscitation fluid. Clinical trials with pyruvate-based fluids in shock resuscitation are urgently warranted.

Advantages and Disadvantages of Using Small and Large Animals in Burn Research: Proceedings of the 2021 Research Special Interest Group

Multiple animal species and approaches have been used for modeling different aspects of burn care, with some strategies considered more appropriate or translatable than others. On April 15, 2021, the Research Special Interest Group of the American Burn Association held a virtual session as part of the agenda for the annual meeting. The session was set up as a pro/con debate on the use of small versus large animals for application to four important aspects of burn pathophysiology: burn healing/conversion; scarring; inhalation injury; and sepsis. For each of these topics, 2 experienced investigators (one each for small and large animal models) described the advantages and disadvantages of using these preclinical models. The use of swine as a large animal model was a common theme due to anatomic similarities with human skin. The exception to this was a well-defined ovine model of inhalation injury; both of these species have larger airways which allow for incorporation of clinical tools such as bronchoscopes. However, these models are expensive and demanding from labor and resource standpoints. Various strategies have been implemented to make the more inexpensive rodent models appropriate for answering specific questions of interest in burns. Moreover, modelling burn-sepsis in large animals has proven difficult. It was agreed that the use of both small and large animal models have merit for answering basic questions about the responses to burn injury. Expert opinion and the ensuing lively conversations are summarized herein, which we hope will help inform experimental design of future research.

Burn-Induced Local and Systemic Immune Response: Systematic Review and Meta-Analysis of Animal Studies

As burn injuries are often followed by a derailed immune response and excessive inflammation, a thorough understanding of the occurring reactions is key to prevent secondary complications. This systematic review, that includes 247 animal studies, shows the post-burn response of 14 different immune cell types involved in immediate and long-term effects, in both wound tissue and circulation. Peripheral blood neutrophil and monocyte numbers increased directly after burns, whereas thrombocyte numbers increased near the end of the first week. Lymphocyte numbers, however, were decreased for at least two weeks. In burn wound tissue, neutrophil and macrophage numbers accumulated during the first three weeks. Burns also altered cellular functions as we found increased migratory potential of leukocytes, impaired antibacterial activity of neutrophils and enhanced inflammatory mediator production by macrophages. Neutrophil surges were positively associated with burn size and were highest in rats. Altogether, this comprehensive overview of the temporal immune cell dynamics shows that unlike normal wound healing, burn injury induces a long-lasting inflammatory response. It provides a fundamental research basis to improve experimental set-ups, burn care and outcome.

Deep neural network classification of in vivo burn injuries with different etiologies using terahertz time-domain spectral imaging

Thermal injuries can occur due to direct exposure to hot objects or liquids, flames, electricity, solar energy and several other sources. If the resulting injury is a deep partial thickness burn, the accuracy of a physician's clinical assessment is as low as 50-76% in determining the healing outcome. In this study, we show that the Terahertz Portable Handheld Spectral Reflection (THz-PHASR) Scanner combined with a deep neural network classification algorithm can accurately differentiate between partial-, deep partial-, and full-thickness burns 1-hour post injury, regardless of the etiology, scanner geometry, or THz spectroscopy sampling method (ROC-AUC = 91%, 88%, and 86%, respectively). The neural network diagnostic method simplifies the classification process by directly using the pre-processed THz spectra and removing the need for any hyperspectral feature extraction. Our results show that deep learning methods based on THz time-domain spectroscopy (THz-TDS) measurements can be used to guide clinical treatment plans based on objective and accurate classification of burn injuries.

Burn Shock and Resuscitation: Review and State of the Science

Burn shock and acute fluid resuscitation continue to spark intense interest and debate among burn clinicians. Following a major burn injury, fluid resuscitation of burn shock is life-saving, but paradoxically can also be a source of increased morbidity and mortality because of the unintended consequence of systemic edema formation. Considerable research over the past two decades has been devoted to understanding the mechanisms of edema formation, and to develop strategies to curb resuscitation fluids and limit edema development. Recognition of burn endotheliopathy - injury to the endothelium's glycocalyx layer- is one of the most important recent developments in our understanding of burn shock pathophysiology. Newer monitoring approaches and resuscitation endpoints, along with alternative resuscitation strategies to crystalloids alone, such as administration of albumin, or plasma, or high dose ascorbic acid, have had mixed results in limiting fluid creep. Clear demonstration of improvements in outcomes with all of these approaches remains elusive. This comprehensive review article on burn shock and acute resuscitation accompanies the American Burn Association's State of the Science meeting held in New Orleans, LA on November 2-3, 2021 and the Proceedings of that conference published in this journal.

Experimental models of acute kidney injury for translational research

Preclinical models of human disease provide powerful tools for therapeutic discovery but have limitations. This problem is especially apparent in the field of acute kidney injury (AKI), in which clinical trial failures have been attributed to inaccurate modelling performed largely in rodents. Multidisciplinary efforts such as the Kidney Precision Medicine Project are now starting to identify molecular subtypes of human AKI. In addition, over the past decade, there have been developments in human pluripotent stem cell-derived kidney organoids as well as zebrafish, rodent and large animal models of AKI. These organoid and AKI models are being deployed at different stages of preclinical therapeutic development. However, the traditionally siloed, preclinical investigator-driven approaches that have been used to evaluate AKI therapeutics to date rarely account for the limitations of the model systems used and have given rise to false expectations of clinical efficacy in patients with different AKI pathophysiologies. To address this problem, there is a need to develop more flexible and integrated approaches, involving teams of investigators with expertise in a range of different model systems, working closely with clinical investigators, to develop robust preclinical evidence to support more focused interventions in patients with AKI.

Large animal models for translational research in acute kidney injury

While extensive research using animal models has improved the understanding of acute kidney injury (AKI), this knowledge has not been translated into effective treatments. Many promising interventions for AKI identified in mice and rats have not been validated in subsequent clinical trials. As a result, the mortality rate of AKI patients remains high. Inflammation plays a fundamental role in the pathogenesis of AKI, and one reason for the failure to translate promising therapeutics may lie in the profound difference between the immune systems of rodents and humans. The immune systems of large animals such as swine, nonhuman primates, sheep, dogs and cats, more closely resemble the human immune system. Therefore, in the absence of a basic understanding of the pathophysiology of human AKI, large animals are attractive models to test novel interventions. However, there is a lack of reviews on large animal models for AKI in the literature. In this review, we will first highlight differences in innate and adaptive immunities among rodents, large animals, and humans in relation to AKI. After illustrating the potential merits of large animals in testing therapies for AKI, we will summarize the current state of the evidence in terms of what therapeutics have been tested in large animal models. The aim of this review is not to suggest that murine models are not valid to study AKI. Instead, our objective is to demonstrate that large animal models can serve as valuable and complementary tools in translating potential therapeutics into clinical practice.

The Effect of Burn Resuscitation Volumes on the Gut Microbiome in a Swine Model

INTRODUCTION

While recent reports underscore the significance of the gut microbiome (GM) in health and disease, its importance in burn outcomes remains unclear. Moreover, aggressive intravenous (IV) fluid resuscitation of patients may alter intestinal flora. Herein, we describe GM changes following a large burn in swine randomized to different volumes of IV Lactated Ringers' (LR).

METHODS

Anesthetized Yorkshire swine sustained 40% total body surface area full-thickness burns and were randomized to different volumes of IV LR: none (n = 5), 15 mL/kg/d (low; n = 6), or 80 mL/kg/d (high; n = 6). At baseline and days 1 and 2, fecal swabs were collected for 16s rDNA sequencing. Proximal jejunum was collected immediately after euthanasia (day 2) for western blot, histopathology, and cytokine analyses.

RESULTS

Burns produced significant shifts in β-diversity and non-significant reductions in α-diversity that did not recover regardless of treatment group. Burn-induced increases in Proteobacteria and decreases in Firmicutes were attenuated by IV fluids in a dose-dependent manner, and also correlated with α-diversity. IV fluids caused a dose-dependent increase in Bacteroides and prevented a transient increase in the opportunistic pathogen Haemophilus parainfluenzae. While high volumes of IV fluids increased intestinal Hsp70 levels (P = 0.0464), they reduced SGLT1 (P = 0.0213) and caspase3 (P = 0.0139) levels. IV fluids elicited a non-specific cytokine response; however, Bacteroidetes levels correlated with intestinal IL18 levels (P = 0.0166, R = 0.4201).

CONCLUSIONS

We present the first report on the gut microbiome in a porcine burn model, and present data to suggest that IV fluids may influence GM and gut functional proteins following a burn. Overall, burn-induced GM diversity shifts may expose diagnostic and/or therapeutic targets to improve outcomes.

A case study demonstrating tolerance of the gut to large volumes of enteral fluids as a complement to IV fluid resuscitation in burn shock

Appropriate intravenous fluid resuscitation has improved early post burn outcomes. However, clinical and pre-clinical evidence suggests that enteral or oral resuscitation may complement intravenous fluid administration. While this strategy is often discussed in the context of resource-limited settings, its implementation could reduce overall IV fluid requirements and simplify management during routine care. Conversely, concerns about this strategy have been raised over impaired gut perfusion and function leading to adverse effects. We present a case of an 82-year-old man with a total burn size of 14% who was encouraged to ingest the oral rehydration solution Drip Drop® starting 7 hours post-burn. In the ensuing 17 hours he consumed over 5 L of oral rehydration solution, which was nearly 1 L more than the total amount of IV fluids he received. There were no adverse gastrointestinal side effects. This demonstrates tolerance of a significant volume of voluntary oral fluids in combination with IV resuscitation. Clinical trials are warranted.

Minimal Effects of Intravenous Administration of Xenogeneic Adipose Derived Stem Cells on Organ Function in a Porcine 40%TBSA Burn Model

Adipose stem cells (ASCs) have shown therapeutic promise for various conditions, including burn injury. While ASCs have immunomodulatory properties, concerns exist over pro-coagulant activity after intravenous (IV) administration. In the present study, we examined IV human ASC delivery in terms of coagulation, organ function, and inflammation in a 40% total body surface area (TBSA) swine burn model. Anesthetized female Yorkshire swine were burned and randomized to receive 15ml/kg Lactated Ringer's containing: no ASCs; a low dose (5x10 5 ASCs/kg), or a high dose (5x10 6 ASCs/kg). For biochemical analysis, blood was collected at baseline (BL), 3, 6, 12, and 24 hours post-burn, while kidney and liver tissue was collected post-euthanasia. A significant, but transient, effect of ASCs was seen on prothrombin times and INR, wherein low doses revealed slight hypercoagulation. Burns increased partial thromboplastin time, fibrinogen, and d-dimer levels, which was unchanged with ASC administration. ASCs tended to exacerbate increases in bilirubin at 3 hours, but this didn't reach statistical significance. A significant effect of ASCs on creatinine and BUN was seen, wherein low doses elevated levels at 24 hours (creatinine, p=0.0012; BUN, p=0.0195). Hepatic and renal TUNEL staining were similar for all groups. A dose-dependent decrease in IL-8 was observed, while low doses significantly increased IL-1RA at 3 (p=0.050), IL-12 at 12 (p=0.021) and IL-6 at 24 hours post-burn (p=0.035). IV administration of xenogeneic ASCs slightly increased coagulation, but effects on burn-induced renal and hepatic dysfunction effects were minimal. Despite some significant immunomodulation, organ dysfunction effects were modest. Collectively, this study provides evidence to be skeptical about xenogeneic ASC administration in regards to burn.

Porcine models of acute kidney injury

Pigs represent a potentially attractive model for medical research. Similar body size and physiological patterns of kidney injury that more closely mimic those described in humans make larger animals attractive for experimentation. Using larger animals, including pigs, to investigate the pathogenesis of acute kidney injury (AKI) also serves as an experimental bridge, narrowing the gap between clinical disease and preclinical discoveries. This article compares the advantages and disadvantages of large versus small AKI animal models and provides a comprehensive overview of the development and application of porcine models of AKI induced by clinically relevant insults, including ischemia-reperfusion, sepsis, and nephrotoxin exposure. The primary focus of this review is to evaluate the use of pigs for AKI studies by current investigators, including areas where more information is needed.

A simplified fluid resuscitation formula for burns in mass casualty scenarios: Analysis of the consensus recommendation from the WHO Emergency Medical Teams Technical Working Group on Burns

BACKGROUND

Burn fluid resuscitation guidelines have not specifically addressed mass casualty with resource limited situations, except for oral rehydration for burns below 40% total body surface area (TBSA). The World Health Organization Technical Working Group on Burns (TWGB) recommends an initial fluid rate of 100 mL/kg/24 h, either orally or intravenously, beyond 20% TBSA burned. We aimed to compare this formula with current guidelines.

METHODS

The TWGB formula was numerically compared with 2-4 mL/kg/%TBSA for adults and the Galveston formula for children.

RESULTS

In adults, the TWGB formula estimated fluid volumes within the range of current guidelines for burns between 25 and 50% TBSA, and a maximal 20 mL/kg/24 h difference in the 20-25% and the 50-60% TBSA ranges. In children, estimated resuscitation volumes between 20 and 60% TBSA approximated estimations by the Galveston formula, but only partially compensated for maintenance fluids. Beyond 60% TBSA, the TWGB formula underestimated fluid to be given in all age groups.

CONCLUSION

The TWGB formula for mass burn casualties may enable appropriate fluid resuscitation for most salvageable burned patients in disasters. This simple formula is easy to implement. It should simplify patient management including transfers, reduce the risk of early complications, and thereby optimize disaster response, provided that tailored resuscitation is given whenever specialized care becomes available.

An Assessment of Research Priorities to Dampen the Pendulum Swing of Burn Resuscitation

On June 17 to 18, 2019, the American Burn Association, in conjunction with Underwriters Laboratories, convened a group of experts on burn resuscitation in Washington, DC. The goal of the meeting was to identify and discuss novel research and strategies to optimize the process of burn resuscitation. Patients who sustain a large thermal injury (involving >20% of the total body surface area [TBSA]) face a sequence of challenges, beginning with burn shock. Over the last century, research has helped elucidate much of the underlying pathophysiology of burn shock, which places multiple organ systems at risk of damage or dysfunction. These studies advanced the understanding of the need for fluids for resuscitation. The resultant practice of judicious and timely infusion of crystalloids has improved mortality after major thermal injury. However, much remains unclear about how to further improve and customize resuscitation practice to limit the morbidities associated with edema and volume overload. Herein, we review the history and pathophysiology of shock following thermal injury, and propose some of the priorities for resuscitation research. Recommendations include: studying the utility of alternative endpoints to resuscitation, reexamining plasma as a primary or adjunctive resuscitation fluid, and applying information about inflammation and endotheliopathy to target the underlying causes of burn shock. Undoubtedly, these future research efforts will require a concerted effort from the burn and research communities.

Burn resuscitation strategy influences the gut microbiota-liver axis in swine

Fluid resuscitation improves clinical outcomes of burn patients; however, its execution in resource-poor environments may have to be amended with limited-volume strategies. Liver dysfunction is common in burn patients and gut dysbiosis is an understudied aspect of burn sequelae. Here, the swine gut microbiota and liver transcripts were investigated to determine the impact of standard-of-care modified Brooke (MB), limited-volume colloid (LV-Co), and limited-volume crystalloid (LV-Cr) resuscitation on the gut microbiota, and to evaluate its' potential relationship with liver dysfunction. Independent of resuscitation strategy, bacterial diversity was reduced 24 h post-injury, and remained perturbed at 48 h. Changes in community structure were most pronounced with LV-Co, and correlated with biomarkers of hepatocellular damage. Hierarchical clustering revealed a group of samples that was suggestive of dysbiosis, and LV-Co increased the risk of association with this group. Compared with MB, LV-Co and LV-Cr significantly altered cellular stress and ATP pathways, and gene expression of these perturbed pathways was correlated with major dysbiosis-associated bacteria. Taken together, LV-Co resuscitation exacerbated the loss of bacterial diversity and increased the risk of dysbiosis. Moreover, we present evidence of a linkage between liver (dys)function and the gut microbiota in the acute setting of burn injury.

A 30% incidence of renal cysts with varying sizes and densities in biomedical research swine is not associated with renal dysfunction

BACKGROUND

Renal cystic disease arising from various etiologies results in fluid-filled cavities within the kidneys. Moreover, preexisting renal dysfunction has been shown to exacerbate multiple pathologies. While swine bred for biomedical research are often clinically inspected for illness/parasites, more advanced diagnostics may aid in uncovering underlying renal abnormalities.

METHODS

Computed tomography was performed in 54 female prepubertal Yorkshire swine to characterize renal cysts; urine and blood chemistry, and histology of cysts were also performed.

RESULTS

Digital reconstruction of right and left kidneys demonstrated that roughly one-third of the animals (17/54; 31%) had one or more renal cyst. Circulating biomarkers of renal function were not different between animals that had cysts and those that did not. Alternatively, urinary glucose (P = .03) was higher and sodium (P = .07) tended to be lower in animals with cysts compared to animals without, with no differences in protein (P = .14) or potassium (P = .20). Aspiration of cystic fluid was feasible in two animals, which revealed that the cystic fluid urea nitrogen (97.6 ± 28.7 vs 911.3 ± 468.2 mg/dL), potassium (29.8 ± 14.4 vs 148.2 ± 24.85 mmol/L), uric acid (2.55 ± 1.35 vs 11.4 ± 5.65 mg/dL), and creatinine (60.34 ± 17.26 vs 268.99 ± 95.79 mg/dL) were much lower than in the urine. Histology demonstrated a cyst that markedly compresses the adjacent cortex and is lined by a single layer of flattened epithelium, bounded by fibrous connective tissue which extends into the parenchyma. There is tubular atrophy and loss in these areas.

CONCLUSION

This study provides valuable insight for future studies focusing on kidney function in swine bred for biomedical research.

Increased oxidative phosphorylation in lymphocytes does not atone for decreased cell numbers after burn injury

The acute systemic inflammatory response syndrome (SIRS) and multiorgan dysfunction (MOD) that occur in large burn injuries may be attributed, in part, to immunosuppressive responses such as decreased lymphocytes. However, the mitochondrial bioenergetics of lymphocytes after severe burn injury are poorly understood. The purpose of this study was to examine mitochondrial function of lymphocytes following severe burns in a swine model. Anesthetized Yorkshire swine (n = 17) sustained 40% total body surface area full-thickness contact burns. Blood was collected at pre-injury (Baseline; BL) and at 24 and 48 h after injury for complete blood cell analysis, flow cytometry, cytokine analysis, and ficoll separation of intact lymphocytes for high-resolution mitochondrial respirometry analysis. While neutrophil numbers increased, a concomitant decrease was found in lymphocytes (P < 0.001) after burn injury, which was not specific to CD4+ or CD8+ lymphocytes. No changes in immune cell population were observed from 24 h to 48 h post-injury. IL 12-23 decreased while a transient increase in IL 4 was found from BL to 24h (P < 0.05). CRP progressively increased from BL to 24h (P < 0.05) and 48h (P < 0.001) post-injury. Routine and maximal mitochondrial respiration progressively increased from BL to 24h (P < 0.05) and 48 h post-injury (P < 0.001). No changes were found in leak respiration or residual oxygen consumption. When considering the reduction in lymphocyte number, the total peripheral lymphocyte bioenergetics per volume of blood significantly decreased from BL to 24h and 48h (P < 0.05). For the first time, we were able to measure mitochondrial activity in intact lymphocyte mitochondria through high-resolution respirometry in a severely burned swine model. Our data showed that the non-specific reduction in peripheral T cells after injury was larger than the increased mitochondrial activity in those cells, which may be a compensatory mechanism for the total reduction in lymphocytes. Additional studies in the metabolic activation of T cell subpopulations may provide diagnostic or therapeutic targets after severe burn injury.

Effect of Intravenous Fluid Volumes on the Adrenal Glucocorticoid Response After Burn Injury in Swine

Severe thermal injury induces metabolic and physiological stress, prompting a disruption in the hypothalamic-pituitary-adrenal axis. The objective of this study was to evaluate potential confounding effects of Lactated Ringer's (LR) resuscitation on adrenal damage and cortisol production following burn. Anesthetized swine were instrumented with jugular catheters and sustained 40% TBSA burns from brass probes heated to 100°C. Animals recovered to consciousness and received IV fluid resuscitation with LR at two different volumes: 15 ml/kg/d (limited volume [LV], n = 6) or 2 ml/kg/%TBSA/d (modified Brooke [MB], n = 6). Nonburned animals (Sham) were both oral and IV fluid restricted (S-FR, n = 4) to induce stress. Computed tomography (CT) angiographies were performed at baseline (BL) and 48 hours postburn, while blood and urine samples were collected at BL, 6, 24, and 48 hours postburn, with euthanasia at 48 hours for adrenal harvesting. Urinary cortisol was elevated following burn/surgery in all animals and returned back to BL in S-FR (404 ± 48 pg/mg creatinine) but not MB (1332 ± 176 pg/mg creatinine; P = .005) or LV (1223 ± 335 pg/mg creatinine; P = .07) by 48 hours. Gene expression of cleavage enzymes (3β-HSD, CYP17, CYP11, and CYP21) along the cortisol synthesis pathway showed minimal changes. Adrenal apoptosis (Terminal deoxynucleotidyl transferase dUTP nick-end labeling [TUNEL] staining) was greatest in the MB group (P ≤ .01) when compared to S-FR, partly due to elevations in c-Jun N-terminal kinase. Adrenal hemorrhaging was also greatest in MB animals, with no differences in tissue volume or wet-to-dry ratio. However, tissue levels of cytokines IL-1β, IL-10, and IL-12 were greatest in LV. Burn injury elevates urinary cortisol and compromises adrenal gland integrity, which is affected by IV fluid volume.

Burn injury

Burn injuries are under-appreciated injuries that are associated with substantial morbidity and mortality. Burn injuries, particularly severe burns, are accompanied by an immune and inflammatory response, metabolic changes and distributive shock that can be challenging to manage and can lead to multiple organ failure. Of great importance is that the injury affects not only the physical health, but also the mental health and quality of life of the patient. Accordingly, patients with burn injury cannot be considered recovered when the wounds have healed; instead, burn injury leads to long-term profound alterations that must be addressed to optimize quality of life. Burn care providers are, therefore, faced with a plethora of challenges including acute and critical care management, long-term care and rehabilitation. The aim of this Primer is not only to give an overview and update about burn care, but also to raise awareness of the ongoing challenges and stigmata associated with burn injuries.

Impact of oral resuscitation on circulating and splenic leukocytes after burns

BACKGROUND

Hemodynamic aberrations after severe burns are treated with aggressive intravenous (IV) fluid resuscitation however, oral resuscitation has been proposed in resource poor scenarios. Previously we have shown that animals receiving oral fluid following burns were able to recover kidney function. However, immune function such as circulating and splenic immune cell populations after oral or intravenous fluid administration was not examined. Herein, we perform a follow up analysis of splenic tissue and plasma from the previous animal study to examine the splenic response following these resuscitation strategies after burn injury.

METHODS

Eighteen anesthetized Yorkshire swine receiving 40%TBSA contact burns were randomized to receive either: (1) no fluids (Fluid Restricted; negative control), (2) 70 mL/kg/d Oral Rehydration Salt solution (Oral), or (3) 2 mL/kg/%TBSA/d of lactated Ringer's solution IV. Blood was drawn for blood cell analysis, and CT scans were performed before and 48 h post-burn, at which point spleens were harvested for histological, Western blot, and RT-PCR analyses.

RESULTS

Splenic artery diameter decreased by -0.97 ± 0.14 mm in fluid-restricted animals, while IV led to an increase of 0.68 ± 0.30 mm. No significant differences were detected in white and red pulp. IV fluids reduced the population of splenic monocytes (CD163; P = 0.001) and neutrophils (MPO protein; P = 0.13), as well as cytokines IL-8 (P = 0.003), IFN-γ (P = 0.11) and TNFα (P = 0.05). Additionally, withholding IV fluids consistently decreased the expression of FoxP3, CCR6, and IL17β in spleen, suggesting a shift in T-cell phenotype with IV resuscitation.

CONCLUSIONS

The route of fluid administration has a minor influence on the changes in circulating and splenic leukocytes post-burn in the acute phase. Further research is needed to help guide resuscitation approaches using immunologic markers of splenic function following burns.

Burn-induced reductions in mitochondrial abundance and efficiency are more pronounced with small volumes of colloids in swine

Severe burn injury results in systemic disruption of metabolic regulations and impaired cardiac function. Restoration of hemodynamic homeostasis utilizing intravenous (IV) fluids is critical for acute care of the burn victim. However, the effects of burns and resuscitation on cardiomyocyte mitochondria are currently unknown. The purpose of this study is to determine cardiac mitochondrial function in a swine burn model with subsequent resuscitation using either crystalloids or colloids. Anesthetized Yorkshire swine (n = 23) sustained 40% total body surface area burns and received IV crystalloids (n = 11) or colloids (n = 12) after recovery from anesthesia. Non-burned swine served as controls (n = 9). After euthanasia at 48 h, heart tissues were harvested, permeabilized, and analyzed by high-resolution respirometry. Citrate synthase (CS) activity was measured, and Western blots were performed to quantify proteins associated with mitochondrial fusion (OPA1), fission (FIS1), and mitophagy (PINK1). There were no differences in state 2 respiration or maximal oxidative phosphorylation. Coupled complex 1 respiration decreased, while uncoupled state 4_O and complex II increased significantly due to burn injury, particularly in animals receiving colloids (P < 0.05). CS activity and electron transfer coupling efficiency were significantly lower in burned animals, particularly with colloid treatment (P < 0.05). Protein analysis revealed increased FIS1 but no differences in mitophagy in cardiac tissue from colloid-treated compared with crystalloid-treated swine. Taken together, severe burns alter mitochondrial respiration in heart tissue, which may be exacerbated by early IV resuscitation with colloids. Early IV burn resuscitation with colloids may require close hemodynamic observation. Mitochondrial stabilizing agents incorporated into resuscitation fluids may help the hemodynamic response to burn injury.

Fluid Stewardship During Critical Illness: A Call to Action

Intravenous fluids (IVFs) are the most common drugs administered in the intensive care unit. Despite the ubiquitous use, IVFs are not benign and carry significant risks associated with under- or overadministration. Hypovolemia is associated with decreased organ perfusion, ischemia, and multi-organ failure. Hypervolemia and volume overload are associated with organ dysfunction, delayed liberation from mechanical ventilation, and increased mortality. Despite appropriate provision of IVF, adverse drug effects such as electrolyte abnormalities and acid-base disturbances may occur. The management of volume status in critically ill patients is both dynamic and tenuous, a process that requires frequent monitoring and high clinical acumen. Because patient-specific considerations for fluid therapy evolve across the continuum of critical illness, a standard approach to the assessment of fluid needs and prescription of IVF therapy is necessary. We propose the principle of "fluid stewardship," guided by 4 rights of medication safety: right patient, right drug, right route, and right dose. The successful implementation of fluid stewardship will aid pharmacists in making decisions regarding IVF therapy to optimize hemodynamic management and improve patient outcomes. Additionally, we highlight several areas of focus for future research, guided by the 4 rights construct of fluid stewardship.