Insulin resistance postburn: underlying mechanisms and current therapeutic strategies

Metformin is associated with reduced risk of mortality and morbidity in burn patients compared to insulin

PURPOSE

The standard of care for burned patients experiencing hyperglycemia associated with the hypermetabolic response is insulin therapy. Insulin treatment predisposes burn patients to hypoglycemia, which increases morbidity and mortality. Metformin has been suggested as an alternative to insulin therapy for glycemic control in burn patients given its safety profile, but further research is warranted. This study investigated whether metformin use in burn patients is associated with improved glycemic control and morbidity/mortality outcomes compared to insulin use alone.

MATERIALS AND METHODS

Using the TriNetX database, we conducted a retrospective study of burned patients who were administered insulin, metformin, or both within one week of injury. Demographic, comorbidity, and burn severity information were collected. Patients were categorized by treatment type, propensity score-matched, and compared for the following outcomes within 3 months: hyperglycemia, hypoglycemia, sepsis, lactic acidosis, and death. Statistical significance was set a priori at p ≤ 0.05.

RESULTS

The insulin cohort was at increased risk for all outcomes (all p < 0.0001) compared to the metformin cohort, and an increased risk for sepsis, lactic acidosis, and death (all p ≤ 0.0002) compared to the insulin/metformin combination cohort. When compared to the metformin cohort, the combination cohort was at increased risk for all outcomes (all p ≤ 0.0107) except death.

CONCLUSIONS

Treatment with metformin after burn is associated with a reduced risk of morbidity and mortality compared to insulin. The combination of insulin and metformin is no more effective in reducing the risk of hyperglycemia and hypoglycemia than insulin alone but is less effective than metformin alone.

Associations of Diabetes and Hyperglycaemia with Extent and Outcomes of Acute Burn Injuries

BACKGROUND

Severe burns may induce hyperglycaemia in the absence of diabetes, but how glucose trajectories relate to burns outcomes is unclear.

AIM

To assess incidence of hyperglycaemia following acute burn injury, and associations with diabetes history and length of stay (LOS).

METHODS

Retrospective cohort study of adults admitted with acute burns to tertiary centres. Blood glucose level (BGL), hyperglycaemic episodes (BGL ≥ 11.1 mmol/L) and hyperglycaemic days were recorded. Stress hyperglycaemia was defined as BGL ≥ 11.1 mmol/L without a diabetes history.

RESULTS

A total of 30 participants had a diabetes history and 260 did not. Participants with known diabetes had higher mean BGLs (9.7 vs. 9.0 mmol/L, p < 0.001), more hyperglycaemic episodes (28.0 vs. 17.2%, p < 0.001) and hyperglycaemic days (51 vs. 21%, p < 0.001), compared to those without diabetes, despite smaller burns (total body surface area 1.0 vs. 14.8%, p < 0.001). Fourteen participants with stress hyperglycaemia had similar BGLs (at admission 10.3 vs. 11.5 mmol/L; during inpatient stay 9.9 vs. 9.8 mmol/L), more severe burns (15.6% vs. 1.0% TBSA) and longer LOS (18 vs. 7 days, p < 0.001) compared to participants with known diabetes. Extent of burns, having NGT nutrition, age, having inpatient BGL monitoring in the setting of diabetes, or having inpatient BGL monitoring in the absence of diabetes were associated with longer LOS.

CONCLUSIONS

In participants with known diabetes, small burn injuries were associated with hyperglycaemia. Stress hyperglycaemia can be triggered by major burn injuries, with early and sustained elevation of BGLs. Further research is warranted to improve inpatient management of BGL in patients with acute burn injury.

1H-nuclear magnetic resonance analysis reveals dynamic changes in the metabolic profile of patients with severe burns

Background

Severe burn injury causes a hypermetabolic response, resulting in muscle protein catabolism and multiple organ damage syndrome. However, this response has not yet been continuously characterized by metabolomics in patients. This study aims to quantify temporal changes in the metabolic processes of patients with severe burns.

Methods

We employed 1H-nuclear magnetic resonance (NMR) spectroscopy to scrutinize metabolic alterations during the initial 35 days following burn injury in a cohort of 17 adult patients with severe burns, with 10 healthy individuals included as controls. Plasma specimens were collected from patients on postburn days 1, 3, 7, 14, 21, 28 and 35. After performing multivariate statistical analysis, repeated-measures analysis of variance and time-series analysis, we quantified changes in metabolite concentrations.

Results

Among the 36 metabolites quantified across 119 samples from burn patients, branched-chain amino acids, glutamate, glycine, glucose, pyruvate, lactate, trimethylamine N-oxide and others exhibited obvious temporal variations in concentration. Notably, these metabolites could be categorized into three clusters based on their temporal characteristics. The initial response to injury was characterized by changes in lactate and amino acids, while later changes were driven by an increase in fatty acid catabolism and microbial metabolism, leading to the accumulation of ketone bodies and microbial metabolites.

Conclusions

Metabolomics techniques utilizing NMR have the potential to monitor the intricate processes of metabolism in patients with severe burns. This study confirmed that the third day after burn injury serves as the boundary between the ebb phase and the flow phase. Furthermore, identification of three distinct temporal patterns of metabolites revealed the intrinsic temporal relationships between these metabolites, providing clinical data for optimizing therapeutic strategies.

[Burns and Diabetes Mellitus: Epidemiology, Clinical Presentation and Prognosis]

Burns in diabetics are quite frequent and serious in relation to diabetic neuropathy, which is common in this population, delaying healing and predisposing to the risk of infection. The objective of this study was to describe the characteristics of burns in diabetics hospitalized at the CTB of Tunis over 18 months. During the study period, 891 patients were hospitalized, including 43 diabetics (5%). The average age of our patients was 57 years old with a male predominance (65%). Type 2 diabetes was present in 86% of cases and type 1 diabetes in 14% of cases. Degenerative complications were reported in 10 cases (23%), such as diabetic retinopathy (n=6), diabetic nephropathy (n=4) and diabetic neuropathy (n=6). The circumstances of burns were related to a domestic accident in 2/3 of the cases (76.7%). Thermal burns were involved in 83.7% of cases. 86% of the patients had decompensated their diabetes during their hospitalization. Sepsis marked the evolution of the patients in 55.8% of cases. In our study, poor prognostic factors were: a glycosylated haemoglobin > 13%, an extent of burns greater than 20%, and a delay in consultation greater than 6 hours. The mortality rate was 18.6%.

Metabolic and Nutritional Support

Hypermetabolism is a hallmark of larger burn injuries. The hypermetabolic response is characterized by marked and sustained increases in catecholamines, glucocorticoids, and glucagon. There is an increasing body of literature for nutrition and metabolic treatment and supplementation to counter the hypermetabolic and catabolic response secondary to burn injury. Early and adequate nutrition is key in addition to adjunctive therapies, such as oxandrolone, insulin, metformin, and propranolol. The duration of administration of anabolic agents should be at minimum for the duration of hospitalization, and possibly up to 2 to 3 years postburn.

Hyperosmolar Hyperglycemic Crisis After Burn Injury in a Patient With Advanced Amyotrophic Lateral Sclerosis: A Case Report

ABSTRACT

Metabolic disturbance in patients of amyotrophic lateral sclerosis is a rare presentation that might be related to disease progression and outcomes. Hypermetabolic status after major burn injury remains a critical issue in the modern medical care. Here, we present a rare case of a patient sporadic amyotrophic lateral sclerosis who suffered from minor burn injury (8% total body surface area), developing critical hyperosmolar hyperglycemic state during early hospitalization. Newly diagnosed diabetes is established and found related to the underlying disease of this patient. The accumulative metabolic alteration among vulnerable patients of amyotrophic lateral sclerosis and burn injury is noteworthy. Judicious monitoring of fluid and metabolic status helps to prevent the occurrence of acute hyperosmolar hyperglycemic state.

Farnesysltransferase Inhibitor Prevents Burn Injury-Induced Metabolome Changes in Muscle

Burn injury remains a significant public health issue worldwide. Metabolic derangements are a major complication of burn injury and negatively affect the clinical outcomes of severely burned patients. These metabolic aberrations include muscle wasting, hypermetabolism, hyperglycemia, hyperlactatemia, insulin resistance, and mitochondrial dysfunction. However, little is known about the impact of burn injury on the metabolome profile in skeletal muscle. We have previously shown that farnesyltransferase inhibitor (FTI) reverses burn injury-induced insulin resistance, mitochondrial dysfunction, and the Warburg effect in mouse skeletal muscle. To evaluate metabolome composition, targeted quantitative analysis was performed using capillary electrophoresis mass spectrometry in mouse skeletal muscle. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and hierarchical cluster analysis demonstrated that burn injury induced a global change in metabolome composition. FTI treatment almost completely prevented burn injury-induced alterations in metabolite levels. Pathway analysis revealed that the pathways most affected by burn injury were purine, glutathione, β-alanine, glycine, serine, and threonine metabolism. Burn injury induced a suppressed oxidized to reduced nicotinamide adenine dinucleotide (NAD⁺/NADH) ratio as well as oxidative stress and adenosine triphosphate (ATP) depletion, all of which were reversed by FTI. Moreover, our data raise the possibility that burn injury may lead to increased glutaminolysis and reductive carboxylation in mouse skeletal muscle.

Ameliorative effect of bone marrow-derived mesenchymal stem cells on burn-induced hepatic and metabolic derangements in rats

AIMS

The current study aims to investigate the therapeutic potential of bone marrow-derived mesenchymal stem cells (MSCs) as a solo therapy in ameliorating both skin lesions and liver injury induced by cutaneous severe burn injury (SBI) in rats.

MAIN METHODS

In anesthetized male adult Wistar albino rats, 30 % total burn surface area and established hepatic injury was achieved via direct contact of each experimental animal's dorsum with heated metal rod (100 °C) for 10 s. On the next day following burn, human MSCs or mouse MSCs was administered locally around the burn site and intraperitonially (0.5 × 10⁶ cells/rat for each route) and outcomes were investigated at 4 and 14 days following burn induction.

KEY FINDINGS

Both types of MSCs significantly improved skin and liver histology, decreased liver enzymes, and ameliorated oxidative stress in hepatocytes of SBI-rats. Further, SBI-induced rises in hepatic apoptotic marker (caspase-3, Bax) and serum inflammatory markers (TNF-α, IL-1β, and IL-6) were reduced following either human or mouse MSC administration. In addition, MSCs augmented insulin receptor substrate-1, phosphorylated protein kinase-B (phospho-Akt), while alleviating serum glucose levels in SBI-rats. These previous effects persisted even at the 14-day time point.

SIGNIFICANCE

Following single administration, bone marrow-derived MSCs is capable of counteracting SBI-induced skin lesions as well as related hepatic complications, specifically via mitigating postburn hyperglycemia and hyperinflammation.

Organophosphate esters exposure in relation to glucose homeostasis and type 2 diabetes in adults: A national cross-sectional study from the national health and nutrition survey

BACKGROUND

Exposure to organophosphate esters (OPEs) may be associated with impaired glucose homeostasis and increased risk of type 2 diabetes (T2D) in adolescent. However, the evidence in general population is scarce, especially for glucose homeostasis. We used data from the National Health and Nutrition Examination Survey (NHANES) 1999-2008 and 2011-2012 to investigate the relationship of urinary OPEs with glucose homeostasis and T2D in adults.

METHODS

A total of 5347 participants aged ≥20 years were included. The exposures were the concentrations of urinary OPEs metabolites [dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP), dimethyl dithiophosphate (DMDTP), diethyl phosphate (DEP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP)]. The health outcomes were prevalence of T2D and glucose homeostasis [i.e., fasting glucose, 2-h plasma glucose during a 75-g oral glucose tolerance test (2 h-OGTT), serum insulin, HemoglobinA1c (HbA1c), HOMA-IR, and HOMA-β]. The multivariable linear regression model was used to evaluate the relationship between OPEs and glucose homeostasis. The multivariable binary logistic regression analysis was used to investigate the relationship between OPEs and prevalence of T2D.

RESULTS

The OPEs compound DMTP was significantly associated with higher levels of serum insulin [β (95%confidence interval, CI) = 0.21 (0.06,0.36), for one unit increase in log₂-transformed exposure] and HOMA IR [β (95%CI) = 0.08 (0.02,0.14)], and increased odds of T2D [odds ratio (95% CI) = 1.05 (1.01-1.08)]. Other OPEs were not statistically associated with the serum markers for glucose homeostasis or T2D prevalence.

CONCLUSION

Our study found that the OPEs compound DMTP might be associated with impaired glucose homeostasis and may increase the prevalence of T2D in U.S. adults. Further longitudinal or experimental studies are warranted to verify our findings in different populations and different OPEs concentrations.

Metabolic Syndrome and Skin: Interactions and Implications

The metabolic syndrome (MetS) has become a global crisis and is believed to affect almost one-quarter of the world's population. Its prevalence has been rising, especially in the younger age group. The interactions of the skin and MetS are myriad. Physiological functions of the skin may confer a protective role, whereas cutaneous diseases may play the role of MetS initiator or amplifier. Cutaneous signs may be some of the earliest manifestations of insulin resistance, the basic pathophysiology behind MetS. Skin changes are also prominent in type 2 diabetes mellitus, the consequence of MetS. Drugs used in dermatological disorders can lead to metabolic dysfunction. Awareness about the risk factors and early lifestyle interventions can help delay or even prevent the life-threatening complications of this syndrome. Dermatologists are in a unique position to predict and prevent MetS or its complications, a long time before the patient visits a physician for systemic problems. To write this review, an internet search was made focusing on articles on skin problems associated with MetS and its components, its risk factors, pathogenesis, and ways to prevent it. Information relevant to dermatological practice was compiled.

Rehabilitative Exercise Training for Burn Injury

Due to improvements in acute burn care over the last few decades, most patients with severe burns (up to 90% of the total body surface) survive. However, the metabolic and cardiovascular complications that accompany a severe burn can persist for up to 3 years post injury. Accordingly, there is now a greater appreciation of the need for strategies that can hasten recovery and reduce long-term morbidity post burn. Rehabilitation exercise training (RET) is a proven effective treatment to restore lean body mass, glucose and protein metabolism, cardiorespiratory fitness, and muscle strength in burn survivors. Despite this, very few hospitals incorporate RET in programs to aid the rehabilitation of patients with severe burns. Given that RET is a safe and efficacious treatment that restores function and reduces post-burn morbidity, we propose that a long-term exercise prescription plan should be considered for all patients with severe burns. In this literature review, we discuss the current understanding of burn trauma on major organ systems, and the positive benefits of incorporating RET as a part of the long-term rehabilitation of severely burned individuals. We also provide burn-specific exercise prescription guidelines for clinical exercise physiologists.

Glucose Metabolism in Burns-What Happens?

Severe burns represent an important challenge for patients and medical teams. They lead to profound metabolic alterations, trigger a systemic inflammatory response, crush the immune defense, impair the function of the heart, lungs, kidneys, liver, etc. The metabolism is shifted towards a hypermetabolic state, and this situation might persist for years after the burn, having deleterious consequences for the patient's health. Severely burned patients lack energy substrates and react in order to produce and maintain augmented levels of glucose, which is the fuel "ready to use" by cells. In this paper, we discuss biological substances that induce a hyperglycemic response, concur to insulin resistance, and determine cell disturbance after a severe burn. We also focus on the most effective agents that provide pharmacological modulations of the changes in glucose metabolism.

Inflammation, Nitro-Oxidative Stress, Impaired Autophagy, and Insulin Resistance as a Mechanistic Convergence Between Arterial Stiffness and Alzheimer's Disease

The average age of the world's elderly population is steadily increasing. This unprecedented rise in the aged world population will increase the prevalence of age-related disorders such as cardiovascular disease (CVD) and neurodegeneration. In recent years, there has been an increased interest in the potential interplay between CVDs and neurodegenerative syndromes, as several vascular risk factors have been associated with Alzheimer's disease (AD). Along these lines, arterial stiffness is an independent risk factor for both CVD and AD. In this review, we discuss several inflammaging-related disease mechanisms including acute tissue-specific inflammation, nitro-oxidative stress, impaired autophagy, and insulin resistance which may contribute to the proposed synergism between arterial stiffness and AD.

Incidence of Laryngotracheal Stenosis after Thermal Inhalation Airway Injury

Inhalation injury is independently associated with burn mortality, yet little information is available on the incidence, risk factors, or functional outcomes of thermal injury to the airway. In patients with thermal inhalation injury, we sought to define the incidence of laryngotracheal stenosis (LTS), delineate risk factors associated with LTS development, and assess long-term tracheostomy dependence as a proxy for laryngeal function. Retrospective cohort study of adult patients treated for thermal inhalation injury at a single institution burn critical care unit from 2012 to 2017. Eligible patients' records were assessed for LTS (laryngeal, subglottic, or tracheal stenosis). Patient characteristics, burn injury characteristics, and treatment-specific covariates were assessed. Descriptive statistics, Mann-Whitney U-tests, odds ratio, and chi-square tests compared LTS versus non-LTS groups. Of 129 patients with thermal inhalation injury during the study period, 8 (6.2%) developed LTS. When compared with the non-LTS group, patients with LTS had greater mean TBSA (mean 30.3, Interquartile Range 7-57.5 vs 10.5, Interquartile Range 0-15.12, P = .01), higher grade of inhalation injury (mean 2.63 vs 1.80, P = .05), longer duration of intubation (12.63 vs 5.44; P < .001), and greater inflammatory response (mean white blood cell count on presentation 25.8 vs 14.9, P = .02, mean hyperglycemia on presentation 176.4 vs 136.9, P = .01). LTS patients had a significantly higher rate of tracheostomy dependence at last follow-up (50 vs 1.7%, P < .001). Six percent of patients with thermal inhalation injury develop LTS. LTS was associated with more severe thermal airway injury, longer duration of intubation, and more severe initial host inflammation. Patients with inhalation injury and LTS are at high risk for tracheostomy dependence. In burn patients with thermal inhalation injury, laryngeal evaluation and directed therapy should be incorporated early into multispecialty pathways of care.

Evidence and Trends in Burn Wound Debridement: An Evidence Map

Treatment of the burn wound is crucial in care of severely burned patients. Surgical strategies differ in technique and timing of wound excision and are considered to have an impact on morbidity and mortality of burn patients. Most techniques and strategies have been established during the last century and are still standard of care. Nonetheless, several newer techniques have been presented and evaluated recently. To summarize the evidence and trends for eschar removal by burn wound debridement currently available, an evidence map as variant of the systematic review, was prepared. For this purpose, a systematic literature search was performed in the PubMed databases until December 2016. While overall evidence in this domain is low, recent publications focus on optimal timing of wound excision, enzymatic debridement, and hydrosurgery. Several studies report the benefit of an early wound excision in terms of shorter hospital stay, lower wound infection rate, and reduction of postburn metabolic changes. Enzymatic debridement has been shown to be an effective tool for early eschar removal and in addition reduces the need for autografting of the debrided burn wound with a relatively high level of evidence (LoE 2-). Wound debridement by means of hydrosurgery is more precise compared to conventional wound excision and preserves viable dermis, but a positive effect on wound healing or scar formation could not been shown (LoE 2). Furthermore, rarely reported techniques comprise larvae therapy, debridement by laser, and other technical adjuncts, but the level of evidence is limited (LoE 4-/5).

Evaluation of the use of sitagliptin for insulin resistance in burn patients

BACKGROUND

Following severe burn injury, patients undergo profound metabolic changes, including insulin resistance and hyperglycemia. Hyperglycemia has been linked to impaired wound healing, increased risk of skin graft loss, increased muscle catabolism, increased infections, and mortality. Sitagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that improves glycemic control by slowing the inactivation of incretin hormones, increasing insulin synthesis and release from pancreatic beta cells and lowering glucagon secretion from pancreatic alpha cells. The objective of this study was to describe our institution's experience with using sitagliptin to help mitigate insulin resistance after burn injury.

METHODS

This was a retrospective chart review that included 22 adult burn patients. Burn patients were prescribed sitagliptin regardless of their previous medical history of type 2 diabetes mellitus. Patients were included in this analysis if they were adults admitted for burn injury during a 13-month period and received at least 3 consecutive doses of sitagliptin. Patients were excluded if they did not have insulin use data 3 days pre- and 3 days post-sitagliptin initiation. The first day of sitagliptin initiation was considered day 0; data from day 0 were not included in either the pre- or post-sitagliptin analysis.

RESULTS

In the 3 days prior to sitagliptin initiation, patients received a median of 114.3 units per day (IQR 49.1, 228) in an attempt to maintain a blood glucose goal of less than 180 mg/dL. In the 3 days after sitagliptin was started, exogenous insulin requirements significantly decreased to a median to 36.3 units per day (IQR 11.7, 95) (P=0.009). Seven patients were on insulin infusions at the time of sitagliptin initiation. After sitagliptin was started, it took a median of 3 days (IQR 2, 3.25) to be liberated from the insulin infusion. In terms of safety, there were two episodes of hypoglycemia (BG<70 mg/dL) after sitagliptin initiation, compared to three episodes prior to sitagliptin initiation (P=0.7).

CONCLUSION

The addition of sitagliptin to burn patients' medication regimens significantly reduced insulin requirements over a 3-day period and allowed liberation from insulin drips.

Nutritional management of a kitten with thermal burns and septicaemia

Case summary

A 3-month-old entire female British Shorthair cat presented for further management of thermal burns after falling into a bath of scalding water. On presentation to the primary care clinician the kitten was obtunded, markedly painful and relatively bradycardic, consistent with a state of shock. The haircoat was wet, with erythematous skin and sloughing from the digital pads and anal mucosa. The primary care clinician administered opioid analgesia, sedation, antibiotics and started intravenous (IV) fluid therapy prior to referral. On arrival to the referral hospital the kitten was obtunded with respiratory and cardiovascular stability but was overtly painful and resistant to handling. The kitten required intensive management with IV and regional analgesia, IV broad-spectrum antibiosis, IV fluid therapy, enteral nutrition and wound management, including surgical debridement and topical antibiotic therapy. Septicaemia developed during the hospitalisation. Multidrug-resistant Escherichia coli and Pseudomonas aeruginosa were cultured, and antibiosis was escalated to IV imipenem. Acute respiratory distress syndrome was suspected following the development of dyspnoea. Early enteral nutrition within 24 h of admission was initiated using an oesophageal feeding tube and a veterinary therapeutic liquid diet. Over the ensuing 72 h the kitten started voluntary intake of food alongside oesophageal tube feeds. The kitten experienced continued weight loss despite the provision of nutritional support to meet, and then later exceed, the estimated resting energy requirements. Caloric intake was gradually increased to a total of 438% of the calculated resting energy requirement using the most recent daily body weight, eventually resulting in stabilisation of weight loss and weight gain.

Relevance and novel information

There is limited published information on the nutritional management of veterinary patients with thermal burn injury. Hypermetabolic states related to burn injuries are induced and maintained by complex interactions of catecholamines, stress hormones and inflammatory cytokines on proteolysis, lipolysis and glycogenolysis. Secondary infections are common following burn injury and the subsequent proinflammatory state perpetuates hypermetabolism and catabolism. These states present a challenge in both predicting and providing adequate nutrition, particularly in a paediatric septic patient. This subset of patients should be monitored closely during hospitalisation to ensure body weight and condition are maintained (while taking into consideration hydration status), and caloric intake is adjusted accordingly to meet nutritional support goals. Extensive research exists regarding the nutritional requirements and metabolic derangements of people with thermal burns. However, the importance of maintaining body weight and body condition in veterinary burn patients, and the association between nutritional support and reduced morbidity and mortality, has not been investigated and remains to be elucidated.

Results of a Multicenter Feasibility Study of an Automated Bedside Glucose Monitoring System in the Burn Intensive Care Setting

Intensive blood glucose regimens required for tight glycemic control in critically ill burn patients carry risk of hypoglycemia and are ultimately limited by the frequency of which serum glucose measurements can be feasibly monitored. Continuous inline glucose monitoring has the potential to significantly increase the frequency of serum glucose measurement. The objective of this study was to assess the accuracy of a continuous glucose monitor with inline capability (Optiscanner) in the burn intensive care setting. A multicenter, observational study was conducted at two academic burn centers. One hundred and six paired blood samples were collected from 10 patients and measured on the Optiscanner and the Yellow Springs Instrument. Values were plotted on a Clarke Error Grid and mean absolute relative difference calculated. Treatment was guided by existing hospital protocols using separately obtained values. 97.2% of results obtained from Optiscanner were within 25% of corresponding Yellow Springs Instrument values and 100% were within 30%. Mean absolute relative difference was calculated at 9.6%. Our findings suggest that a continuous glucose monitor with inline capability provides accurate blood glucose measurements among critically ill burn patients.

Review: Insulin resistance and mitochondrial dysfunction following severe burn injury

The insulin signaling pathway plays a pivotal role in glucose metabolism and metabolic homeostasis. Disruption of this pathway is commonly seen in critical illness such as following severe burn injuries where homeostatic control is lost, leading to "insulin resistance" with poor blood glucose control. The aberrant signaling pathways involved in insulin resistance following burn injury include increases in hyperglycemic stress hormones, pro-inflammatory cytokines and free radical production. Leakage of mitochondrial sequestered self-antigens and signaling between mitochondria and endoplasmic reticulum also contribute to insulin resistance. Greater understanding of molecular processes involved in burn-related insulin resistance could potentially lead to the development of novel therapeutic approaches to improve patient management.

Anabolic and anticatabolic agents used in burn care: What is known and what is yet to be learned

Major thermal injury induces profound metabolic derangements secondary to an inflammatory "stress-induced" hormonal environment. Several pharmacological interventions have been tested in an effort to halt the hypermetabolic response to severe burns. Insulin, insulin growth factor 1, insulin growth factor binding protein 3, metformin, human growth hormone, thyroid hormones, testosterone, oxandrolone, and propranolol, among others, have been proposed to have anabolic or anticatabolic effects. The aim of this broad analysis of pharmacological interventions was to raise awareness of treatment options and to help establishing directions for future clinical research efforts. A PubMed search was conducted on the anabolic and anticatabolic agents used in burn care. One hundred and thirty-five human studies published between 1999 and 2017 were included in this review. The pharmacological properties, rationale for the treatments, efficacy considerations and side effect profiles are summarized in the article. Many of the drugs tested for investigational purposes in the severely thermally injured are not yet gold-standard therapies in spite of their potential benefit. Propranolol and oxandrolone have shown great promise but further evidence is still needed to clarify their potential use for anabolic and anticatabolic purposes.

Nutrition: reducing the hypermetabolic response to thermal injury

Nutritional support is seen as a vital component in the battle to attenuate the extreme hypermetabolic response experienced by patients suffering from large thermal injuries. Protein catabolism precipitating protein malnutrition places patients at greater risk of wound infection and sepsis due to delayed wound healing. Underfeeding, aggressive feeding, feeding routes, timing of initiation of feeding and tight insulin control have all been explored extensively in the quest to understand what nutritional treatment will best attenuate the hypermetabolic response. Despite this it is suggested that the majority of patients with large thermal injuries do not receive adequate nutritional support immediately post injury. Nurses have a pivotal role to play in ensuring that thermal injury patients receive appropriate nutritional support based on the best available evidence.

Activation of AMPK alleviates cardiopulmonary bypass-induced cardiac injury via ameliorating acute cardiac glucose metabolic disorder

Recent years, studies have demonstrated that hyperglycemia is one of the main manifestations after cardiac surgeries, which contributes to myocardial injuries and increases the chance of subsequent complications and mortality in such patients. However, strategies targeting at glucose metabolic disorder after cardiac surgeries to attenuate myocardial injuries are inadequately studied. In this study, a rat model of cardiopulmonary bypass (CPB) was applied to investigate the role of Adenosine 5'-monophosphate-activated protein kinase (AMPK) in modulating myocardial glucose metabolic-induced cardiac injuries after cardiac surgery. The results revealed that CPB elicited significant cardiac dysfunction, and pronouncedly elevated the markers of myocardial injuries including serum creatine kinase MB and cardiac troponin I. Additionally, blunted myocardial glucose uptake after CPB was associated with decreased membrane glucose transporter 4 (GLUT4) content. However, pretreatment of AMPK agonist 5-aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR) at the beginning of CPB activated AMPK, enhanced phosphorylation of Akt substrate 160 (AS160), and increased myocardial membrane content of GLUT4. Meanwhile, improved myocardial glucose uptake and more importantly alleviated cardiac injury were also observed after CPB pretreated with AICAR. Moreover, the application of a mutant form of AS160 (AS160-4P) abolished the beneficial effect of AICAR, as evidenced by impaired cardiac glucose uptake, reduced myocardial membrane GLUT-4 translocation, increased cardiac injury markers, and deterioration of cardiac function after CPB. In conclusion, it was suggested in this study that preactivation of AMPK by AICAR improved myocardial glucose uptake by promoting AS160 dependent myocardial membrane GLUT-4 translocation, which ultimately provided a potent cardioprotective effect.

Clearance of Indocyanine Green in Severe Pediatric Burns

BACKGROUND

Clearance of indocyanine green dye (ICGc) reflects sinusoidal perfusion and hepatocyte cell membrane function. Thus, ICGc is a reflection of the functional reserve of intact hepatocytes. The purpose of this study was to identify predictors of ICGc in severely burned children during the acute hospitalization and at the time of discharge from the intensive care unit (ICU). A secondary aim was to determine the relationship between liver size and patient ICGc.

METHODS

Twenty-six children (0.8-17 years old) with 35% or greater total body surface area burned (%TBSA-B) were included. Assessment of ICGc (in milliliters per minute per meter squared) was done during the acute hospitalization (median: 6 days after admission, median: 14 days postburn) and at the time of discharge from the ICU (median: 19 days after admission, median: 27 days postburn). Age, TBSA-B, % third-degree burns, inhalation injury, preexisting chronic malnutrition, hematocrit, liver dysfunction, and time from burn injury were incorporated in multiple linear regressions as predictive variables of ICGc. Only variables with p < 0.05 were retained in the final models.

RESULTS

Time from injury and age were the strongest predictors of ICGc during the acute admission but not at the time of discharge from the ICU. Time from injury was negatively associated with ICGc, whereas age was positively associated. At the time of discharge from the ICU, ICGc was increased in proportion to the %TBSA-B, whereas inhalation injury and preexisting chronic malnutrition were associated with lower ICGc. There was no correlation between change-to-predicted liver length and ICGc.

CONCLUSIONS

The intrinsic ability of the liver to extract ICG from plasma was lower in younger burned patients during the acute admission and in those with preexisting chronic malnutrition and inhalation injury at the time of discharge from the ICU.

LEVEL OF EVIDENCE

Prognostic/Epidemiologic, level III.

Effects of obesity on burn resuscitation

The effects of obesity on resuscitation after severe burn are not well understood. Formulas to calculate 24-h resuscitation volumes incorporate body weight, which in obese patients often leads to excessive fluid administration and potential complications such as pulmonary edema, extremity or abdominal compartment syndrome, and longer mechanical ventilation. We evaluated the impact of obesity on 24-h fluid resuscitation after severe burn using a cohort of 145 adults admitted to the burn ICU from January 2014 to March 2017 with >20% total body surface area burns. Patients were divided into four groups based on body mass index: normal weight (index of <25), overweight (25-29.9), obese (30-39.9), and morbidly obese (>40). Median total body surface area burn was 39.4% (interquartile range: 23.5%-49.5%). Patients were 74.5% male and demographics and injury characteristics were similar across groups. Resuscitation volumes exceeded the predicted Parkland formula volume in the normal and overweight groups but were less than predicted in the obese and morbidly obese categories (p<0.001). No difference was found in 24-h urine output between groups (p=0.08). Increasing body mass index was not associated with increased use of renal replacement therapy. Only total body surface area burned, and age were independent predictors of hospital mortality (p<0.001). We conclude that using body weight to calculate resuscitation in obese patients results in a predicted fluid volume that is higher than the volume actually given, which can lead to over-resuscitation if rates are not titrated regularly to address fluid responsiveness.

Alcohol Modulation of the Postburn Hepatic Response

The widespread and rapidly increasing trend of binge drinking is accompanied by a concomitant rise in the prevalence of trauma patients under the influence of alcohol at the time of their injury. Epidemiological evidence suggests up to half of all adult burn patients are intoxicated at the time of admission, and the presence of alcohol is an independent risk factor for death in the early stages post burn. As the major site of alcohol metabolism and toxicity, the liver is a critical determinant of postburn outcome, and experimental evidence implies an injury threshold exists beyond which burn-induced hepatic derangement is observed. Alcohol may lower this threshold for postburn hepatic damage through a variety of mechanisms including modulation of extrahepatic events, alteration of the gut-liver axis, and changes in signaling pathways. The direct and indirect effects of alcohol may prime the liver for the second-hit of many overlapping physiologic responses to burn injury. In an effort to gain a deeper understanding of how alcohol potentiates postburn hepatic damage, the authors summarize possible mechanisms by which alcohol modulates the postburn hepatic response.

Mortality Rate Associated with Admission Hyperglycemia in Traumatic Femoral Fracture Patients Is Greater Than Non-Diabetic Normoglycemic Patients but Not Diabetic Normoglycemic Patients

Background: Admission hyperglycemia is associated with increased morbidity and mortality in trauma patients. However, admission hyperglycemia is not only associated with stress-induced hyperglycemia (SIH) but also with diabetic hyperglycemia (DH); furthermore, patients with normoglycemia may not only have non-diabetic normoglycemia (NDN) but also have a possibility of diabetic normoglycemia (DN), with the diabetes under control. This study aimed to assess the effects of SIH and DH on the mortality outcomes of traumatic femoral fracture patients with NDN and DN. Methods: Admission hyperglycemia was diagnosed as a serum glucose ≥200 mg/dL upon arrival at the emergency department. Diabetes mellitus (DM) was determined by patient history and/or admission HbA1c ≥ 6.5%. DH and SIH were diagnosed by admission hyperglycemia in patients with and without DM. DN and NDN were determined by absence of admission hyperglycemia in patients with and without DM. These patients were allocated into four groups: SIH (n = 75), DH (n = 280), DN (n = 309), and NDN (n = 1326), with detailed information retracted from the Trauma Registry System at a level I trauma center between 1 January 2009, and 31 December 2016. Patients with incomplete registered data were excluded. The adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for mortality were estimated through a stepwise model selection of a multiple regression model that was adjusted by controlling the cofounding variables such age, sex, co-morbidities, and Injury Severity Score. Results: Compared to NDN, a 9.8-fold (95% CI 1.54–62.05; p = 0.016) and a 5.8-fold (95% CI 1.46–22.67; p = 0.012) increase in the adjusted mortality odds ratio of patients with SIH and DH, respectively, were found in this study. In addition, the adjusted odds of mortality between SIH (AOR = 0.3; 95% CI 0.03–2.99; p = 0.302) as well as DH patients (AOR = 0.6; 95% CI 0.20–1.89; p = 0.394) and DN patients had no significant difference. Conclusions: This study demonstrated that SIH and DH patients with traumatic femoral fractures had higher mortality when compared with NDN patients, but not when compared with DN patients, with or without adjustment of the differences in patient’s age, sex, co-morbidities, and injury severity.

Stress-Induced Hyperglycemia, but Not Diabetic Hyperglycemia, Is Associated with Higher Mortality in Patients with Isolated Moderate and Severe Traumatic Brain Injury: Analysis of a Propensity Score-Matched Population

Background: Admission hyperglycemia is associated with higher morbidity and mortality in patients with traumatic brain injury (TBI). Stress-induced hyperglycemia (SIH), a form of hyperglycemia induced by the stress response, is associated with increased patient mortality following TBI. However, admission hyperglycemia occurs not only in SIH but also in patients with diabetic hyperglycemia (DH). Current information regarding whether trauma patients with SIH represent a distinct group with differential outcomes compared to those with DH remains limited. Methods: Serum glucose concentration ≥200 mg/dL upon arrival at the emergency department was defined as hyperglycemia. Presence of diabetes mellitus (DM) was determined by patient history and/or admission glycated hemoglobin (HbA1c) level ≥6.5%. In the present study, the patient cohort included those with moderate and severe TBI, as defined by an Abbreviated Injury Scale (AIS) score ≥3 points in the head, and excluded those who had additional AIS scores ≥3 points in any other region of the body. A total of 1798 adult patients with isolated moderate to severe TBI were allocated into four groups: SIH (n = 140), DH (n = 187), diabetic normoglycemia (DN, n = 186), and non-diabetic normoglycemia (NDN, n = 1285). Detailed patient information was retrieved from the Trauma Registry System at a level I trauma center between 1 January 2009, and 31 December 2015. Unpaired Student’s t- and Mann–Whitney U-tests were used to analyze normally and non-normally distributed continuous data, respectively. Categorical data were compared using the Pearson chi-square or two-sided Fisher’s exact tests. Matched patient populations were allocated in a 1:1 ratio according to propensity scores calculated by NCSS software. Logistic regression was used to evaluate the effect of SIH and DH on the adjusted mortality outcome. Results: In patients with isolated moderate to severe TBI, the presence of SIH and DH led to 9.1-fold and 2.3-fold higher odds of mortality, respectively, than patients with NDN. After adjusting for confounding factors, including sex and age, pre-existing co-morbidities, existence of different kinds of intracerebral hemorrhage, and injury severity, patients with SIH still had 6.6-fold higher odds of mortality than those with NDN; however, DH did not present significantly higher adjusted mortality odds. SIH and DH presented different effects on outcomes after TBI. The results also suggested that the pathophysiological effect associated with SIH was different from that of DH. Conclusions: This study demonstrated that patients with SIH and DH had significantly higher mortality than patients with NDN. However, the adjusted mortality was significantly higher only in the selected propensity score-matched patients with SIH and not in those with DH.

Burn injury outcomes in patients with pre-existing diabetic mellitus: Risk of hospital-acquired infections and inpatient mortality

BACKGROUND

Diabetes mellitus (DM) is a major cause of illness and death in the United States, and diabetic patients are at increased risk for burn injury. We therefore sought to examine the impact of pre-existing DM on the risk of inpatient mortality and hospital acquired infections (HAI) among burn patients.

METHODS

Adult patients (≥18 years old) admitted from 2004 to 2013 were analyzed. Weighted Kaplan-Meier survival curves - adjusting for patient demographics, burn mechanism, presence of inhalation injury, total body surface area, additional comorbidities, and differential lengths of stay - were used to estimate the 30-day and 60-day risk of mortality and HAIs.

RESULTS

A total of 5539 adult patients were admitted and included in this study during the study period. 655 (11.8%) had a pre-existing DM. The crude incidence of HAIs and in-hospital mortality for the whole burn cohort was 8.5% (n=378) and 4.4% (n=243), respectively. Diabetic patients were more likely to be older, female, have additional comorbidities, inhalational injury, and contact burns. After adjusting for patient and burn characteristics, the 60-day risk of HAI among patients with DM was significantly higher, compared to non-diabetic patients (RR 2.07, 95% CI 1.28, 6.79). However, no significant difference was seen in the 60-day risk of mortality (RR 1.34, 95% CI 0.44, 3.10).

CONCLUSIONS

Pre-existing DM significantly increases the risk of developing an HAI in patients following burn injury, but does not significantly impact the risk of inpatient mortality. Further understanding of the immune modulatory mechanism of burn injury and DM is imperative to better attenuate the acquisition of HAIs.

Higher Mortality in Trauma Patients Is Associated with Stress-Induced Hyperglycemia, but Not Diabetic Hyperglycemia: A Cross-Sectional Analysis Based on a Propensity-Score Matching Approach

Background: Stress-induced hyperglycemia (SIH) is a form of hyperglycemia secondary to stress and commonly occurs in patients with trauma. Trauma patients with SIH have been reported to have an increased risk of mortality. However, information regarding whether these trauma patients with SIH represent a distinct group with differential outcomes when compared to those with diabetic hyperglycemia (DH) remains limited. Methods: Diabetes mellitus (DM) was determined by patient history and/or admission glycated hemoglobin (HbA1c) ≥6.5%. Non-diabetic normoglycemia (NDN) was determined by a serum glucose level <200 mg/dL in the patients without DM. Diabetic normoglycemia (DN) was determined by a serum glucose level <200 mg/dL in the patients with DM. DH and SIH was diagnosed by a serum glucose level ≥200 mg/dL in the patients with and without DM, respectively. Detailed data of these four groups of hospitalized patients, which included NDN (n = 7806), DN (n = 950), SIH (n = 493), and DH (n = 897), were retrieved from the Trauma Registry System at a level I trauma center between 1 January 2009 and 31 December 2015. Patients with incomplete registered data were excluded. Categorical data were compared with Pearson chi-square tests or two-sided Fisher exact tests. The unpaired Student's t-test and the Mann-Whitney U-test were used to analyze normally distributed continuous data and non-normally distributed data, respectively. Propensity-score-matched cohorts in a 1:1 ratio were allocated using NCSS software with logistic regression to evaluate the effect of SIH and DH on the outcomes of patients. Results: The SIH (median [interquartile range: Q1-Q3], 13 [9-24]) demonstrated a significantly higher Injury Severity Score (ISS) than NDN (9 [4-10]), DN (9 [4-9]), and DH (9 [5-13]). SIH and DH had a 12.3-fold (95% confidence interval [CI] 9.31-16.14; p < 0.001) and 2.4-fold (95% CI 1.71-3.45; p < 0.001) higher odds of mortality, respectively, when compared to NDN. However, in the selected propensity-score-matched patient population, SIH had a 3.0-fold higher odd ratio of mortality (95% CI 1.96-4.49; p < 0.001) than NDN, but DH did not have a significantly higher mortality (odds ratio 1.2, 95% CI 0.99-1.38; p = 0.065). In addition, SIH had 2.4-fold higher odds of mortality (95% CI 1.46-4.04; p = 0.001) than DH. These results suggest that the characteristics and injury severity of the trauma patients contributed to the higher mortality of these patients with hyperglycemia upon admission, and that the pathophysiological effect of SIH was different from that of DH. Conclusions: Although there were worse mortality outcomes among trauma patients presenting with hyperglycemia, this effect was only seen in patients with SIH, but not DH when controlling for age, sex, pre-existed co-morbidities, and ISS.

The clinically used PARP inhibitor olaparib improves organ function, suppresses inflammatory responses and accelerates wound healing in a murine model of third-degree burn injury

BACKGROUND AND PURPOSE

The PARP inhibitor olaparib has recently been approved for human use for the therapy of cancer. Considering the role of PARP in critical illness, we tested the effect of olaparib in a murine model of burn injury, in order to begin exploring the feasibility of repurposing olaparib for the therapy of burn patients.

EXPERIMENTAL APPROACH

Mice were subjected to scald burn injury and randomized into vehicle or olaparib (10 mg·kg^-1 ·day^-1 i.p.) groups. Outcome variables included indices of organ injury, clinical chemistry parameters, plasma levels of inflammatory mediators (at 24 h, 7 and 21 days) and burn wound size (at 21 days).

KEY RESULTS

Olaparib reduced myeloperoxidase levels in heart and lung homogenates and reduced malondialdehyde levels in all tissues 24 h post-burn. Olaparib also reduced circulating alkaline aminotransferase, amylase and blood urea nitrogen and creatinine levels, indicative of protection against hepatic, pancreatic and renal dysfunction. Pro-inflammatory mediator (TNF-α, IL-1β, IFN-γ, GCSF, GM-CSF, eotaxin, KC, MIP-1-α and IL-3, 6 and 12) levels as well as the levels of several mediators that are generally considered anti-inflammatory (IL-4, 10 and 13) were reduced by olaparib. Plasma troponin-I levels (an indicator of skeletal muscle damage) was also attenuated by olaparib. Finally, olaparib stimulated wound healing.

CONCLUSIONS AND IMPLICATIONS

The clinically approved PARP inhibitor olaparib improves organ function, suppresses inflammatory responses and accelerates wound healing in murine burn injury. The data raise the potential utility of olaparib for severe burn injury.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Specific Etiologies Associated With the Multiple Organ Dysfunction Syndrome in Children: Part 2

OBJECTIVE

To describe a number of conditions and therapies associated with multiple organ dysfunction syndrome presented as part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Multiple Organ Dysfunction Workshop (March 26-27, 2015). In addition, the relationship between burn injuries and multiple organ dysfunction syndrome is also included although it was not discussed at the workshop.

DATA SOURCES

Literature review, research data, and expert opinion.

STUDY SELECTION

Not applicable.

DATA EXTRACTION

Moderated by an expert from the field, issues relevant to the association of multiple organ dysfunction syndrome with a variety of conditions and therapies were presented, discussed, and debated with a focus on identifying knowledge gaps and the research priorities.

DATA SYNTHESIS

Summary of presentations and discussion supported and supplemented by relevant literature.

CONCLUSIONS

Sepsis and trauma are the two conditions most commonly associated with multiple organ dysfunction syndrome both in children and adults. However, many other pathophysiologic processes may result in multiple organ dysfunction syndrome. In this article, we discuss conditions such as liver failure and pancreatitis, pathophysiologic processes such as ischemia and hypoxia, and injuries such as trauma and burns. Additionally, therapeutic interventions such as medications, blood transfusions, transplantation may also precipitate and contribute to multiple organ dysfunction syndrome. The purpose of this article is to describe the association of multiple organ dysfunction syndrome with a variety of conditions and therapies in an attempt to identify similarities, differences, and opportunities for therapeutic intervention.

Postburn Hypermetabolism: Past, Present, and Future

Hypermetabolism is the ubiquitous response to a severe burn injury, which was first described in the nineteenth century. Despite identification of important components of this complex response, hypermetabolism is still not well understood in its entirety. This article describes this incredibly fascinating response and the understanding we have gained over the past 100 years. Additionally, this article describes novel insights and delineates treatment options to modulate postburn hypermetabolism with the goal to improve outcomes of burn patients.

Animal models of insulin resistance: A review

Insulin resistance can be seen as a molecular and genetic mystery, with a role in the pathophysiology of type 2 diabetes mellitus. It is a basis for a number of chronic diseases like hypertension, dyslipidemia, glucose intolerance, coronary heart disease, cerebral vascular disease along with T2DM, thus the key is to cure and prevent insulin resistance. Critical perspicacity into the etiology of insulin resistance have been gained by the use of animal models where insulin action has been modulated by various transgenic and non-transgenic models which is not possible in human studies. The following review comprises the pathophysiology involved in insulin resistance, various factors causing insulin resistance, their screening and various genetic and non-genetic animal models highlighting the pathological and metabolic characteristics of each.

Effect of Human Burn Wound Exudate on Pseudomonas aeruginosa Virulence

Burn wound sepsis is currently the main cause of morbidity and mortality after burn trauma. Infections by notorious pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii impair patient recovery and can even lead to fatality. In this study, we investigated the effect of burn wound exudates (BWEs) on the virulence of those pathogens. BWEs were collected within 7 days after burn trauma from 5 burn patients. We first monitored their effect on pathogen growth. In contrast to A. baumannii and S. aureus, P. aeruginosa was the only pathogen able to grow within these human fluids. Expression of typical virulence factors such as pyocyanin and pyoverdine was even enhanced compared the levels seen with standard laboratory medium. A detailed chemical composition analysis of BWE was performed, which enabled us to determine the major components of BWE and underline the metabolic modifications induced by burn trauma. These data are essential for the development of an artificial medium mimicking the burn wound environment and the establishment of an in vitro system to analyze the initial steps of burn wound infections. IMPORTANCE Microbial infection of severe burn wounds is currently a major medical challenge. Of the infections by bacteria able to colonize such injuries, those by Pseudomonas aeruginosa are among the most severe, causing major delays in burn patient recovery or leading to fatal issues. In this study, we investigated the growth properties of several burn wound pathogens in biological fluids secreted from human burn wounds. We found that P. aeruginosa strains were able to proliferate but not those of the other pathogens tested. In addition, burn wound exudates (BWEs) stimulate the expression of virulence factors in P. aeruginosa. The chemical composition analysis of BWEs enabled us to determine the major components of these fluids. These data are essential for the development of an artificial medium mimicking the burn wound environment and for in vitro analysis of the initial step in the development of burn wound infections.

Nutrition chez le brûlé

Nutrition is a challenge for burn patients. Emphasized points are early enteral amounts by means of a naso-gastric tube, semi-recumbent position > 30°, gastro-intestinal survey improved by kinetics, weight evolution, nutritional amounts assessment to prevent proteino-energetic deficiency. Feeding is difficult with children, as with seniors often associating a preexisting starvation. Nutritional supplements are useful in medium severity patients. For overweight patients, hypo caloric and hyperprotidic diet is the better choice. Non hemodialysed kidney failure patients need potassium limitation. In case of perineal burns, short constipation or faecal collector rather than colostomy prevent local contamination. Enteral amounts are difficult to administrate in prone position following ARDS (recumbent, post pyloric tube). In extensive burns, quality of nutrients is more suitable than quantity. Old caloric formulas lead to badly tolerated over-nutrition, while indirect calorimetry or Toronto formula allow a better assessment. Immunonutrition (supplementation with trace elements, glutamine, arginine, omega 3 fatty acids, and rational control of blood glucose) could reduce oxidative stress and hyper metabolism induced by burn trauma.

Comorbidity Factors and Brain Mechanisms Linking Chronic Stress and Systemic Illness

Neuropsychiatric symptoms and mental illness are commonly present in patients with chronic systemic diseases. Mood disorders, such as depression, are present in up to 50% of these patients, resulting in impaired physical recovery and more intricate treatment regimen. Stress associated with both physical and emotional aspects of systemic illness is thought to elicit detrimental effects to initiate comorbid mental disorders. However, clinical reports also indicate that the relationship between systemic and psychiatric illnesses is bidirectional, further increasing the complexity of the underlying pathophysiological processes. In this review, we discuss the recent evidence linking chronic stress and systemic illness, such as activation of the immune response system and release of common proinflammatory mediators. Altogether, discovery of new targets is needed for development of better treatments for stress-related psychiatric illnesses as well as improvement of mental health aspects of different systemic diseases.

Cardiovascular Dysfunction Following Burn Injury: What We Have Learned from Rat and Mouse Models

Severe burn profoundly affects organs both proximal and distal to the actual burn site. Cardiovascular dysfunction is a well-documented phenomenon that increases morbidity and mortality following a massive thermal trauma. Beginning immediately post-burn, during the ebb phase, cardiac function is severely depressed. By 48 h post-injury, cardiac function rebounds and the post-burn myocardium becomes tachycardic and hyperinflammatory. While current clinical trials are investigating a variety of drugs targeted at reducing aspects of the post-burn hypermetabolic response such as heart rate and cardiac work, there is still a paucity of knowledge regarding the underlying mechanisms that induce cardiac dysfunction in the severely burned. There are many animal models of burn injury, from rodents, to sheep or swine, but the majority of burn related cardiovascular investigations have occurred in rat and mouse models. This literature review consolidates the data supporting the prevalent role that β-adrenergic receptors play in mediating post-burn cardiac dysfunction and the idea that pharmacological modulation of this receptor family is a viable therapeutic target for resolving burn-induced cardiac deficits.

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Chaque année, le congrès de la SFB est l'occasion d'une mise au point sur un thème (« table ronde ».) Celui choisi en 2015 était la nutrition. Huit orateurs se sont succédés, faisant le point sur les données actuelles de la science, les pratiques dans les centres, et les recommandations actuelles, datant de 2013. Cet article se propose de diffuser les interventions.

Release of insulin from PLGA-alginate dressing stimulates regenerative healing of burn wounds in rats

Burn wound healing involves a complex set of overlapping processes in an environment conducive to ischaemia, inflammation and infection costing $7.5 billion/year in the U.S.A. alone, in addition to the morbidity and mortality that occur when the burns are extensive. We previously showed that insulin, when topically applied to skin excision wounds, accelerates re-epithelialization and stimulates angiogenesis. More recently, we developed an alginate sponge dressing (ASD) containing insulin encapsulated in PLGA [poly(D,L-lactic-co-glycolic acid)] microparticles that provides a sustained release of bioactive insulin for >20 days in a moist and protective environment. We hypothesized that insulin-containing ASD accelerates burn healing and stimulates a more regenerative, less scarring healing. Using heat-induced burn injury in rats, we show that burns treated with dressings containing 0.04 mg insulin/cm(2) every 3 days for 9 days have faster closure, a higher rate of disintegration of dead tissue and decreased oxidative stress. In addition, in insulin-treated wounds, the pattern of neutrophil inflammatory response suggests faster clearing of the burned dead tissue. We also observe faster resolution of the pro-inflammatory macrophages. We also found that insulin stimulates collagen deposition and maturation with the fibres organized more like a basket weave (normal skin) than aligned and cross-linked (scar tissue). In summary, application of ASD-containing insulin-loaded PLGA particles on burns every 3 days stimulates faster and more regenerative healing. These results suggest insulin as a potential therapeutic agent in burn healing and, because of its long history of safe use in humans, insulin could become one of the treatments of choice when repair and regeneration are critical for proper tissue function.

Chronic stress impacts the cardiovascular system: animal models and clinical outcomes

Psychological stresses are associated with cardiovascular diseases to the extent that cardiovascular diseases are among the most important group of psychosomatic diseases. The longstanding association between stress and cardiovascular disease exists despite a large ambiguity about the underlying mechanisms. An array of possibilities have been proposed including overactivity of the autonomic nervous system and humoral changes, which then converge on endothelial dysfunction that initiates unwanted cardiovascular consequences. We review some of the features of the two most important stress-activated systems, i.e., the humoral and nervous systems, and focus on alterations in endothelial function that could ensue as a result of these changes. Cardiac and hematologic consequences of stress are also addressed briefly. It is likely that activation of the inflammatory cascade in association with oxidative imbalance represents key pathophysiological components of stress-induced cardiovascular changes. We also review some of the commonly used animal models of stress and discuss the cardiovascular outcomes reported in these models of stress. The unique ability of animals for adaptation under stressful conditions lessens the extrapolation of laboratory findings to conditions of human stress. An animal model of unpredictable chronic stress, which applies various stress modules in a random fashion, might be a useful solution to this predicament. The use of stress markers as indicators of stress intensity is also discussed in various models of animal stress and in clinical studies.

Protective effect of pretreatment with propofol against tumor necrosis factor-α-induced hepatic insulin resistance

Insulin resistance is common in critically ill patients and seriously affects their prognosis. The anesthetic propofol (2,6-diisopropylphenol) has been shown to cause insulin resistance in rats; however, the specific mechanism underlying this phenomenon remains unknown. Thus, the aim of the present study was to determine the molecular mechanism through which propofol influences insulin resistance in the liver. The current study assessed the effects of propofol on the phosphorylation level of key enzymes involved in the insulin signaling pathway, as well as the glycogen content in primary mouse hepatocytes. Propofol administration was demonstrated to considerably reduce the phosphorylation levels of Akt (Ser473) and glycogen synthase kinase (GSK)-3β (Ser9) in the primary mouse hepatocytes. In addition, propofol was shown to downregulate the phosphoinositide 3-kinase (PI3K)/Akt/GSK-3β signaling pathway and inhibit glycogen synthesis in hepatocytes. Thus, the present results indicated that propofol induced insulin resistance in primary mouse hepatocytes. Notably, pretreatment with propofol in tumor necrosis factor (TNF)-α-induced primary mouse hepatocytes with insulin resistance was demonstrated to alleviate the inhibitory effects of TNF-α on the PI3K/Akt/GSK-3β signaling pathway and glycogen synthesis. These results indicated that propofol exerts a protective effect against insulin resistance in primary mouse hepatocytes induced by TNF-α, indicating that propofol therapy may be clinically feasible to alleviate insulin resistance in critically ill patients.

Diabetes mellitus and burns. Part I-basic science and implications for management

The number of diabetic patients presenting to burn services is predicted to increase significantly over the next decades. Diabetes mellitus represents an independent risk factor for sustaining burn injuries and mediates alterations to key physiological systems including the vascular, renal, nervous, gastrointestinal and immune system. The effects of the pathophysiological permutations need to be carefully considered during both the acute as well as the long-term rehabilitation phase of injury. The purpose of the first part of this review is to outline the metabolic permutations observed in diabetes mellitus pertinent to the clinical presentation and management of burn patients.

Effects of pharmacological interventions on muscle protein synthesis and breakdown in recovery from burns

OBJECTIVE

The pathophysiological response to burn injury disturbs the balance between skeletal muscle protein synthesis and breakdown, resulting in severe muscle wasting. Muscle loss after burn injury is related to increased mortality and morbidity. Consequently, mitigation of this catabolic response has become a focus in the management of these patients. The aim of this review is to discuss the literature pertaining to pharmacological interventions aimed at attenuating skeletal muscle catabolism in severely burned patients.

DATA SELECTION

Review of the literature related to skeletal muscle protein metabolism following burn injury was conducted. Emphasis was on studies utilizing stable isotope tracer kinetics to assess the impact of pharmacological interventions on muscle protein metabolism in severely burned patients.

CONCLUSION

Data support the efficacy of testosterone, oxandrolone, human recombinant growth hormone, insulin, metformin, and propranolol in improving skeletal muscle protein net balance in patients with severe burns. The mechanisms underlying the improvement of protein net balance differ between types and dosages of drugs, but their main effect is on protein synthesis. Finally, the majority of studies have been conducted during the acute hypermetabolic phase of the injury. Except for oxandrolone, the effects of drugs on muscle protein kinetics following discharge from the hospital are largely unknown.