Endogenous anabolic hormones and hypermetabolism: effect of trauma and gender differences

Resting energy expenditure measured by indirect calorimetry in mechanically ventilated patients during ICU stay and post-ICU hospitalization: A prospective observational study

PURPOSE

The metabolic course during and after critical illness is unclear. We performed repeated indirect calorimetry (IC) measurements during ICU- and post-ICU hospitalization to determine resting energy expenditure (REE).

METHODS

Prospective observational design. In ventilated ICU patients, IC measurements were performed every three days until hospital discharge. Measured REE as predicted by the Harris-Benedict equation (HBE-REE) and 25 kcal/adjusted body weight/day (25-REE) were compared.

RESULTS

In 56 patients (38% females, 71[13]years, BMI 29(27;31)kg/m2), 189 ICU IC measurements were performed. Measured REE did not differ from HBE-REE at ICU admission, but was lower than 25-REE. Measured REE was increased compared to baseline on ICU-admission-day four (29(29-30)kcal/kg/day; mean difference 3.1(1.4-4.9)kcal/kg/day, p < 0.001) and thereafter during ICU admission. During post-ICU ward stay, 44 measurements were performed in 23 patients, showing a higher mean REE than during ICU stay (33(31-35)kcal/kg/day; mean difference 2.6(1.2-3.9)kcal/kg/day, p < 0.001). The REE in the ICU and ward was >110% of HBE-REE from day four onwards.

CONCLUSIONS

Critically ill mechanically ventilated patients were shown to have a resting energy expenditure (REE) > 110% of predicted REE on ICU admission day four and thereafter. Indirect calorimetry measurements suggest that the mean energy requirements during post-ICU hospitalization are higher than those in the ICU.

Burns: Classification, Pathophysiology, and Treatment: A Review

Burns and their treatment are a significant medical problem. The loss of the physical barrier function of the skin opens the door to microbial invasion and can lead to infection. The repair process of the damage caused by the burn is impaired due to the enhanced loss of fluids and minerals through the burn wound, the onset of hypermetabolism with the concomitant disruption of nutrient supply, and derangements in the endocrine system. In addition, the initiated inflammatory and free radical processes drive the progression of oxidative stress, the inhibition of which largely depends on an adequate supply of antioxidants and minerals. Clinical experience and research provide more and more data to make the treatment of patients with thermal injury increasingly effective. The publication discusses disorders occurring in patients after thermal injury and the methods used at various stages of treatment.

Bioelements in the treatment of burn injuries - The complex review of metabolism and supplementation (copper, selenium, zinc, iron, manganese, chromium and magnesium)

Appropriate nutrition is a key component of burn treatment and should be regarded as an integral part of the therapeutic process in burn patients. A nutritional intervention plan should not only allow for adequate quantities of energy and protein but also carefully consider the supply of macro- and micronutrients. As a result of the severe inflammatory response, oxidative stress, and hypermetabolic state, accompanied by often extensive exudation in burn patients, there is a considerable loss of macro- and micronutrients, including essential trace elements. This leads to certain complications, involving e.g. more frequent infections and impaired wound healing. Our current body of knowledge is still insufficient, and the studies carried out to date focus for the most part on the imbalances in trace elements, such as copper (Cu), selenium (Se), and zinc (Zn). Nevertheless, there are many other trace elements involved in immune functions, regulating gene expression or antioxidant defense, and many of those have not been properly investigated in a clinical setting. Due to the insufficient amount of unambiguous literature data and relatively few, often dated, studies carried out with small patient groups, further evaluation of macro- and microelements in burn patients seems indispensable, e.g. to bring up to date local nutritional protocols.

Sex-specific metabolic and functional differences in human umbilical vein endothelial cells from twin pairs

BACKGROUND AND AIMS

Gonadal hormones are mainly thought to account for sex and gender differences in the incidence, clinical manifestation and therapy of many cardiovascular diseases. However, intrinsic sex differences at the cellular level are mostly overlooked. Here, we assessed sex-specific metabolic and functional differences between male and female human umbilical vein endothelial cells (HUVECs).

METHODS

Cellular metabolism was investigated by bioenergetic studies (Seahorse Analyser) and a metabolomic approach. Protein levels were determined by Western blots and proteome analysis. Vascular endothelial growth factor (VEGF)-stimulated cellular migration was assessed by gap closure. HUVECs from dizygotic twin pairs were used for most experiments.

RESULTS

No sex differences were observed in untreated cells. However, sexual dimorphisms appeared after stressing the cells by serum starvation and treatment with VEGF. Under both conditions, female cells had higher intracellular ATP and metabolite levels. A significant decline in ATP levels was observed in male cells after serum starvation. After VEGF, the ratio of glycolysis/mitochondrial respiration was higher in female cells and migration was more pronounced.

CONCLUSIONS

These results point to an increased stress tolerance of female cells. We therefore propose that female cells have an energetic advantage over male cells under conditions of diminished nutrient supply. A more favourable energy balance of female HUVECs after serum starvation and VEGF could potentially explain their stronger migratory capacity.

Differences in Outcomes Based on Sex for Pediatric Patients Undergoing Pyloromyotomy

BACKGROUND

Males and females are known to have varied responses to medical interventions. Our study aimed to determine the effect of sex on surgical outcomes after pyloromyotomy.

MATERIALS AND METHODS

Using the Kids' Inpatient Database for the years 2003-2012, we performed a serial, cross-sectional analysis of a nationally representative sample of all patients aged <1 y who underwent pyloromyotomy for hypertrophic pyloric stenosis. The primary predictor of interest was sex. Outcomes included mortality, in-hospital complications, cost, and length of stay. Regression models were adjusted by race, age group, comorbidity, complications, and whether operation was performed on the day of admission with region and year fixed effects.

RESULTS

Of 48,834 weighted operations, 81.8% were in males and 18.2% were in females. The most common reported race was white (47.3%) and most of the patients were ≥29 days old (72.5%). There was no difference in the odds of postoperative complications, but females had a significantly longer length of stay (incidence rate ratio, 1.28; 95% confidence interval [95% CI], 1.18-1.39; P ≤ 0.01), higher cost (5%, 95% CI, 1.02-1.08; P ≤ 0.01), and higher odds of mortality (odds ratio, 3.26; 95% CI, 1.52-6.98; P ≤ 0.01).

CONCLUSIONS

Our study demonstrated that females had worse outcomes after pyloromyotomy compared with males. These findings are striking and are important to consider when treating either sex to help set physician and family expectations perioperatively. Further studies are needed to determine why such differences exist and to develop targeted treatment strategies for both females and males with pyloric stenosis.

Anabolic and anticatabolic agents in critical care

PURPOSE OF REVIEW

A complex network of hormones and other effectors characterize the hypermetabolic response in critical illness; these mediators work together to induce numerous pathophysiologic alterations. Increased incidence of infection, multiorgan failure, long-term debilitation, delays in rehabilitation, and death result from an inability to meet the prohibitively elevated protein and energy requirements, which occur during illness and can persist for several years. Pharmacologic interventions have been successfully utilized to attenuate particular aspects of the hypermetabolic response; these modalities are a component of managing critically ill patients - including those patients with severe burns. Here, we review recent advances in pharmacologically attenuating the hypermetabolic and catabolic responses.

RECENT FINDINGS

Propranolol, a nonspecific β-adrenergic receptor antagonist, is one of the most widely used anticatabolic therapies. Oxandrolone, testosterone, and intensive insulin therapy represent anabolic pharmacological strategies. Promising therapies, such as metformin, glucagon-like peptide 1, peroxisome proliferator-activated receptor agonists, are currently being investigated.

SUMMARY

Profound metabolic derangements occur in critically ill patients; this hypermetabolic response is a major contributor to adverse outcomes. Despite the pharmacological therapies currently available to counteract this devastating cascade, future studies are warranted to explore new multimodality agents that will counteract these effects while maintaining glycemic control and preventing unfavorable complications.

Rehabilitation in the Acute Versus Outpatient Setting

Rehabilitation of patients with burn injuries aims to restore strength, coordination, and mobility as closely to normal as possible and should begin immediately after initial admission. In the acute phase, baseline assessments are made against which all subsequent rehabilitation success is held. In the intermediate phase, active, full range-of-motion movement, ambulation of steadily increasing distances, and resistive exercise and stretching aid in the prevention of muscle and bone atrophy and preserve muscle memory and coordination. In the long-term outpatient rehabilitation phase, individualized patient-centered exercise programs can be advantageous in achieving measurable and lasting positive rehabilitation outcomes.

Burn injury: review of pathophysiology and therapeutic modalities in major burns

Despite a considerable decrease in their incidence worldwide, burn injuries remain one of the commonest forms of trauma and account for a weighty proportion of trauma cases in health-care emergencies around the globe. Although the latest data reveal a substantial decline in burn-related mortality and hospital admissions in the US over the past three decades, severe thermal injuries continue to trigger devastating morbidity and significant mortality while their management remains a dynamic challenge for the entire medical and paramedical community. Concrete evidence continues to be established regarding burn-associated pathophysiologic responses, and their destructive sequelae and deleterious effects in survivors at cellular, systemic as well as socio-economic level. Better understanding of these responses have contributed to advances in therapeutic strategies, improved long-term outcomes and catalyzed the reintegration of victims back into society. This paper describes the current understanding of the pathophysiology of a burn injury and characterizes both local and systemic pathophysiologic responses in terms of metabolic, hemodynamics, cardiac, renal, hepatic, gastro-intestinal, immunologic, endocrine as well as male reproductive systems in an attempt to understand the corresponding treatment modalities for this unique patient population.

Impaired Immune Response in Elderly Burn Patients: New Insights Into the Immune-senescence Phenotype

OBJECTIVE

Comparing the inflammatory and immunological trajectories in burned adults versus burned elderly patients to gain novel insights and better understanding why elderly have poor outcomes.

SUMMARY BACKGROUND DATA

Despite receiving the same treatment and clinical consideration as all other burn patients, elderly patients continue to have substantially poorer outcomes compared with adults. In light of an aging population, gaining a better understanding of their susceptibility to complications and creating new treatment strategies is imperative.

METHODS

We included 130 burn patients (94 adults: <65 years old and 36 elderly: ≥65 years old) and 10 healthy controls in this study. Immune activity and expression was assessed using bioplex at various time points. Clinical outcomes such as infection, sepsis, and mortality were prospectively collected.

RESULTS

Elderly burn patients had significantly lower burn size but significantly higher Baux scores. Morbidity and mortality was significantly increased in the elderly cohort. Immune biomarkers indicated that elderly are immune compromised and unable to respond with the expected inflammatory response during the early phase after injury. This trajectory changes to a hyperinflammatory pattern during the later phase after burn. These findings are even more pronounced when comparing sepsis versus nonsepsis patients as well as survivors versus nonsurvivors in the elderly.

CONCLUSIONS

Elderly burned patients mount a delayed immune and dampened inflammatory response early after burn injury that changes to an augmented response at later time points. Late-onset sepsis and nonsurvivors had an immune exhaustion phenotype, which may represent one of the main mediators responsible for the striking mortality in elderly.

Predictors of muscle protein synthesis after severe pediatric burns

BACKGROUND

Following a major burn, skeletal muscle protein synthesis rate increases but is often insufficient to compensate for massively elevated muscle protein breakdown rates. Given the long-term nature of the pathophysiologic response to burn injury, we hypothesized that muscle protein synthesis rate would be chronically elevated in severely burned children. The objectives of this study were to characterize muscle protein synthesis rate of burned children over a period of 24 months after injury and to identify predictors that influence this response.

METHODS

A total of 87 children with 40% or greater total body surface area (TBSA) burned were included. Patients participated in stable isotope infusion studies at 1, 2, and approximately 4 weeks after burn and at 6, 12, and 24 months after injury to determine skeletal muscle protein fractional synthesis rate. Generalized estimating equations with log link normal distribution were applied to account for clustering of patients and control for patient characteristics.

RESULTS

Patients (8 ± 6 years) had large (62, 51-72% TBSA) and deep (47% ± 21% TBSA third degree) burns. Muscle protein fractional synthesis rate was elevated throughout the first 12 months after burn compared with established values from healthy young adults. Muscle protein fractional synthesis rate was lower in boys, in children older than 3 years, and when burns were greater than 80% TBSA.

CONCLUSION

Muscle protein synthesis is elevated for at least 1 year after injury, suggesting that greater muscle protein turnover is a component of the long-term pathophysiologic response to burn trauma. Muscle protein synthesis is highly affected by sex, age, and burn size in severely burned children. These findings may explain the divergence in net protein balance and lean body mass in different populations of burn patients.

LEVEL OF EVIDENCE

Prognostic study, level III.

Initiation of nutritional support is delayed in critically ill obese patients: a multicenter cohort study

BACKGROUND

A high catabolic rate characterizes the acute phase of critical illness. Guidelines recommend an early nutritional support, regardless of the previous nutritional status.

OBJECTIVE

We aimed to assess whether the nutritional status of patients, which was defined by the body mass index (BMI) at admission in an intensive care unit (ICU), affected the time of nutritional support initiation.

DESIGN

We conducted a cohort study that reported a retrospective analysis of a multicenter ICU database (OUTCOMEREA) by using data prospectively entered from January 1997 to October 2012. Patients who needed orotracheal intubation within the first 72 h and >3 d were included.

RESULTS

Data from 3257 ICU stays were analyzed. The delay before feeding was different according to BMI groups (P = 0.035). The delay was longer in obese patients [BMI (in kg/m²) ≥30; n = 663] than in other patients with either low weight (BMI <20; n = 501), normal weight (BMI ≥20 and <25; n = 1135), or overweight (BMI ≥25 and <30; n = 958). The association between nutritional status and a delay in nutrition initiation was independent of potential confounding factors such as age, sex, and diabetes or other chronic diseases. In comparison with normal weight, the adjusted RR (95% CI) associated with a delayed nutrition initiation was 0.92 (0.86, 0.98) for patients with low weight, 1.00 (0.94, 1.05) for overweight patients, and 1.06 (1.00, 1.12) for obese patients (P = 0.004).

CONCLUSIONS

The initiation of nutritional support was delayed in obese ICU patients. Randomized controlled trials that address consequences of early compared with delayed beginnings of nutritional support in critically ill obese patients are needed.

Phosphodiesterase (PDE) inhibitor torbafylline (HWA 448) attenuates burn-induced rat skeletal muscle proteolysis through the PDE4/cAMP/EPAC/PI3K/Akt pathway

Treatment of rats after burn-injury with the cyclic AMP phosphodiesterase (PDE) inhibitor, torbafylline (also known as HWA 448) significantly reversed changes in rat skeletal muscle proteolysis, PDE4 activity, cAMP concentrations and mRNA expression of TNFα, IL-6, ubiquitin and E3 ligases. Torbafylline also attenuated muscle proteolysis during in vitro incubation, and this effect was blocked by the inhibitor Rp-cAMPS. Moreover, torbafylline significantly increased phospho-Akt levels, and normalized downregulated phospho-FOXO1 and phospho-4E-BP1 in muscle of burn rats. Similarly, torbafylline also normalized phosphorylation levels of Akt and its downstream elements in TNFα+IFNγ treated C2C12 myotubes. Torbafylline enhanced protein levels of exchange protein directly activated by cAMP (Epac) both in skeletal muscle of burn rats and in TNFα+IFNγ treated C2C12 myotubes. Pretreatment with a specific antagonist of PI3K or Epac significantly reversed the inhibitory effects of torbafylline on TNFα+IFNγ-induced MAFbx mRNA expression and protein breakdown in C2C12 myotubes. Torbafylline inhibits burn-induced muscle proteolysis by activating multiple pathways through PDE4/cAMP/Epac/PI3K/Akt.

Traumatic injury among females: does gender matter?

BACKGROUND

Trauma remains one of the leading causes of morbidity and mortality worldwide. Generally, the incidence of traumatic injuries is disproportionately high in males. However, trauma in females is underreported.

AIM

To study the epidemiology and outcome of different mechanisms and types of traumatic injuries in women.

METHODS

We conducted a traditional narrative review using PubMed, MEDLINE and EMBASE, searching for English-language publications for gender-specific trauma between January 1993 and January 2013 using key words "trauma", "gender", "female" and "women".

RESULTS

Among 1150 retrieved articles, 71 articles were relevant over 20 years. Although it is an important public health problem, traumatic injuries among females remain under-reported.

CONCLUSION

There is a need for further research and evaluation of the exact burden of traumatic injuries among females together with the implementation of effective community based preventive programs.

Comparison of intensive insulin therapy versus conventional glucose control in traumatic brain injury patients on parenteral nutrition: A pilot randomized clinical trial

BACKGROUND

Parenteral nutrition (PN) is a valuable life saving intervention, which can improve the nutritional status of hospitalized malnourished patients. PN is associated with complications including hyperglycemia. This study was conducted to compare two methods of blood glucose control in traumatic brain injury patients on PN.

MATERIALS AND METHODS

A randomized, open-label, controlled trial with blinded end point assessment was designed. Traumatic brain injury patients (GCS = 4-9) on PN, without diabetes, pancreatitis, liver disease, kidney complication, were participated. Patients were randomly assigned to receive continuous insulin infusion to maintain glucose levels between 4.4 mmol/l (80 mg/dl) and 6.6 mmol/l (120 mg/dl) (n = 13) or conventional treatment (n = 13). Patients in the conventional group were not received insulin unless glucose levels were greater than 10 mmol/l (>180 mg/dl). These methods were done to maintain normoglycemia in ICU. The primary outcome was hypo/hyperglycemic episodes. Other factors such as C-reactive protein, blood electrolytes, liver function tests, lipid profile and mid-arm circumference were compared.

RESULTS

Mean glucose concentration were significantly lower in IIT group (118 ± 28 mg/dl) vs conventional group (210 ± 31 mg/dl) (P < 0.01). No hypoglycemic episode occurred in two groups. Triglyceride (P = 0.02) and C-reactive protein (P = 0.001) was decreased in the IIT group, significantly. There were also significant differences in the electrolytes, with magnesium and phosphorus being lower in the IIT group (P = 0.05).

CONCLUSION

In this pilot study, blood glucose level, CRP and TG were lower in IIT group. Further data collection is warranted to reach definitive conclusions.

Gender-specific differences in severely injured patients between 2002 and 2011: data analysis with matched-pair analysis

INTRODUCTION

Previous studies reported divergent results concerning the effect of gender on patient outcome after severe injury. Results suggest that women have better outcomes because they have lower rates of sepsis and multi-organ failure. The objective of this analysis was to study gender differences in a Level 1 trauma center in Germany.

METHODS

Patients who were admitted to hospital between 2002 and 2011 with an Injury Severity Score (ISS) ≥16 were included. Data were collected from the Trauma Registry of the German Society for Trauma Surgery and from hospital records. The effects of gender on a variety of parameters were investigated. To eliminate the influence of differences in ISS, an analysis of groups with similar ISS was performed. Also, a matched-pair analysis of 422 patients was performed.

RESULTS

A total of 962 patients met the inclusion criteria. The mortality rate was lower in male patients (25.4% versus 36.59%). Female patients had more severe head injuries, received less fluid volume and had a lower rate of sepsis. Men were more frequently involved in motorcycle accidents and sustained more penetrating trauma. Women were more frequently involved in pedestrian accidents and sustained more falls from under 3 m. The effects of gender were reduced when the data were analyzed by matching ISS. The mortality rate was significantly different in the ISS 26 to 35 group but in mostly all groups, the mortality rate was higher in women. In the matched-pair analysis, the rate of sepsis and the length of the ICU stay were significantly lower in women and the mortality rate showed no significant difference (28.1% for male patients versus 33.01% for female patients). Women died after an average of 5.22 days, and men died after an average of 9.02 days.

CONCLUSIONS

Gender-based differences in patient outcome after severe trauma were observed in this study. Women are more likely to die in the first days after trauma. Upon extended hospital stay, women had a better survival rate because they had a lower rate of sepsis. No significant differences in mortality rate could be found, but there was a trend towards a higher rate in female patients.

Burn injury induces high levels of phosphorylated insulin-like growth factor binding protein-1

PURPOSE

Burn injury is associated with early apoptotic death of T cells. Insulin-like growth factor-1 (IGF-I) is able to protect T cells from apoptosis. Association of IGF-I with its IGFBP (Binding Protein)-1 limits its bioavailability and serine phosphorylation of IGFBP-1 lowers this further because of an increased affinity for IGF-I. The level of phosphorylated IGFBP-1 has been shown to increase in pediatric burn patients. Thus we hypothesized that a longitudinal study of burn patients would demonstrate 1) increased IGFBP-1 levels, 2) increased IGFBP-1 phosphorylation and 3) decreased IGF-I levels over time.

METHODS

We conducted a prospective observational study in adult burn patients admitted to UNC Jaycee Burn Center. Plasma levels of insulin, insulin-like growth factor 1 (IGF-I) and insulin-like growth factor binding protein 1 (IGGBP-1) were measured on admission up to 10 days post admission. ELISA was used to measure serum levels of insulin, IGF-I and IGFBP-1. Serine phosphorylation of IGFBP-1 was measured by Western blot with and without the incubation of calf intestinal phosphatase (CIP). Significant findings: There was a significant positive correlation of increasing %TBSA burn and increasing levels of serum IGFBP-1 from admittance blood draws. Levels of IGF-I also decreased with increasing Total Body Surface Area (TBSA, p<0.05). In patients studied longitudinally (n=84) we found that IGFBP-1 levels are significantly (p<0.05) increased 1-72 hours post burn (mean±SEM serum concentration; burn=172±23 ng/mL, normal=13±3 ng/mL) and that levels of IGF-I are reduced. IGFBP-1 is serine phosphorylated in burn patients. In patients surviving past 72 hours IGFBP-1 remained phosphorylated over the study period.

CONCLUSIONS

IGFBP-1 and its serine phosphorylation regulate and limit IGF-I bioavailability. Our results suggest that increases in IGFBP-1 and persistent serine phosphorylation of IGFBP-1 correlate with the severity of burn injury, and may contribute to burn-associated T cell apoptosis and subsequent immune dysfunction by reducing the bioavailability of this important cell survival factor.

Molecular and organismal changes in offspring of male mice treated with chemical stressors

Both gene methylation changes and genetic instability have been noted in offspring of male rodents exposed to radiation or chemicals, but few specific gene targets have been established. Previously, we identified the gene for ribosomal RNA, rDNA, as showing methylation change in sperm of mice treated with the preconceptional carcinogen, chromium(III) chloride. rDNA is a critical cell growth regulator. Here, we investigated the effects of paternal treatments on rDNA in offspring tissue. A total of 93 litters and 758 offspring were obtained, permitting rigorous mixed-effects models statistical analysis of the results. We show that the offspring of male mice treated with Cr(III) presented increased methylation in a promoter sequence of the rDNA gene, specifically in lung. Furthermore polymorphic variants of the multi-copy rDNA genes displayed altered frequencies indicative of structural changes, as a function of both tissue type and paternal treatments. Organismal effects also occurred: some groups of offspring of male mice treated with either Cr(III) or its vehicle, acidic saline, compared with those of untreated mice, had altered average body and liver weights and levels of serum glucose and leptin. Males treated directly with Cr(III) or acidic saline presented serum hormone changes consistent with a stress response. These results establish for the first time epigenetic and genetic instability effects in a gene of central physiological importance, in offspring of male mice exposed preconceptionally to chemicals, possibly related to a stress response in these males.

Gender influences outcomes in trauma patients with elevated systolic blood pressure

BACKGROUND

This analysis explored the association between gender and systolic blood pressure (SBP) in trauma patients and then established how gender influenced outcomes in those with elevated SBP.

METHODS

Demographics and outcomes were compared using the Los Angeles County Trauma System Database and multivariable modeling determined predictors for SBP, pneumonia, and mortality.

RESULTS

Age and male sex were significant predictors for increased SBP, whereas the Injury Severity Score (ISS) ≥16 was a significant predictor for decreased SBP. In both male and female TBI patients, SBP ≥160 mmHg was associated with increased pneumonia (Adjusted odds ratio [AOR] = 1.74, P = .002 and AOR = 2.37, P = .046, respectively), whereas SBP ≥160 mmHg was a predictor for mortality only among male TBI patients (AOR = 1.48, P = .03). In non-TBI patients, SBP ≥160 mmHg was not a predictor for pneumonia or mortality in either sex.

CONCLUSIONS

In this retrospective review of trauma registry data, men presented with higher SBP. In patients with TBI, regardless of gender, increased SBP was associated with increased pneumonia, and in men with TBI increased SBP was associated with increased mortality. The cause and relevance of these epidemiological findings require further investigation.

The GH/IGF-1 system in critical illness

The Growth Hormone and Insulin-like Growth Factor-1 (IGF-1) axis plays a pivotal role in critical illness, with a derangement leading to profound changes in metabolism. Protein wasting with skeletal muscle loss, delayed wound healing, and impaired recovery of organ systems are some of the most feared consequences. The use of human recombinant Growth Hormone (rhGH) and Insulin-like Growth Factor-1 (IGF-1) - alone and in combination - has been studied extensively in preclinical and clinical trials. This article reviews the current knowlegde and clinical practice of the use of rhGh and IGF-1 in critically ill patients, with a special focus on the trauma and burns patient population.

Hormonal status in protracted critical illness and in-hospital mortality

Introduction

The aim of this study was to determine the relationship between hormonal status and mortality in patients with protracted critical illness.

Methods

We conducted a prospective observational study in four medical and surgical intensive care units (ICUs). ICU patients who regained consciousness after 7 days of mechanical ventilation were included. Plasma levels of insulin-like growth factor 1 (IGF-1), prolactin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, estradiol, progesterone, testosterone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS) and cortisol were measured on the first day patients were awake and cooperative (day 1). Mean blood glucose from admission to day 1 was calculated.

Results

We studied 102 patients: 65 men and 37 women (29 of the women were postmenopausal). Twenty-four patients (24%) died in the hospital. The IGF-1 levels were higher and the cortisol levels were lower in survivors. Mean blood glucose was lower in women who survived, and DHEA and DHEAS were higher in men who survived.

Conclusions

These results suggest that, on the basis of sex, some endocrine or metabolic markers measured in the postacute phase of critical illness might have a prognostic value.

IGF-I concentration and changes in critically ill patients

BACKGROUND

Insulin-like growth factor 1 (IGF-I) is an anabolic growth factor that affects nitrogen balance and its changing trend is not clearly understood in critically ill patients. This study was carried out to evaluate the association between serum IGF-I levels and its changing trend in critically ill patients.

METHODS

In this nested case-control study, all consecutive patients admitted to the medical ICU of Rasoul-e-Akram and Firuzgar hospital (Tehran, Iran) from January through October 2008 were included. IGF1 concentration was measured within the first 24h of ICU admission and the fourth, seventh and tenth day since admission. Patients were followed until discharge from ICU or expiration.

RESULTS

The study population consisted of 90 patients (mean age: 58.01 ± 22.56), 31 (34.4%) of who died and 59 (65.6%) were discharged. On admission, 43 patients (47.7%) had low IGF-I levels, whereas 47 (52.3%) had normal or high levels. The concentration of IGF-I was not significantly different in every 4 measurements between expired and discharged patients. Significant decrease was seen between first to fourth day IGF-I concentration (p = 0.005). Changing trend was not statistically different in two groups of patients.

CONCLUSIONS

There was no relation between low IGF-I concentration on admission day and increased adverse outcome, but overall these patients had lower IGF1. No clear association was found between changing trend of IGF1 and mortality. Stress on admission time may cause decreasing pattern of IGF-I in the first 4 days of admission.

An evaluation of the neuroendocrine response to sleep in pediatric burn patients

INTRODUCTION

Previous work demonstrated reduced stage 3+4 and rapid eye movement (REM) sleep following burn injury. This study evaluated the hormonal effects of drug intervention on measures of endocrine status. A secondary objective examined the relationship between hormones and sleep stage distribution.

METHODS

Forty patients 3-18 years of age with a mean percent total body surface area burn of 50.1 +/- 2.9 were randomly assigned to zolpidem or haloperidol utilizing a blinded crossover design. Polysomnography was performed 6 nights, 3/week over 2 weeks. Each week's first night of monitoring was conducted without medication, serving as a baseline. Hormonal levels (epinephrine, norepinephrine, growth hormone, melatonin, dehydroepiandrosterone [DHEA], serotonin, cortisol) were obtained at 0600 h each study day.

RESULTS

Both drugs were associated with increased DHEA levels (P < .03); no other hormones were affected by medication. Significant inverse correlation was observed between REM sleep and epinephrine (r = -.34, P = .004) and norepinephrine levels (r = -.45, P = .02). A positive relationship existed between serotonin and sleep stage 3+4 (r = 0.24, P = .01) and REM (r = 0.48, P = .01). No other significant associations were identified between hormones and sleep.

CONCLUSIONS

This work characterizes the relationship between sleep deprivation and select endocrine parameters postburn. Drug interventions utilized in this study were either ineffective or insufficient in modulating improved hormonal response. Significance of zolpidem's and haloperidol's effect on serum levels of DHEA is unclear. The inverse correlation of epinephrine with REM may suggest that hypermetabolism associated with burns is partly due to lack of REM sleep. Questions remain regarding the effects of sleep deprivation on metabolism and clinical outcome.

Using ordinal logistic regression to evaluate the performance of laser-Doppler predictions of burn-healing time

Background

Laser-Doppler imaging (LDI) of cutaneous blood flow is beginning to be used by burn surgeons to predict the healing time of burn wounds; predicted healing time is used to determine wound treatment as either dressings or surgery. In this paper, we do a statistical analysis of the performance of the technique.

Methods

We used data from a study carried out by five burn centers: LDI was done once between days 2 to 5 post burn, and healing was assessed at both 14 days and 21 days post burn. Random-effects ordinal logistic regression and other models such as the continuation ratio model were used to model healing-time as a function of the LDI data, and of demographic and wound history variables. Statistical methods were also used to study the false-color palette, which enables the laser-Doppler imager to be used by clinicians as a decision-support tool.

Results

Overall performance is that diagnoses are over 90% correct. Related questions addressed were what was the best blood flow summary statistic and whether, given the blood flow measurements, demographic and observational variables had any additional predictive power (age, sex, race, % total body surface area burned (%TBSA), site and cause of burn, day of LDI scan, burn center). It was found that mean laser-Doppler flux over a wound area was the best statistic, and that, given the same mean flux, women recover slightly more slowly than men. Further, the likely degradation in predictive performance on moving to a patient group with larger %TBSA than those in the data sample was studied, and shown to be small.

Conclusion

Modeling healing time is a complex statistical problem, with random effects due to multiple burn areas per individual, and censoring caused by patients missing hospital visits and undergoing surgery. This analysis applies state-of-the art statistical methods such as the bootstrap and permutation tests to a medical problem of topical interest. New medical findings are that age and %TBSA are not important predictors of healing time when the LDI results are known, whereas gender does influence recovery time, even when blood flow is controlled for.

The conclusion regarding the palette is that an optimum three-color palette can be chosen 'automatically', but the optimum choice of a 5-color palette cannot be made solely by optimizing the percentage of correct diagnoses.

Ghrelin inhibits skeletal muscle protein breakdown in rats with thermal injury through normalizing elevated expression of E3 ubiquitin ligases MuRF1 and MAFbx

We previously determined that ghrelin synthesis was downregulated after burn injury and that exogenous ghrelin retained its ability both to stimulate food intake and to restore plasma growth hormone levels in burned rats. These observations and the finding that anabolic hormones can attenuate skeletal muscle catabolism led us to investigate whether ghrelin could attenuate burn-induced skeletal muscle protein breakdown in rats. These studies were performed in young rats (50-60 g) 24 h after approximately 30% total body surface area burn injury. Burn injury increased total and myofibrillar protein breakdown in extensor digitorum longus (EDL) muscles assessed by in vitro tyrosine and 3-methyl-histidine release, respectively. Continuous 24-h administration of ghrelin (0.2 mg.kg(-1).h(-1)) significantly inhibited both total and myofibrillar protein breakdown in burned rats. Ghrelin significantly attenuated burn-induced changes in mRNA expression of IGFBP-1 and IGFBP-3 in liver. In EDL, ghrelin attenuated the increases in mRNA expression of the binding proteins, but had no significant effect on reduced expression of IGF-I. Ghrelin markedly reduced the elevated mRNA expression of TNF-alpha and IL-6 in EDL muscle that occurred after burn. Moreover, ghrelin normalized plasma glucocorticoid levels, which were elevated after burn. Expression of the muscle-specific ubiquitin-ligating enzyme (E3) ubiquitin ligases MuRF1 and MAFbx were markedly elevated in both EDL and gastrocnemius and were normalized by ghrelin. These results suggest that ghrelin is a powerful anticatabolic compound that reduces skeletal muscle protein breakdown through attenuating multiple burn-induced abnormalities.

Pathophysiologic response to severe burn injury

OBJECTIVE

To improve clinical outcome and to determine new treatment options, we studied the pathophysiologic response postburn in a large prospective, single center, clinical trial.

SUMMARY BACKGROUND DATA

A severe burn injury leads to marked hypermetabolism and catabolism, which are associated with morbidity and mortality. The underlying pathophysiology and the correlations between humoral changes and organ function have not been well delineated.

METHODS

Two hundred forty-two severely burned pediatric patients [>30% total body surface area (TBSA)], who received no anabolic drugs, were enrolled in this study. Demographics, clinical data, serum hormones, serum cytokine expression profile, organ function, hypermetabolism, muscle protein synthesis, incidence of wound infection sepsis, and body composition were obtained throughout acute hospital course.

RESULTS

Average age was 8 +/- 0.2 years, and average burn size was 56 +/- 1% TBSA with 43 +/- 1% third-degree TBSA. All patients were markedly hypermetabolic throughout acute hospital stay and had significant muscle protein loss as demonstrated by a negative muscle protein net balance (-0.05% +/- 0.007 nmol/100 mL leg/min) and loss of lean body mass (LBM) (-4.1% +/- 1.9%); P < 0.05. Patients lost 3% +/- 1% of their bone mineral content (BMC) and 2 +/- 1% of their bone mineral density (BMD). Serum proteome analysis demonstrated profound alterations immediately postburn, which remained abnormal throughout acute hospital stay; P < 0.05. Cardiac function was compromised immediately after burn and remained abnormal up to discharge; P < 0.05. Insulin resistance appeared during the first week postburn and persisted until discharge. Patients were hyperinflammatory with marked changes in IL-8, MCP-1, and IL-6, which were associated with 2.5 +/- 0.2 infections and 17% sepsis.

CONCLUSIONS

In this large prospective clinical trial, we delineated the complexity of the postburn pathophysiologic response and conclude that the postburn response is profound, occurring in a timely manner, with derangements that are greater and more protracted than previously thought.

Oxandrolone in Pediatric Patients with Severe Thermal Burn Injury

Objective

To review the rolo of oxandrolone in pediatric patients with severe thermal burn injury.

Data Sources:

MEDLINE (1950–April 2008) and Science Citation Index (1900–April 2008) searches were performed using the key terms oxandrolone, burn, and children.

Study Selection And Data Extraction:

All English-language articles that evaluated the efficacy and safety of oxandrolone in pediatric patients with severe thermal burn injury were included in this review.

Data Synthesis:

Oxandrolone stimulates protein synthesis by binding to androgen receptors. The efficacy and safety of adjunct oxandrolone therapy in pediatric patients (≤18 y old) with severe thermal burn injury (total body surface area burn >20%) were evaluated in 8 clinical studies. Oral oxandrolone 0.1 mg/kg twice daily increased protein synthesis, lean body mass accretion, and muscle strength; improved serum visceral protein concentrations; promoted weight gain; and increased bone mineral content. During the postburn rehabilitation period, oxandrolone 0.1 mg/kg/day improved muscle strength, especially when combined with exercise. Based on clinical studies, oxandrolone 0.1 mg/kg twice daily is safe when given for up to 12 months. However, mild increases in serum liver transaminase concentrations and reversible sexual changes were observed during therapy. Although data on the efficacy and safety of oxandrolone in severely burned children are supported by prospective, randomized, controlled studies, limitations of available data aro that they originated from a single study center and that wound healing measurement is lacking in children with severe thermal burns.

Conclusions:

The benefits of adjunct oxandrolone therapy in severely burned pediatric patients have been demonstrated in the acute postburn injury and long-term postburn rehabilitation periods. Close monitoring of liver function, sexual development, and growth pattern is recommended during oxandrolone treatment.

Gender differences in pediatric burn patients: does it make a difference?

OBJECTIVE

There is evidence that females have a better outcome in intensive care units (ICUs) when compared with males. The aim of the present study was to compare hospital course and physiologic markers between severely burned pediatric females and males.

SUMMARY BACKGROUND DATA

One-hundred eighty-nine children sustaining a >or=40% total body surface area burn were divided into females (n = 76) and males (n = 113).

METHODS

: Patient demographics, clinical parameters, and mortality were noted. Muscle protein synthesis was determined by stable isotope technique. Resting energy expenditure (REE) was measured by indirect calorimetry and body composition by dual x-ray absorptiometry. Serum hormones, proteins, and cytokines were determined. Cardiac function and liver size were determined by repeated ultrasound measurements.

RESULTS

There were no significant differences between females and males for mortality, demographics, burn size, nutritional intake, or concomitant injuries. ICU stay was in females: 29+/-3 days whereas the stay in males was 38+/-3 days, P < 0.05. Females had a significant attenuated loss in muscle protein net balance (females: -0.028+/-0.001% vs. males: -0.05+/-0.007%) and an increase in lean body mass (Delta females: 5+/-4% vs. Delta males: -1+/-3%), P < 0.05. Percent-predicted REE was significantly decreased in females compared with males, P < 0.05. Systemic inflammatory markers and stress hormone levels were significantly decreased in females, P < 0.05. Cardiac and liver dysfunction were significantly attenuated in females compared with males, P < 0.05.

CONCLUSIONS

Female burned patients exert an attenuated inflammatory and hypermetabolic response compared with males. This decrease is reflected in improved muscle protein net balance and preservation of lean body mass, which are associated with shortened hospital stay.

[Evaluation of energy expenditure in children. Physiological and clinical implications and measurement methods]

The present article reviews the importance of the study of energy metabolism and its methods of assessment in children. Classically, energy requirements have been assessed by predictive equations based on anthropometric data. However, there are several physiologic and pathogenic states that may cause discrepancies between estimated and real values and consequently direct measurements of energy expenditure should be used. The gold standard to assess total energy expenditure during prolonged periods is the doubly labeled water method, which is mainly used for research studies. The best approach for resting energy expenditure determination in the clinical setting is indirect calorimetry. However, this method does not provide data on energy consumption under free-living conditions and its use in some critical care patients is restricted by technical limitations. Several other approaches to assess activity have been developed, based on heart rate, body temperature measurements, motion sensors and combined methods.

Age differences in inflammatory and hypermetabolic postburn responses

OBJECTIVE

The aim of this study was to identify contributors to morbidity and death in severely burned patients <4 years of age.

METHODS

A total of 188 severely burned pediatric patients were divided into 3 age groups (0-3.9 years, 4-9.9 years, and 10-18 years of age). Resting energy expenditure was measured through oxygen consumption, body composition through dual-energy x-ray absorptiometry, liver size and cardiac function through ultrasonography, and levels of inflammatory markers, hormones, and acute-phase proteins through laboratory chemistry assays.

RESULTS

Resting energy expenditure was highest in the 10- to 18-year-old group, followed by the 4- to 9.9-year-old group, and was lowest in the 0- to 3.9-year-old group. Children 0 to 3.9 years of age maintained lean body mass and body weight during acute hospitalization, whereas children >4 years of age lost body weight and lean body mass. The inflammatory cytokine profile showed no differences between the 3 age groups, whereas liver size increased significantly in the 10- to 18-year-old group and was lowest in the 0- to 3.9-year-old group. Acute-phase protein and cortisol levels were significantly decreased in the toddler group, compared with the older children. Cardiac data indicated increased cardiac work and impaired function in the toddler group, compared with the other 2 age groups.

CONCLUSIONS

Increased mortality rates for young children are associated with increased cardiac work and impaired cardiac function but not with the inflammatory and hypermetabolic responses.

Suplementação de antioxidantes: enfoque em queimados

Na queimadura, os radicais livres são produzidos durante a reposição de fluídos, alterando numerosos componentes, como os ácidos nucléicos, os lipídios e as proteínas. Sendo assim, se, por um lado, essa restauração do fluxo sanguíneo é, em geral, necessária para recuperar a função celular normal, por outro lado a reintrodução do sangue oxigenado nos tecidos isquêmicos contribui para uma produção excessiva de radicais livres derivados do oxigênio, exacerbando a lesão mediada pela isquemia. O papel dos neutrófilos ativados na célula após a queimadura também tem recebido atenção especial. A partir do sistema NADPH oxidase os neutrófilos aderidos podem produzir uma explosão de radical superóxido, produzindo um dano tecidual importante. A queimadura, além de aumentar a produção de radicais livres, também é capaz de impedir os mecanismos de defesa antioxidante, submetendo o paciente queimado ao estresse oxidativo, o qual se constitui em fator perpetuante da resposta inflamatória sistêmica, levando à piora progressiva do estado metabólico. Com esses dados, objetiva-se revisar os principais estudos com a suplementação de antioxidantes em pacientes críticos, com ênfase em pacientes queimados, e descrever os possíveis benefícios dessa intervenção.

Insulin therapy in the pediatric intensive care unit

BACKGROUND & AIMS

Hyperglycemia is a major risk factor for increased morbidity and mortality in the intensive care unit. Insulin therapy has emerged in adult intensive care units and several pediatric studies are currently being conducted. This review discusses hyperglycemia and the effects of insulin on metabolic and non-metabolic pathways, with a focus on pediatric critical illness.

METHODS

A PubMed search was performed by using the following keywords and limits (("hyperglycemia"[MeSH terms] or ("insulin resistance"[MeSH major topic]) and ("critical care"[MeSH terms] or "critical illness"[MeSH terms])) in different combinations with ("metabolism"[MeSH terms] or "metabolic networks and pathways"[MeSH terms]) and ("outcome"[all fields]) and ("infant"[MeSH terms] or "child"[MeSH terms] or "adolescent"[MeSH terms]). Quality assessment of selected studies included clinical pertinence, publication in peer-reviewed journals, objectivity of measurements and techniques used to minimize bias. Reference lists of such studies were included.

RESULTS

The magnitude and duration of hyperglycemia are associated with increased morbidity and mortality in the pediatric intensive care unit (PICU), but prospective, randomized controlled studies with insulin therapy have not been published yet. Evidence concerning the mechanism and the effect of insulin on glucose and lipid metabolism in pediatric critical illness is scarce. More is known about the positive effect on protein homeostasis, especially in severely burned children. The effect in septic children is less clear and seems age dependent. Some non-metabolic properties of insulin such as the modulation of inflammation, endothelial dysfunction and coagulopathy have not been fully investigated in children.

CONCLUSION

Future studies on the effect of insulin on morbidity and mortality as well as on the mechanisms through which insulin exerts these effects are necessary in critically ill children. We propose these studies to be conducted under standardized conditions including precise definitions of hyperglycemia and rates of glucose intake.

Metabolic modulators following trauma sepsis: Sex hormones

BACKGROUND

The development of metabolic perturbations following severe trauma/sepsis leading to decreased energy production, hyperglycemia, and lipolysis is often rapid. Gender is increasingly recognized as a major factor in the outcome of patients suffering from trauma/sepsis. Moreover, sex hormones influence energy, glucose, and lipid metabolism. Metabolic modulators, such as peroxisome proliferator-activated receptor-gamma coactivator-1 and peroxisome proliferator-activated receptor-alpha, which are required for mitochondrial energy production and fatty acid oxidation, are regulated by the estrogen receptor-beta and consequently contribute to cardioprotection following trauma hemorrhage. Additionally, sex steroids regulate inflammatory cytokines that cause hypermetabolism/catabolism via acute phase response, leading to increased morbidity and mortality.

MEASUREMENTS

This article examines the following: (1) the evidence for gender differences; (2) energy, glucose, and lipid metabolism and the acute phase protein response; (3) the mechanisms by which gender/sex hormones affect the metabolic modulators; and (4) the tissue-specific effect of sex hormone receptors and the effect of genomic and nongenomic pathways of sex hormones following trauma.

RESULTS AND CONCLUSIONS

The available information indicates that sex steroids not only modulate the immune/cardiovascular responses but also influence various metabolic processes following trauma. Thus, alteration or modulation of the prevailing hormone milieu at the time of injury appears to be a novel therapeutic adjunct for improving outcome after injury.

SEX DIFFERENCES IN THE LONG-TERM OUTCOME AFTER A SEVERE THERMAL INJURY

We have recently shown that during the acute phase, postburn female pediatric burn patients had significantly increased levels of anabolic hormones with an associated decreased hypermetabolism leading to a significant shorter intensive care unit stay compared with male patients. The aim of the present study was to determine possible differences between girls and boys in body composition, hypermetabolism, and hormone pattern in the long term. Sixty-two children (1-16 years old) who sustained a severe thermal injury (>or=40% total body surface area) were included into the study. Patients were further divided into girls (n = 22) and boys (n = 40). Patient demographics, nutritional support, and mortality were noted. Resting energy expenditure (REE) was measured by indirect calorimetry, body composition by dual-energy x-ray absorptiometry (Hologic Inc, Waltham, Mass) at discharge, 3, 6, 9, 12, 18, and 24 months after burn. In addition, blood was drawn at the same time points, and serum hormones were measured. There were no significant differences between girls and boys for demographics, nutritional intake, or concomitant injuries. Predicted REE was significantly decreased in girls at discharge, 6, 12, and 18 months postburn (P < 0.05). Dual-energy x-ray absorptiometry scan showed that girls had improved change in bone mineral content and percent fat compared with boys (P < 0.05). There were no differences in changes in height, body weight, lean body mass, and total fat between groups. Girls had significantly higher levels of insulinlike growth factor 1, insulinlike growth factor binding protein 3, free thyroxine index, T4, and insulin when compared with boys (P < 0.05). No differences were found for T3 uptake, osteocalcin, cortisol, growth hormone, and parathyroid hormone (PTH) between groups. Data indicate that girls have a reduced REE associated with changes in bone content and endogenous anabolic hormones.

Blood transfusions are associated with increased risk for development of sepsis in severely burned pediatric patients

OBJECTIVE

To determine the risk of developing sepsis following transfusion of blood products in severely burned pediatric patients.

DESIGN

Retrospective, cohort study.

SETTING

Shriners Hospital for Children and University Hospital.

PATIENTS

Severely burned pediatric patients with >30% total body surface area (TBSA) burn.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Two hundred seventy-seven pediatric burn patients over a period of 7 yrs (1997-2004) were included in the study, with 25 patients being septic at admission and therefore excluded. Patients were stratified according to TBSA burn and presence or absence of inhalation injury. The amounts of packed red blood cells (RBCs) and fresh frozen plasma (FFP) were recorded during hospital stay before the development of sepsis. Blood product administration was normalized for the number of surgeries and divided into two groups: high (RBCs>20/FFP>5) or low (RBCs<20/FFP<5) amount of blood products. Sepsis was diagnosed based on the criteria set by the Society of Critical Care Medicine in conjunction with positive blood culture or presence of organisms in the organs at autopsy. By stratifying the groups into low and high blood transfusion, we found that patients with >60% TBSA burn with inhalation injury have an 8% risk of developing sepsis in the low RBC group, which increases to 58% in the high RBC group (p<.05). Similar results were found for RBCs per operation, FFP, and FFP per operation (p<.05). There were no differences in age and gender between groups.

CONCLUSIONS

Pediatric burn suffering from a 60% TBSA burn with concomitant inhalation injury are more likely to develop sepsis if they are given high amounts of blood products, indicating an immunocompromised state following blood transfusion.

The use of anabolic agents in catabolic states

OBJECTIVE

We plan to review the current problem of lean mass erosion in catabolic states, caused by injury and critical illness. This protein loss is driven by the hormonal imbalance and excess inflammation referred to as the "stress response to injury." We then plan to provide the current concepts on the use of available anabolic agents to attenuate the excess catabolism.

DATA SOURCE

The available published literature on the pathogenesis of acute catabolic states and the use of anabolic and anticatabolic agents, their indications, mechanism of action, and potential complications was reviewed.

DATA EXTRACTION

The current understanding and experience of the available anabolic and anticatabolic agents as well as the rationale for the use of each anabolic agent are described.

CONCLUSION

We conclude that the preservation of lean body mass (body protein) is extremely important in the management of critical care populations, as lean mass loss leads to severe morbidity and increased mortality. Essentially, all of the available anabolic agents stimulate protein synthesis and decrease protein breakdown, but all have different mechanisms of action. Adequate nutrition, especially protein intake, is essential for any anabolism to occur. Combined anabolic therapy also appears to be advantageous. Although controlling the inflammatory response would also be of major benefit in further controlling protein loss, effective and safe anti-inflammatory agents have not yet become clinically available for this purpose.

Metabolic changes after polytrauma: an imperative for early nutritional support

Major trauma induces marked metabolic changes which contribute to the systemic immune suppression in severely injured patients and increase the risk of infection and posttraumatic organ failure. The hypercatabolic state of polytrauma patients must be recognized early and treated by an appropriate nutritional management in order to avoid late complications. Clinical studies in recent years have supported the concept of "immunonutrition" for severely injured patients, which takes into account the supplementation of Ω-3 fatty acids and essential aminoacids, such as glutamine. Yet many aspects of the nutritional strategies for polytrauma patients remain controversial, including the exact timing, caloric and protein amount of nutrition, choice of enteral versus parenteral route, and duration. The present review will provide an outline of the pathophysiological metabolic changes after major trauma that endorse the current basis for early immunonutrition of polytrauma patients.

The influence of age and gender on resting energy expenditure in severely burned children

INTRODUCTION

Recent evidence suggests that female severely burned children have higher endogenous anabolic hormone levels and a shorter ICU stay compared with males. The purpose of this study was to analyze the influence of age and gender on resting energy expenditure (REE) in severely burned children from acute hospitalization through 12 months postburn.

METHODS

A total of 100 pediatric patients with > 40% total body surface area (TBSA) burn were enrolled in a prospective study and followed by indirect calorimetry measurements. The REE was expressed as actual REE kcal/d, percent of predicted REE, and REE/ body mass index (BMI). Statistical analysis was performed by Student t test and one-way ANOVA for repeated measures. Significance was accepted at P < 0.05.

RESULTS

The measured REE was significantly higher in males versus females at all time points (P < 0.05). The percent of predicted REE was significantly higher in males versus females during the acute hospitalization, at discharge, 6 and 9 months postburn (P < 0.05). The REE/BMI showed a significant difference between males and females at the acute and discharge time period (P < 0.05). In children 3 to 9.9 years of age, the measured REE and the percent of predicted REE were significantly higher in males versus females during the acute study, at discharge and 6 months postburn (P < 0.05). The measured REE at discharge, 9 and 12 months postburn for children >10 years of age was significantly higher in males compared with females (P < 0.05).

CONCLUSION

Data show that female children exert a decreased hypermetabolic response compared with male children, which may improve burn outcomes in females.

Inhibition of cardiac PGC-1alpha expression abolishes ERbeta agonist-mediated cardioprotection following trauma-hemorrhage

PGC-1alpha (peroxisome proliferator-activated receptor [PPARgamma] coactivator-1alpha) activates PPARalpha and mitochondrial transcription factor A (Tfam), which regulate proteins, fatty acid and ATP metabolism (i.e., FAT/CD36, MCAD, and COX I). Recently we found that the salutary effects of estradiol (E2) on cardiac function following trauma-hemorrhage (T-H) are mediated via estrogen receptor (ER)beta. In this study we tested the hypothesis that ERbeta-mediated cardioprotection is induced via up-regulation of PGC-1alpha through PPARalpha or Tfam-dependent pathway. Male rats underwent T-H and received ERalpha agonist propylpyrazole-triol (PPT), ERbeta agonist diarylpropionitrile (DPN), E2, or vehicle. Another group was treated with antisense PGC-1alpha oligonucleotides prior to administration of DPN. E2 and DPN treatments attenuated the decrease in cardiac mitochondrial ATP, abrogated the T-H-induced lipid accumulation, and normalized PGC-1alpha, PPARalpha, FAT/CD36, MCAD, Tfam, and COX I after T-H. In contrast, PPT administration did not abrogate lipid accumulation. Moreover, in PPT-treated animals mitochondrial ATP remained significantly lower than those observed in DPN- or E2-treated animals. Prior administration of antisense PGC-1alpha prevented DPN-mediated cardioprotection and increase in ATP levels and Tfam but not in PPARalpha following T-H. These findings suggest that the salutary effects of E2 on cardiac function following T-H are mediated via ERbeta up-regulation of PGC-1alpha through Tfam-dependent pathway.

Ghrelin stimulates food intake and growth hormone release in rats with thermal injury: synthesis of ghrelin

Ghrelin, a 28-residue octanoylated peptide recently isolated from the stomach, exhibits anti-cachectic properties through regulating food intake, energy expenditure, adiposity, growth hormone secretion and immune response. Burn injury induces persistent hypermetabolism and muscle wasting. We therefore hypothesized that ghrelin may also play a role in the pathophysiology of burn-induced cachexia. Overall ghrelin expression in the stomach over 10 days after burn was significantly decreased (p = 0.0003). Total plasma ghrelin was reduced 1 day after burn. Thus, changes in ghrelin synthesis and release may contribute to burn-induced dysfunctions. Ghrelin (30 nmol/rat, i.p.) greatly stimulated 2 h food intake in rats on five separate days after burn and in control rats. On post-burn day 15, plasma growth hormone levels were significantly lower than in controls, and this was restored to normal levels by ghrelin (10 nmol/rat, i.p.). These observations suggest that ghrelin retains its ability to favorably modulate both the peripheral anabolic and the central orexigenic signals, even after thermal injury despite ongoing changes due to prolonged and profound hypermetabolism, suggesting that long-term treatment with ghrelin may attenuate burn-induced dysfunctions.

Resting energy expenditure in severely burned children: Analysis of agreement between indirect calorimetry and prediction equations using the Bland–Altman method

INTRODUCTION

Knowledge of a child's resting energy expenditure (REE) is essential in optimizing nutritional support for severely burned children. The provision of adequate nutritional support is vital in order to avoid the consequences of malnutrition or overfeeding. Nutritional requirements for severely burned children are often based on equations for estimates of REE. The accuracy of the predictive equations of REE has been questioned and many authors have advocated the measurement of REE. This study tests the hypothesis that estimates of REE vary significantly from measured REE (MREE) in a population of severely burned children, and are not accurate for determining nutritional requirements.

METHODS

In 91 severely burned children aged between 3 and 18 years, REE was measured by indirect calorimetry (MREE) at the height of the hypermetabolic response and compared with predicted equations (PREE) from the Food and Agriculture/World Health Organization/United Nations University (FAO/WHO/UNU), Schofield-HW and Harris-Benedict. Agreement between indirect calorimetry and predicted equations was assessed following the Bland-Altman method.

RESULTS

In the entire cohort group, predicted REE from all three equations were significantly lower compared to MREE (p<0.05). There was poor agreement between the MREE and predicted using all three equations. The Schofield-HW equation showed the lowest mean MREE-PREE difference: 635+/-526 kcal/day (limits of agreement -608 and 1878 kcal/day; 95% confidence interval for the bias 525-745 kcal/day). Additionally, all three equations under predicted REE and were not significantly different from one another (p=0.98).

CONCLUSIONS

Until more accurate predicted equations are developed, we recommend indirect calorimetry measurements for determining resting energy expenditure in severely burned children.