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

Persisting neuroendocrine abnormalities and their association with physical impairment 5 years after critical illness

Background

Critical illness is hallmarked by neuroendocrine alterations throughout ICU stay. We investigated whether the neuroendocrine axes recover after ICU discharge and whether any residual abnormalities associate with physical functional impairments assessed 5 years after critical illness.

Methods

In this preplanned secondary analysis of the EPaNIC randomized controlled trial, we compared serum concentrations of hormones and binding proteins of the thyroid axis, the somatotropic axis and the adrenal axis in 436 adult patients who participated in the prospective 5-year clinical follow-up and who provided a blood sample with those in 50 demographically matched controls. We investigated independent associations between any long-term hormonal abnormalities and physical functional impairments (handgrip strength, 6-min walk distance, and physical health-related quality-of-life) with use of multivariable linear regression analyses.

Results

At 5-year follow-up, patients and controls had comparable serum concentrations of thyroid-stimulating hormone, thyroxine (T₄), triiodothyronine (T₃) and thyroxine-binding globulin, whereas patients had higher reverse T₃ (rT₃, p = 0.0002) and lower T₃/rT₃ (p = 0.0012) than controls. Patients had comparable concentrations of growth hormone, insulin-like growth factor-I (IGF-I) and IGF-binding protein 1 (IGFBP1), but higher IGFBP3 (p = 0.030) than controls. Total and free cortisol, cortisol-binding globulin and albumin concentrations were comparable for patients and controls. A lower T₃/rT₃ was independently associated with lower handgrip strength and shorter 6-min walk distance (p ≤ 0.036), and a higher IGFBP3 was independently associated with higher handgrip strength (p = 0.031).

Conclusions

Five years after ICU admission, most hormones and binding proteins of the thyroid, somatotropic and adrenal axes had recovered. The residual long-term abnormality within the thyroid axis was identified as risk factor for long-term physical impairment, whereas that within the somatotropic axis may be a compensatory protective response. Whether targeting of the residual abnormality in the thyroid axis may improve long-term physical outcome of the patients remains to be investigated.

Trial registration ClinicalTrials.gov: NCT00512122, registered on July 31, 2007 (https://www.clinicaltrials.gov/ct2/show/NCT00512122).

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03858-1.

A review of potential biomarkers for assessing physical and psychological trauma in paediatric burns

Biological markers that evaluate physical healing as well as psychological impact of a burn are essential for effective treatment of paediatric burns. The objective of this review is to summarize the evidence supporting the use of biomarkers in children with burns. An extensive review of the literature was performed using PubMed. A total of 59 biomarkers were identified relating to burn presence, specifically relating to processes involved in inflammation, wound healing, growth and metabolism. In addition, biomarkers involved in the stress response cascade following a burn trauma were also identified. Although many biomarkers have been identified that are potentially associated with burn-related physical and psychological trauma, an understanding of burn biology is still lacking in children. We propose that future research in the field of children’s burns should be conducted using broad screening methods for identifying potential biomarkers, examine the biological interactions of different biomarkers, utilize child-appropriate biological fluids such as urine or saliva, and include a range of different severity burns. Through further research, the biological response to burn injury may be fully realized and clinically relevant diagnostic tests and treatment therapies utilizing these biomarkers could be developed, for the improvement of healing outcomes in paediatric burn patients.

Cardiac Structure and Function in Well-Healed Burn Survivors

Long-term burn survivors have reduced aerobic capacity, placing them at increased risk for cardiovascular disease, morbidity, and mortality. However, the exact mechanism contributing to a reduced aerobic capacity remains incompletely understood, but may be related to adverse cardiovascular remodeling. Therefore, it was hypothesized that well-healed burn survivors would exhibit adverse left ventricular (LV) remodeling and impaired LV function. To test this hypothesis, 22 well-healed moderately burned individuals (age: 41 ± 14 years; BMI: 27.7 ± 5.4 kg/m2; male/female: 12/10; extent of burn: 37 ± 12 %BSA), 11 well-healed severely burned individuals (age: 43 ± 12 years; BMI: 29.5 ± 5.8 kg/m2; male/female: 8/3; extent of burn: 73 ± 11 %BSA), and 12 healthy, age-matched controls (age: 34 ± 9 years; BMI: 28.6 ± 5.2 kg/m2; male/female: 5/7) were enrolled in the study. All subjects were sedentary, performing less than 30 minutes of aerobic exercise per day, 3 days per week. LV morphology and function were assessed via cardiac magnetic resonance imaging. In contrast to the hypothesis, neither the presence nor severity of burn injury adversely affected LV morphology or function, when compared with equally sedentary nonburned controls. However, of note, LV mass of all three groups was in the lowest 5th percentile compared with normative values. Finally, group differences in LV morphology were largely explained by differences in aerobic capacity. Taken together, these data suggest a prior burn injury itself does not result in pathological remodeling of the LV and support a role for aerobic exercise training to improve cardiac function.

The Link between Hypermetabolism and Hypernatremia in Severely Burned Patients

Hypernatremia is common in critical care, especially in severely burned patients. Its occurrence has been linked to increased mortality. Causes of hypernatremia involve a net gain of sodium or a loss of free water. Renal loss of electrolyte-free water due to urea-induced osmotic diuresis has been described as causative in up to 10% of hypernatremic critical ill patients. In this context, excessive urea production due to protein catabolism acts as major contributor. In severe burn injury, muscle wasting occurs as result of hypermetabolism triggered by ongoing systemic inflammation. In this retrospective study, severely burned patients were analysed for the occurrence of hypernatremia and subsequent signs of hypermetabolism. The urea: creatinine ratio—as a surrogate for hypermetabolism—sufficiently discriminated between two groups. Four of nine hypernatremic burn patients (44%) had a highly elevated urea: creatinine ratio, which was clearly associated with an increased urea production and catabolic index. This hypermetabolism was linked to hypernatremia via an elevated urea- and reduced electrolyte-fraction in renal osmole excretion, which resulted in an increased renal loss of electrolyte-free water. In hypermetabolic severely burned patients, the electrolyte-free water clearance is a major contributor to hypernatremia. A positive correlation to serum sodium concentration was shown.

Factors mediating demographic determinants of injury mortality

PURPOSE

Elevated injury mortality rates persist for men and people of color despite attempts to standardize trauma care in the United States. This study investigates the role of injury characteristics and access to trauma care as mediators of the relationships between race, ethnicity, sex, and injury mortality.

METHODS

Data on prehospital and trauma center care were examined for adult injured patients in Maryland who were transported by emergency medical services to designated trauma centers (n = 15,355) or who died while under emergency medical services care (n = 727). Potential mediators of the relationship between demographic characteristics and injury mortality were identified through exploratory analyses. Total, direct, and indirect effects of race, ethnicity, and sex were estimated using multivariable mediation models.

RESULTS

Prehospital time, hospital distance, injury mechanism, and insurance status mediated the effect of African American race, resulting in a 5.7% total increase (95% CI: 1.6%, 9.9%) and 5.6% direct decrease (95% CI: 1.1%, 9.9%) in odds of death. Mechanism, insurance, and distance mediated the effect of Hispanic ethnicity, resulting in an 11.4% total decrease (95% CI: 6.4%, 16.2%) and 13.4% direct decrease (95% CI: 8.1%, 18.3%) in odds of death. Injury severity, mechanism, insurance, and time mediated the effect of male sex, resulting in a 27.3% total increase (95% CI: 21.6%, 10.9%) and a 6.2% direct increase (95% CI: 1.8%, 10.9%) in odds of death.

CONCLUSIONS

Distance, injury characteristics, and insurance mediate the effects of demographic characteristics on injury mortality and appear to contribute to disparities in injury mortality.

Children with severe burns display no sex differences in exercise capacity at hospital discharge or adaptation after exercise rehabilitation training

BACKGROUND AND OBJECTIVE

Females have a 50% increased risk of death from burn injury compared to males. However, whether exercise capacity and exercise induced training adaptations differ between burned boys and girls is unknown. This project tested the hypothesis that girls with burns have lower exercise capacity and different exercise induced training adaptations.

METHODS

Twenty-five girls were matched to 26 boys (mean, 95%CI; years 13 [12,14], cm 151 [143,161], kg 54 [45,63]; each P>0.05) for burn injury (% total body surface area burn, 54 [45,62]; P=0.82). Lean body mass (LBM), strength (peak torque) and cardiorespiratory fitness (peak VO₂) were normalized to kg LBM and compared as a percentage of age-sex matched non-burned children (n=26 boys, years 13 [12,14]; n=25 girls, years 13 [12,14]) at discharge (DC) and after aerobic and resistance rehabilitation exercise training (RET).

RESULTS

Using a 2-way factorial ANOVA (group×time), we found both groups had similar 11% change in LBM (87.3% of non-burned values [82.2,92.3]) and after the RET (92.8% [87.2,98.3]; main effect, time P<0.0001). Peak torque increased similarly by 16% in both groups (% of age-sex matched non-burned DC, 55.9 [51.3,60.5]; after RET, 77.5 [72.1,82.9]; main effect, time P<0.0001). Likewise, peak VO₂ increased in both groups by 15% (% of age-sex matched non-burned DC, 56.8 [52.4,61.2] to RET, 72.2 [67.6,76.8]; main effect, time; P<0.0001). Burned children exercise at greater percentage of their peak VO₂ and peak HR compared to non-burned children (Interaction, group×time, P<0.0001).

CONCLUSION

The burn injury does not have sex-dependent effects on LBM or exercise capacity in severely burn injured children. Differences in relative peak VO₂ and peak HR suggest the need for burn specific exercise programs for improving the efficacy of a rehabilitation program.

The biochemical alterations underlying post-burn hypermetabolism

A severe burn can trigger a hypermetabolic state which lasts for years following the injury, to the detriment of the patient. The drastic increase in metabolic demands during this phase renders it difficult to meet the body's nutritional requirements, thus increasing muscle, bone and adipose catabolism and predisposing the patient to a host of disorders such as multi-organ dysfunction and sepsis, or even death. Despite advances in burn care over the last 50 years, due to the multifactorial nature of the hypermetabolic phenomenon it is difficult if not impossible to precisely identify and pharmacologically modulate the biological mediators contributing to this substantial metabolic derangement. Here, we discuss biomarkers and molecules which play a role in the induction and mediation of the hypercatabolic condition post-thermal injury. Furthermore, this thorough review covers the development of the factors released after burns, how they induce cellular and metabolic dysfunction, and how these factors can be targeted for therapeutic interventions to restore a more physiological metabolic phenotype after severe thermal injuries. This article is part of a Special Issue entitled: Immune and Metabolic Alterations in Trauma and Sepsis edited by Dr. Raghavan Raju.

FIVE-YEAR OUTCOMES AFTER LONG-TERM OXANDROLONE ADMINISTRATION IN SEVERELY BURNED CHILDREN: A RANDOMIZED CLINICAL TRIAL

Administration of oxandrolone, a nonaromatizable testosterone analog, to children for 12 months following severe burn injury has been shown to improve height, increase bone mineral content (BMC), reduce cardiac work, and augment muscle strength. Surprisingly, the increase in BMC persists well beyond the period of oxandrolone administration. This study was undertaken to determine if administration of oxandrolone for 2 years yields greater effects on long-term BMC and bone mineral density (BMD). Patients between 0 and 18 years of age with ≥30% of total body surface area burned were consented to an IRB-approved protocol and randomized to receive either placebo (n = 84) or 0.1 mg/kg oxandrolone orally twice daily for 24 months (n = 35). Patients were followed prospectively from the time of admission until 5 years postburn in a single-center, intent-to-treat setting. Height, weight, BMC, and BMD were recorded annually through 5 years postinjury. The long-term administration of oxandrolone for 16 ± 1 months postburn (range, 12.1-25.2 months) significantly increased whole-body (WB) BMC (p < 0.02) and lumbar spine (LS) BMC (p < 0.05); these effects were significantly pronounced for a longer time in patients who were in growth spurt years (7-18 years). When adjusted for height, sex, and age, LS BMD was found to significantly increase with long-term oxandrolone administration (p < 0.0009). Fewer patients receiving oxandrolone exhibited LS BMD z scores below -2.0 as compared with controls, indicating a significantly reduced risk for future fracture with oxandrolone administration. Long-term oxandrolone patients had significantly greater height velocity than controls throughout the first 2-year postburn (p < 0.05). No adverse side effects were attributed to the long-term administration of oxandrolone. A comparison of the current patients receiving long-term oxandrolone to previously described patients receiving 12 months of oxandrolone revealed that long-term oxandrolone administration imparted significantly greater increases in WB-BMC, WB-BMD, and LS-BMD (p < 0.05). In conclusion, the administration of oxandrolone for up to 24 months to severely burned pediatric patients significantly improves WB BMC, LS BMC, LS BMD, and height velocity. The administration of long-term oxandrolone was more efficacious than administration for 12 months. Additionally, fewer patients in the oxandrolone cohort met the diagnostic criteria for pediatric osteoporosis, pointing to a reduced risk for future bone fracture. This study demonstrates that administering oxandrolone for up to 2 years following severe burn injury results in greater improvements in BMC, BMD, and height velocity.

In-depth analysis of clotting dynamics in burn patients

BACKGROUND

Studies associating coagulopathic changes with burn injury have relied on limited tests such as partial thromboplastin time (PTT) and international normalized ratio (INR). Understanding the clotting dynamics and associated risk factors after burn injury could influence management. This work aimed to identify real-time changes in coagulation after burn injury not indicated by PTT or INR alone.

MATERIALS AND METHODS

Nine burn-injured patients at a regional burn center were enrolled for blood collection at admission and set intervals over 96 h. Patient demographics, management, and laboratory data (PTT and INR) were collected. Plasma assays determined factors II, V, VII, VIII, IX, X, XI, antithrombin, and protein C functional activity as well as PAP, D-Dimer, fibrin monomer, TFPI, IL-1b, IL-6, IL-10, IL-12p.70, and TNF-α concentrations.

RESULTS

Overall, five patients died. These patients had higher mortality scores and were more acidotic. All patients had normal coagulation studies (INR < 1.5, PTT < 45 s) within 24 h of admission, and only two were abnormal after. Increased factor VIII and IX activity were identified in seven patients at admission. Decreased antithrombin and protein C activity were seen in all patients. Patients had increased PAP, D-Dimer, and fibrin monomer concentrations throughout their hospital course. At admission, increased fold changes were seen in IL-6 (2.5-117) and IL-10 (2.4-32), whereas IL-1b and TNF-α levels were depressed in all patients.

CONCLUSIONS

Extensive changes not identified by PTT or INR were seen after burn injury that may explain perturbed coagulation in these patients. This approach further characterizes the impact thermal injury has on coagulation.

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.

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.

Effect of isokinetic training on muscle strength, size and gait after healed pediatric burn: a randomized controlled study

OBJECTIVE

The aim of this study was to investigate the effects of isokinetic training program on muscle strength, muscle size and gait parameters after healed pediatric burn.

DESIGN

Randomized controlled trial.

SUBJECTS

Thirty three pediatric burned patients with circumferential lower extremity burn with total body surface area (TBSA) ranging from 36 to 45%, and ages from 10 to 15 years participated in the study and were randomized into isokinetic group and a control group. Non-burned healthy pediatric subjects were assessed similarly to burned subjects and served as matched healthy controls.

METHODS

Patients in the isokinetic group (n=16) participated in the isokinetic training program for 12 weeks for quadriceps dominant limb, 3 times per week, at angular velocity 150°/s, concentric mode of contraction, time rest between each set for 3 min, 3 sets/day and control group (n=17) participated in home based physical therapy exercise program without isokinetic.

MAIN MEASURES

Assessment of quadriceps strength by isokinetic dynamometer, quadriceps size and gait parameters were performed at baseline and at the end of the training period for both groups.

RESULTS

Patients in isokinetic group showed a significant improvement in quadriceps strength, quadriceps size and gait parameters as compared with those in the control group. Quadriceps strength and percentage of improvement was 79.25 ± 0.93 Nm (68.40%) for isokinetic group and 51.88 ± 1.31 Nm (9.84%) for the control group. Quadriceps size and percentage of improvement was 31.50 ± 0.89 cm (7.47%) for isokinetic group and 29.26 ± 1.02 cm (1.02%) for the control group. Stride length, step length, velocity and cadence and percentage of improvement for isokinetic group was 135.50 ± 2.82 (53.97%), 63.25 ± 2.97 (63.77%), 135.94 ± 1.65 (81.42%), 137.63 ± 1.36 (66.96%) and for the control group was 94.00 ± 2.69 (6.68%), 43.76 ± 1.34 (15.15%), 81.11 ± 1.91 (8.6%), 90.35 ± 1.32 (9.01%) respectively.

CONCLUSIONS

Participation in the isokinetic training program resulted in a greater improvement in quadriceps muscle strength, size and gait parameters in pediatric burn.

17β-Estradiol reappropriates mass lost to the hypermetabolic state in thermally injured rats

BACKGROUND

The hypermetabolic response to severe thermal injury is unlike any physiologic response seen in medicine. While some parallels can be drawn to shock and sepsis states, this response is typified by its intensity and duration. Our group has been interested in the myriad effects of estrogens after injury, specifically the ability of estrogens to reduce inflammatory responses. Given this, and the known link between severe inflammation and the hypermetabolic response, we examined the effects of a single dose of 17β estradiol administered after a severe thermal injury in rats.

METHODS

Twelve male Sprague-Dawley rats were subject to either a sham burn or a 40% total body surface area burn, followed by fluid resuscitation. Burned animals were divided into a vehicle and treatment group, with injections given 15 min after the injury. Animals were monitored for a period of 45 d, with markers of hypermetabolism (weight, fecal output, food intake, and serum insulin and glucose) measured daily.

RESULTS

We identified a significant difference in daily measured weights between the burned groups. We observed a sparing of body mass during the acute phase lasting 2 wk after the injury and an improved recovery phase during the remainder of the study. Glucose and insulin levels during the first week of the study did not differ between the treatment groups.

CONCLUSION

Estrogen may have a role in preserving body mass after severe thermal injury. Further studies are required to determine if this spared body mass composition.

Thermal injury activates the eEF2K-dependent eEF2 pathway in pediatric patients

BACKGROUND

Burn induces a hypermetabolic state characterized by alterations in protein metabolism, which is associated with increased morbidity and mortality. Eukaryotic elongation factor 2 (eEF2) plays a crucial role in regulating protein synthesis in many diseases, but whether it participates in burn-induced hypermetabolism is unclear. The aim of this study was to determine the expression of eEF2 and the upstream eEF2-inactivating kinase, eEF2K, in severely burned pediatric patients.

METHODS

Eight pediatric patients (> 40% total body surface area) and 3 nonburned pediatric volunteers were enrolled. Muscle and skin biopsies were collected at early (0-10 days postburn [dpb]), middle (11-49 dpb), and late (50-365 dpb) time points. Resting energy expenditure (REE), body composition, and muscle protein fractional synthesis rate (FSR) were measured. Proteins were extracted and analyzed by Western blotting. To further investigate the protein synthesis pathway, microarray data from muscle and skin were examined from 22 nonburned and 20 burned children.

RESULTS

Burn patients exhibited a profound hypermetabolic response, as seen by a significant increase in REE (P < .05) and loss of lean body mass without altered muscle FSR, indicating a shift to catabolism after thermal injury. In muscle, the phosphorylation of eEF2K-dependent eEF2 was down regulated early and middle postburn. Similar changes in eEF2K and eEF2 levels occurred in skin at the early time point. Total amounts of eEF2 and eEF2K were not altered.

CONCLUSION

Burn induces prolonged activation of eEF2K and eEF2. Alterations in these mediators may contribute to profound hypermetabolism in severely burned patients.

Mortality after thermal injury: no sex-related difference

BACKGROUND

Young women have been reported to be more likely to survive than men after severe trauma. Girls also have less inflammation and hypermetabolism after major burns. Yet burned women have been found to have a twofold greater risk of death than men. Our aim was to find out if there is a sex-related difference in mortality after thermal injury, particularly in the age group between 16 years and 49 years, when hormonal differences would be most influential.

METHODS

All patients admitted to the Linköping University Hospital Burn Unit with thermal injuries during the years 1993-2008 were included and the variables percentage burned total body surface area (TBSA%), age, type of burn, mechanical ventilation, and year were included in a multiple regression (Poisson log) model.

RESULTS

Of 1,119 patients with thermal injury, 792 (71%) were men. Crude mortality was 5% among men, and 8% among women (p = 0.04). After adjustment for age and TBSA%, there was no correlation between mortality and sex, in any age group. Eight men and four women died in the group of young adults (16-49 years) in which TBSA% correlated with mortality (p < 0.01) but age did not. Mortality was 14% (32 of 221) among the men and 23% (23 of 102) of women in the group of older adults (50 years and older), and both age and TBSA% correlated with mortality (p < 0.001).

CONCLUSIONS

There is no relevant sex-related difference in survival after thermal injury. The conclusion is, however, tempered by the few deaths, particularly among younger adults.

Randomized controlled trial to determine the efficacy of long-term growth hormone treatment in severely burned children

BACKGROUND

Recovery from a massive burn is characterized by catabolic and hypermetabolic responses that persist up to 2 years and impair rehabilitation and reintegration. The objective of this study was to determine the effects of long-term treatment with recombinant human growth hormone (rhGH) on growth, hypermetabolism, body composition, bone metabolism, cardiac work, and scarring in a large prospective randomized single-center controlled clinical trial in pediatric patients with massive burns.

PATIENTS AND METHODS

A total of 205 pediatric patients with massive burns over 40% total body surface area were prospectively enrolled between 1998 and 2007 (clinicaltrials.gov ID NCT00675714). Patients were randomized to receive either placebo (n = 94) or long-term rhGH at 0.05, 0.1, or 0.2 mg/kg/d (n = 101). Changes in weight, body composition, bone metabolism, cardiac output, resting energy expenditure, hormones, and scar development were measured at patient discharge and at 6, 9, 12, 18, and 24 months postburn. Statistical analysis used Tukey t test or ANOVA followed by Bonferroni correction. Significance was accepted at P < 0.05.

RESULTS

RhGH administration markedly improved growth and lean body mass, whereas hypermetabolism was significantly attenuated. Serum growth hormone, insulin-like growth factor-I, and IGFBP-3 was significantly increased, whereas percent body fat content significantly decreased when compared with placebo, P < 0.05. A subset analysis revealed most lean body mass gain in the 0.2 mg/kg group, P < 0.05. Bone mineral content showed an unexpected decrease in the 0.2 mg/kg group, along with a decrease in PTH and increase in osteocalcin levels, P < 0.05. Resting energy expenditure improved with rhGH administration, most markedly in the 0.1 mg/kg/d rhGH group, P < 0.05. Cardiac output was decreased at 12 and 18 months postburn in the rhGH group. Long-term administration of 0.1 and 0.2 mg/kg/d rhGH significantly improved scarring at 12 months postburn, P < 0.05.

CONCLUSION

This large prospective clinical trial showed that long-term treatment with rhGH effectively enhances recovery of severely burned pediatric patients.

Extent and magnitude of catecholamine surge in pediatric burned patients

Increased catecholamine (CA) levels after severe burn are associated with stress, inflammation, hypermetabolism, and impaired immune function. The CA secretion profiles in burned patients are not well described. Mechanisms, duration, and extent of CA surge are unknown. The purpose of this large unicenter study was to evaluate the extent and magnitude of CA surge after severe burn in pediatric patients. Patients admitted between 1996 and 2008 were enrolled in this study. Twenty-four-hour urine collections were performed during acute hospitalization and up to 2 years postburn. Results from the samples collected from 12 normal, healthy volunteers were compared with the data from the burned patients. Relevant demographic and clinical information was obtained from medical records. Student t-test and one-way ANOVA were used to analyze the data where appropriate. Significance was accepted at P < 0.05. Four hundred thirteen patients were enrolled in this study; 17 patients died during acute hospitalization. Burn caused a marked stress and inflammatory response, indicated by massive tachycardia and elevated proinflammatory cytokines. In burned patients, CA levels are consistently and significantly modulated after burn when compared with the levels in normal, healthy volunteers. Catecholamine levels were significantly higher in boys compared with girls, correlated with burn size in burns greater than 40%, and were increased in older children. There were differences over time in survivors versus nonsurvivors, with CA levels significantly higher in nonsurvivors at two time points. Inflammatory cytokines show a similar profile during the study period. Our study gives clinicians a useful insight into the extent and magnitude of CA elevation to better design treatment strategies.

Naturally existing CD11c(low)CD45RB(high) dendritic cells protect mice from acute severe inflammatory response induced by thermal injury

Despite a good understanding of the process that initiates and promotes host inflammation induced by acute injury, little is known about the host immune cells responsible for the inhibition of inflammatory response to thermal injury. The aim of this study was to investigate the potential effect of naturally existing CD11c(low)CD45RB(high) dendritic cells (CD11c(low)CD45RB(high) DCs) on acute severe inflammatory response and mortality rate in burned mice. Changes in the percentage of distinct subsets of splenic DCs and production of cytokines (IL-6, TNF-α, CCL-2) as well as CC chemokine (CCL)-2 were measured by FACS at various time points. The influence of CD11c(low)CD45RB(high) DCs on IL-6, TNF-α, CCL-2 as well as IL-10 levels and mortality rate was observed following a single intraperitoneal injection of DCs to scald mice. Levels of IL-6, CCL-2 and TNF-α were peaked at postburn hours (PBHs) 12, and percentages of CD11c(low)CD45RB(high) DCs were elevated at PBH 12-24. A single intraperitoneal injection of CD11c(low)CD45RB(high) DCs to 15% total body surface area in scald mice led to significant decrease in IL-6, TNF-α and CCL-2, and lethality, but up-regulation of IL-10 compared with untreated mice from PBH 0 to 48. CD11c(low)CD45RB(high) DCs can effectively down-regulate the production of inflammatory cytokines and reduce the mortality rate in 15% TBSA scald injury mice.

Effects of burn injury on markers of hypermetabolism in rats

The basic metrics of hypermetabolism have not been thoroughly characterized in rat burn injury models. We examined three models expected to differ in sensitivity to burn injury to identify that which group(s) exhibited the most clinically relevant metabolic response. Six and 12 weeks old male CD (6 week mCD and 12 week mCD) rats, and 12 weeks old female Fischer (12 week fFI) rats received a 20% total body surface area burn, followed by saline resuscitation. Activity, core body temperature, heart rate (via implanted telemetry devices), body weight, food and water intake, and fecal output were measured daily for 1 week before and after burn. Rats lost weight initially postburn but resumed weight gain by 1 week, except for 12 week mCD rats. Core body temperature increased above normal 2 days postburn and returned to baseline by 1 week. Food intake, normalized to body weight, remained unchanged postburn for 12 week mCD rats, but decreased in 6 week mCD rats and increased in 12 week fFI rats. Heart rate in the 12 week mCD and 12 week fFI rats remained at 10 to 15% above baseline, whereas, in 6 week mCD, heart rates returned to baseline after 4 days. Activity levels were unchanged for 12 week fFI and 6 week mCD rats postburn, but decreased for 12 week mCD rats. Postburn hypermetabolism was most significant and sustained in 12 week mCD rats, of least consequence and brief in 6 week mCD rats, and intermediate in 12 week fFI rats. The disparate responses indicate that the choice of animal model should be carefully considered in hypermetabolism studies.

Measurement of body composition in burned children: is there a gold standard?

BACKGROUND

Maintaining lean body mass (LBM) after a severe burn is an essential goal of modern burn treatment. An accurate determination of LBM is necessary for short- and long-term therapeutic decisions. The aim of this study was to compare 2 measurement methods for body composition, whole-body potassium counting (K count) and dual x-ray absorptiometry (DEXA), in a large prospective clinical trial in severely burned pediatric patients.

METHODS

Two-hundred seventy-nine patients admitted with burns covering 40% of total body surface area (TBSA) were enrolled in the study. Patients enrolled were controls or received long-term treatment with recombinant human growth hormone (rhGH). Near-simultaneous measurements of LBM with DEXA and fat-free mass (FFM) with K count were performed at hospital discharge and at 6, 9, 12, 18, and 24 months post injury. Results were correlated using Pearson's regression analysis. Agreement between the 2 methods was analyzed with the Bland-Altman method.

RESULTS

Age, gender distribution, weight, burn size, and admission time from injury were not significantly different between control and treatment groups. rhGH and control patients at all time points postburn showed a good correlation between LBM and FFM measurements (R(2) between 0.9 and 0.95). Bland-Altman revealed that the mean bias and 95% limits of agreement depended only on patient weight and not on treatment or time postburn. The 95% limits ranged from 0.1 +/- 2.9 kg for LBM or FFM in 7- to 18-kg patients to 16.3 +/- 17.8 kg for LBM or FFM in patients >60 kg.

CONCLUSIONS

DEXA can provide a sufficiently accurate determination of LBM and changes in body composition, but a correction factor must be included for older children and adolescents with more LBM. DEXA scans are easier, cheaper, and less stressful for the patient, and this method should be used rather than the K count.