The management of acute bone loss in severe catabolism due to burn injury

Children's growth and motor development following a severe burn: a systematic review

Background

The epidemiological data on post-burn growth, body composition and motor development is ambiguous and scattered. The aim of this systematic review was therefore to summarize the current body of evidence on post-burn growth, body composition and motor development in children.

Methods

A literature search was conducted in PubMed, EMBASE and Web of Science up to March 2021. We considered observational studies that reported (1) metrics on weight, height, body composition, bone mineral content, bone mineral density or motor development, in (2) paediatric burn patients and (3) published in a peer-reviewed journal.

Results

A total of 16 studies were included. Each of the included studies used quantitative methods, but with differing methodology: prospective cohort studies (n = 8), retrospective chart reviews (n = 3), case-control studies (n = 2), cross sectional studies (n = 2) and a retrospective cohort study (n = 1). When combined, the included studies represented 2022 paediatric burn patients, with a mean age of 7.7 (±3.2) years. The average burn size was 52.8% (±12.7) of the total body surface area. Identified outcome measures included weight (n = 12), height (n = 7), muscular strength (n = 4), bone mineral content (n = 5), bone mineral density (n = 5), body mass index (n = 3), fat mass (n = 5), lean body mass (n = 7) and fine and gross motor development (n = 1).

Conclusions

Following an initial decline, patients' growth and motor development started to recover during the first or second year post-burn. Nonetheless, burns may have a profound and prolonged effect on the paediatric burn patients' muscular strength, bone mineral content and lean body mass. It should be noted that the vast majority of studies included only patients with burns covering ≥30% total body surface area. The evidence presented in this review may thus not be representative of the whole paediatric burn population.

Large animal models of thermal injury

Burn injury results in a triad of inter-related adaptive responses: a systemic inflammatory response, a stress response, and a consequent hypermetabolic state which supports the former two. These pathological responses extend beyond the site of injury to affect distant organs and influence long-term outcomes in the patient. Animal models have proven valuable in advancing our understanding of mechanisms underlying the multifactorial manifestations of burn injury. While rodent models have been unprecedented in providing insights into signaling pathways, metabolic responses, protein turnover, cellular and molecular changes; small animal models do not replicate hypermetabolism, hyperinflammation, and wound healing after a burn injury as seen in humans. Herein, we provide a concise review of preferred large animal models utilized to understand burn pathophysiology based on organ systems and associated dysfunction. Additionally, we present a detailed protocol of contact burn injury in the Yorkshire pig model with a focus on preoperative care, anesthesia, analgesia, wound excision and grafting, dressing application, and frequency of dressing changes.

Severe Burn-Induced Inflammation and Remodeling of Achilles Tendon in a Rat Model

Severe burn causes systemic inflammation and hypercatabolism, resulting in damage to multiple organs distant to the burn site, including the musculoskeletal system. Bone mass and muscle loss have been reported. However, tendon that connects bone and muscle has not been studied in comparable detail. Here we aimed to characterize the molecular and functional changes in Achilles tendon triggered by severe burn. Forty male Sprague-Dawley rats received 40% total body surface area scald burn. Achilles tendons were collected up to 14 days postburn. Sham-treated animals served as a control group. We analyzed tendons for changes in expression of IL-6, IL-1β, TNF, MMP9, MMP13, TGFβ1, Collagens I and III, and for morphological and biomechanical changes. Gene expression of IL-6 and IL-1β as well as MMP9 and MMP13 increased in rat tendon 3 days after burn. Col3a1 increased at day 3 and col1a1 at day 7. At day 14, TGFβ1 increased, whereas the protein ratio for collagens I/III decreased, indicating tendon remodeling. Histological analysis with H&E and Picrosirius red staining further revealed a decrease in organized collagen fibers 14 days after burn. Biomechanical analysis showed a decrease in stiffness and ultimate force of tendons in burn rats.We conclude that tendinopathy was observed in Achilles tendon 14 days after severe burn, via the induction of inflammation and remodeling. The present study provides a model of tendinopathy that may be used for the development of therapeutic approaches after burn.

Risk of osteoporosis and fracture in victims with burn injury

Osteoporosis is a well-known bone disorder affecting people worldwide. Patients with osteoporosis have an increased risk of bone fracture. This study provides new information on the risk of developing osteoporosis post burn injury and the risk of fracture among those with osteoporosis developed.

INTRODUCTION

The relationship between burn injury and hip fracture risk is unclear. Population-based evaluation on relationships between burn injury and osteoporosis development and subsequent fractures is limited. We conducted a retrospective cohort study as the investigation.

METHODS

From the insurance data of Taiwan, we established a cohort of 43,532 patients with a burn injury in 2000-2012 and a comparison cohort of 174,124 individuals without such an injury, frequency matched by sex, age, and diagnosis date. Both cohorts were followed up to the end of 2013 to evaluate the occurrence of osteoporosis and hip fracture.

RESULTS

The incidence of osteoporosis was greater in the burn cohort than in the comparison cohort (6.40 vs. 4.75 per 1,000 person-years) with an adjusted IRR of 1.35 (95% confidence interval = 1.32-1.39). The incidence rates in both cohorts were greater in women than in men, increased with age, income, and Charlson comorbidity index. Patients with burns involving 20%-49% of total body surface area and with burns confined to the lower/upper limbs had the greatest incidence rates, 8.32 and 8.58 per 1,000 person-years, respectively. Osteoporosis incidence increased further to 22.7 per 1,000 person-years for burn victims with comorbid diabetes. The risk of fracture was over five-fold greater for burn victims with osteoporosis developed than for comparisons without osteoporosis.

CONCLUSION

Patients who have a burn injury deserve prevention intervention to reduce the risk of osteoporosis and fracture.

Burn Injury Has Skeletal Site-Specific Effects on Bone Integrity and Markers of Bone Remodeling

To further understand the mechanisms of perturbations in bone remodeling following severe burn injury, the biomechanical properties, genetic expression, and serological markers were evaluated in rodents at six time intervals within 6 weeks following injury. Moreover, these effects were observed in rodent tibia and lumbar vertebrae to explore possible skeletal site localization of this pathologic bone loss. Rodents underwent either thermal injury (100°C water, 30 seconds, 30% BSA) or sham burn. Bone mineral density was evaluated though peripheral quantitative computer tomography, and specialized apparatus measured the weight bearing capacity of tibia and lumbar vertebrae. Markers of bone resorption (RANK ligand, osteocalcin) and bone formation (osteoprotegerin, procollagenase type 1 alpha 2) were measured at 7, 14, and 21 days following injury, and serum RANK-ligand levels were observed at these time intervals. Rodent body mass, bone mineral density, and weight bearing capacity were negatively influenced both acutely and several weeks following burn injury. Moreover, a genetic expression profile favoring increased bone resorption and lower bone formation was demonstrated. Our serum analysis findings of significantly increased RANKL 1 and 2 weeks following injury support the increased expression of bone resorption markers. Furthermore, these effects occurred sooner and were more pronounced in the rodent lumbar vertebrae than tibia. These results suggest that severe burn injury results in perturbations in bone remodeling secondary to increased bone resorption and diminished bone formation, impacting both bone mineral density and weight bearing capacity. Furthermore, these processes had a skeletal site effect more pronounced in the lumbar vertebrae. With a better understanding of the mechanisms of burn-injury bone loss, targeted therapies can be implemented to improve long-term clinical outcomes.

Hip fracture risk in patients with burn injury: a retrospective cohort study in Taiwan

This work aimed to evaluate the hip fracture risk for patients with burn injury. A total of 16,430 patients with burn injury had an adjusted hazard ratio of 1.54 to encounter a hip fracture, compared with controls without the injury. These results encourage future studies focusing on mechanisms leading to fracture associated with burn injury.

INTRODUCTION

The relationship between burn injury and hip fracture risk is unclear. We conducted a retrospective cohort study to investigate this relationship.

METHODS

From insurance data of Taiwan, we identified a cohort with 16,430 burn patients in 2000-2010 and a comparison cohort of 65,716 persons without the history of burn, frequency matched by sex, age, and diagnosis date. Both cohorts were followed up to the end of 2011 to evaluate the risk of hip fracture.

RESULTS

Patients with burn injury were 1.62-fold more likely than comparisons to encounter a hip fracture (6.95 vs. 4.28 per 1000 person-years), with an adjusted hazard ratio (aHR) of 1.54 (95% confidence interval (CI) = 1.40-1.68). The fracture incidence increased with age and is slightly greater for women than for men in both cohorts. The fracture risk was greater for patients with burn in the eyes, face, and head with an incidence of 7.14 per 1000 person-years, or an aHR of 2.09 (95% CI = 1.53, 2.86). Diabetes and osteoporosis were also associated with an increased hip fracture risk.

CONCLUSION

Burn injury is associated with an increased risk of hip fracture. Diabetes and osteoporosis are associated with an enhanced risk.

Fracture admissions after burns: A retrospective longitudinal study

BACKGROUND

Severe burn triggers systemic responses that result in reduced muscle mass and changes in bone formation, with recent evidence also suggesting systemic effects on bone after minor burns. The aim of this study was to assess if people hospitalised with a burn have increased admissions for fractures after discharge.

METHODS

A population-based longitudinal study using linked hospital morbidity and death data from Western Australia was undertaken of all persons hospitalised for a first burn (n=30,997) during the period 1980-2012. Australian population-based annual rates for fracture admissions for the period 1993-2012 were obtained from the Australian Institute of Health and Welfare. Rates of hospital admissions for fractures in the burn cohort and the Australian population were standardised, using the direct method, to the age and gender structure of the Western Australian population at the 2006. Annual standardised fracture admission rates for the period 1993-2012 were graphed with estimated 95% confidence intervals. Age and gender specific fracture rates were also examined.

RESULTS

A total of 4004 members of the burn cohort had at least one fracture admission for a total of 6096. The median (IQR) time to the first fracture admission after burn was 6.9 years (2.8-13.6) and the median age (IQR) at first fracture admission was 31 years (20-49). The burn cohort experienced admissions for fractures at a rate approximately twice that of the Australian population. While rates were generally higher for males in the burn cohort when compared with males in the Australian population, female burn patients had significantly higher rates over the entire study period when compared with the female Australian population. Elevated rates were observed for those younger than 20 years at the time of the burn admission; however, rates were significantly and consistently elevated during the study period for those 20 years and older at the time of the burn.

CONCLUSIONS

Burn patients experienced significantly higher age and gender standardised rates of admissions for fractures after discharge from hospital for their index burn. Further prospective research is indicated to clarify any underlyling pathogenic processes linked to the burn that may increase a patient's risk of having a fracture serious enough to undergo admission.

Nutrition Support Strategies for Severely Burned Patients

Significant weight loss is a common complication of a major burn injury. Before the modern era of early enteral nutrition support, such a complication contributed significantly to impaired wound healing, raised risk of infectious morbidity, and ultimately increased mortality. Nutrition management of the burn patient is designed to promote wound healing while minimizing loss of lean body mass. The burn patient characteristically demonstrates an increase in energy expenditure after the initial injury and period of resuscitation. Studies have demonstrated that early institution of enteral feeding can attenuate the stress response, abate hypermetabolism, and improve patient outcome.

Clinically Relevant Concentrations of Ketamine Inhibit Osteoclast Formation In Vitro in Mouse Bone Marrow Cultures

Ketamine has been used safely in clinics for decades for analgesia and anesthesia. It is increasingly popular in clinical practice due to its new uses and importance for emergency procedures. It is known that ketamine is sequestered in the bone marrow and the major receptors for ketamine, noncompetitive N-methyl-d-aspartate receptors (NMDARs), are expressed in osteoclasts (OCs) and osteoblasts. However, the impact of ketamine on OCs or osteoblasts is unknown. In this study, we investigated the effects of ketamine on osteoclastogenesis and regulation of NMDARs expression in vitro. Bone marrows (BMs) or bone marrow macrophages (BMMs) were cultured in the presence of macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL) with or without ketamine for up to 6 days. OC formation peaked at day 5. On day 5 of culture, ketamine inhibited OC formation from both BM and BMM cultures at clinically relevant concentrations (3-200 µM). Ketamine inhibited RANKL-induced expression of nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1 (NFATc1) in BMM cultures. Inhibition of ketamine on RANKL-induced osteoclastogenesis is associated with down-regulation of NMDARs. In addition, ketamine significantly inhibited the M-CSF induced migration of BMMs, inhibited cell fusion and significantly increased mature OC apoptosis. We conclude that clinically relevant concentrations of ketamine inhibit OC formation in both BM and BMM cultures in vitro through inhibiting migration and fusion process and enhancing mature OC apoptosis. It is likely that ketamine regulates osteoclastogenesis, at least in part, via its effects on NMDAR expression. J. Cell. Biochem. 118: 914-923, 2017. © 2016 Wiley Periodicals, Inc.

Effects of whole-body vibration exercise on bone mineral content and density in thermally injured children

BACKGROUND

Loss of bone mass, muscle mass, and strength leads to significant disability in severely burned children. We assessed the effects of exercise combined with whole-body vibration (WBV) on bone mass, lean mass (LM), and muscle strength in children recovering from burns.

METHODS

Nineteen burned children (≥30% total body surface area [TBSA] burns) were randomly assigned to a 6-week exercise regimen either alone (EX; n=10) or in combination with a 6-week WBV training regimen (EX+WBV; n=9). WBV was performed concurrent to the exercise regimen for 5days/week on a vibrating platform. Dual-energy X-ray absorptiometry quantified bone mineral content (BMC), bone mineral density (BMD), and LM; knee extension strength was assessed using isokinetic dynamometry before and after training. Alpha was set at p<0.05.

RESULTS

Both groups were similar in age, height, weight, TBSA burned, and length of hospitalization. Whole-body LM increased in the EX group (p=0.041) and trended toward an increase in the EX+WBV group (p=0.055). On the other hand, there were decreases in leg BMC for both groups (EX, p=0.011; EX+WBV, p=0.047), and in leg BMD for only the EX group (EX, p<0.001; EX+WBV, p=0.26). Truncal BMC decreased in only the EX group (EX, p=0.009; EX+WBV, p=0.61), while BMD decreased in both groups (EX, p<0.001; EX+WBV group, p<0.001). Leg strength increased over time in the EX group (p<0.001) and the EX+WBV group (p<0.001; between-group p=0.31).

CONCLUSIONS

Exercise in combination with WBV may help attenuate regional bone loss in children recovering from burns. Studies are needed to determine the optimal magnitude, frequency, and duration of the vibration protocol, with attention to minimizing any potential interference with wound healing and graft closure.

Long-term musculoskeletal morbidity after adult burn injury: a population-based cohort study

OBJECTIVE

To investigate if adults who are hospitalised for a burn injury have increased long-term hospital use for musculoskeletal diseases.

DESIGN

A population-based retrospective cohort study using linked administrative health data from the Western Australian Data Linkage System.

SUBJECTS

Records of 17,753 persons aged at least 20 years when hospitalised for a first burn injury in Western Australia during the period 1980-2012, and 70,758 persons who were age and gender-frequency matched with no injury admissions randomly selected from Western Australia's electoral roll.

MAIN OUTCOME MEASURES

Admission rates and cumulative length of stay for musculoskeletal diseases. Negative binomial and Cox proportional hazards regression modelling were used to generate incidence rate ratios (IRR) and HRs with 95% CIs, respectively.

RESULTS

After adjustment for pre-existing health status and demographic characteristics, the burn cohort had almost twice the hospitalisation rate for a musculoskeletal condition (IRR, 95% CI 1.98, 1.86 to 2.10), and spent 3.70 times as long in hospital with a musculoskeletal diagnosis (95% CI 3.10 to 4.42) over the 33-year period, than the uninjured comparison cohort. Adjusted survival analyses of incident post-burn musculoskeletal disease admissions found significant increases for the 15-year post burn discharge period (0-6 months: HR, 95% CI 2.51, 2.04 to 3.11; 6 months-2 years: HR, 95% CI 1.77, 1.53 to 2.05; 2-15 years: HR, 95% CI 1.32, 1.23 to 1.42). Incident admission rates were significantly elevated for 20 years post-burn for minor and severe burn injury for a range of musculoskeletal diseases that included arthropathies, dorsopathies, osteopathies and soft tissue disorders.

CONCLUSIONS

Minor and severe burn injuries were associated with significantly increased post-burn incident admission rates, long-term hospital use and prolonged length of stay for a range of musculoskeletal diseases. Further research is required that facilitates identification of at-risk patients and appropriate treatment pathways, to reduce the long-term morbidity associated with burns.

Investigation of Bone Health Subsequent to Vitamin D Supplementation in Children Following Burn Injury

BACKGROUND

The effect of supplemental vitamin D on fracture occurrence following burn injuries is unclear. The objective of this study was to evaluate postintervention incidence of fractures in children during the rehabilitative phase postburn (PB) following participation in a randomized clinical trial of vitamin D supplementation.

MATERIALS AND METHODS

Follow-up for fracture evaluation was obtained in 39 of 50 patients randomized to daily enteral vitamin D2, D3, or placebo throughout the acute burn course. Serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, D2, D3, calcitonin, and bone alkaline phosphatase (BAP) measurements were obtained PB day 7, midpoint, discharge, and 1-year PB. Urinary calcium was obtained PB day 7 and midpoint. Dual-energy x-ray absorptiometry (DXA) was performed at discharge and 1-year PB.

RESULTS

Fractures were reported in 6 of 39 respondents. Four fractures occurred in the placebo group, 2 in the D2 group, and none in the D3 group. Serum vitamin D, calcitonin, BAP, and urinary calcium were similar between fracture groups. The group with fracture morbidity had larger burn size (83.8% ± 4.9% vs 53.0% ± 2.9%, P < .0001), greater full-thickness burn (69.7% ± 9.4% vs 39.4% ± 4.1%, P = .02), and increased incidence of inhalation injury (33% vs 6%, P = .04). Decreased bone mineral density z score was noted at discharge in the placebo fracture compared with no-fracture group (P < .05).

CONCLUSION

This preliminary report suggests there may be benefit of vitamin D3 in reducing postdischarge fracture risk. Results reaffirm the importance of monitoring bone health in pediatric patients postburn.

Long-term persistance of the pathophysiologic response to severe burn injury

Background

Main contributors to adverse outcomes in severely burned pediatric patients are profound and complex metabolic changes in response to the initial injury. It is currently unknown how long these conditions persist beyond the acute phase post-injury. The aim of the present study was to examine the persistence of abnormalities of various clinical parameters commonly utilized to assess the degree hypermetabolic and inflammatory alterations in severely burned children for up to three years post-burn to identify patient specific therapeutic needs and interventions.

Methodology/Principal Findings

Patients: Nine-hundred seventy-seven severely burned pediatric patients with burns over 30% of the total body surface admitted to our institution between 1998 and 2008 were enrolled in this study and compared to a cohort non-burned, non-injured children. Demographics and clinical outcomes, hypermetabolism, body composition, organ function, inflammatory and acute phase responses were determined at admission and subsequent regular intervals for up to 36 months post-burn. Statistical analysis was performed using One-way ANOVA, Student's t-test with Bonferroni correction where appropriate with significance accepted at p<0.05. Resting energy expenditure, body composition, metabolic markers, cardiac and organ function clearly demonstrated that burn caused profound alterations for up to three years post-burn demonstrating marked and prolonged hypermetabolism, p<0.05. Along with increased hypermetabolism, significant elevation of cortisol, catecholamines, cytokines, and acute phase proteins indicate that burn patients are in a hyperinflammatory state for up to three years post-burn p<0.05.

Conclusions

Severe burn injury leads to a much more profound and prolonged hypermetabolic and hyperinflammatory response than previously shown. Given the tremendous adverse events associated with the hypermetabolic and hyperinflamamtory responses, we now identified treatment needs for severely burned patients for a much more prolonged time.

Bone loss during the acute stage following burn injury

The aim of this study was to investigate the effect of burn injury on bone metabolism and bone densitometry in the early period. Twenty-one patients with >25% total body surface area (TBSA) burns and 20 healthy controls participated. TBSA burned, ambulation, and functional status were recorded. After 30 days, we measured bone mineral densities of the L1-L4 vertebrae, the left distal forearm, and the left proximal femur in the patients. At 1 and 4 weeks after the burn, changes in bone turnover were assessed in patients by changes in deoxypyridinoline levels in the urine and osteocalcin in the serum and compared with the values of control group. In patients, Z-scores < -1 were found in 71.42% of left distal forearm, 23.80% of left proximal femur, and in 42.85% of L1-L4 vertebrae measurements. No significant correlations existed between Z-scores and TBSA, Functional Ambulation Scale, or Functional Independent Measure. When compared with controls, there was no statistically significant decrease of osteocalcin (a marker of bone formation) levels in patients 1 and 4 weeks after burn injury. However, when compared with controls, a statistically significant difference was found regarding deoxypyridinoline (a marker for bone resorption) in patients 1 and 4 weeks after burn injury (P < .001 and P < .001, respectively). Decreases in bone mineral density occurred during the first month following burn injury, which seemed to be linked with increases in bone resorption during this period. No correlation existed between reduction in bone mineral density and functional status.

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.

The effect of oxandrolone on the endocrinologic, inflammatory, and hypermetabolic responses during the acute phase postburn

OBJECTIVE AND SUMMARY BACKGROUND DATA

Postburn long-term oxandrolone treatment improves hypermetabolism and body composition. The effects of oxandrolone on clinical outcome, body composition, endocrine system, and inflammation during the acute phase postburn in a large prospective randomized single-center trial have not been studied.

METHODS

Burned children (n = 235) with >40% total body surface area burn were randomized (block randomization 4:1) to receive standard burn care (control, n = 190) or standard burn care plus oxandrolone for at least 7 days (oxandrolone 0.1 mg/kg body weight q.12 hours p.o, n = 45). Clinical parameters, body composition, serum hormones, and cytokine expression profiles were measured throughout acute hospitalization. Statistical analysis was performed by Student t test, or ANOVA followed by Bonferroni correction with significance accepted at P < 0.05.

RESULTS

Demographics and clinical data were similar in both groups. Length of intensive care unit stay was significantly decreased in oxandrolone-treated patients (0.48 +/- 0.02 days/% burn) compared with controls (0.56 +/- 0.02 days/% burn), (P < 0.05). Control patients lost 8 +/- 1% of their lean body mass (LBM), whereas oxandrolone-treated patients had preserved LBM (+9 +/- 4%), P < 0.05. Oxandrolone significantly increased serum prealbumin, total protein, testosterone, and AST/ALT, whereas it significantly decreased alpha2-macroglobulin and complement C3, P < 0.05. Oxandrolone did not adversely affect the endocrine and inflammatory response as we found no significant differences in the hormone panels and cytokine expression profiles.

CONCLUSIONS

In this large prospective, double-blinded, randomized single-center study, oxandrolone shortened length of acute hospital stay, maintained LBM, improved body composition and hepatic protein synthesis while having no adverse effects on the endocrine axis postburn, but was associated with an increase in AST and ALT.

Hypovitaminosis D in acutely injured pediatric burn patients

PROBLEM

The prevalence of vitamin D insufficiency, its etiology, and associated sequelae among acutely injured burn patients is unknown.

OBJECTIVE

This study assessed vitamin D and endocrine status, as well as the effect of anabolic agents, in pediatric patients who had sustained burns in excess of 25% total body surface area (TBSA).

SUBJECTS

Sixty-nine patients with a mean TBSA burn of 50.6+/-2.2% (range 27% to 94%) and full thickness injury of 41.3+/-3.0% (range 0% to 94%) were studied. Subjects ranged in age from 0.6 to 18 years (mean, 5.8+/-0.6 years). Main outcome measures Blood samples were obtained for serum 25-hydroxyvitamin D (D25), 1,25-dihydroxyvitamin D (D1,25), albumin, cortisol, triiodothyronine (T3), tetraiodothyronine (T(4)), thyroid stimulating hormone (TSH), and parathormone (PTH).

RESULTS

Two hundred eighty morning blood samples of D25 and D1,25 demonstrated that 45% and 26.2% were low and 8.9% and 11% were very low, respectively. At least one low D25 or D1,25 level occurred in 62.3% of all subjects. Very low levels were noted in 23.2% of all patients. There was an increased incidence of hyperparathyroidism in patients with very low serum D25. Vitamin D25 and D1,25 levels were lower in subjects with larger burns or inhalation injury, as well as those treated with thyroxine or oxandrolone. Serum albumin, cortisol, T(4), and TSH were not correlated with concentration of vitamin D.

CONCLUSIONS

Demonstration of a high incidence of low serum vitamin D indicates vitamin D status may be significantly compromised in burned children. It is unclear why vitamin D deficiency exists in this population. The most effective way to improve vitamin D status remains elusive at this time.

Support of the metabolic response to burn injury

Severe burn causes metabolic disturbances that can last for a year after injury; persistent and profound catabolism hampers rehabilitative efforts and delays the meaningful return of individuals to society. The simplest, effective anabolic strategies for severe burn injuries are: early excision and grafting of the wound; prompt treatment of sepsis; maintenance of environmental temperature at 30-32 degrees C; continuous feeding of a high carbohydrate, high protein diet, preferably by the enteral route; and early institution of vigorous and aerobic resistive exercise programmes. To further keep erosion of lean body mass to a minimum, administration of anabolic agents, recombinant human growth hormone, insulin, oxandrolone, or anticatabolic drugs such as propranolol are alternative approaches. Exogenous continuous low-dose insulin infusion, beta blockade with propranolol, and use of the synthetic testosterone analogue oxandrolone are the most cost effective and least toxic pharmacological treatments to date.

Four-Year Review of Burns as an Etiologic Factor in the Development of Long Bone Fractures in Pediatric Patients

Reduced bone density has been documented in children after burns. This loss of bone may place children at heightened risk for fractures. The medical records of all acutely injured patients with burns in excess of 40% TBSA burn admitted to our institution between January 1, 1997, through December 31, 2000, were reviewed for fracture incidence. Patients with fractures sustained during the course of initial trauma were not included in the review. One hundred four records were reviewed. These patients had a mean age of 6.7 +/- 0.51 years, (range, 0.2 to 18.0) and a mean %TBSA burn of 59.9 +/- 1.60 (range, 40 to 98) with a mean full-thickness %burn of 51.7 +/- 2.16 (range, 0 to 95). Fifteen long bone fractures were documented in six patients during the review time frame. All fractures were initially suspected by physical therapy personnel upon regularly scheduled therapy sessions and subsequently verified by x-ray. All fractures identified by this review occurred in children less than 3 years of age. Most fractures were noted during the rehabilitation phase of injury (range, 73 to 283 days after burn) once wounds were more than 95% healed, except for one child, who sustained multiple fractures during the acute recovery phase at a referring hospital. A 5.8% incidence of fractures was noted in patients with burns in excess of 40% (6 of 104 admissions). The etiology of the fractures is unknown, although the hormonal milieu postburn, depressed vitamin D status, inadequate protein intake, and decreased weight-bearing activity are potential contributory factors. In addition, infants and toddlers tend to provide more resistance to therapy because of an inherent lack of cognition. This may account for the increased breaks in this population.

Current pharmacotherapy for the treatment of severe burns

The pharmacotherapy of burn care has evolved from the first topical antibiotics instituted > 30 years ago. These have helped greatly to reduce the incidence of burn wound sepsis, but a better understanding of the principles of burn care has resulted in earlier burn wound excision and complete coverage with autograft, cadaver skin, synthetic dressings, and amnion. This has markedly reduced septic complications and ameliorated the hypermetabolic response to burn injury. The hypermetabolic response, which is mediated by hugely increased levels of circulating catecholamines, prostaglandins, glucagon and cortisol, causes profound skeletal muscle catabolism, immune deficiency, peripheral lipolysis, reduced bone mineralisation, reduced linear growth, and increased energy expenditure. Supportive therapy and pharmacological manipulation, acutely and during rehabilitation, with growth hormone, insulin and related proteins, oxandrolone and propranolol can ameliorate the hypermetabolic response, improving survival and long-term outcome. Despite judicious use of topical and systemic antibiotics, opportunistic nosocomial bacterial resistance threatens to annul the improved survival of patients with severe burns. Patterns of emerging resistance encountered in burn units need to be considered, in light of a decreasing antibiotic armamentarium. A holistic approach to pharmacotherapy of severely burned patients including current practice in antimicrobial control, analgesia, sedation, and anxiety management is required. Current therapy of frequently encountered problems, such as post-burn pruritus, prophylaxis of deep venous thrombosis and peptic ulceration, and pharmacological manipulation of inhalation injury in the burned patient is described. Current pharmacotherapy to ameliorate psychosocial problems associated with burns such as acute stress disorder, depression and post traumatic stress disorder are discussed. Better analgesics, newer antibiotics and immune stimulating drugs are required to reduce mortality and morbidity in large burns.

The effect of prolonged euglycemic hyperinsulinemia on lean body mass after severe burn

BACKGROUND

The hypermetabolic response to burn increases protein catabolism. Euglycemic hyperinsu-linemia with exogenous insulin maintains muscle protein by continued stimulation of net protein synthesis. Our aim was to determine the effect of euglycemic hyperinsulinemia over the entire hospitalization on muscle anabolism by investigating lean body mass (LBM) as the primary endpoint.

METHODS

Eighteen subjects between the ages of 2 and 18 with burns of more than 40% were prospectively randomized into 2 groups, a control (n = 9) and a treatment group (n = 9). The treatment group was given continuous intravenous insulin at a rate of at least 1.5 microU/kg/min to maintain serum glucose levels between 100 to 140 mg/dL. Treatment was instituted 24 to 48 hours after arrival and continued until the patient's injury was 95% healed. All patients received continuous enteral feeding. Patients underwent body composition studies by dual-energy x-ray absorptiometry (DEXA) scan on postoperative day 6 after initial burn excision and when 95% healed.

RESULTS

Nutritional intakes were not different between groups. In the control, subjects continued catabolism resulted in peripheral muscle wasting and centripetal obesity with diminished truncal LBM. The treatment group had improvement in lean body mass (P =.004) and bone mass (P =.025). The treatment group also had less peripheral muscle wasting with overall increases in upper/lower extremity LBM (P =.005). Hospital length of stay in days per percent of total body surface area burned was decreased in the insulin group (control = 1.03 +/- 0.1 vs 0.7 +/- 0.9 for insulin patients; P <.05).

CONCLUSIONS

Euglycemic hyperinsulinemia throughout the hospital course mitigates muscle catabolism and preserves lean body mass.

The effect of calcitonin and growth hormone on urinary deoxypyridinoline levels in burned patients

Reduced bone formation and bone loss have been documented in patients following burn injury. Urinary deoxypyridinoline (DPD) is accepted as a marker of collagen breakdown activity. Because calcitonin (CT) diminishes bone resorption and growth hormone (GH) increases bone formation and density in GH-deficient patients, we studied the short-term effects of CT and GH on urinary DPD levels in burned patients. In 30 patients with severe burns, urinary DPD levels were investigated for 3 days following hospitalisation. Then the patients were divided into 3 groups of 10. In the CT group, CT 100U was injected subcutaneously daily for 5 days. In the GH group, GH 0.1mg/kg was injected subcutaneously three times in a week. In the control group, isotonic saline solution 0.1mg/kg was injected subcutaneously three times in a week. In all groups, following the last dose of the agents, urinary DPD levels were investigated for 3 days again. Mean burn size and age were not significantly different between the groups. Urinary DPD level obtained in the early period was 16.5 +/- 3.1nM in the CT group, 10.4 +/- 5.3nM in the GH group and 18.6 +/- 2.7nM in the control group. There were no statistical differences among the groups (P > 0.5, for all). Urinary DPD level obtained in the late period was 4.5 +/- 1.0nM in the CT group, 14.4 +/- 5.9nM in the GH group and 36.6 +/- 2.1nM in the control group. The differences between the CT group and control group, the CT group and GH group and the GH group and control group were statistically significant (P < 0.001, P < 0.01, P < 0.01, respectively). In the comparison of early and late urinary DPD levels, a significant decrease was only obtained in the CT group (P < 0.001, Z:6.5). In the other 2 groups, DPD levels increased in the late period. We concluded that GH is not effective in decreasing urinary DPD levels. On the contrary, CT was found to very effective in decreasing urinary DPD levels. This decrease in urinary DPD levels may be associated with diminished bone loss

Vitamin D depletion following burn injury in children: a possible factor in post-burn osteopenia

BACKGROUND

Children burned > 40% total body surface area (TBSA) have chronically low bone mineral density (BMD) and increased risk for fractures and adult-onset osteoporosis. Because they are advised to avoid sunlight to prevent burn scar hyperpigmentation, we hypothesized that they develop vitamin D depletion, which could contribute to post-burn osteopenia.

METHODS

We studied 24 children, ages 5-20 years, burned > or = 40% TBSA 7.1 +/- 3.8 (SD) years, range 1.9-13.3 years, previously (n = 12) and 2.0 +/- 0.2, range 1.4-2.1 years, previously (n = 12), of which half received recombinant human growth hormone during the first post-burn year. We measured lumbar spine BMD, serum 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), intact PTH (iPTH), and osteocalcin.

RESULTS

Serum 25(OH)D was low in 10/11 patients and 1,25(OH)2D was low in 5/11 at 7 years post-burn. Serum 25(OH)D was low in 10/12, while 1,25(OH)2D was low in 0/12 at 2 years; osteocalcin was low in 9/12 in the 7-year group; iPTH levels were in the lowest quartile in 5/12 patients at 7 years and 10/12 patients at 2 years. Serum 25(OH)D levels correlated with BMD z-scores, r = 0.53, p < 0.05, and inversely with iPTH levels, r = -0.66, p < 0.05, in the 7-year group.

CONCLUSION

Burned children have low circulating levels of 25(OH)D which correlated with BMD z-scores, suggesting that post-burn vitamin D depletion may play a role in the chronically low bone density observed in these children.

Time- and dose-related interactions between glucocorticoid and cyclic adenosine 3',5'-monophosphate on CCAAT/enhancer-binding protein-dependent insulin-like growth factor I expression by osteoblasts

Glucocorticoid has complex effects on osteoblasts. Several of these changes appear to be related to steroid concentration, duration of exposure, or specific effects on growth factor expression or activity within bone. One important bone growth factor, insulin-like growth factor I (IGF-I), is induced in osteoblasts by hormones such as PGE2 that increase intracellular cAMP levels. In this way, PGE2 activates transcription factor CCAAT/enhancer-binding protein-delta (C/EBPdelta) and enhances its binding to a specific control element found in exon 1 in the IGF-I gene. Our current studies show that preexposure to glucocorticoid enhanced C/EBPdelta and C/EBPbeta expression by osteoblasts and thereby potentiated IGF-I gene promoter activation in response to PGE2. Importantly, this directly contrasts with inhibitory effects on IGF-I expression that result from sustained or pharmacologically high levels of glucocorticoid exposure. Consistent with the stimulatory effect of IGF-I on bone protein synthesis, pretreatment with glucocorticoid sensitized osteoblasts to PGE2, and in this context significantly enhanced new collagen and noncollagen protein synthesis. Therefore, pharmacological levels of glucocorticoid may reduce IGF-I expression by osteoblasts and cause osteopenic disease, whereas physiological transient increases in glucocorticoid may permit or amplify the effectiveness of hormones that regulate skeletal tissue integrity. These events appear to converge on the important role of C/EBPdelta and C/EBPbeta on IGF-I expression by osteoblasts.

The role of bone densitometry in the diagnosis and management of the severely burned patient with bone loss

Children and adults who suffer severe burn injuries develop abnormalities in bone and mineral metabolism. The most prominent of these is a reduction in bone formation. Events occurring immediately following burn injury that are likely contributors to the reduced bone formation include an increase in endogenous glucocorticoid production, functional growth hormone deficiency, hypoparathyroidism, and interoperative immobilization. The proinflammatory cytokines interleukin-1 beta and interleukin-6 may also contribute. To date, the effects of burn injury on bone formation have been equivocal. However, the major reduction in bone formation without any consistent change in resorption suggests an uncoupling of formation and resorption. A consequence of this is lumbar spine bone loss as detected by dual-energy X-ray absorptiometry by 6 wk postburn. In both cross-sectional and longitudinal studies, the initial low bone density remains decreased in relation to unburned age-matched peers. The reduced bone density increases the risk for postburn fractures and for reduced peak bone mass, increasing the risk of these patients for adult-onset osteoporosis.