Theresa Mayes

Significance of obesity on nutritional, immunologic, hormonal, and clinical outcome parameters in burns☆

OBJECTIVE The potential additive effect of obesity on selected nutritional, immunologic, hormonal, and clinical outcome parameters was evaluated. DESIGN Fifteen obese patients were randomly matched for age, percentage of burn, percentage of third-degree burn, and inhalation injury to 15 nonobese patients. SETTING Subjects were admitted to Shriners Burns Institute or University Hospital in Cincinnati, Ohio. RESULTS The results of this study established a significant relationship between obesity and morbidity. Incidence of infection was greatest in the obese group (P < .03). Bacteremia (P < .008) and clinical sepsis (P < .005) occurred concomitant with obesity. The obese group required significantly (P < .05) more days on mechanical ventilatory support. Exogenous insulin supplementation (obese = 14.5 +/- 5.3 days, nonobese = 6.2 +/- 2.2 days) and antibiotic therapy (obese = 8.5 +/- 2.3 days, nonobese = 3.4 +/- 1.5 days) were required more than twice as many days in the obese group, although these trends did not reach statistical significance. Resting energy expenditure measurements were significantly higher in the obese group during weeks 1 (P < .0006) and 2 (P < .02), and the trend continued into weeks 3 and 4. Transferrin values for the obese group remained suppressed throughout the first 4 weeks after the burn, whereas the transferrin levels of the nonobese group were normal by week 4. Compared with normal-weight burn patients, obese burn patients had markedly lower alpha 2-macroglobulin values and higher glucagon levels throughout the study period. APPLICATIONS/CONCLUSIONS The data demonstrate the many metabolic and biochemical aberrations associated with obesity, distinct from the burn injury itself, and suggest that the overweight burn patient is at increased risk of morbidity. Given the prevalence of obesity in the United States, greater attention clearly needs to be given to its prevention and management.

The 2002 Clinical Research Award. An evaluation of the safety of early vs delayed enteral support and effects on clinical, nutritional, and endocrine outcomes after severe burns.

Early enteral support is believed to improve gastrointestinal, immunological, nutritional, and metabolic responses to critical injury; however, this premise is in need of further substantiation by definitive data. The purpose of this prospective study was to examine the effectiveness and safety of early enteral feeding in pediatric patients who had burns in excess of 25% total body surface area. Seventy-seven patients with a mean percent total body surface area burn of 52.5 +/- 2.3 (range 26-91), percent full thickness injury of 44.7 +/- 2.8 (range 0-90), and age ranging from 3.1 to 18.4 (mean 9.3 +/- 0.5) were randomized to two groups: early (feeding within 24 hours of injury) vs control (feeding delayed at least 48 hours postburn). Nutrient intake was measured daily, indirect calorimetry was performed biweekly, and blood and urine samples were obtained for the assay of cortisol, glucagon, insulin, gastrin, epinephrine, norepinephrine, dopamine, triiodothyronine, tetraiodothyronine, albumin, transferrin, prealbumin, retinol-binding protein, glucose, nitrogen balance, and 3-methylhistidine throughout the study period. Three protocol violations occurred, and two patients were transferred to another hospital; these patients were excluded from the study. No patient in either group experienced tube feeding aspiration. No differences were evident in infection, diarrhea, hospital length of stay, or mortality outcomes. A higher incidence of reportable adverse events coincided with early feeding (22 vs 8%), but this was not statistically significant. The delayed feeding group demonstrated a significant caloric deficit during postburn week (PBW) 1 (P <.0001) and PBW2 (P =.0022). Serum insulin (P =.0004) and triiodothyronine (P =.0162) were higher in the early fed group during PBW1. A decrease in 3-methylhistidine output (suggesting a decrease in protein breakdown) was also evident during PBW1 (P =.0138). No other significant trends in study outcome variables were noted. In conclusion, provision of enteral nutrients shortly after burn injury reduces caloric deficits and may stimulate insulin secretion and protein retention during the early phase postburn. These data, however, do not necessarily reaffirm the safety of early enteral feeding, nor do they associate earlier feeding with a direct improvement in endocrine status or a reduction in morbidity, mortality, hypermetabolism, or hospital stay. Future studies are needed to establish precise feeding implementation times that maximize clinical benefit while minimizing morbidity in the critically injured burn patient.

The 1994 Clinical Research Award. A prospective clinical study of the polysomnographic stages of sleep after burn injury.

Although subjective evidence suggests that patients with burns are deprived of sleep, previous clinical studies have been limited to observational data and have not to date included electroencephalographic or polysomnographic recordings. The purpose of this study was to characterize the sleep pattern of patients suffering from thermal injury. Biweekly 24-hour polysomnographic measurements (electromyography, electrooculography, and electroencephalography) were performed with 12 leads. This measuring permitted continuous recording of intrinsic electrical activity in skeletal muscles via chin electrodes, eye movement via outer canthal electrodes, and brain wave activity with the other bipolar electrodes. Determinations were obtained on 11 patients with thermal injuries for a total of 43 24-hour periods. The patients had a mean age of 8.31 +/- 1.5 years (range 1.4 to 16 years), a mean total body surface area burn of 55.1% +/- 16.5% (range 17.5% to 90.5%), and a mean full-thickness burn of 48.5% +/- 8.1% (range 10.5% to 90.5%). Although mean total sleep time was seemingly adequate (625.1 +/- 31.6 min/patient/24 hrs), large aberrations in sleep stage distribution were noted. Significant decreases in stage 3 + 4 and in rapid eye movement (deep sleep) and increases in stages 1 and 2 (light sleep) were noted, suggesting a cycling back to stages 1 or 2 after disruption of sleep. Overall, in 43 runs 40% of the subjects were completely lacking stage 3 + 4, and 19% were missing rapid eye movement during an entire 24-hour run.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of Predicted and Measured Energy Requirements in Burned Children

OBJECTIVE The energy predictions of nine calculations for pediatric patients were compared with measured resting energy expenditure (MREE) by means of indirect calorimetry to determine the optimal means of energy projection in the burn population younger than 3 years of age. METHODOLOGY Nutritional sufficiency and maintenance of preburn weight were factors in the confirmation of energy needs. Demographic factors were also studied: preburn weight, percent burn, percent third-degree burn, and age. Group 1 consisted of 24 patients younger than 3 years of age (range = 7 months to 2.6 years) with a percent burn of 30.6 +/- 2.0 and percent third-degree burn of 21.9 +/- 2.6. Group 2, consisting of 24 patients 5 to 10 years old matched by percent burn and percent third-degree burn, was included to determine whether differences between actual and projected needs were evident in older, prepubescent patients. STATISTICAL ANALYSIS Analysis of variance was used to ascertain the most reliable multiplier for MREE needed to maintain at least 95% of preburn weight at discharge while ensuring adequate nutrition. Multiple regression analysis was used to determine the relationship between energy requirement and body weight, percent burn, and age. RESULTS An additional 30% of MREE provided a consistent ratio of actual energy intake to required intake. MREE x 1.3 was used as a guide to study the existing calculations. For both groups, the four equations that predicted energy in healthy children most often underestimated MREE x 1.3, whereas the five formulas for children with burns tended to overpredict energy. Regression analysis yielded two new sets of equations using age, preburn weight, and percent burn (< 3 years = Mayes 1 [r2 = .71], 5 to 10 years = Mayes 3 [r2 = 70] or percent third-degree burn (< 3 years = Mayes 2 [r2 = .68], 5 to 10 years = Mayes 4 [r2 = .67]). CONCLUSIONS The application of a 30% factor to MREE is supported in burn patients younger than 10 years of age. Standard energy projections do not provide an accurate assessment of energy needs in the pediatric burn population; thus, two sets of equations that more closely predict energy needs are proposed.

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.

Energy Requirements of Pediatric Patients With Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

INTRODUCTION The primary purpose of this study was to compare the measured resting energy requirements (MREE) of children with Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) with that of children with burns of similar size. A secondary goal was to develop a predictive equation useful in estimating the energy of children with SJS/TEN. METHODS This retrospective study included 30 patients admitted to our pediatric burn unit between 12/91 and 03/06. All patients were admitted within 10 days of injury and had at least 1 metabolic cart measurement. Fifteen patients with SJS/TEN comprised group 1. Group 2 consisted of 15 burn patients matched for total wound size, age, preinjury weight, and gender. Caloric intake and discharge weight (percent of preburn weight) were recorded. RESULTS The energy needs of the SJS/TEN group were 22% less than the burn group. Correlation between MRE x 1.3 and caloric intake was 0.89 for the SJS/TEN group and 0.92 for the burn group (P < .0001). Both the SJS/TEN and burn groups were managed by nutrition goals based on the MREE x 1.3, and patients were 95.1% +/- 6.3% and 98.9% +/- 6% of preinjury weight at discharge, respectively, in each group. An equation for the estimation of energy requirements in pediatric SJS/TEN patients was statistically generated: (24.6 x weight in kg) + (% wound x 4.1) + 940. CONCLUSION The energy requirement in pediatric SJS/TEN patients is less than that following burn injury. The application of a 30% factor to MREE is supported in SJS/TEN and thermal injury.

Metabolic effects of vitamin D on serum calcium, magnesium, and phosphorus in pediatric burn patients

Severe burn injury results in profound metabolic derangements. Recently, we have shown that vitamin D metabolism is disturbed after burn injury. Vitamin D is essential for calcium and phosphorus homeostasis and skeletal bone integrity. The role of vitamin D on magnesium homeostasis is not well understood. The purpose of this study was to assess the effects of vitamin D deficiency on serum electrolytes. Forty-one pediatric burn patients with a mean (± SEM) total body surface area burn of 53.1 ± 2.9% and full-thickness injury of 44.2 ± 4.1% were studied from July 1996 to December 2000. The mean age of the patients was 6.5 ± 0.8 years. Patients were studied for 6 weeks after admission to the hospital. Blood samples were obtained weekly for serum 25-hydroxycholecalciferol (25D), 1,25-dihydroxycholecalciferol (1,25D), and daily for calcium, magnesium, and phosphorus. Total intravenous (IV) replacement of calcium, magnesium, and phosphorus was also quantitated retrospectively. Bivariate and multivariate correlational analysis was used for statistical comparison. For the study duration, multivariate analysis demonstrated a positive correlation between 25D and serum calcium (r = .47, P <.05 ) and 1,25D and calcium (r =.27, P <.05). Overall, calcium had a positive correlation with phosphorus and a negative correlation with IV calcium replacement (ie, patients with lower calcium received more IV replacement). During the initial week of hospitalization (week 0), decreased 25D (mean 11.6 ng/ml; normal range 15-57 ng/ml) and 1,25D (mean 13.9 pg/ml; normal range 15-75 pg/ml) did not correlate with any other measured variable. In week 1, 1,25D (mean 15.2 ng/ml) had a positive correlation (r =.410, P <.05) with calcium (mean 7.70 mg/dl). Hypovitaminosis D observed in burn injury correlates with serum calcium and phosphorus abnormalities. Early after injury (< 1 week) there was no observed correlation between vitamin D and other variables possibly because of the effects of burn shock. After 1 week, vitamin D appears to significantly effect phosphorus homeostasis. The relationship between vitamin D and magnesium is not well established. These results may indicate a role for vitamin D replacement therapy during the initial phase of burn resuscitation.

Lack of Effect of Sleep on Energy Expenditure and Physiologic Measures in Critically Ill Burn Patients

OBJECTIVE Energy expenditure measurements, performed while patients are in standardized resting conditions, are often used as an indicator of care by which to evaluate the adequacy of nutrition support regimens. Little attention has been directed toward examining potential errors incurred by deriving daily energy needs based on a single 15- to 20-minute measurement. This study was designed to differentiate energy expenditure during periods of sleep (defined as time spent in any of the standard sleep stages) and wakefulness in pediatric burn patients. DESIGN Twenty-four-hour indirect calorimetry, polysomnography, and physiologic assessments (mean arterial pressure, heart rate, body temperature, oxygen saturation, and respiratory rate) were conducted simultaneously in 14 patients, who were thermally injured and tracheally intubated, for a total of 45 24-hour intervals. SUBJECTS Mean age of the patients was 10.8+/-1.2 years. Mean total body surface area of the injury was 55.7+/-4.7%, and mean full-thickness burn was 48.8+/-6.0%. STATISTICAL ANALYSES PERFORMED A nested general linear analysis of variance model was used to evaluate the association between sleep, wakefulness, and energy needs; adjustments were made for postburn day and multiple test runs per patient. RESULTS On average, subjects slept 699+/-46 minutes/day. They experienced a large number of awakenings from sleep (mean=53+/-6.3 awakenings per 24 hours). Patients had mean energy expenditure of 2,529+/-396 kcal/day while awake and 2,360+/-291 kcal/day while asleep, and these mean values did not differ significantly. No differences in physiologic measurements during the awake and sleep states were found. APPLICATIONS There appears to be little difference in the metabolism of seriously injured burn patients while asleep and while awake. The study deemphasizes the importance of performing indirect calorimetry at rest in critically ill pediatric burn patients, and it supports the extrapolation of daily energy expenditure from a 15- to 20-minute steady-state measurement obtained during either sleep or wakefulness.

Clinical safety and efficacy of probiotic administration following burn injury.

Provision of probiotics has been limited postburn by questionable potential for bacterial translocation and risk of infection in an immune-compromised population. The purpose of this study was to evaluate the safety of probiotic administration in acutely burned, pediatric patients. Subjects were randomized to receive probiotic (n = 10) vs placebo (n = 10) twice daily. The investigational product was initiated within 10 days of burn, and daily supplementation continued until wound closure. Nursing staff was provided education regarding optimal procedures to minimize potential for study product cross contamination. Clinical outcomes (infection, antibiotic, antifungal, and operative days, tolerance, and mortality) were recorded. Length of stay was modified for burn size. Student’s t-test, &khgr;2 test, and nonparametric Wilcoxon’s rank-sum test were used for comparative analysis. No differences were noted (probiotic; placebo) for age (7.1 ± 2.2; 6.9 ± 1.7), burn size (38.0 ± 5.9; 45.5 ± 4.45), full thickness (24.6 ± 5.6; 32.1 ± 5.4), postburn day admit (0.8 ± 0.4; 1.1 ± 0.4), or inhalation injury (10%; 20%). Infection days, antibiotic use, constipation, and emesis were similar between groups. Trends toward increased antifungal and laxative use as well as diarrhea incidence were evident in the controls (P < .30). Flatulence was statistically higher with probiotics. The control group trended toward higher requirement for excision/graft procedure. Medical length of stay was not significantly different between groups; however, time required to complete wound healing was shortened with probiotics. This study documents safety and provides preliminary efficacy data relative to probiotic supplementation postburn.

A Microbiologic Study of Enteral Feeding Hang Time in a Burn Hospital: Can Feeding Costs be Reduced Without Compromising Patient Safety?

BACKGROUND Procedural changes for hospitalized patients must always balance safety with fiscal constraints. Microbiologic contamination of enteral feeding solutions has been previously associated with nosocomial infections. Formula manipulation and hang time contribute to microbial load, and there is considerable variation in hang time recommendations in the medical literature. With cost containment in mind, the purpose of this performance improvement study was to determine if an increase in hang time of a modular tube feeding product would increase microbial load or affect the nosocomial infection rate in pediatric burn patients. METHODS This biphasic trial initially evaluated the microbial load of the feeding after delivery of two 4-hour aliquots into a container using the same delivery set (total hang time of 8 hours; number of tests = 20). Second, once this feeding procedure was deemed microbiologically safe, tube feedings were administered to patients, and both microbial load and nosocomial infection rate were monitored for 1 year. RESULTS Contamination levels at the end of the 8-hour period using the same feeding set with 2 consecutive 4-hour feeding aliquots (number of tests = 38) were lower than standard recommendations. The hospitals nosocomial infection rate was not altered by this procedural change, and feeding-set expenses were reduced. CONCLUSIONS The hang time of our enteral feeding administration set can be increased safely from 4 hours to 8 hours, with the tube feeding preparation added as two 4-hour aliquots without a significant change in microbial load or nosocomial infection rate, thus promoting simultaneous fiscal responsibility and patient safety.