Total Energy Expenditure, Protein Kinetics, and Body Composition in Recovering Burn Children.

Measures of total and resting energy expenditure, protein turnover, body composition and
other nutritional and outcome-based measures will be made in patients receiving inpatient
rehabilitative care for their burn injury. Patients will consist of acutely burned patients
initially admitted to our hospital with burns of 40% of their total body, who have recently
recovered from their acute phase of injury and have achieved wound closure as defined by
less than 5% open wound area (Group A). In addition, patients admitted to the hospital for
"acute rehabilitation", which includes patients in need of rehabilitative therapy will also
be included. This latter group (Group B) is unique in that the patients may have open wound
areas remaining due to difficulty healing, however are not critically ill. Group B may
differ from the typical rehabilitation population seen at our hospital because of their open
wounds and because they received care for their initial injury elsewhere. They are included
here due to their apparent nutritional compromise and their unique energy and protein
requirements that are difficult to predict according to our clinical experience. These
patients are most likely to require artificial nutrition support and will benefit from
information gained by this study.

Measurements will be made at baseline as defined at the time of wound closure (or at the
time of admission for Group B). Subsequent measures will be done as follows: 1) total
energy expenditure will be assessed weeks 1-3 and again at weeks 7-9. During weeks 1 and 7,
protein turnover studies will take place. Indirect calorimetry and physical activity
measures will take place on 2 consecutive days during each week. Lean body mass
measurements will be done at the time of wound closure and at discharge. The study will end
at the time of discharge.

Resting and total energy expenditure will be done using indirect calorimetry for resting
energy expenditure and the doubly labeled water method for total energy expenditure.
Briefly, the methodology for doubly labeled water is as follows. Two pre-dose urine
specimens will be collected prior to an oral dose containing 0.22 g/kg total body water of
100% 18O water (or 1.2 g/kg per body weight of 10% 18O water) and 0.11 g/kg per body weight
of 99.9% deuterium oxide. Three post-dose urine voids will be collected, followed by
collection of a morning urine void daily for 7 days. Total energy expenditure by this
method will represent the average energy expenditure over a 21-day period. It will be
obtained at weeks 1-3 and again at weeks 7-9 weeks during the rehabilitative phase. Resting
energy expenditure will be determined using indirect calorimetry by a metabolic cart on 2
consecutive days of each week. Physical activity will be determined by having the patients
wear an physical activity monitor (Actical Physical Monitoring System, mini-Mitter, Co.,
Inc, Bend Oregon) on their wrist, ankle or hand for the entire day twice a week
(corresponding to the metabolic cart measurement). This will be worn on 2 days of each
week. Protein nutritional status and turnover will be measured using N15 glycine. Three
methyl-histidine will be measured at the time of N15 glycine studies (weeks 1 and 7) to
assess the contribution of muscle mass to protein turnover. On the day of tracer study,
each patient will provide a urine sample, and this urine sample will be collected to
determine the basal level of N15 enrichment in urea and ammonia. Then the patient will
receive a single dose (4mg/kg, less than 2% of normal daily intake of 1.1g per person) of
15N glycine tracer. For this, patients will drink a dose of 15N glycine (4mg.kg
1dissolved in 20 ml of saline) mixed in 50 cc of apple juice or other liquid beverage,
followed by a 50 cc wash of water. 24 hour urine collection will commence immediately.
Twenty-four hour urines will be used for determining the 15N NH3 and 15N urea enrichment.
Each urine container will contain 5 ml of 15N HCl for trapping the urinary ammonium. Urine
will be collected each day for 3 days, for determination of the total urinary nitrogen, urea
creatinine, and ammonia excretion.

Lean body mass, fat mass and bone mineral density and content will be determined at baseline
(or at the time of wound closure- as is routine care) and at discharge. Body composition
components (lean body mass, fat mass and bone mineral density) will be determined for the
lumbar spine and the whole body using dual energy x-ray absorptiometry (DXA) with a
Discovery QDR 4500 A (Hologic, Waltham, MA) in burned and healthy children. Scanning will
be performed by study staff trained and certified in the use of DXA. DXA uses x-ray beams
at two photon energies to estimate body composition. Prior to the scan, height will be
measured at the time of each measurement session with the subjects standing barefoot and in
light clothing using a stadiometer. Measures will be recorded to the nearest 0.5 centimeters
respectively. Weight will be taken using a balance scale and recorded to the nearest 0.5
kilograms. DXA measurements will be done by having the patient lie flat on his or her back
on the DXA scanning table. Subjects will be positioned by the scanner so that the spine is
straight on the table pad. For the lumbar spine measurement, a knee positioner will be
placed under the patient's lower legs so that the patient's knees and hip are at a 90 degree
angle. To align the C-arm (scanning arm ) of the DXA, a laser line will be positioned 1-2
inches below the patient's ileac crest, centered around the patient's midline. The scan time
approximates 10 seconds, exposure is 0.38 mRem. For the whole body scan, the subject will
lay on his or her back with their body straight, arms at sides, palms down, separated from
thighs. The scanner will rotate the subject's legs inward 25 degrees until the toes touch,
using tape around the feet to maintain this position. The subject will be instructed to
breathe normally. The total scan time approximates 2.5 to 3.5 minutes with an exposure of
0.26 mRem. Total body fat and lean body mass will be determined by the DEXA as described as
part of the whole body bone mineral density scan (only 1 scan session required). Measures
of % body fat content and % lean body mass content for the whole body will be obtained using
the DEXA software. These values will be compared to age and sex matched pediatric reference
data for body composition {{217 Ellis, K.J. 2000; }}.

Because measures of LBM can be confounded by hydration status, a second measure of LBM using
bioelectrical impedance will be made at these points and compared.

Inclusion Criteria:

- Patients > 2 less than 18 who have been admitted to our hospital for treatment of an
initial wound size of 40% or greater total body surface area burn, which has
subsequently healed

Exclusion Criteria:

- hemodynamically unstable

- not receiving enteral nutrition