Abstract 1695 Poster Session III, Mondays 5/3 (poster 87)

Measurements of energy balance require complicated and sometimes invasive techniques, which are not practical for use in the neonatal period. Our objective was to develop a method that could rapidly and accurately determine energy balance in neonates using ITC. We previously reported ITC as a rapid, non-invasive means of determining energy expenditure in infants (APS 1997). Twelve healthy neonates (3.27 ± 0.34 kg, GA 39.3 ± 1.2 weeks, and age 30.5 ± 7.0 hrs) were enrolled for this study. Mean body surface temperature (MBST) was measured using a 600L infrared camera (Inframetrics Inc.). The camera converts a baby's naturally emitted radiation between 8-12 µm into electrical signals, which was then processed into a thermal pattern. The computer then calculates the MBST from the scan. Scanning was done prior to a formula feed (9.24 ± 2.17 kcal/kg) and at 30-minute intervals for a total of 3 hours. The mean MBST was 34.03 ± 0.96 °C. It was also noted that the MBST dropped slightly post-prandially, then returned to baseline at the end of the 3-hour studies. We believe this drop is a function of blood diversion from the periphery following feeding (APS 1998). The mean MBST was then combined with other measurements (ambient temperature, humidity, and body surface area) and using heat theory, energy expenditure was determined. The total energy expenditure over the 3-hour period was then subtracted from the energy intake to predict energy balance. The mean energy expenditure of the twelve infants was 3.93 ± 0.73 kcal/hr/kg. Energy expenditure was partitioned as follows: radiant heat loss (1.33 ± 0.39 kcal/hr/kg), convective heat loss (1.13 ± 0.32 kcal/hr/kg), evaporative heat loss (1.24 ± 0.09 kcal/hr/kg), and conductive heat loss (0.23 ± 0.04 kcal/hr/kg). The infants studied had a minimum energy balance value of -10.06 kcal/kg, a maximum value of 6.10 kcal/kg, and a mean value of -2.13 ± 4.26 kcal/kg. The mean difference between MBST and ambient temperature (ΔT) was 6.66 ± 1.98 °C. We analyzed the factors influencing energy balance. ΔT and energy balance varied inversely (energy balance = 1.79(ΔT) + 9.82 r2-value of 0.69). It was concluded that energy balance is a function of ΔT, and ITC is a useful method to determine energy balance in neonates not prone to excessive nutrient losses in urine, feces, or breath.