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It is essential that adequate calories are provided to newborns to cover their energy expenditure. This is difficult to measure and varies significantly between individuals. The aim of this study was to develop an equation to predict the basal energy requirements of stable surgical infants, using easily measurable parameters. Resting energy expenditure (REE) was measured using computerized open-circuit indirect calorimetry. One hundred twenty-two measurements were made on different days in 46 stable nonventilated infants. The measured REE was 34.41 +/- 0.46 cal/kg/min; (mean +/- SEM). Three body-size measurements correlated significantly with REE (cal/min): weight in kilograms (r = .87; P < .00001), body surface area in square meters (r = .86; P < .00001), and lean body mass in kilograms (r = .81; P < .00001). Five other independent variables correlated significantly with REE (cal/kg/min): heart rate in beats per minute (r = .60; P < .00001), postnatal age in days (r = .49; P < .00001) caloric intake in cal/kg/min (r = .44; P < .00001), gestational age in weeks (r = .43; P < .00001), and rectal temperature in degrees Celsius (r = .19; P = .04). Weight, heart rate, age, gestational age, and temperature were regarded as independent predictor variables of REE for the multiple stepwise regression analysis. Three variables entered this highly significant equation: REE (cal/min) = -74.436 + (34.661 x weight in kg) + (0.496 x heart rate in beats/min) + (0.178 x age in days) (r = .92; F = 230.07; significance, F < .00001).(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship was determined between resting energy expenditure (REE) and interleukin (IL)6 level following surgery in infants. Sixteen infants of mean(s.e.m.) weight 3.2(0.2) kg undergoing uncomplicated surgery were studied. The operative stress score was recorded and plasma IL-6 levels were measured before and 4, 8, 12 and 24 h after surgery. Respiratory gas exchange was measured by indirect calorimetry before and at 2, 4, 6, 8, 10, 12, 24 and 48 h. Urinary nitrogen excretion was measured and calculated. IL-6 levels increased significantly after surgery (P = 0.006) and were maximal at 12 h. There was a linear correlation between the increase in IL-6 level and operative severity score (r = 0.61, P = 0.012). REE increased significantly after operation (P < 0.001), peaking at 2-4 h, and returned to baseline levels by 12 h. The changes in REE preceded those in IL-6. IL-6 is a marker of the stress response in infants and may play a role in the subsequent modulation of this response.

Glucose is the main source of nonprotein calories in total parenteral nutrition (TPN). However, its use has been associated with various nutritional, metabolic, and respiratory complications. The aim of this study was to determine, in the stable surgical newborn infant, the characteristics of carbohydrate metabolism, in particular the maximum oxidative threshold for intravenous glucose and the thermogenic effect of glucose. Twenty-one studies were done on 11 infants (weight 2.82 +/- 0.19 kg) receiving TPN containing constant amounts of amino acids (2.5 g/kg/d) and fat (3.0 g/kg/d), and different amounts of glucose (range, 10 to 25 g/kg/d). Oxygen consumption (VO2), carbon-dioxide production (VCO2), and resting energy expenditure (REE) were measured by indirect calorimetry. Urinary nitrogen excretion rate was measured and substrate utilization calculated from the nonprotein respiratory quotient (NPRQ). There was a positive correlation between the predictor variable glucose intake and the dependent variables VO2 (r = .55; P < .05), VCO2 (r = .83; P < .0001), REE (r = .65; P < .005), NPRQ (r = .94; P < .0001), respiratory rate (r = .46; P = .06), and plasma triglycerides level (r = .67; P < .01). When glucose intake exceeded 18 g/kg/d the NPRQ was greater than 1.0, indicating glucose conversion to fat. Above this level of intake, the gradient of the correlation between the predictor variable glucose intake and the dependent variables VCO2 and REE increased. From this study we conclude that: (1) Glucose intake is the principal determinant of glucose utilization and exerts an influence on the metabolism of exogenous fat.(ABSTRACT TRUNCATED AT 250 WORDS)