Energy Retention, Energy Expenditure, and Growth in Healthy Immature Infants

Abstract

Summaryinfants developed transient late metabolic acidosis (14) during the course of the studies. This interfered with energy retention and studies were during On l5 weight gain (4), but since the infants remained active and apparimmature infants of mean birth weight 1581 g. Mean gross energy ently well, these results have been included, inasmuch as they intake was 757 kJ/kg (181 kcal) and 79 % of this was retained, so enabled us to examine energy balance during periods of poor that metabolizable energy was 602 kJ/kg (143 kcal). Mean resting weight gain. metabolic rate was 244 kJ/kg (58.1 kcal), and it increased with advancing maturity. Minimum resting metabolism averaged 199 FEEDING kJ/kg (47.5 kcal). Energy expended in activity increased with maturity, but amounted to less than 17 % of the total energy All the infants were fed on V Formula (Cow and Gate Baby turnover. Postprandial metabolism caused the mean VOz to rise Foods Ltd., Trowbridge, England). No studies were undertaken by 17 % in the hour after a feed, and during 24 hr resulted in until a daily feed intake of 180 ml/kg or more had been achieved, consumption of energy equivalent to about 10 % of the resting which was usually by the middle of the second week of life. Mean metabolism. Stored energy amounted to 230 kJ/kg (55 kcal) and feed intake during study periods was 227 ml/kg (range 198-262).was linearly related to weight gain (r = 0.92). Energy cost of The feeds were given 2-3 hourly depending on the size of the weight gain was 24 kJ/g (5.7 kcal) and energy stored in new tissue infants. was 16.8 kJ/g (4.0 kcal). Maintenance energy requirement at zero growth rate was about 270 kJ/kg (64 kcal). FEED COMPOSlTIONV Formula is a filled milk prepared from skimmed milk, lactose Speculation and vegetable oils, with the following composition (per 100 ml Data on energy balance in immature infants are scanty. There prepared feed): fat, 3.1 g; protein, 1.8 g; CHO (lactose), 7.0 g; is need for information on energy retention, maintenance energy mineral salts 0.4 g (Nay 26 mg; K 9 61 mg; Ca, 62 mg; PO43 50 mg) requirements, postprandial energy expenditure, and energy cost of energy 260 kJ (62 kcal). The gross energy, determined us growth. We have attempted to provide such information, but our bomb calorimetry (20) on 23 separate occasions was 344 kJ/100 data show wide variation between infants. However, in spite of this ml (SD 1% 32 more than the specified energy, the for variation, a relationship is present between energy retention which is derived from theoretical considerations as "metabolizable and weight gain, the main limiting factor in weight gain probably (32). being energy absorption from the gut. We need more data to show whether efticiency of energy utilization alters with different levels

Energy Balance, Physical Activity, and Thermogenic Effect of Feeding in Premature Infants

“…The infant's VOz and VC02 is obtained by the difference of O2 and C 0 2 fractions measured at the inlet and the outlet. From these data and total urinary N, energy expenditure is computed on the basis of oxygen volumes required to oxidize CHO, lipid, and protein (equations [9][10][11][12]. During calorimetry the activity state of each infant was monitored minute by minute using the scale developed by Briick el al.…”

“…activity scales based primarily on visual observation of the infant's body movements (7,(9)(10)(11)(12)(13)(14)(15)(16). Their aim were either to investigate the rate of physical activity as an index of the infant's brain function (1 3, 14, 16), or to assess criteria for physical rest in metabolic studies (7,9,11,12,15,16,(31)(32)(33)(34)(35)(36).…”

“…However, measurements of energy expenditure in premature babies have been generally of short duration (5,(7)(8)(9), i.e. approximately 1-3 h. Therefore the extent to which these limited periods of measurement can be extrapolated to 24 h is still uncertain.…”

“…Although several methods have been developed to score changes in spontaneous physical activity of infants (7, 9-16), it is not known to what extent these scores are related to the rate of energy expenditure. Because the thermogenic response itself can be influenced by several factors such as duration of measurement, feeding frequency, size and type of test meal, the published measurements give variable results (9,12,(17)(18)(19)(20). The aims of the present study was to measure the energy metabolism of premature babies of less than 34 gestational wk, to assess the magnitude of intradaily variations in energy expenditure and to partition the latter between muscular activity and thermogenic response to feeding.…”

“…Although several methods have been developed to score changes in spontaneous physical activity of infants (7,(9)(10)(11)(12)(13)(14)(15)(16), it is not known to what extent these scores are related to the rate of energy expenditure. Because the thermogenic response itself can be influenced by several factors such as duration of measurement, feeding frequency, size and type of test meal, the published measurements give variable results (9,12,(17)(18)(19)(20).…”