Reduction of oxygen consumption, insensible water loss, and radiant heat demand with use of a plastic blanket for low-birth-weight infants under radiant warmers

Eight very low-birth-weight premature infants (mean birth weight 1.11 +/- 0.05 [SEM]kg, mean gestation 30 +/- 1 weeks, and mean age 9 +/- 2 days) were studied under servocontrolled radiant warmers with and without a loosely fitted, transparent, and flexible Saran plastic blanket. Metabolic rate was significantly less in all infants when covered by the blanket (oxygen consumption was 7.99 +/- 1.13 mL/kg/min v 9.00 +/- 1.10 mL/kg/min uncovered, P less than .001). There were also significant reductions in insensible water loss (1.86 +/- 0.18 v 1.25 +/- 0.20 mL/kg/h, P less than .01) and in heat demand from the radiant warmer (14.3 +/- 1.3 v 9.9 +/- 1.4 mW/cm2, P less than .001) when infants were nursed under the blanket compared with the control condition, respectively. Covering the critically ill, very low-birth-weight infant nursed under a radiant heater with a thin, transparent layer of Saran is beneficial in reducing oxygen consumption, insensible water loss, and the need for exposure to high levels of radiant heat. Further investigation to confirm the benefits and possible complications of plastic blankets should be conducted before routine use can be recommended.     

Partitioning of heat losses and gains in premature newborn infants under radiant warmers

The partition of heat loss into convective and evaporative components, and heat gain into metabolic rate of production and radiant heat needed to maintain thermal equilibrium was determined in ten premature neonates (weight 1.39 +/- .08 [SEM] kg, gestation 31 +/- 1 weeks) who were nursed naked and supine on open radiant warmer beds. Warmer beds were servocontrolled to maintain each infant's abdominal skin temperature at three different levels: 35.5, 36.5, and 37.5 degrees C. The quantity of radiant heat delivered by the warmer in vivo was measured directly and compared with the heat need calculated from the partition. Convective heat loss comprised the major component of net heat loss and increased significantly with servocontrol temperature from 2.86 +/- .24 to 3.27 +/- .23 kcal/kg/h (P less than .01), and to 3.72 +/- .26 kcal/kg/h (P less than .001). Evaporative heat loss increased with servocontrol temperature from .96 +/- .13 to 1.41 +/- .33 kcal/kg/h, and to 1.35 +/- .32 kcal/kg/h, but this increase was not significant. Metabolic rate decreased from 2.08 +/- .17 to 1.90 +/- .14 kcal/kg/h, and to 1.78 +/- .16 kcal/kg/h with increased servocontrol temperature, but this decrease was not significant. Radiant heat needed to maintain infants at higher temperatures increased from 1.73 to 2.80 kcal/kg/h, and to 3.32 kcal/kg/h. The radiant heat delivered by the warmer to infants was directly proportional to the heat need calculated from the partition (r = .68, P less than .001).     

Cardiovascular changes in preterm infants nursed under radiant warmers

Radiant heat is known to increase insensible water loss and, to a certain extent, oxygen consumption. Little is known about its cardiovascular effects. We measured cardiac output, stroke volume, heart rate, and lower limb and skin blood flow in 20 preterm newborn infants nursed in an incubator and under a radiant warmer at an abdominal skin temperature of 36.5 degrees C. Mean (+/- SEM) birth weight was 1.57 (0.06) kg, gestational age 31.7 (0.4) weeks, and weight at examination 1.69 (0.02) kg; median postnatal age was 15 days. Skin and limb blood flow measurements increased by 44% to 55% with radiant heat (P less than .001 and P less than .01, respectively). Cardiac output increased by 5.4% (P less than .02) under the radiant warmer secondary to a small but significant (P less than .05) increase in heart rate. The changes in cardiac output during radiant heat administration are comparable to those reported for oxygen consumption.     

Metabolic rate of neonates with congenital heart disease.

Seven infants under one month of age with controlled congestive heart failure showed a mean oxygen consumption of 9-4 +/- 1-6 SD ml/kg per min, a mean respiratory quotient of 0-71 +/- 0-05 SD, and a mean metabolic rate of 63 +/- 12 SD cal/kg per 24 h. This compares with a group of infants with congenital heart disease not in heart failure with Vo2 of 6-5 +/- 1-2 SD ml/min per kg, respiratory quotient of 0-80 +/- 0-11 SD, and basal metabolic rate of 45 +/- 8 SD cal/kg per 24 h. These differences are significant (P less than 0.001). The findings of a greater metabolic rate associated with congestive heart failure are thus extended to the newborn period.     

Radiant heat loss versus radiant heat gain in premature neonates under radiant warmers

Premature infants nursed on open radiant warmer beds are exposed to short-wavelength infrared power density distributed evenly over the bed surface. Additionally, infants' sides are exposed to relatively cooler nursery walls, and to the radiant warmer bed platform which may heat and reradiate to the baby. Therefore, infants may not only gain heat from the warmer (Q radiant warmer) but lose or gain radiant heat to the sides as well (+/- Q radiant loss). In order to quantitate these parameters, ten premature newborn infants nursed under radiant warmers servocontrolled to 36.5 degrees C skin temperature (weight 1.27 +/- 0.24 SD kg, gestation 31 +/- 3 weeks) were investigated, and partitional calorimetry previously reported. In the present study, calculation of net rate of radiant heat transfer (Q net radiant) was made from these data (-2.63 +/- -1.52 kcal/kg/h), and compared to direct measurements of Q radiant warmer (-2.49 +/- -0.90 kcal/kg/h). The present report further partitions net radiant heat transfer to evaluate Q radiant loss: -0.13 +/- 1.82 kcal/kg/h (range -3.16 to 1.93). From these calculations mean radiant temperature of this environment was estimated (45.3 +/- 4.3 degrees C) and compared to the radiant warmer temperature received (45.0 +/- 2.9 degrees C). This information suggests other strategies to reduce radiant heat loss as well as convective and evaporative losses in premature neonates nursed on open radiant warmer beds.     

Optimal thermal management for low birth weight infants nursed under high-powered radiant warmers

Servocontrol of skin temperature for the critically ill premature neonate nursed on a radiant warmer bed has been assumed to be analogous to skin temperature control for infants nursed in convection-warmed incubators. There are significant differences between these two warming techniques, and no definitive data exist to aid the clinical specialist in governing radiant warmer control. Eighteen low birth weight premature infants less than 2 weeks of age were studied under powerful overhead radiant warmers to determine the optimal skin temperature for servocontrol of radiant heater output. Anterior abdominal wall temperature was servocontrolled at 35.5 degrees, 36.5 degrees, and 37.5 degrees C in a randomized fashion for three periods of 90 minutes each after thermal equilibrium was established. Oxygen consumption was measured during the entire 90-min sample period at each temperature by a computerized metabolic apparatus to determine the optimal thermal neutral control temperature defined as minimal oxygen consumption with normal body temperature. Skin, deep rectal, and environmental temperature measurements, as well as behavior assessments, were made concurrently. Oxygen consumption was significantly elevated at 35.5 degrees C (8.62 +/- 0.73 mL/kg/min, mean +/- SEM) compared with 36.5 degrees C (7.30 +/- 0.55 mL/kg/min). Changing servocontrol temperature to 37.5 degrees C produced no further significant decrease in oxygen consumption (7.41 +/- 0.70 mL/kg/min), and nine infants manifested supranormal deep rectal temperatures (greater than 37.5 degrees C). Optimal abdominal skin temperature control at 36.5 degrees C (slightly warmer than previously reported but less than 37.5 degrees C) is recommended for premature neonates nursed on radiant warmer beds.(ABSTRACT TRUNCATED AT 250 WORDS)     

Semipermeable polyurethane membrane as an artificial skin for the premature neonate

A thin and semipermeable polyurethane membrane adherently applied to premature neonates as an artificial skin was investigated as an atraumatic surface barrier sufficient to reduce transepidermal water loss without inhibiting natural infant skin development during the first few days of life. A sample group of 18 neonates (birth weight [mean +/- SEM] 1.39 +/- 0.12 kg, gestation [mean +/- SEM] 31 +/- 1 weeks) received two 3 X 3-cm polyurethane patches adherent over the chest and abdomen. Transepidermal water loss was measured before and after application and after membrane removal. During longitudinal study, seven infants were treated day 1 through day 4 of life and were evaluated for skin integrity 24 hours after patch removal on day 5. Polyurethane membranes produced an acute and significant reduction in transepidermal water loss for the 18 subjects: 21.1 +/- 2.0 g/m2/h before application v 10.5 +/- 1.4 g/m2/h with membranes in place (P less than .001). Immediately after patch removal, transepidermal loss returned to 22.8 +/- 3.0 g/m2/h. Throughout the first four days of life, daily measurements of water loss were significantly less: 53% to as much as 72% reduction from polyurethane-covered sites when compared with adjacent naked skin. After polyurethane membrane removal, skin development of transepidermal barrier function was comparable over both sites. Dressings did not lose adhesive or plastic properties during an extended time in either radiant warmer or incubator environments, electronic monitoring through membranes was not impeded, and adhesive injuries were not observed. An adherent, semipermeable polyurethane membrane may be effective as an atraumatic artificial barrier to prevent large transepidermal water loss and protect the skin of the premature neonate.     

Intravenous alimentation and insensible water loss in low-birth-weight infants.

Insensible water loss (IWL) was measured in six premature infants, between 4 and 21 days of age, by continuous weight monitoring on an electronic balance inside an incubator. Multiple measurements of IWL were made during the sequential infusion of 10% dextrose in 0.225% NaCl, 10% dextrose-amino acid solution, or 10% dextrose-amino acid and a commercial intravenous fat emulsion. Each solution was administered for three hours by constant infusion through a scalp vein needle. The order of the infusion was random and a 30- to 60-minute infusion with 5% dextrose water was given between each solution. During the infusion of 10% dextrose in 0.225% NaCl and 10% dextrose + amino acid solution, IWL was 1.0 +/- 0.8 gm/kg/hr and 1.1 +/- 0.8 gm/kg/hr, respectively. In contrast, IWL increased significantly to 1.6 +/- 0.7 gm/kg/hr when additional calories were given using the 10% dextrose-amino acid with the intravenous fat emulsion (P less than .005). There was a positive correlation between calorie intake and IWL. These data suggest that parenteral nutrition solutions with intravenous fat emulsion are rapidly metabolized and the increase in IWL is probably secondary to an increase in thermogenesis.     

Oxygen consumption and insensible water loss in premature infants under radiant heaters

Oxygen consumption ((Vo2), carbon dioxide production (Vco2), and insensible water loss (IWL) were measured simultaneously in nine nondistressed, appropriately grown, premature infants less than 2 weeks old, nursed in a conventional, blow-warmed incubator, and were compared with measurements made on the same infants under a radiant heater. The infants had a pronounced increase (148% on average) in IWL when under the radiant heater (P < .001) whereas Vo2 increased by only 4.6% (P = .073). Abdominal skin temperature (servocontrolled to maintain 36.5 C) and esophageal temperature were the same under both conditions, but ambient air temperature was 0.7 C higher in the incubator (P < 05). Although a positive correlation was found between the increase in IWL and the change in Vo2 (r = .75, P < .01), the large increase in IWL (and, therefore, evaporative heat loss) under the radiant heater is out of proportion to, and cannot be accounted for, by the change in metabolic heat production. The heat transfer processes involved in maintaining body temperature constant under these conditions require further study.     

Effect of the energy source on changes in energy expenditure, respiratory quotient, and nitrogen balance during total parenteral nutrition in children

The effects of three isocaloric intravenous nutritional regimens were studied in seven infants and children, ages 2 months to 9 yr, with congenital gastrointestinal anomalies (four patients) or with prior history of malignant disease admitted in remission for bone marrow transplantation (three patients). Energy metabolism, as measured by the basal metabolic rate (BMR), and substrate utilization, as measured by the respiratory quotient (RQ), were studied to determine the effect of different levels of carbohydrate and fat on nitrogen retention in each patient. Solution A provided 8% of energy as amino acids, 87% as carbohydrate, and 5% as fat. Solution B provided 8% of energy as amino acids, 60% as carbohydrate, and 32% as fat. Solution C provided 8% of energy as amino acids, 34% as carbohydrate, and 58% as fat. Administration of solution A (high carbohydrate, low fat) was associated with moderately increased mean (+/- SD) BMR and RQ and with low nitrogen retention (19.1 +/- 12.7%, 1.06 +/- 0.14, and 98 +/- 28 mg N/kg/day). Both the BMR and the RQ decreased when less carbohydrate and more lipid was given: BMR 4.3 +/- 11.6% (p less than 0.005), RQ 0.92 +/- 0.09 (p less than 0.001) for solution B; BMR 3.94 +/- 10.6% (p less than 0.005), RQ 0.86 +/- 0.09 (p less than 0.001) for solution C. Among the solutions tested, optimal nitrogen retention [163 +/- 60 mg N/kg/day (p less than 0.01)] was noted with solution B. Our data support the conclusion that a physiologic balance of fat and carbohydrate results in optimal nitrogen retention.     

Improved prognosis in severely hypothermic newborn infants treated by rapid rewarming

We introduced a rapid rewarming technique as part of standard therapy in 16 newborn infants with effects of severe environmental hypothermia. On admission, mean rectal temperature was 31.0 +/- 2.7 degrees C, mean gestational age was 33.4 +/- 4.5 weeks, and mean birth weight was 1.76 +/- 0.71 kg. Thirteen infants were admitted within 30 hours of delivery, and the remainder at 2 to 3 weeks of age. Infants were rewarmed under a radiant warmer. The mean time required to reach a rectal temperature of 36.5 degrees C was 3.96 +/- 2.37 hours. Major medical entities encountered included thrombocytopenia (eight patients), metabolic acidosis (eight), respiratory distress (eight), renal failure (six), apnea (four), patent ductus arteriosus (four), seizures (four), intracranial hemorrhage (three), infection (three), and necrotizing enterocolitis (two). No complications could be attributed to the rapid rewarming technique. Of three infants who died, all weighed less than 1.25 kg at birth. This 81% survival is in contrast to the high mortality (25% to 50%) noted previously among infants treated by gradual rewarming.     

Metabolic consequences of intrauterine growth retardation in very low birthweight infants

By the combination of energy and macronutrient balances, continuous open circuit computerized indirect calorimetry, and anthropometry, we have compared small for gestational age (SGA) and appropriate for gestational age (AGA) very low birthweight infants with respect to metabolizable energy intake (mean +/- SE: 125.9 +/- 2.5 versus 130.4 +/- 3.5 kcal/kg X day), energy expenditure (67.4 +/- 1.3 versus 62.6 +/- 0.9 kcal/kg X day), storage of energy and macronutrients and growth. Fourteen studies in six SGA infants (gestational age, 33.1 +/- 0.3 weeks; birthweight, 1120 +/- 30 g) and 22 studies in 13 AGA infants (gestational age, 29.3 +/- 0.4 weeks; birthweight, 1155 +/- 40 g) were performed. The SGA infants had a lower absorption of fat (68.7 +/- 3.2 versus 79.7 +/- 1.7%) and protein (69.1 +/- 3.2 versus 83.4 +/- 1.5%) and hence increased (P less than 0.001) energy loss in excreta (29.9 +/- 2.8 versus 18.2 +/- 1.5 kcal/kg X day). The significant hypermetabolism of SGA infants by 4.8 kcal/kg X day was associated with an increased fat oxidation. Despite lower energy storage, SGA infants were gaining weight (19.4 +/- 0.9 g/kg X day), length (1.25 +/- 0.14 cm/week), and head circumference (1.16 +/- 0.9 cm/week) at higher rates than the AGA group. The energy storage per g weight gain was lower (P less than 0.001) in the SGA group (3.0 +/- 0.14 versus 4.26 +/- 0.26 kcal) reflecting higher water, lower fat (22.2 +/- 1.8 versus 33.8 +/- 2.5%; P less than 0.001) and lower protein (7.7 +/- 0.5 versus 12.5 +/- 0.8%; P less than 0.001) contents of weight gain in the SGA group.     

Consequences of incomplete carbohydrate absorption from fruit juice consumption in infants.

BACKGROUND: Most infants consume fruit juices by 6 months of age. However, fruit juices containing sorbitol may be associated with carbohydrate malabsorption without clinical symptoms. We hypothesized that increased physical activity and metabolic rate may be associated with carbohydrate malabsorption. METHODS: Physical activity and metabolic rate were determined in 14 healthy infants ([mean +/- SD] age, 5.1 +/- 0.8 months; weight, 7.8 +/- 1.1 kg; length, 67 +/- 4.2 cm; and body fat, 26% +/- 5%) for 3 hours in a respiratory chamber. Seven were fed pear juice, and the other 7 were fed white grape juice (120 mL) after a 2-hour fast. Pear juice contains sorbitol and a high fructose-glucose ratio, whereas white grape juice is sorbitol free and has a low fructose-glucose ratio. Carbohydrate absorption was determined by breath hydrogen gas analysis. The study was double-blinded. RESULTS: When compared with the infants without carbohydrate malabsorption (peak breath hydrogen level < 20 ppm above baseline), 5 of the 7 infants fed pear juice and 2 of the 7 infants fed white grape juice exhibited carbohydrate malabsorption (peak breath hydrogen level > or = 20 ppm above baseline; P < .01). These infants also exhibited both increased physical activity (P < .001) and metabolic rate (P < .05) after juice consumption in comparison with infants with normal carbohydrate absorption. When grouped according to the type of juice consumed, only infants fed pear juice exhibited increases in physical activity (P < .01). CONCLUSIONS: Carbohydrate malabsorption is associated with increased physical activity and metabolic rate in infants. Most of the infants who had carbohydrate malabsorption consumed pear juice. Therefore, fruit juices containing sorbitol and high levels of fructose may not be optimal for young infants.     

The heat balance of small babies nursed in incubators and under radiant warmers

The heat balance of 12 healthy preterm babies (mean birth weight 1.58 kg, gestation 32 weeks, age 7 days) was studied first in an incubator and then under a radiant warmer during normal nursing. Heat production and heat loss by radiation, convection and evaporation were measured in presumed thermoneutral conditions. Although rectal and mean skin temperatures were normal and the same in both environments, there were important differences. Radiation was the major source of heat loss in the incubator and convective losses were low. Under the radiant warmer convection was the major source of heat loss and heat was gained by radiation. A small rise in metabolic heat production occurred under the radiant warmer. Respiratory water loss was low in both environments. Skin water loss was significantly higher under the radiant warmer. The most immature baby (gestation 28 weeks) could not be kept warm in the incubator despite high air temperature, because the evaporative heat loss from her skin was very high. Her body temperatures were normal under the radiant warmer. It is concluded that both devices provide acceptable thermal environments for most preterm babies but that incubators without humidification may be inadequate for immature babies with a high skin water loss.     

Oxygen consumption in premature infants in an incubator of proven clinical efficacy

Oxygen consumption was measured under carefully controlled conditions during non-REM sleep in 16 infants less than 1,500 g in a computer-controlled incubator and a skin servo-controlled incubator. Oxygen consumption was 7.16 +/- SE 0.35 ml/kg/min in the computer-controlled incubator and 6.84 +/- SE 0.37 ml/kg/min in the skin servo-controlled incubator. Oxygen consumption was similar in the two incubator systems.     

Continuous skeletal muscle paralysis: effect on neonatal pulmonary mechanics

Pancuronium bromide (Pavulon) is used to induce skeletal muscle paralysis in preterm infants, presumably for effective ventilatory support during acute respiratory failure. Twelve infants with respiratory failure were evaluated for sequential changes in pulmonary mechanics during continuous pancuronium administration (0.1 mg/kg every two to three hours) for more than 48 hours. The study weight of the neonates ranged from 980 to 2,950 g, and the postconceptional age ranged from 27 to 41 weeks. Pulmonary compliance, resistance, and resistive work of breathing were determined, using least mean square analysis technique, daily for three days and after discontinuation of pancuronium (even though there was no clinical improvement in ventilatory management). The dynamic pulmonary compliance decreased from 0.38 +/- 0.05 to 0.30 +/- 0.04 mL/cm H2O/kg (mean +/- SE) (P less than .05) and the total pulmonary resistance increased 51% from 115.6 +/- 21.3 to 174.9 +/- 27.3 cm H2O/L/s (P less than .005) during prolonged skeletal muscle paralysis. Upon discontinuation of pancuronium, the dynamic pulmonary compliance increased 43% to 0.43 +/- 0.4 mL/cm H2O/kg (P less than .05) and the total pulmonary resistance decreased by 41% (P less than .005). These data question the advisability of prolonged skeletal muscle paralysis in neonates and suggest the need for further detailed evaluation of the effects of prolonged paralysis on neonatal pulmonary mechanics.     

Oxidation of intravenous lipid in infants and children with systemic inflammatory response syndrome and sepsis

During sepsis in adults, fat becomes a preferred fuel; however, oxidation may be impaired relative to the circulating fatty acid levels. Little is known about the ability of infants and children to oxidize lipids during systemic inflammation (SIRS) and sepsis. The aim of this study was to examine the oxidation of exogenous lipid in these patients. Sixteen patients with SIRS/sepsis and eight controls with no evidence of sepsis were studied by indirect calorimetry during an i.v. lipid utilization test (1 h of 0.3 g/kg/h glucose followed by 3 h of 0.1 g/kg/h glucose plus 0.15 g/kg/h lipid). The respiratory quotient (RQ) (1.0 for carbohydrate utilization and 0.7 for fat utilization) was measured. Results were compared by repeated-measures analysis of variance (ANOVA), paired or unpaired t tests. There was no difference in baseline RQ between controls and patients with SIRS/sepsis (mean +/- SD; 0.82 +/- 0.08 versus 0.82 +/- 0.04). The RQ of controls dropped significantly to 0.78 +/- 0.08 at 240 min (p < 0.001). The RQ of patients with SIRS/sepsis also fell to 0.78 +/- 0.06 (p < 0.01). Infants and children with SIRS/sepsis are able to oxidize i.v. lipid.     

Renal calcification incidence in very low birth weight infants

Serial ultrasound examinations were performed on 31 neonates with birth weights of less than 1,500 g for the detection of renal calcifications. Renal calcifications occurred in 20 (64%) of the infants at a mean age of 39.3 +/- 26.7 days of life. Infants with renal calcifications had shorter gestations (28.2 +/- 1.8 v 31 +/- 1.4 weeks, P less than .004) and lighter birth weights (924 +/- 195 v 1,338 +/- 100 g, P less than .004) than those infants without renal calcifications (n = 11). Furosemide administration was more common in the infants with renal calcifications (65% v 9.1%, P less than .001). The mean total dose of furosemide administered before renal calcifications were noted was 9.59 +/- 7.25 mg/kg. The 20 neonates with renal calcifications had a mean urine calcium level of 12.0 +/- 6.8 mg/kg/24 hours, mean urine calcium to creatinine ratio of 1.32 +/- 1.03 (range 0.3 to 4.45), and a mean alkaline phosphatase concentration of 961 +/- 327 IU. Initial parathyroid hormone levels were not different between the two groups, and subsequent determinations in infants with renal calcifications did not differ significantly from initial values. Renal calcifications are fairly common among very low birth weight infants, particularly in those receiving supplemental calcium and furosemide therapy. Although long-term implications of such findings are not known, close monitoring of renal function by serial determinations of urine calcium and urine calcium to creatinine ratios may identify those infants at risk for renal calcifications.     

Energy expenditure and deposition of breast-fed and formula-fed infants during early infancy

The energy intake, expenditure, and deposition of 40 breast-fed and formula-fed infants were investigated at 1 and 4 mo of age to explore possible differences in energy utilization between feeding groups. Energy intake was calculated from 5-d test-weighing records or pre- and postweighing of formula bottles, in combination with bomb calorimetry of the milks. Total daily energy expenditure (TDEE) was determined by the doubly labeled water method. Sleeping metabolic rate (SMR) and minimal observable energy expenditure were measured by indirect calorimetry. Activity was estimated as the difference between TDEE and SMR. Energy deposition was estimated from dietary intake and TDEE. Energy intakes were significantly higher for the formula-fed than breast-fed infants at 1 mo (118 +/- 17 versus 101 +/- 16 kcal/kg/d) and 4 mo (87 +/- 11 versus 72 +/- 9 kcal/kg/d) (p less than 0.001). TDEE averaged 67 +/- 8 and 64 +/- 7 kcal/kg/d at 1 mo and 73 +/- 9 and 64 +/- 8 kcal/kg/d at 4 mo for the formula-fed and breast-fed infants, respectively, and differed between feeding groups (p less than 0.04). SMR and minimal observable energy expenditure (kcal/min) were higher among the formula-fed infants at 1 and 4 mo (p less than 0.005). The energy available for activity and the thermic effect of feeding did not differ between feeding groups. Rates of weight gain (g/d) and energy deposition (kcal/kg/d) tended to be greater among the formula-fed infants at 1 and 4 mo (p less than 0.006).(ABSTRACT TRUNCATED AT 250 WORDS)     

Supplementation of pooled human milk with casein hydrolysate: energy and nitrogen balance and weight gain composition in very low birth weight infants

Growth and nitrogen and energy balances were studied with a combined technique of nutrient balance and indirect calorimetry measurement in two groups of eight very low birth weight infants fed pooled pasteurized human milk (HM) or cow's milk casein hydrolysate supplemented HM (HM-Pr). There was no difference in the amount of energy absorbed (91 +/- 17 kcal/kg/day with HM-Pr versus 95 +/- 8 with HM-P) or in the growth rate. The infants fed HM-Pr had a higher nitrogen intake (602 +/- 80 versus 395 +/- 64 mg/kg/day; p less than 0.001), urinary nitrogen excretion (160 +/- 64 versus 78 +/- 16 mg/kg/day; p less than 0.005) and nitrogen retention (326 +/- 32 versus 252 +/- 48 mg/kg/day; p less than 0.01). They also had increased plasma concentrations of essential amino acids, urea nitrogen, and total protein without metabolic imbalance. Energy expenditure was higher (58 versus 49 kcal/kg/day; p less than 0.005) and energy storage lower (33 versus 47 kcal/kg/day; p less than 0.05) with HM-Pr. In percent of weight gain, protein and fat accretion represented 12 and 14% in HM-Pr group versus 10 and 27% in HM group. Very low birth weight infants fed casein hydrolysate supplemented pooled HM achieved a growth rate and a weight gain composition similar to the fetus.