Energy Expenditure In Preterm Infants Research Articles

Relationship between energy expenditure and stress behaviors of preterm infants in the neonatal intensive care unit.

This research evaluated the relationship between behaviors and energy expenditure in preterm infants receiving nursing interventions. This study was an explorative secondary data analysis from a previous study. The current study investigated energy expenditure calculated using heart rate-based energy expenditure-estimate across 500 repeated measures for 37 infants. Research results indicate that preterm infants expend more energy when they show the following seven behaviors: grimace, sucking, diffusion squirm, fist, gape face, salute, and sneezing. The interventions for preterm infants should be flexible, according to the infant's stress behaviors and conditions of energy expenditure.

ABSTRACT 688

Background and aims: Background: Preterm infants are especially vulnerable to inadequate growth because of low energy reserves. Neonatal clinicians must moderate the stimuli resulting from interventions according to the stress responses and energy expenditure of their patients. Aims: The purpose of this research was to evaluate the relationship between behaviors and energy expenditure in preterm infants receiving nursing interventions. Methods: This study was an explorative secondary data analysis from a previous study. The research data which were from 37 preterm infants, included physiological signals, stress behaviors, and nursing interventions in neonatal intensive care units. The current study investigated energy expenditure calculated using Heart-based Energy Expenditure-estimate (HR-based EE-estimate). Results: A significantly positive relationship was observed between energy expenditure and seven stress behavioral responses in preterm infants while receiving nursing interventions. Research results indicate that preterm infants expend more energy when they show these seven behaviors. These seven stress behaviors were grimace, sucking, diffusion squirm, fist, gape face, salute, and sneezing. Conclusions: Research revealed behaviors linked to increase energy expenditure in preterm infants receiving interventions. Because of immature physiological mechanism and low energy levels, preterm infants are easily overtaxed and show exhaustion and show few stress behavioral responses and obtunded. In order to provide quality care, neonatal clinicians should always simultaneously assess the energy expenditure levels and stress behaviors of preterm infants.

Energy expenditure in preterm infants during periods of environmental stress in the neonatal intensive care unit.

To explore the energy expenditure (EE) in a group of preterm infants during the periods of environmental stress, and to explore the relationship between EE and physiological stress signals of preterm infants. Research design was an explorative secondary analysis of 4164 research data from 37 preterm infants which included physiological signals and environmental stressors in neonatal intensive care units. The current study investigated the data of EE calculated using heart-rate-based EE estimate. A significantly positive relationship between EE and different levels of nursing intervention was found (P < 0.005). In addition, there was a significantly negative relationship between EE and oxygen saturation (P < 0.001). These research results confirmed that environmental stressors may impact the growth and developmental outcomes in preterm infants by increasing their EE. Neonatal clinicians should minimize excessive stimulations in order to conserve energy for the growth and developmental needs of preterm infants. Research found a significant relationship between an increase in EE and a decrease in oxygen saturation in preterm infants. The authors further hypothesized that EE of preterm infants may be predicted by estimating the oxygen saturation. Further study using different research methods and an enlarged sample size is needed.

Energy Expenditure in Preterm Infants Supplemented With Canola Oil Versus Medium-Chain Triglyceride Oil

Objective. To test the hypothesis that intestinal fat losses and energy expenditure (EE) are lower in preterm infants (PTIs) supplemented with medium-chain triglyceride (MCT) oil than in those supplemented with canola oil (CO). Design/Methods. A total of 6 PTIs were studied in a randomized, crossover design. Gestational age was 28 to 34 weeks, and birth weight was 920 to 1269 g. Infants were randomized to supplementation with either 34 kcal (4 g) CO per kg per day or 34 kcal (4.4 g) MCT oil per kg per day for 3 days followed by 3 days of the other oil. EE was measured at baseline, after 3 days of the first oil supplementation, and after 3 days of the alternate oil supplementation based on indirect calorimetry. Also, 72-hour stool samples were collected. Results. The coefficient of added fat absorption was 99.5% ± 0.9% of the MCT oil versus 90.0% ± 16.2% of the CO (P = .056). EE increased after CO supplementation by 4.33 ± 5.96 kcal/kg/d and by 4.17 ± 3.97 kcal/kg/d after MCT (nonsignificant). Thus, after correction for net additional energy intake, energy retained from 34 kcal/kg of added fat was 26.1 ± 6.9 kcal/kg/d after CO and 30.1 ± 5.0 kcal/kg/d after MCT (P = .09). Conclusions. MCT oil may be better absorbed than CO in growing PTIs. The metabolic cost of absorption of MCT oil and CO are similar.

Effect of Body Weight on Temperature Control and Energy Expenditure in Preterm Infants

The purpose of this study was to compare resting energy expenditure (REE) in premature infants of different body weights during weaning from the incubator. We hypothesized that premature infants would respond to weaning from an incubator with an increase in REE, and that the increment would be larger in infants with lower body weights than in those with higher body weights. Stable preterm infants with body weights between 1800-2200 g were enrolled. REE was measured using indirect calorimetry at 1 hour before weaning and 3 hours after turning off the incubator. REE measurements from infants with higher body weight (2000-2200 g, Group A) were compared to those of infants with lower body weight (1800-2000 g, Group B). A total of 22 patients were studied (10 in Group A and 12 in Group B). REE increased significantly after weaning in both groups (Group A: from 62 +/- 7 kcal/kg/day to 69 +/- 8 kcal/kg/day, p = 0.045 and Group B: from 65 +/- 5 kcal/kg/day to 70 +/- 7 kcal/kg/day, p = 0.001). However, there was no significant difference in REE increments between the two groups. REE increased significantly in infants during weaning from an incubator. The increase in REE increment was similar in smaller (1800-2000 g) and larger (2000-2200 g) babies in this study. Weaning of preterm babies from an incubator may be safely started when their body weight reaches 1800 g.

Effect of Birth Weight and Postnatal Age upon Resting Energy Expenditure in Preterm Infants

Our objective was to establish the role of gestational age, birth weight, and postnatal age upon resting energy expenditure (REE) in incubated preterm infants. We hypothesized that at the time these infants are close to being weaned from their incubator, their REE is inversely related to gestational age or birth weight and directly related to postnatal age and weight gain. Infants born at a birth weight of 500 to 2000 g were eligible for the study when they reached a weight of 1500 to 2100 g. All infants were clinically and thermally stable while cared for in a skin servo controlled incubator. REE (kcal/kg body weight/d) was measured 2 hours after feeding while the infants were quietly asleep, using a Datex oxygen consumption analyzer (DELTATRAC II (TM); Datex-Ohmeda Instrumentarium, Helsinki, Finland), based on the principles of indirect calorimetry. There were 42 infants recruited in the study. In univariate analysis, no significant correlation was found between gestational age and REE, but REE was significantly and inversely correlated with birth weight ( R(2) = 0.243, P < 0.001). There was also a significant correlation between REE and postnatal age ( R(2) = 0.203, P = 0.003) and with weight gain ( R(2) = 0.176, P = 0.006). In backward stepwise regression analysis, the effect of birth weight or postnatal age or daily weight gain (g) upon REE remained significant even after taking into account sex, energy intake, and type of feeding. Birth weight, postnatal age, and daily weight gain significantly affect REE, even after taking into account energy intake, sex, and type of feeding. Weight may be a more important parameter in the control of thermoregulation of the preterm infant than gestational age.

Changes in Energy Expenditure in Preterm Infants During Weaning: A Randomized Comparison of Two Weaning Methods from an Incubator

Changes in Energy Expenditure in Preterm Infants During Weaning: A Randomized Comparison of Two Weaning Methods from an Incubator

Changes in Energy Expenditure in Preterm Infants During Weaning: A Randomized Comparison of Two Weaning Methods from an Incubator

We aimed to compare resting energy expenditure (REE) of infants exposed to either one of two weaning methods and to confirm the increase in REE during weaning from incubator. The study was a prospective randomized clinical trial of weaning preterm infants using either of two methods. REE was measured at baseline and 6, 23, 30, and 47 h, using indirect calorimetry. At measurement, infants were clinically and thermally stable, asleep, 2 h after feeding. Forty-two patients were randomized to "open incubator" (n = 23) or "warming bassinet" (n = 19). The groups did not differ in baseline clinical characteristics. REE increased significantly in both groups within 23 h, and remained stable at 30 and 47 h. At 6 and 23 h, the incubator group had significantly higher increase in REE than the warming bassinet group. By 30 h and at 47 h post-weaning, the REE of both groups became similar. In conclusion, REE increases significantly at weaning from incubator. The warming bassinet delays the increase in REE observed when infants are weaned using a turned off incubator. Whether one method is superior to the other in terms of thermic stress cannot be determined from this study.

Exploration of the Contribution of Biobehavioral Variables to the Energy Expenditure of Preterm Infants

Variation in energy expended by preterm infants may be due to infant maturity and history of resolved acute lung disease (respiratory distress syndrome [RDS]) as well as growth, caloric intake, and activity. Indirect calorimetry was used in this exploratory, short-term longitudinal study to estimate energy expenditure (EE) from measures of inspired and expired O2 and CO2. The sample included 35 assessments for 10 preterm infants (5 with and 5 without RDS history). Lung disease history (resolved RDS, no RDS diagnosis), weight gain (g/d) from the day on which birth weight had been regained to the study day, mean activity level, the number of the assessment (1-6), and the interaction of lung disease history and time were included in a linear mixed model for repeated measures. Time was an index of postconceptional and postnatal age; all 3 were highly correlated. Because of high correlation with weight gain, caloric intake was not included in the analytic model. Lung disease history, mean activity level, and time were significant contributors to EE. A more precise measure of medical status than absence or presence of lung disease history, evenly spaced repetitions of EE assessment, and exploration of contexts in which the infants exhibit a higher activity level are needed in a replication study with a larger sample.

Measuring energy expenditure in preterm and unstable infants

Measuring energy expenditure in preterm and unstable infants

Longitudinal evaluation of energy expenditure in preterm infants with birth weight less than 1000 g.

The aim of the present study was to obtain serial values of O2 consumption (VO2), CO2 production (VCO2) and energy expenditure (EE) in healthy but extremely-low-birth-weight infants (birth weight <1000 g), during the first 5 weeks after birth. A total of seventeen spontaneously breathing and appropriate-for-gestational-age (birth weight and body length above the 10th and below the 90th percentile) preterm infants with gestational age 25-28 weeks and birth weight 590-990 g were enrolled in the study. Calorimetry was performed using an open-circuit calorimeter on days 6, 12, 18, 24, 30 and 36 of postnatal life. During the 5 weeks of observation, VO2 increased from 4.7 (SD 0.5) to 9.1 (SD 1.0) ml/kg per min, VCO2 from 4.5 (SD 0.4) to 8.3 (SD 0.6) ml/kg per min and EE from 115 (SD 12) to 310 (SD 71) kJ/kg per d. The energy intake was always higher than EE, even at days 6 and 12. The RER decreased from 0.99 (SD 0.09) at day 12 to 0.91 (SD 0.05) at day 30. On all study days, there were highly significant positive correlations between energy intake and weight gain, EE and weight gain, and EE and energy intake (P<0.05). Multiple regression analysis showed that on most study days EE was more affected by energy intake than by weight gain. We conclude that in healthy preterm infants with birth weight <1000 g, EE increases by about 150 % in the first 5 weeks after birth, and that the EE values are related to energy intake and weight gain independent of postnatal age.

Use of infrared thermographic calorimetry to determine energy expenditure in preterm infants

Measurement of infant energy expenditure in the clinical setting is difficult and is rarely done. Both indirect and direct calorimetry require long measurement periods and frequent calibration. The objective of this study was to validate in infants a newly developed method of determining energy expenditure, infrared thermographic calorimetry (ITC), against an established method, respiratory indirect calorimetry (IC). ITC measures mean infant body surface temperature. ITC was used in conjunction with heat loss theory to calculate radiant, convective, evaporative, and conductive heat losses and thereby determine total energy expenditure. Ten healthy preterm infants were studied by obtaining concurrent ITC and IC measurements over a 3.5-5.5-h study period. Continuous IC measurements were compared with ITC measurements taken every 10 min during study periods. IC values were summed over 10-min intervals covering the 5 min before and 5 min after each ITC measurement, to allow comparisons between the 2 methods. Comparison of paired ITC and IC mean measurements for all 10 infants over the entire study period showed no significant difference between the 2 methods. However, individual paired IC and ITC values were significantly different for 7 of 10 infants. The overall mean difference between the 2 methods was 1.3%. ITC is an accurate, noninvasive method for measurement of heat loss and energy expenditure in healthy preterm infants, and therefore it may be a useful clinical and research tool.

Protein turnover and energy expenditure in preterm infants.

Protein turnover and energy expenditure in preterm infants.

Measurement of Energy Expenditure in Preterm Infants. 1: How long to measure? † 1410

Measurement of Energy Expenditure in Preterm Infants. 1: How long to measure? † 1410

Estimation of CO2 production in enterally fed preterm infants using an isotope dilution stable tracer technique.

Estimates of the rate of CO2 production may be useful in preterm infants, but assessment of the rate of respiratory excretion of CO2 (VCO2) may not always be practical in infants requiring constant care. We hypothesized that the rate of dilution of 13CO2 (RaCO2) would be a valid index of CO2 production in preterm infants. Twelve studies of RaCO2 and VCO2 were performed in six enterally fed preterm infants. RaCO2 was measured using a 2-hour, primed, constant, orogastric infusion of NaH13CO3 with formula and an assessment of the plateau 13C enrichment of expired CO2. VCO2 was measured over two 10-minute intervals during the infusion using a flow-through system. Energy expenditure was estimated from these data and the food quotient. Mean (+/- SD) rate of CO2 production using RaCO2 (348 +/- 32 mumol/kg/min) was 114% of that estimated using VCO2 (304 +/- 51 mumol/kg/min). The ratio of VCO2/RaCO2 is equal to the fractional recovery of tracer CO2 in the expired air during the course of the tracer infusion. In studies of short duration, this ratio is generally less than 100% because of isotope exchange. For five pairs of studies performed on consecutive days, each individual value of RaCO2 on day 2 was multiplied by the mean of the individual ratios of VCO2/RaCO2 on day 1 (0.78); corrected RaCO2 was 306 +/- 19 mumol/kg/min compared with 307 +/- 59 mumol/kg/min for VCO2. Thus, RaCO2, particularly when corrected for isotope recovery, may be a useful index of group mean CO2 production and energy expenditure in preterm infants.

A gradient-layer calorimeter for measurement of energy expenditure of infants.

We have developed and validated a gradient-layer calorimeter for direct measurement of energy expenditure of preterm infants. Infant calorimeters must be operated and tested differently from adult calorimeters, because the calorimeter must be warmed during operation to limit heat loss from the infant, the calorimeter wall temperature (which is selected on the basis of the infant's maturity) must be precisely controlled, and energy expenditure (heat output) is typically < 10 W. We calibrated our calorimeter by varying the heat produced by a dry source (manikin or light bulb) with airflow (n = 42) and without airflow (n = 8) at various water jacket temperatures (n = 7) and by a wet source (combustion of ethyl alcohol) with airflow (n = 9). With no air moving, qc = 0.740 Vc + 0.029 Twj-0.697, where qc (W) is the estimated output of the heat source measured by the calorimeter, Vc (mV) is the gradient-layer voltage of the calorimeter, and Twj (degree C) is the temperature of the water jacket surrounding the walls of the device. From this equation and enthalpy calculations, the slope and intercept of the regression line relating the estimated heat production to the actual heat produced from alcohol combustion are 1.029 +/- 0.046 and -0.549 +/- 0.484 (SE), respectively. The slope is not significantly different from unity, and the intercept is not significantly different from zero. Thus we can accurately estimate the energy expenditure of preterm infants from the equations describing our calorimeter, and we can accurately resolve the total heat output into a dry (nonevaporative) component and a wet (evaporative) component.

Comparison of Short Term Indirect Calorimetry and Doubly Labeled Water Method for the Assessment of Energy Expenditure in Preterm Infants

The accuracy of 8-hour indirect calorimetry (IDC) as an estimate of energy expenditure was investigated in 8 healthy preterm infants (birth weight 1,270 +/- 193 g, gestational age 32 +/- 3 weeks, mean +/- SD) in comparison with an analysis over 5 days using the doubly-labeled water (2H2(18)O) method (DLW). The infants that were fed continuously by nasogastric drip with 120 kcal/kg/day of special infant formula were measured twice under thermoneutral conditions in a closed system indirect calorimeter during 8 h with a 4-day interval; simultaneously isotope decay was measured by isotope ratio mass spectrometry in urine samples collected daily during 5 days from 6 h after an oral dose of 2H2(18)O on the first day of IDC, all during the 4th postnatal week. The mean differences between carbon dioxide production rate (rCO2) measured either by single 8-hour IDC or by duplicate 8-hour IDC and the 5-day DLW method, using the two-point analysis or the multipoint analysis were not significantly different from zero. The rCO2 calculated from the DLW method using the two-point analysis differed -1.4 +/- 1.7% from that measured by the multipoint analysis. The mean differences between the metabolic rate estimated from 8 h of IDC and from the 5-day DLW method based on a measured RQ of 0.90 was -6.7 +/- 6.2% and based on the RQ of the feeding -4.5 +/- 6.0%. These differences were not significantly different from zero. We conclude that IDC over 8 h and two-point DLW measurement over 5 days, both methods that can be applied with relative ease in practice, offer an adequate average estimate of energy expenditure in continuously fed preterm infants under thermoneutral conditions.

Whole Body Protein Turnover Measured with 13C-Leucine and Energy Expenditure in Preterm Infants

Our study was undertaken in preterm infants to examine the relationship of whole body protein kinetics with protein intake and energy expenditure. Leucine kinetics were determined in seven low birth wt preterm infants fed human milk or human milk enriched with protein (2.5 to 4.3 g protein/kg.d). The infants received a short (4-h) constant infusion of L-[1-13C]leucine and leucine turnover and oxidation were calculated from 13C-plasma leucine and expired 13CO2 enrichments measured by mass spectrometry. Energy expenditure was measured by indirect calorimetry. Nonoxidative leucine disposal (an estimate of protein synthesis) and leucine derived from protein (an estimate of protein breakdown) were, respectively, 2.98 +/- 0.82 and 2.06 +/- 0.74 mumol/kg.min. Whole body protein turnover and deposition, derived from leucine kinetics, were 8.22 +/- 2.31 and 2.17 +/- 0.50 g/kg.d, whereas energy expenditure was 56.3 kcal/kg.day. Protein turnover was correlated with protein intake but not with protein deposition. Energy expenditure was correlated with protein turnover, synthesis, and breakdown but not with protein deposition. These data are in agreement with the fact that protein deposition depends upon protein intake, but they also suggest that an elevated protein deposition is not necessarily the result of a rapid protein turnover or associated with an elevated energy expenditure.

Whole Body Protein Turnover Measured with 13C-Leucine and Energy Expenditure in Preterm Infants

ABSTRACT: Our study was undertaken in preterm infants to examine the relationship of whole body protein kinetics with protein intake and energy expenditure. Leucine kinetics were determined in seven low birth wt preterm infants fed human milk or human milk enriched with protein (2.5 to 4.3 g protein/kg.d). The infants received a short (4-h) constant infusion of l-[1-13C]leucine and leucine turnover and oxidation were calculated from 13C-plasma leucine and expired 13CO2 enrichments measured by mass spectrometry. Energy expenditure was measured by indirect calorimetry. Nonoxidative leucine disposal (an estimate of protein synthesis) and leucine derived from protein (an estimate of protein breakdown) were, respectively, 2.98 ± 0.82 and 2.06 ± 0.74 μmol/kg.min. Whole body protein turnover and deposition, derived from leucine kinetics, were 8.22 ± 2.31 and 2.17 ± 0.50 g/kg.d, whereas energy expenditure was 56.3 kcal/kg.day. Protein turnover was correlated with protein intake but not with protein deposition. Energy expenditure was correlated with protein turnover, synthesis, and breakdown but not with protein deposition. These data are in agreement with the fact that protein deposition depends upon protein intake, but they also suggest that an elevated protein deposition is not necessarily the result of a rapid protein turnover or associated with an elevated energy expenditure.

Effects of Waterbed Flotation on Indicators of Energy Expenditure In Preterm Infants

The purpose of this investigation was to study the effects of nonoscillating waterbeds on three indices of energy expenditure: activity level, heart rate, and behavioral state. Subjects were 22 healthy preterm infants in a neonatal intensive care unit who had reached 31-35 weeks postconceptional age, and whose average weight was 1,482 grams at the onset of the study. Infants were placed on a waterbed for 3 consecutive days and on a standard incubator mattress for 3 consecutive days. Infants served as their own controls on and off the waterbed. Treatment order was randomly counterbalanced. One-hour observations of activity and state occurring in conjunction with heartbeat counts were the repeated measures on each day over both treatment and control conditions. Infants experienced longer durations of quiet sleep, less active awake and fuss states, and fewer state changes and awakenings while on the waterbed. Heart rates were higher after infants were taken off the waterbed. The findings suggest that nonoscillating waterbed flotation is a simple, cost-effective intervention that reduces energy expenditure.