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Objective: To evaluate thermal responses, weight gain, and resting energy expenditure (REE) in preterm infants weaned from an infant incubator to a warming bassinet after reaching a body weight of either 1,500 or 1,600 g, respectively., Methods: Preterm infants weighing ≤ 1,500 g were randomly allocated for weaning from a convective incubator after reaching 1,500 g body weight (study group) or 1,600 g (controls). Postweaning body temperature was recorded at short intervals. REE was measured before and after weaning, while the weight gain was calculated daily., Results: All 21 enrolled infants were weaned successfully to a bassinet (room temperature). REE inside the incubator and in the warming bassinette was similar between infants weaned at 1,500 g and at 1,600 g (2.9 ± 6.8 vs. 1.1 ± 4.8 kcal/kg/d, respectively (p = 0.7). REE increased slightly after weaning in both groups. Weight gain and days from randomization to discharge did not differ between groups., Conclusion: Weaning very low birth weight infants from an incubator to a warming bassinet at a body weight of 1,500 g is feasible and has no significant deleterious effects on weight gain and REE. The many benefits provided by such greater accessibility to premature infants are discussed., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Objective: Oral probiotic supplementation reduces the risk of necrotizing enterocolitis (NEC) in preterm infants. Concerns about safety and purity of probiotic preparations have limited their use in preterm infants. The authors administered probiotic bacteria to mothers of preterm infants, thereby avoiding the risks of direct exposure of infants to probiotic bacteria., Design: This prospective, randomized, double blind, placebo-controlled trial at the Tel Aviv Medical Center (June 2007-November 2009) examined the effects of maternal oral probiotic supplementation on the incidence of NEC, death, and sepsis in very low birth weight (VLBW) infants fed with maternal breast milk. Mothers were assigned to supplementation with Lactobacillus acidophilus and Bifidobacteria lactis 2 × 10(E) [DOSAGE ERROR CORRECTED] CFU/d or to placebo starting from 1 to 3 days postpartum. The primary outcome measures were NEC, sepsis, and death., Results: In total 49 mothers of 58 VLBW infants were recruited. A total of 25 infants were in the probiotic group and 33 in the placebo group. The overall incidence of Bell stage II to III NEC was 12%, with an incidence of 4% in the infants of the probiotic group and 18.2% in the placebo group (p = 0.12), respectively. Sepsis and mortality rates were similar., Conclusion: Postpartum maternal supplementation with probiotic bacteria may decrease the incidence of NEC in breastfed infants., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

We undertook this in vitro study to quantify the effect that addition of magnesium (Mg) sulfate to neonatal serum, as compared with adult serum, might have on ionized Mg (Mg (2+)) concentration. We used one cord blood sample and one adult blood sample that we made hypermagnesemic by adding various amounts of magnesium sulfate to study five levels of serum Mg. Each sample was then studied at one of three levels of pH, from extreme alkalosis to extreme acidosis. We measured the changes in serum Mg (2+) and serum ionized calcium (Ca (2+)) in reaction to these changes in pH and Mg. At each pH level, there was an exponential increase in the serum Mg (2+) (and no significant change in serum Ca (2+)) with increasing serum Mg. Multiple regression analysis using Mg (2+) as the dependent variable and baseline Ca (2+), phosphorous, albumin, and blood type (adult versus cord blood) as well as blood pH and serum Mg as independent variables indicated that serum Mg and pH were the only variables significantly influencing serum Mg (2+). Within the range of serum Mg considered, the addition of magnesium sulfate in vitro causes an exponential increase in Mg (2+) and no significant change in serum Ca (2+)., (Copyright Thieme Medical Publishers.)

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.

The aim of this study was to determine the feasibility of a study of the effect of positioning on energy expenditure in preterm infants. We performed a prospective, randomized, clinical cross-over pilot study of eight healthy, appropriate weight for gestational age, gavage-fed, clinically stable preterm infants at the postmenstrual age of 30 weeks. Prior to the study and in accord with our feeding protocol, infants uniformly received either their own mother's milk or a preterm formula. Each infant was studied in four different positions after randomization to eight different sequences. Infants were studied asleep, 90 minutes after feeding, after 20 minutes of being nursed in a given position. They were cared for in a servo-controlled convective incubator during the metabolic measurements, which were performed by indirect calorimetry. Energy expenditure was not significantly affected by the body position in which the infant was studied. The difference between the highest and the lowest mean energy expenditure was 3.7% of the highest one. We conclude that attempts to minimize energy expenditure by modifying infant positioning are likely to be insignificant, from a practical standpoint, because of the nonsignificant or minimal differences in energy expenditure.

The objective of this study was to test the hypothesis that in discordant twins, the smaller infant has higher absolute nucleated red blood cell (RBC) count than the larger sibling. We compared absolute nucleated RBC counts, hematocrits, absolute leukocyte counts, absolute granulocyte counts, absolute lymphocyte counts, RBC counts and platelet counts obtained in the first 12 hours of life in 30 discordant twin sets. The smaller infant had a higher absolute nucleated red blood cell count and lower platelet counts than its larger sibling. Platelet counts correlated inversely with absolute nucleated RBC counts ( R(2) = 24.5%; p < 0.001) and absolute nucleated RBCs correlated directly with percent intertwin weight differences ( R(2) = 17.8%; p = 0.02). In discordant twins, the smaller infant has higher absolute nucleated RBC count and lower platelet counts than the larger sibling. We speculate that the hematologic alterations in the smaller fetus are linked to relative fetal hypoxia.

Small preterm infants usually require a heated environment to survive. After weaning, some infants become hypothermic, and eventually require external thermal support for an additional period. We hypothesized that preterm infants respond to weaning from an incubator by increasing their resting metabolic rate. Thermally stable infants were studied when they had reached a weight of at least 1600 g. Resting energy expenditure was measured 2 hours before weaning and at 6, 23, 30, and 53 hours after weaning. Two-way analysis of variance for repeated measures was used for analysis. Sixteen infants with mean birthweight of 1270 +/- 375 g and gestational age 31 +/- 2.3 weeks were studied. After weaning, there was a significant increase in energy expenditure from 95.0 +/- 21.9 kcal/d in the incubator, to a 30-hours peak of 111.9 +/- 10.5 kcal/d after weaning. Weaning from a convective incubator results in an increase in metabolic rate in very low birth weight infants. We speculate that the infants' ability to increase metabolic rate might influence weaning success.

In neonates, quantitative ultrasound has been shown to be predictive of bone breakability and an index of biophysical property of bone. There are no data on bone speed of sound (SOS) in appropriate for gestational age (AGA) twins. The purpose of this study was to test the hypothesis that AGA twins who had normal intrauterine growth have bone SOS similar to that of AGA singletons. We measured tibial midshaft bone SOS within the first 96 hours of life in 25 pairs of AGA twins, 27 to 40 weeks gestation, and compared them with our data of 73 singletons. There were no significant differences in bone SOS between twin and singleton infants in any of the parameters studied. We found no significant difference in bone SOS between twins of the same pair. AGA twins have bone SOS very similar to that of AGA singletons. We suggest that intrauterine weight sparing occurs also in terms of biophysical properties of bone.

Wide pulse pressure is considered to be a sign of patent ductus arteriosus (PDA). We tested the hypothesis that, following indomethacin therapy, PDA closure is associated with a significant decrease in pulse pressure. Thirty-two ventilated preterm infants were echocardiographically diagnosed within the first 24 hours of life with PDA. Systolic, diastolic, and mean arterial blood pressures were measured prior to indomethacin treatment and after echocardiographically confirmed PDA closure. Following PDA closure, systolic and diastolic blood pressures and mean arterial pressure increased significantly without a significant change of pulse pressure (17 +/- 7 to 20 +/- 12 torr). We conclude that in preterm infants with PDA, systolic, diastolic, and mean arterial blood pressures increase significantly within first few days of life. Pulse pressure does not appear to be affected by early PDA closure. We speculate that high pulmonary resistance in the first days of life prevents significant diastolic aortic runoff and leaves pulse pressure unaffected by PDA, as well as by its closure.

Studies of the effect of body position during and after bolus feeding upon gastric emptying or gastric residual have not had consistent results. We tested the hypotheses that right lateral decubitus leads to less gastric residual than left lateral decubitus and that the prone position leads to less gastric residual than the supine position. A prospective randomized clinical trial with triple crossover of healthy growing, appropriate for gestational age preterm infants. Each infant was successively studied while fed in the four different positions. Gastric residuals were measured at 1 and 3 hours after initiation of feeding and returned. Thirty-one patients were studied. At 1 hour, right lateral decubitus led to less significant residuals than the left lateral decubitus and the prone position led to less residual than the left lateral decubitus. The amount of gastric residuals 1 hour after a meal appears to be in the following decreasing order: left, supine, prone, right.

We investigated whether the presence or absence of physiologic labor may affect the neonatal nucleated red blood cell (RBC) count. We compared absolute nucleated RBC counts taken at approximately 6 hours of life in term infants born by elective cesarean delivery without trial of labor ( n = 32) and in vaginally delivered infants ( n = 28). Venous blood samples were analyzed and differential cell counts were performed manually; absolute nucleated RBC were counted and expressed as an absolute number. There were no significant differences between groups in birth weight, gestational age, maternal age, gravidity, parity, maternal analgesia during labor, 1- and 5-minute Apgar scores, and infant sex. There was a significantly higher hematocrit and RBC count in the vaginally delivered group as compared with the cesarean group. The absolute nucleated RBC, corrected leukocyte and lymphocyte, and platelet counts were strikingly similar in both groups. We conclude that labor does not affect the neonatal nucleated RBC count. This finding supports the speculation that physiologic labor does not induce a fetal hypoxemia severe or prolonged enough to produce hematological evidence of increased erythropoiesis.

Mercury-in-glass thermometers are considered the "gold-standard" for temperature measurements, but require at least 4 minutes for accuracy. Electronic thermometers sample temperature measurements over a shorter period. The objective of this study was to evaluate the accuracy and reproducibility of the Penguin (Medisim, Jerusalem, Israel) and the IVAC (San Diego, CA) Temp plus II thermometers in preterm infants. Axillary temperature was obtained in 50 thermally stable preterm infants each time with the mercury-in-glass, the IVAC, and the Penguin thermometers. Analysis of variance F-test, and linear regression analyses were used to test correlation of each electronic thermometer with the mercury-in-glass one, and the effect of body weight. Temperature measurement taken with the Penguin thermometer was significantly higher than that measured with the two other ones, p < 0.001. The differences in means and in variances were not significantly different between IVAC and mercury-in-glass, while the variance of the Penguin measurement was higher than that of the two other instruments (p < 0.001). The IVAC instrument correlated more tightly with the mercury-in-glass (r = 0.89, p < 0.001) than did the Penguin (r = 0.54, p < 0.001). There was an inverse correlation between the deviation of the Penguin measurement from the mercury-in-glass and the weight of the patient ( p < 0.08), while no significant correlation was found between the deviation of the IVAC measurement from the mercury in glass and the patient's weight (p = 0.56). Measurements of axillary temperature using the Penguin thermometer in incubated preterm infants are less accurate and less reproducible than those obtained using the IVAC or the glass thermometers.

The objective of this study is to study the absolute number of nucleated red blood cells (RBC) at birth, an index of active fetal erythropoiesis, in infants with G6PD deficiency and in controls. We tested the hypothesis that hematocrit and hemoglobin would be lower, and absolute nucleated RBC counts higher, in the G6PD deficient and that these changes would be more prominent in infants exposed passively to fava bean through maternal diet. Thirty-two term infants with G6PD deficiency were compared with 30 term controls. Complete blood counts with manual differential counts were obtained within 12 hours of life. Absolute nucleated RBC and corrected leukocyte counts were computed from the Coulter results and the differential count. G6PD deficient patients did not differ from controls in terms of gestational age, birth weight, or Apgar scores or in any of the hematologic parameters studied, whether or not the mother reported fava beans consumption in the days prior to delivery. Although intrauterine hemolysis is possible in G6PD deficient fetuses exposed passively to fava beans, our study supports that such events must be very rare.

We prospectively tested the hypothesis that prevention of lateral movement of the head, using a specially designed head support apparatus, would prevent oxygen desaturation in preterm infants restrained in car seats. Preterm infants reaching 34 to 35 weeks' gestation were studied at the week of discharge in 3 different conditions for 20 minutes each time: supine decubitus, sitting position in a newborn car seat, and sitting position in the car seat equipped with an apparatus that supports the head, while monitored by pulse oxymetry. Data are expressed as percent of time over each period during which the oxygen saturation was below 90, 92, 94, or 96%. Statistical analysis was by analysis of variance (ANOVA) followed by paired Student t-test for differences of means. There were no significant differences among groups in percent of time with oxygen saturation below 96, 94, 92, or 90%. Oxygenation is not improved in relatively healthy preterm infants placed in a car seat when their head is supported to prevent lateral movements by a special apparatus.