[Polychlorobiphenyls in human milk, adipose tissue, plasma and umbilical cord blood; levels and correlates]

In a longitudinal study involving 17 women, PCB concentrations (PCBs 138, 153 and 180) were determined in cord blood (17 newborns), breast milk (10 women), maternal adipose tissue (8 women), maternal plasma collected during the last trimester of pregnancy (17 women) and maternal plasma collected 10 days post partum (7 women). Significant correlations were found (p less than 0.05) between PCB levels in cord blood, breast milk and adipose tissue and maternal plasma collected before birth, and between breast milk and maternal plasma collected post partum. In 2 vegetarian women the PCB levels in maternal plasma and cord blood were significantly lower than in the other women (p less than 0.05). If in future studies the PCB levels observed prove to be detrimental to child development, these correlations may offer the possibility of identifying a group of newborns at risk for occurrence of developmental defects due to PCB exposure before birth.

[The use of corticosteroids in bronchopulmonary dysplasia]

In order to study the effect of dexamethasone on the ventilatory function of 13 neonates with bronchopulmonary dysplasia, a retrospective investigation was carried out in the University Hospital Rotterdam, Sophia Children's Hospital, Neonatal Intensive Care Unit. Thirteen preterm neonates, 7 boys and 6 girls, born after 26 4/7-32 weeks' gestation with birth weights between 680 and 1800 g were studied. At the age of 21 days they all showed clinical and radiological evidence of BPD and despite maximal therapy they deteriorated during the last week before entering into the study. The potentially successful dexamethasone schedule of Avery was started. After four days' therapy only 3 patients out of 13 were still on the ventilator. Ventilatory support could be stopped in all neonates after 4.7 (SD 2.0) days. No hypertension or hyperglycaemia was seen. Only 1 child had a positive blood culture; this was successfully treated. In the end two children died. The use of corticosteroids in bronchopulmonary dysplasia in this study showed a positive short-term effect. Long-term sequelae and the risk of infection are still controversial.

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.

Effects of high carnitine supplementation on substrate utilization in low-birth-weight infants receiving total parenteral nutrition

Parenterally fed preterm neonates are known to be at risk for carnitine deficiency. We studied substrate utilization in low-birth-weight infants receiving total parenteral nutrition (TPN) with (A) and without (B) supplementation of 48 mg carnitine.kg-1.d-1 on days 4-7 (birth weights 1334 +/- 282 vs 1318 +/- 248 g, gestational age 32 +/- 2 vs 32 +/- 2 wk, A vs B, respectively). TPN consisted of 11 g glucose.kg-1.d-1 and 2.4 g.kg-1.d-1 of both protein and fat. Plasma carnitine concentrations at day 7 were for free carnitine 11.8 +/- 5.0 vs 164 +/- 56 mumol/L and for acyl carnitine 3.8 +/- 2.0 vs 33.9 +/- 15.4 mumol/L, respectively. Indirect calorimetry at day 7 showed a higher fat oxidation (0.21, -0.31 to +0.60 vs 1.18, 0.70 to 1.95 g. kg-1.d-1, respectively, P less than 0.02, median and interquartile range) in group B and a higher protein oxidation (0.37, 0.30-0.43 vs 0.63, 0.53-0.88 g.kg-1.d-1, P less than 0.001). The time to regain birth weight was also higher in group B (7, 5.5-9 vs 9, 7-14 d, P less than 0.05). Carnitine supplementation and calorie intake were the best explanatory variables for metabolic rate (R2 = 0.45, P less than 0.002). We conclude that carnitine supplementation of TPN in this dosage does not seem advisable.

Cerebral lesions in preterm infants after tocolytic indomethacin

The incidence and type of cerebral lesions in 159 infants born before 30 weeks gestation were studied, using ultrasound. Indomethacin was given as part of tocolytic management to mothers with a high incidence of early rupture of membranes and preterm labour; and 76 fetuses were exposed to the drug as a result. For the remaining 83 pregnancies, in which there was a high incidence of chronic fetal distress and in utero hypoxia, tocolysis was either not started or limited to fenoterol. The neonatal course was similar for both groups of infants, except that patent ductus arteriosus was less commonly diagnosed in the 76 infants exposed to indomethacin. However, the incidence of periventricular leukomalacia was increased among infants exposed to any tocolytic agent; and cystic lesions occurred more commonly in those exposed to indomethacin.

Glucose production and oxidation in preterm infants during total parenteral nutrition

During total parenteral nutrition in preterm infants, glucose may be infused at high rates, but it is not known if the endogenous glucose production is fully suppressed under these circumstances. Eight preterm appropriate for gestational age (AGA) (birth wt: 1613 +/- 151 g, gestational age: 31.1 +/- 1.5 wk) and eight preterm small for gestational age (SGA) newborn infants (1185 +/- 241 g, 32.9 +/- 2.6 wk) receiving a glucose infusion rate of 7.55 +/- 0.56 and 8.16 +/- 0.65 mg/kg.min, respectively, were studied during continuous total parenteral nutrition at postnatal d 8. Glucose oxidation rate was determined with a primed constant infusion of [U-13C] glucose, measuring the 13CO2 production in breath gas by isotope ratio mass spectrometry and the glucose production rate in plasma by gas chromatography mass spectrometry. In breath gas of AGA and SGA infants, 60 and 65%, respectively, of the infused tracer appeared as 13CO2. The glucose production rates were 7.97 +/- 1.61 and 8.12 +/- 1.84 mg/kg.min in AGA and SGA infants, respectively, indicating that no significant endogenous glucose production occurred. The glucose oxidation calculated from the glucose production and 13CO2 production was 4.74 +/- 0.99 mg/kg.min in AGA infants and was significantly different from the carbohydrate oxidation rate of 6.62 +/- 1.23 mg/kg.min measured by simultaneous indirect calorimetry. In SGA infants, however, the glucose and carbohydrate oxidation rates were not significantly different at 5.33 +/- 1.56 and 6.16 +/- 2.45 mg/kg.min. It is concluded that 1-wk-old AGA or SGA preterm infants receiving total parenteral nutrition of 80 kcal/kg.d produce no endogenous glucose and their glucose oxidation rates are similar at 63-65% of the glucose infused. It is suggested that the significant difference between glucose and carbohydrate oxidation rates observed in AGA but not in SGA infants is due either to a higher rate of lipogenesis from carbohydrates, or, less likely, to a higher rate of glycogen oxidation.

Five years of cefotaxime use in a neonatal intensive care unit

In 1983 our antibiotic regimen for suspected neonatal septicemia was changed from amoxicillin-gentamicin to cefotaxime-amoxicillin. During the subsequent 5-year period we studied the effect of this change in regimen on the bacterial flora of the infants in the unit and the occurrence of serious infections. This was done with bacteriologic surveillance and analysis of the positive blood cultures from 1978 through 1987. A change in the relative numbers of isolated pathogens was observed; Klebsiella sp. and Escherichia coli decreased whereas Enterobacter sp. increased. The susceptibility of the Enterobacter isolates to cefamandole decreased from 85.3% in 1982 to 52.9% in 1983. The susceptibility of these bacteria to cefotaxime was 55.2% in 1983 and 55.0% in 1987. No change in susceptibilities to cefotaxime, amoxicillin or gentamicin was found in other pathogens. Although colonization with Enterobacter strains has increased and the susceptibility of these bacteria to the cephalosporins has decreased, the incidence of serious infections with Gram-negative bacteria decreased.

Quantitation of oxidation of medium-chain triglycerides in preterm infants

Medium-chain triglycerides, with a chain length of eight and 10 carbon atoms, form up to 50% of the total fat content in some preterm infant formulas. In 20 small preterm infants (birthwt: 1153 +/- 227 g; mean +/- SD) fed a special formula containing 40% MCT, a primed constant oral infusion study of 1-13C-potassium octanoate was conducted to quantify the oxidation of MCT. A plateau in 13C enrichment in breath CO2 was reached in all patients within 1-3 h. Simultaneously, substrate utilization was measured using a closed system indirect calorimeter. No significant difference was found between appropriate for gestational age (n = 8) and small for gestational age (n = 12) infants in the percentage of the administered tracer that was oxidized (44.9 +/- 9.1% versus 48.5 +/- 11.0%). In all patients, the recovery was calculated to be 47.1 +/- 10.2%, which is less than previously estimated and corresponds to a mean MCT oxidation of 1.26 +/- 0.27 g/kg/d. With indirect calorimetry, a total fat oxidation of 1.42 +/- 0.84 g/kg/d in appropriate for gestational age and 2.00 +/- 0.85 g/kg/d in small for gestational age infants was found, indicating that MCT accounted for around 85% of the total fat oxidation in appropriate for gestational age versus 65% in small for gestational age infants.

Effect of replacing glucose with lipid on the energy metabolism of newborn infants

1. Indirect calorimetry and primed constant infusion of [U-13C]glucose were combined in 28 appropriate-for-gestational age newborn, parenterally fed infants, in order to measure glucose utilization and glucose oxidation and to estimate lipogenesis from glucose. 2. The infants were randomly allocated to either a group receiving glucose as the non-protein energy source or a group having one-quarter of the glucose energy replaced by intravenous fat. The energy intake (370 kJ day-1 kg-1) and protein intake (3.4 g day-1 kg-1) were similar in both groups. 3. Energy expenditure (P less than 0.005), non-protein carbon dioxide production (P less than 0.005) and non-protein oxygen consumption (P less than 0.05) were lower in the lipid-supplemented group. 4. The significant excess of glucose utilization over oxidation (P less than 0.001) can be accounted for by lipid synthesis from glucose. 5. Fat synthesis from glucose was higher in the glucose/amino acid group (P less than 0.02), but total fat storage was higher in the lipid-supplemented group (P less than 0.02). Nitrogen balance was similar in both groups. 6. As lipogenesis from glucose is an energy- and oxygen-consuming and a carbon dioxide-producing process, the data suggest that the differences between the glucose-only group and the lipid-supplemented group are due to different rates of lipogenesis from glucose.

Renal functional impairment in preterm neonates related to intrauterine indomethacin exposure

Renal function was measured during the first 4 postnatal days in 9 preterm neonates (gestational age 26.2 to 31 wk) exposed to indomethacin during the last 2 days of pregnancy (group I). The data were compared to those obtained from nine control neonates (gestational age 28 to 34.5 wk) (group II). Five of the nine neonates in group I were markedly edematous at birth, none of group II were edematous. Urine production in group I was low (32.2 +/- 16.8 ml/kg.day on day 1 increasing to 68.6 +/- 21.4 ml/kg.day on day 4) and differed significantly from group II [75.2 +/- 26.8 ml/kg.day on day 1 increasing to 84.8 +/- 20.9 ml/kg.day on day 4 (p less than 0.001)]. Fluid intake was adapted to urine production when necessary. A continuous inulin infusion was started directly after admission and continued for 5 days. Renal function was evaluated for 3 consecutive days after at least 48 h of insulin infusion. The values of the inulin clearance, serum creatinine, urine osmolarity, osmolar clearance, and free water clearance were stable in both groups during the study period. Inulin clearance was lower in group I than in group II (p less than 0.001), whereas serum creatinine was higher in group I than in group II (p less than 0.0001). Urine osmolarity was higher in group I (p less than 0.01), whereas osmolar clearance and free water clearance were lower in group I (p less than 0.02, respectively, p less than 0.01). There was no difference in fractional sodium excretion between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Glomerular filtration rate in the preterm infant: the relation to gestational and postnatal age

In 41 preterm neonates with a gestational age (GA) varying from 27 to 36 weeks, glomerular filtration rate (GFR) was measured by means of the continuous inulin infusion technique. The reliability of the technique was confirmed. During postnatal development GFR was found to increase in two ways: firstly, an increase with advancing gestational age, associated with the increase in body weight (BW) [GFR (ml/min) = 0.15 X GA-3.20, r = 0.48, P = 0.0048]; secondly, a postnatal increase, being independent from increment in BW. An increase in GFR (ml/min.kg) from 0.88 +/- 0.23 to 1.18 +/- 0.28 was observed between day 4 and day 11 postnatally (P less than 0.008). This latter increase is probably associated with changes in renal haemodynamics. No significant influence of artificial ventilation on GFR could be demonstrated in preterm neonates.

Prenatal evaluation and outcome of fetal obstructive uropathies

Between January 1982 and January 1986, 76 pregnant women between 15 and 40 weeks of gestation were referred because of suspected fetal obstructive urinary tract pathology. A total of 14 high-level (ureter) and 17 low-level (urethral) obstructions were diagnosed. High-level obstructions were at the uretero-pelvic level in 11 and at the uretero-vesical level in 3 cases. Increased amniotic fluid volume was observed in 28 per cent. The survival rate was 86 per cent. In the 17 cases of urethral obstruction, oligohydramnios was present in 70 per cent, associated structural defects in 30 per cent, and abnormal karyotype in 6 per cent. Pregnancy was terminated because of progressive massive hydronephrosis in 41 per cent; intrauterine or neonatal death occurred in 47 per cent, resulting in a survival rate of only 12 per cent.

Normalization of glucose homeostasis by a long-acting somatostatin analog SMS 201-995 in a newborn with nesidioblastosis

A female child was admitted to the hospital few days after birth with severe hypoglycemia and convulsive episodes. Plasma insulin levels were elevated and oral and intravenous administration of glucose were unable to keep blood glucose above 2 mmol/l limit. Intravenous infusion of a long acting somatostatin analog, SMS 201-995, at a dosage gradually increasing from 2 to 50 micrograms/24 hr, was accompanied by a dramatic fall in circulating insulin levels. Normality of glucose homeostasis was restored and convulsive spells ceased. Fasting blood glucose levels stabilized between 3.4 and 4.7 mmol/l. No rebound phenomenon was observed during short term interruptions of the SMS 201-995 infusion. A subtotal pancreatectomy was performed during SMS treatment, and the diagnosis of nesidioblastosis was confirmed by immunocytologic and electron-microscopic studies. It is concluded that this new potent and long acting somatostatin derivative may be useful in the management of hyperinsulinism in the neonate.

Glucose oxidation rates in newborn infants measured with indirect calorimetry and [U-13C]glucose

Indirect calorimetry and primed constant infusion of [U-13C]glucose were combined in 16 appropriate-for-gestational age newborn, parenterally fed infants, in order to measure glucose utilization and glucose oxidation respectively. Glucose intake ranged between 10.0 and 24.1 g day-1 kg-1 and energy intake between 156.9 and 439.3 kJ day-1 kg-1. Glucose utilization (P less than 0.001), glucose oxidation (P less than 0.001) and metabolic rate (P less than 0.005) increased significantly with rising glucose intake. The significant difference between glucose utilization and oxidation (P less than 0.001) can be accounted for by an increasing storage as fat. As lipogenesis from glucose consumes 15-24% of the original glucose energy, the increasing metabolic rate accompanying rising glucose intake is probably due to increasing lipogenesis.

The effect of energy intake and expenditure on the recovery of 13CO2 in the parenterally fed neonate during a 4-hour primed constant infusion of NAH13CO3

The use of 13CO2 excretion to measure the oxidation of 13CO2 labeled substrates is increasing as it is both noninvasive and lacks the radiation exposure associated with the use of 14C. No standards are available for 13CO2 recovery in breath from the bicarbonate pool in the neonate. A primed constant infusion of NaH13CO3 over 4 h was used with open circuit indirect calorimetry in 15 appropriate for gestational age newborn infants (gestational age 28-39 wk; postnatal age 2-52 days), on varying amounts of intravenous feeding (37-114 kcal X kg-1 X day-1). Following a bolus of 6.9 mumol X kg-1 of NaH13CO3, a maintenance infusion of 4.6 mumol X kg-1 X h-1 was started. The 13C enrichment in breath rose rapidly to reach a plateau by 90 min with less than 5% variation of the plateau. Recovery of the tracer in breath ranged from 69.6-83.5% and was significantly correlated with 1) energy intake (37-114 kcal X kg-1 X day-1); 2) metabolic rate (34.6-56.1 kcal X kg-1 X day-1); 3) VCO2 (4.86-7.43 ml X kg X -1 X min-1). There was no correlation with the level of protein or fat intake. We provide an equation that can be used to calculate the correction factor when doing constant infusion substrate oxidation studies with a 13C label in neonates.

A calorimetric system for metabolic studies of newborn babies

This paper describes a closed circuit calorimetric system designed to determine the amount of energy required for synthesis of new tissue in a newborn baby. This amount can be estimated from the difference between indirect and direct calorimetric measurements. The system allows the simultaneous measurement of oxygen consumption, carbon dioxide production, evaporative water loss and heat loss through convection and radiation in newborn babies under 2.5 kg bodyweight. The babies are exposed to a well defined climate, they can be observed continuously and are fed via a nasogastric tube during the experiment, which may last 24 h or more. Special features of the system are the compensation methods for O2 and CO2 measurements and the double gradient layer for the measurement of dry heat loss. The overall accuracy of the system is of the order of 0.1 W. The value obtained for the energy cost of growth is in close agreement with Hommes' theoretical estimate.

Oxygen consumption and CO2 production of low-birth-weight infants in two sleep states

The influence of sleep states on the metabolic rate and on the respiratory quotient (RQ) of low-birth-weight infants during continuous feeding was analyzed. Gestational age at birth varied between 29 and 35 weeks, postnatal age between 2 and 56 days and body weight between 0.81 and 2.11 kg. The mean oxygen consumption and carbon dioxide production were 10% higher, while the rise in SD was about 3-fold during REM sleep compared with NREM sleep. The RQ, however, was equal in both states. The sequence of the two sleep states did not have any influence on the analyzed parameters. Averaged over all the measurements, no statistically significant linear trend in oxygen consumption as a function of time could be found. However, small non-zero trends could be found, the direction of which appeared to depend on the sequence of the states.

Influence of variations in the ambient humidity on insensible water loss and thermoneutral environment of low birth weight infants

Total evaporative water loss, transepidermal as well as respiratory water loss was measured in 8 infants on day 1, 11 infants from day 2 to 8 and 8 infants after day 8. Measurements were performed at two levels of humidity, either vapor pressure of 16 or 25 mmHg (2 133 or 3 333 Pa). Evaporative water loss was 40% lower at the higher humidity. Neither metabolic rate nor body temperature showed a significant difference between the two levels of humidity. The effect of the change in humidity on the neutral thermal environment was calculated, the neutral temperature being 0.05 degrees C lower when the vapor pressure is increased by 1 mmHg (133.3 Pa). We conclude that a high humidity is of limited value in nursing infants born after 30-40 weeks.

Longitudinal studies on metabolic rate, heat loss, and energy cost of growth in low birth weight infants

Longitudinal studies on total and resting metabolic rate and total heat loss were made in 14 LBW infants, age 1-58 d. Metabolic rate was calculated from indirect calorimetry, heat loss was measured by direct calorimetry. Total metabolic rate and total heat loss were lowest during the first week of life, 178.9 +/- 18.0 and 171.8 +/- 15.5 kJ X kg-1 X 24 h-1, respectively. During the age period of 8-58 d both total metabolic rate and heat loss showed a very slight increase with age: mean total metabolic rate was 278.8 +/- 2.6 and mean total heat loss 257.0 +/- 3.4 kJ X kg-1. during the first week of life and 248.0 +/- 2.5 during d 8-58. The energy cost of components of new tissue was calculated from the energy balance equation. Ecomponents during the second week of life was 25.5 +/- 4.9 kJ/g weight gain and 11.9 +/- 0.4 kJ/g weight gain over subsequent weeks. The net energy cost of tissue synthesis, calculated from the difference between indirect and direct calorimetry was 3.2 +/- 1.1 kJ/g weight gain during the second week and 1.1 +/- 0.1 kJ/g weight gain in the following weeks. A neonate who receives a caloric intake of 535 kJ X kg-1 X 24 h-1 and is growing at a rate of 17 g X kg-1 X 24 h-1 will use 42% of the caloric intake for maintenance and thermoregulation, 6% for activity, 38% for the components of new tissue, 4% for tissue synthesis and 10% for loss in faeces and urine.

New standards for neutral thermal environment of healthy very low birthweight infants in week one of life

It is generally accepted that low birthweight infants should be nursed at thermal neutral temperature--the environment in which oxygen consumption is at a minimum. Low birthweight infants do not, however, always show an increase in oxygen consumption at a temperature outside the neutral range, but react with a change in body temperature. We redefined therefore the neutral temperature for these infants as 'the ambient temperature at which the core temperature of the infant at rest is between 36.7 and 37.3 degrees C and the core and mean skin temperatures are changing less than 0.2 and 0.3 degrees C/hour respectively'. Using this definition, new guidelines of the neutral temperature have been made for healthy infants of 29-34 weeks' gestation. The neutral temperature during the first week of life is dependent on gestational age and postnatal age, whereas after the first week it depends on body weight and postnatal age. Using this definition and the guidelines, the appropriate environmental temperature for the individual patient can be chosen.