Early Postnatal Outcome and Care after in Utero Exposure to Lithium: A Single Center Analysis of a Belgian Tertiary University Hospital

Knowledge of the impact of in utero exposure to lithium during the postnatal period is limited. Besides a possible teratogenic effect during the first trimester, exposure during the second and third trimesters might lead to neonatal effects. Uniform guidelines for postnatal management of these neonates are lacking. The aim was to retrospectively describe all neonates admitted to the University Hospitals Leuven after in utero exposure to lithium (January 2010 to April 2020), and to propose a postnatal care protocol. Descriptive statistics were performed. For continuous parameters with serial measurements, median population values were calculated. In total, 10 mother-neonate pairs were included. The median gestational age was 37 (interquartile range, IQR, 36-39) weeks. Neonatal plasma lithium concentration at birth was 0.65 (IQR 0.56-0.83) mmol/L with a median neonate/mother ratio of 1.02 (IQR 0.87-1.08). Three neonates needed respiratory support, 7/10 started full enteral (formula) feeding on day 1. The median length of neonatal stay was 8.5 (IQR 8-12) days. One neonate developed nephrogenic diabetes insipidus. This study reported in detail the postnatal characteristics and short-term neonatal outcomes. A postnatal care protocol was proposed, to enhance the quality of care for future neonates, and to guide parental counselling. Future prospective protocol evaluation is needed.

Evolution of circulating thyroid hormone levels in preterm infants during the first week of life: perinatal influences and impact on neurodevelopment

Background For several decades, transient hypothyroxinemia of prematurity (THOP) has been a topic of debate. The pathophysiology is incompletely understood and consensus on the therapeutic approach is lacking. This study aimed at gaining a better insight into the pathogenesis by studying the trends in thyroid hormone (TH) levels during the first week of life. Methods This single-center prospective observational study analyzed the plasma levels of total thyroxine (T4) and free thyroxine (fT4), total triiodothyronine (T3), thyroid-stimulating hormone (TSH) and T4-binding globulin (TBG) in cord blood and at the end of the first week of life in 120 preterm infants (gestational age [GA] <37 weeks). The change over time was calculated (delta, ∆). The impact of perinatal and subsequently postnatal variables on ∆ was studied by hierarchical multiple regression. The impact of ∆ on the neurodevelopmental outcome at the corrected ages of 9 and 24 months, measured by the Bayley Scales of Infant Development (BSID)-II, was assessed by logistic regression. Results ∆fT4 levels were negatively affected by GA and use of dopamine, whereas only GA was associated with low ∆T3 levels. Negative ∆fT4 levels were present in 75% of the extremely low-for-gestational-age infants, whereas 23.5% had a negative ∆T3 level. There was an increased risk for an abnormal mental developmental score (<85) with decreasing ∆T3 at 9 months, corrected age, but not at 24 months. Conclusions A negative evolution in circulating TH levels is principally an immaturity phenomenon, whereas dopamine can further suppress the hypothalamic-pituitary-thyroid axis. There is at least a temporary negative effect of this evolution on the infants' neurodevelopment.

Review shows that thyroid hormone substitution could benefit transient hypothyroxinaemia of prematurity but treatment strategies need to be clarified

AIM

Thyroid hormones are crucial for foetal and neonatal brain development. This paper provides an overview of the normal role of thyroid hormones in foetal brain development and the pathophysiology of transient hypothyroxinaemia of prematurity (THOP). It also discusses the diagnostic and therapeutic controversies around THOP and looks at directions for future research.

METHODS

We used the PubMed and Embase databases to identify papers published in English from 1969 to June 2018. This identified 20 papers about the impact of THOP on neurodevelopment and seven randomised controlled trials about therapeutic approaches from 1981-2016.

RESULTS

THOP has been researched for more than three decades. The impact of temporarily low thyroxine levels, without any increase in pituitary-secreted thyroid-stimulating hormone at a critical timeframe in an infant's brain development, is still debated. Heterogeneity in THOP definitions, difficulties with thyroid hormone assessment, identifying patients at risk and a clear lack of sufficiently powered studies add to the current controversy. There are indications that thyroid hormone substitution might be useful in extremely low gestational age neonates with THOP.

CONCLUSION

Some preterm infants could benefit from THOP treatment, but more studies are needed to clarify further treatment strategies, including the optimal timing of initiation and duration.

The placenta in fetal thyroid hormone delivery: from normal physiology to adaptive mechanisms in complicated pregnancies

Context: Thyroid hormones are indispensable for normal fetal development. Since the fetus depends to a large extent on maternal thyroid hormone supply through the placenta, this challenges maternal thyroid economy. Several molecular mechanisms are involved in placental thyroid hormone transport and metabolism. Chronic pregnancy complications, associated with utero-placental hypoxia, trigger the development of accelerated placental maturation in order to improve fetal-placental exchange to strengthen the offspring's chance of survival. This review provides an overview of normal maternal-fetal thyroid hormone supply and explores the presence of placental adaptive mechanisms in complicated pregnancies with chronical utero-placental hypoxia to improve the thyroid hormone supply to the fetus under pressure, to end with reflections about the long term health consequences.Evidence acquisition: This work is based on a comprehensive literature review of the PubMed and Embase database, including relevant articles from 1969 to June 2018.Conclusions: The placenta is actively involved in fetal thyroid hormone delivery through a combination of stimulatory and inhibitory mechanisms. Parallel with histological adaptations to improve transplacental fetal-maternal exchange, there are indications of placental adaptive mechanisms in thyroid hormone transport and metabolism in case of complicated pregnancies, from animal models and in-vitro experiments. Evidence from human in-vivo studies is limited due to heterogeneity in study populations, small study samples, and technical limitations. Further research is necessary to reveal the role of the placenta in pathological circumstances. The placenta might thus be considered as the infants' black box of pregnancy. Results will contribute to more insights in the concept of fetal programming, which lays the foundations of optimum health, growth, and neurodevelopment across the lifespan.

Risk factors for large-for-gestational age infants in pregnant women with type 1 diabetes

Background

The rate of neonatal overweight remains generally high in type 1 diabetes (T1DM). Since glycemic control has improved over time other contributors need to be identified. Our aim is to evaluate the risk factors for large-for-gestational age infants (LGA) in women with T1DM and to evaluate whether the rate of LGA decreased over time.

Methods

Retrospective analysis of the medical files of pregnant women with T1DM attending our university hospital form 01-01-1992 till 31-07-2014. The generalized mixed model was used to adjust for several pregnancies over time in the same women. A multivariable model was used to evaluate independent risk factors for LGA.

Results

Over a 22-year period, 259 pregnancies in 180 T1DM women were identified. Mean diabetes duration of women was 13.7 ± 7.1 years, with a mean age of 29.5 ± 5.2 years. Macrosomia (>4Kg) was present in 16.2 % of deliveries, LGA was present in 45.2 % and these numbers did not change over time (resp. p = 0.19 and p = 0.70). Over time, significant more women were overweight (23.3 % vs. 39.3 %, p = 0.009) and more women had excessive weight gain during pregnancy (21.3 % vs. 37.7 %, p = 0.019). Compared to women with a non-LGA baby, women with a LGA baby had a higher weight at delivery (84.1 ± 11.1 vs. 80.4 ± 10.8, p = 0.016), had more often excessive weight gain (45.3 % vs. 25.2 %, p = 0.003) and had less strict glycaemic control in the first and third trimester [HbA1c of resp. 49 ± 10 mmol/mol (6.7 % ±0.9) vs. 47 ± 8 mmol/mol (6.5 % ±0.8), p = 0.01 and 44 ± 5 mmol/mol (6.2 % ±0.5) vs. 42 ± 6 mmol/mol (6.0 % ±0.6), p = 0.01]. In the forward multivariable analysis, excessive weight gain [OR 1.95 (1.08–3.53), p = 0.027], HbA1c level in early [OR 1.43 (1.05–1.95), p = 0.023] and late pregnancy [OR 1.70 (1.07–2.71), p = 0.026] remained independent predictors for LGA.

Conclusions

LGA remains a frequent complication in T1DM. Excessive weight gain and HbA1c in early and late pregnancy are important risk factors for LGA in our population. These findings highlight the importance of strict maternal glycemic control and simultaneous striving to appropriate gestational weight gain to minimize the risk of fetal overgrowth in T1DM pregnancies.

Neonatal creatinemia trends as biomarker of subsequent cognitive outcome in extremely low birth weight neonates

BACKGROUND AND AIMS

Serum creatinine is traditionally used as a marker of renal function in neonates and relates to gestational age and disease severity in extremely low birth weight (ELBW) infants. Creatinine is commonly used as a biomarker for early morbidity, but we aim to compare postnatal creatinemia trends as a biomarker for subsequent cognitive outcome. We hypothesize that impaired microcirculation not only in the kidney, but also in general (i.e. brain development) can explain this possible link.

STUDY DESIGN AND OUTCOME MEASURES

A cohort of ELBW infants was analyzed by Bayley Scales of Infant Development (BSID-II) at the corrected age of 2years old. Besides other perinatal indicators, neonatal creatinemia trends of survivors (n=140) and BSID scores (n=96) are compared and analyzed using optimal matching analysis. Hierarchical clustering analysis is applied to identify createnimia trends.

RESULTS

Four different creatinemia trends were identified (persistently high, normal, low, high but normalizing). A low creatinemia trend is significantly associated with the lowest percentages of postnatal corticosteroids, NSAIDS and intraventricular hemorrhage (p=0.005, p=0.013 and p=0.041 respectively) compared to a normal or persistently high creatinemia trend and associated with the best cognitive outcome (+13 points compared to the mean creatinemia trend and +23 points compared to a persistently high creatinemia trend).

CONCLUSIONS

Creatinemia trends after birth are not only useful to predict renal function, but are also associated with cognitive outcome in extremely low birth weight infants. Neonates who have low creatinemia trends after birth, have the highest BSID scores at the age of two years old.

Cognitive assessment of very low birth weight infants using the Dutch version of the PARCA-R parent questionnaire

OBJECTIVE

Very low birth weight (VLBW) infants are at an increased risk of long-term cognitive impairment. Early identification and timely interventions are important. We aimed to validate the Dutch version of the revised Parent Report of Children's Abilities (PARCA-R) questionnaire.

METHODS

The subjects were survivors from the Belgian participating centers to the NIRTURE trial. As part of a study-related follow-up, PARCA-R was sent out at the age of 2 years. As part of a normal hospital follow-up, these infants were assessed by the Bayley Scales of Infant Development - second edition (BSID-II) at the age of 9, 18 and 36 months. MRI was performed at term in the group of VLBW infants of ZOL Genk as standard care.

RESULTS

PARCA-R was sent out to 193 surviving infants. BSID-II was performed in 36% (n=70) at 9 months, in 30% (n=58) at 18 months and in 12% (n=23) at 36 months. MRI was available for 32 infants. We received 86 responses to the PARCA-R. Parent report composite (PRC) scores were significantly correlated with the Mental Development Index (MDI) (p<0.0001 (9 months); p=0.003 (18 months); p=0.01 (36 months)). PRC scores were significantly lower in those with an abnormal MRI (92 vs.124; p=0.04).

CONCLUSION

We support the use of the PARCA-R as a time and cost efficient alternative for identifying cognitive delay.

PRACTICE IMPLICATIONS

We suggest that the combination of BSID-II, MRI at term and PARCA-R would be the ideal testing method for identifying VLBW infants at risk for cognitive developmental delay by two years of age.

Relationship between insulin-like growth factor I levels, early insulin treatment, and clinical outcomes of very low birth weight infants

OBJECTIVES

Insulin regulates the secretion of insulin-like growth factor I (IGF-I) in the newborn, and low levels of IGF-I have been linked to neonatal morbidity. As part of the Neonatal Insulin Replacement Therapy in Europe Trial, we investigated the impact of early insulin treatment on IGF-I levels and their relationship with morbidity and growth.

STUDY DESIGN

Prospective cohort analyses of data collected as part of an international randomized controlled trial. Blood samples (days 1, 3, 7, and 28), were taken for IGF-I bioassay from 283 very low birth weight infants (<1500 g).

RESULTS

Early insulin treatment led to a late increase in IGF-I levels between day 7 and 28 (P = .028). In the first week of life IGF-I levels were lower in infants with early hyperglycemia; mean difference -0.10 μg/L (95% CI -0.19, -0.02, P = .02). Lower levels of IGF-I at day 28 were independently associated with an increased risk of chronic lung disease, OR 3.23 (95% CI, 1.09-9.10), and greater IGF-I levels were independently associated with better weight gain, 0.10 kg (95% CI, 0.03-0.33, P = .02).

CONCLUSIONS

Early intervention with insulin is related to increased IGF-I levels at 28 days. Low IGF-I levels are associated with hyperglycemia, increased morbidity, and reduced growth. Increasing IGF-I levels may improve outcomes of very low birth weight infants.

Validation of the continuous glucose monitoring sensor in preterm infants

OBJECTIVE

Recent studies have highlighted the need for improved methods of monitoring glucose control in intensive care to reduce hyperglycaemia, without increasing the risk of hypoglycaemia. Continuous glucose monitoring is increasingly used in children with diabetes, but there are little data regarding its use in the preterm infant, particularly at extremes of glucose levels and over prolonged periods. This study aimed to assess the accuracy of the continuous glucose monitoring sensor (CGMS) across the glucose profile, and to determine whether there was any deterioration over a 7 day period.

DESIGN

Prospectively collected CGMS data from the NIRTURE Trial was compared with the data obtained simultaneously using point of care glucose monitors.

SETTING

An international multicentre randomised controlled trial.

PATIENTS

One hundred and eighty-eight very low birth weight control infants.

OUTCOME MEASURES

Optimal accuracy, performance goals (American Diabetes Association consensus), Bland Altman, Error Grid analyses and accuracy.

RESULTS

The mean (SD) duration of CGMS recordings was 156.18 (29) h (6.5 days), with a total of 5207 paired glucose levels. CGMS data correlated well with point of care devices (r=0.94), with minimal bias. It met the Clarke Error Grid and Consensus Grid criteria for clinical significance. Accuracy of single readings to detect set thresholds of hypoglycaemia, or hyperglycaemia was poor. There was no deterioration over time from insertion.

CONCLUSIONS

CGMS can provide information on trends in glucose control, and guidance on the need for blood glucose assessment. This highlights the potential use of CGMS in optimising glucose control in preterm infants.

Standard two-compartment formulation for total parenteral nutrition in the neonatal intensive care unit: A fluid tolerance based system

The nutrient requirements of most (pre) term newborns receiving intensive care appear to be relatively fixed. The range of optimal fluid load however, is perceived as being quite narrow and highly variable in time. We designed four amino acid-dextrose mixtures for a standardized neonatal parenteral nutrition, delivering a fixed amount of nutrients in four dilutions with water and corresponding to a fluid load of 90, 110, 130 or 170 ml/kg per day. The addition of a lipid emulsion completes the TPN. In a pilot study, we followed the weight of 30 very low birthweight infants on this parenteral nutrition. After a stabilisation period, the weight gain was found to be similar to the normal fetal weight accretion in utero. We have now infused these solutions in to more than 1000 infants, without significant complications. These formulations proved to have substantial advantages compared to the individualized prescription in terms of availability, safety and time- and cost-effectiveness.

Creatinine reference values in ELBW infants: impact of quantification by Jaffe or enzymatic method

OBJECTIVE

Serum creatinine (Scr) reflects to a certain extent glomerular filtration rate in neonates, but postnatal observations also depends on the technique used to quantify Scr (Jaffe colorimetry or enzymatic quantification).

METHODS

In an attempt to quantify differences between these techniques, we compared postnatal Scr trends in two consecutive cohorts of extremely low birth-weight (ELBW) neonates before and following a switch from uncompensated Jaffe to enzymatic Scr quantification. Postnatal Scr (Days 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 21, 28, and 42) in 151 ELBW neonates (uncompensated Jaffe) was compared to 116 more recently admitted ELBW neonates (enzymatic).

RESULTS

Although clinical characteristics were similar between both cohorts, median postnatal Jaffe Scr values were significantly higher compared to enzymatic quantification (all days, at least p < 0.001) throughout postnatal life. While both cohorts displayed a similar trend with an initial increase with a Scr peak on Days 3 and 4 and a subsequent decrease, the difference in within-day median values fluctuated between 11 and 24 mmol.L(-1). There is neither fixed nor relative difference in Scr between both techniques.

CONCLUSIONS

When using Scr to estimate renal function in ELBW neonates, clinicians should in addition to the postnatal changes and other covariates of renal function, also consider the technique applied. We provide reference values and comparison between both techniques.

Does intravenous paracetamol administration affect body temperature in neonates?

INTRODUCTION

Intravenous paracetamol (acetaminophen) has recently been registered for treatment of pain in neonates but the pharmacodynamics, including effects on body temperature, have not been reported.

METHODS

A pooled analysis on body temperature recordings in neonates exposed to intravenous paracetamol was performed. Body temperature was recorded by skin probe and registered before and every 2 h following initiation of single or repeated intravenous paracetamol administration (up to 48 h). Repeated measures ANOVA and paired analysis were used to quantify differences following paracetamol exposure.

RESULTS

The pooled analysis was based on 99 neonates (median weight 2.7 (range 0.5-5.4) kg, median postmenstrual age 37 (range 27-50) weeks). Based on observations in 93 normothermic (<37.8°C) neonates and six neonates with fever, it was documented that paracetamol administration does not affect body temperature in normothermic patients. In neonates with fever, the median decrease (-0.8°C) is most prominent in the first 2 h (p<0.01) following paracetamol administration with subsequent further normalisation.

CONCLUSIONS

Administration of intravenous paracetamol does not result in hypothermia in normothermic neonates. In those with fever, maximal temperature reduction is achieved within 2 h following paracetamol administration.

Prevalence and determinants of hyperglycemia in very low birth weight infants: cohort analyses of the NIRTURE study

OBJECTIVES

To investigate the prevalence and determinants of hyperglycemia in the preterm population, as part of the Neonatal Insulin Therapy in Europe (NIRTURE) Trial.

STUDY DESIGN

We conducted prospective cohort analyses of continuous glucose monitoring data from control infants participating in an international randomized controlled trial. Data were collected from 188 very low birth weight infants (<1500 g).

RESULTS

In the first week of life, 80% of infants had evidence of glucose levels >8 mmol/L, and 32% had glucose levels >10 mmol/L >10% of the time. Independent risk factors for hyperglycemia included increasing prematurity, small size at birth, use of inotropes, lipid infusions, and sepsis. There was a lack of association between rate of dextrose infused and risk of hyperglycemia.

CONCLUSION

The prevalence of hyperglycemia in the very low birth weight infant is high, with marked variability in prevalence between infants, not simply related to rates of glucose infused, but to other potentially modifiable risk factors.

Cerebral and systemic hemodynamic effects of intravenous bolus administration of propofol in neonates

OBJECTIVES

To assess variability of systemic hemodynamics and its covariates following bolus propofol administration in (pre)term neonates, and to analyze the effect of propofol on cerebral tissue oxygenation index (TOI) and fractional tissue oxygen extraction measured by near-infrared spectroscopy.

METHODS

In (pre)term neonates, we recorded mean arterial blood pressure (MABP), saturation (SaO(2)), heart rate (HR) and TOI from 5 min before up to 60 min after intravenous bolus propofol (3 mg kg(-1)) administration during elective chest tube removal. Covariate analysis included postmenstrual age (PMA <or= or >37 weeks), postnatal age (PNA <or= or >10 days), comedication (fentanyl +/- midazolam) and congenital cardiopathy (yes/no). Fractional tissue oxygen extraction was calculated as (SaO(2) - TOI)/SaO(2).

RESULTS

Twenty recordings in 19 neonates were assessed. Following propofol administration, an abrupt, minor decrease in HR and SaO(2) was seen with fast recovery, while MABP decreased up to 1 h. TOI decreased during the first 3 min, reflecting an imbalance between cerebral oxygen delivery and demand. Despite sustained decrease in MABP, TOI then returned to baseline, suggesting a better balance between oxygen delivery and demand. PNA <or=10 days, comedication and absence of cardiopathy were associated with more subtle decreases in cerebral oxygenation and faster recovery.

CONCLUSIONS

Propofol-induced decrease in HR, SaO(2) and cerebral oxygenation is short lasting while a decrease in MABP is observed up to 60 min. The variability in the effects of propofol is influenced by PNA, comedication or cardiopathy. Near-infrared spectroscopy can be used to assess hemodynamic effects of hypnotics on the cerebral oxygenation.

Array comparative genomic hybridization as a diagnostic tool for syndromic heart defects

OBJECTIVES

To investigate different aspects of the introduction of array comparative genomic hybridization (aCGH) in clinical practice.

STUDY DESIGN

A total 150 patients with a syndromic congenital heart defect (CHD) of unknown cause were analyzed with aCGH at 1-Mb resolution. Twenty-nine of these patients, with normal results on 1Mb aCGH, underwent re-analysis with 244-K oligo-microarray. With a logistic regression model, we assessed the predictive value of patient characteristics for causal imbalance detection. On the basis of our earlier experience and the literature, we constructed an algorithm to evaluate the causality of copy number variants.

RESULTS

With 1-Mb aCGH, we detected 43 structural variants not listed as clinically neutral polymorphisms, 26 of which were considered to be causal. A systematic comparison of the clinical features of these 26 patients to the remaining 124 patients revealed dysmorphism as the only feature with a significant predictive value for reaching a diagnosis with 1-Mb aCGH. With higher resolution analysis in 29 patients, 75 variants not listed as clinically neutral polymorphisms were detected, 2 of which were considered to be causal.

CONCLUSIONS

Molecular karyotyping yields an etiological diagnosis in at least 18% of patients with a syndromic CHD. Higher resolution evaluation results in an increasing number of variants of unknown significance.

Maternal bariatric surgery: adverse outcomes in neonates

BACKGROUND

The obesity epidemic in developed countries has led to an increased prevalence of obese women of reproductive age. As maternal obesity has far-reaching consequences for both mother and child, the consensus is that weight loss before pregnancy will reduce obesity-related morbidity and mortality. Therefore, an increasing number of women become pregnant after undergoing obesity surgery.

RESULTS AND DISCUSSION

From the literature, data shows that perinatal outcome after bariatric surgery is generally considered as favourable for both mother and child. Only a few case reports highlight the possibility of side effects on the foetus and neonate. We report on five cases with severe intracranial bleeding, all possibly related to vitamin K deficiency following maternal bariatric surgery.

CONCLUSION

These reports indicate that careful nutritional follow-up during pregnancy after obesity surgery is mandatory, because nutritional deficiencies such as vitamin K deficiency can lead to life-threatening bleeding.

Vallecular cyst as a cause of congenital stridor: report of five patients

BACKGROUND

Vallecular cysts are an unusual cause of congenital stridor.

OBJECTIVE

To describe the imaging findings in five patients, with emphasis on the usefulness of sonographic studies.

MATERIALS AND METHODS

Between 1990 and 2007, five patients with a cystic lesion situated in the anterior neck, at the vallecular space, were seen in our institution. Clinical records and imaging findings were retrospectively reviewed.

RESULTS

All patients presented with persistent inspiratory stridor that was present from the first week of life. Neck US was performed as part of the investigations in four and showed a vallecular cyst. The diagnosis was confirmed with flexible bronchoscopy in four infants and CT in one; all were resected. Pathology showed a multilayered epithelial border with normal thickness and differentiation; there were no signs of malignancy.

CONCLUSION

Although vallecular cysts are very rare, they should be considered in the differential diagnosis of congenital stridor. When the commonest causes have been ruled out, neck US may be diagnostic. The diagnosis can be confirmed with flexible bronchoscopy or further imaging such as CT or MRI.

Cefazolin plasma protein binding saturability during pregnancy

This article aims to document cefazolin (CFZ) plasma binding and its covariates during pregnancy and compare these observations with previously reported observations in nonpregnant adults. Maternal CFZ plasma samples were collected during in utero surgery. The unbound CFZ fraction was reported by median and range. Correlation (Spearman) and multiple regression were used to identify covariates (total CFZ concentration, albuminemia, gestational age) of the unbound CFZ fraction. Observations during pregnancy were compared with observations in nonpregnant adults (unpaired t test, multiple regression). Plasma (N = 130) samples were collected during 30 interventions. The median unbound CFZ fraction was 0.25 (range 0.14-0.41). Correlations between the unbound CFZ fraction and total CFZ plasma concentration (0.46), time after administration (-0.38), albuminemia (-0.39) and gestational age (-0.19) were statistically significant. The median unbound CFZ fraction was higher during pregnancy when compared to observations in nonpregnant adults (0.25 vs. 0.19, P < 0.001). In a multiple-regression model, total plasma CFZ concentration and albuminemia were covariates of the unbound CFZ fraction (r(2) = 0.4). The concept of saturability of CFZ plasma protein binding has been confirmed during pregnancy, but the free CFZ fraction is higher, likely explained by the lower albuminemia during pregnancy.

The effect of changes in tPCO2 on the fractional tissue oxygen extraction--as measured by near-infrared spectroscopy--in neonates during the first days of life

The cerebral fractional oxygen extraction (FOE) reflects the balance between cerebral oxygen delivery (OD) and consumption (VO(2)). PCO(2) affects the cerebral blood flow (CBF): hypocapnia decreases CBF and OD and increases FOE. We recently showed that the fractional tissue oxygen extraction (FTOE) reflects FOE and hypothesized that a decrease in tPCO(2) increases FTOE. In this study we looked at the effect of changes in tPCO(2) on FTOE. We analysed 23 measurements in 13 neonates with birth weight below 1500 g and need for intensive care. Exclusion criteria were congenital malformations or cerebral complications. The tissue oxygenation index (TOI), tPCO(2), mean arterial blood pressure (MABP), heart rate (HR) and peripheral oxygen saturation (SaO(2)) were continuously recorded for 4h during the first days of life and FTOE was calculated. Over the whole group we found a significant negative (r=-0.227) correlation between tPCO(2) and FTOE and a significant positive (r=0.258) correlation between tPCO(2) and TOI. After correction for MABP these correlations remained significant. Over the whole group we found a significant positive correlation between tPCO(2) and TOI and a significant negative correlation between tPCO(2) and FTOE, which remained significant after correction for MABP. This implies that tPCO(2) influences the cerebral oxygenation independently of MABP. We therefore believe that for the interpretation of cerebral oxygenation in mechanically ventilated neonates during the first days of life continuous measurements of tPCO(2) are needed. Moreover we suggest FTOE to become a continuous parameter in the clinical setting for the non-invasive measurement of the neonatal brain oxygenation.

Oxygen-induced retinopathy in mice: amplification by neonatal IGF-I deficit and attenuation by IGF-I administration

In preterms, low serum levels of IGF (IGF-I) correlate with retinopathy of prematurity (ROP). In mice, IGF-I is a prerequisite for normal retinal development. We further explored the link between IGF-I and oxygen-induced retinopathy (OIR). To assess the role of endogenous IGF-I, pups were redistributed into smaller versus larger litters at birth; in one subgroup, we measured body weight and circulating IGF-I; in another, we applied hyperoxia and assessed retinal neovascularization (NV). To screen for the potential role of exogenous IGF-I, we administered a single bolus of rhIGF-I on postnatal day (P) 4 to pups in normal litters, and applied hyperoxia; body weight and IGF-I were measured; maturation and NV were assessed. Neonatal mice in larger litters had a lower body weight than mice in smaller litters; they had lower levels of circulating IGF-I, and developed more OIR (p = 0.002). Mice who had received rhIGF-I, weighed more and had higher endogenous IGF-I levels; they matured faster and developed less OIR (p = 0.00001). These findings in mice are the first to support the notion that higher availability of endogenous or exogenous IGF-I reduces OIR risk, and thus sharpen the perspective that ROP may be preventable by briefly up-regulating IGF-I after birth.

Early insulin therapy in very-low-birth-weight infants

BACKGROUND

Studies involving adults and children being treated in intensive care units indicate that insulin therapy and glucose control may influence survival. Hyperglycemia in very-low-birth-weight infants is also associated with morbidity and mortality. This international randomized, controlled trial aimed to determine whether early insulin replacement reduced hyperglycemia and affected outcomes in such neonates.

METHODS

In this multicenter trial, we assigned 195 infants to continuous infusion of insulin at a dose of 0.05 U per kilogram of body weight per hour with 20% dextrose support and 194 to standard neonatal care on days 1 to 7. The efficacy of glucose control was assessed by continuous glucose monitoring. The primary outcome was mortality at the expected date of delivery. The study was discontinued early because of concerns about futility with regard to the primary outcome and potential harm.

RESULTS

As compared with infants in the control group, infants in the early-insulin group had lower mean (+/-SD) glucose levels (6.2+/-1.4 vs. 6.7+/-2.2 mmol per liter [112+/-25 vs. 121+/-40 mg per deciliter], P=0.007). Fewer infants in the early-insulin group had hyperglycemia for more than 10% of the first week of life (21% vs. 33%, P=0.008). The early-insulin group had significantly more carbohydrate infused (51+/-13 vs. 43+/-10 kcal per kilogram per day, P<0.001) and less weight loss in the first week (standard-deviation score for change in weight, -0.55+/-0.52 vs. -0.70+/-0.47; P=0.006). More infants in the early-insulin group had episodes of hypoglycemia (defined as a blood glucose level of <2.6 mmol per liter [47 mg per deciliter] for >1 hour) (29% in the early-insulin group vs. 17% in the control group, P=0.005), and the increase in hypoglycemia was significant in infants with birth weights of more than 1 kg. There were no differences in the intention-to-treat analyses for the primary outcome (mortality at the expected date of delivery) and the secondary outcome (morbidity). In the intention-to-treat analysis, mortality at 28 days was higher in the early-insulin group than in the control group (P=0.04).

CONCLUSIONS

Early insulin therapy offers little clinical benefit in very-low-birth-weight infants. It reduces hyperglycemia but may increase hypoglycemia (Current Controlled Trials number, ISRCTN78428828.)

Postmenstrual age and CYP2D6 polymorphisms determine tramadol o-demethylation in critically ill neonates and infants

To document determinants of O-demethylation in critically ill (pre)term neonates and infants, tramadol (M) and O-demethyl tramadol (M1) concentrations were quantified in eighty-six 24 h urine collections and 168 plasma samples. A significant correlation of urine log M/M1 (0.98, SD 0.66) and plasma log M/M1 (0.78, SD 0.45) with postmenstrual age (PMA) (r = -0.69 and -0.65) was observed. One-way analysis of variance documented a significant decrease in urine log and plasma log M/M1 with increasing CYP2D6 activity score (F value 11.6 and 22.55). PMA and CYP2D6 activity score determined the urine and plasma log M/M1 (R 0.59 and 0.64) in a forward multiple regression model. We therefore conclude that PMA and CYP2D6 polymorphisms determined O-demethylation activity in (pre)term neonates and young infants, illustrating the impact of pharmacogenetics on drug metabolism in neonates although a relevant part of the interindividual varaibility remained unexplained. Besides compound-specific relevance, CYP2D6 iso-enzyme specific data on in vivo ontogeny of O-demethylation can contribute to safer and more effective administration of drugs metabolized by the same route in this population.

Both postnatal and postmenstrual age contribute to the interindividual variability in tramadol glucuronidation in neonates

INTRODUCTION

Although of pharmacokinetic and -dynamic relevance, data on ontogeny of UDP-glucuronosyltransferase (UGT) activity in neonates are scant. We therefore wanted to assess the impact of both postnatal and postmenstrual age (PNA/PMA) on the interindividual variability of glucuronidation to overall tramadol urinary elimination in neonates.

METHODS

O-demethyl tramadol (M1) and M1-glucuronide (M1G) were determined in 24 hour urine collections during continuous intravenous tramadol administration in neonates. Glucuronidation fraction (%) was calculated by the ratio of M1G to the sum of M1G and M1 free (M1total). Fractions (%) in early (<day 8) or late neonatal life (day 8-28) were compared (Mann-Whitney U) and forward multiple regression was applied to assess the impact of various covariates.

RESULTS

Urine collections were available in 59 neonates with a PNA of 6 (1-28) days and a PMA of 38 (SD 4) weeks. Mean M1G/M1total was 27 (SD 15) % and was significantly lower in early compared to late neonatal life (22 versus 32%, p=0.0001). In a forward multiple regression model, both PMA and early versus late neonatal life remained independent variables to explain the interindividual variability in M1G/M1total.

CONCLUSIONS

Besides PMA, there is an additional, independent impact of PNA since phenotypic glucuronidation activity is significantly lower in the first week of postnatal life. These findings should be taken into account in the assessment of compounds for whom glucuronidation is of pharmacokinetic, pharmacodynamic or toxicological relevance.

A randomised controlled trial of early insulin therapy in very low birth weight infants, "NIRTURE" (neonatal insulin replacement therapy in Europe)

Background

Studies in adult intensive care have highlighted the importance of insulin and improved glucose control on survival, with 32% reduction in mortality, 22% reduction in intensive care stay and halving of the incidence of bacteraemia. Very low birth weight infants requiring intensive care also have relative insulin deficiency often leading to hyperglycaemia during the first week of life. The physiological influences on insulin secretion and sensitivity, and the potential importance of glucose control at this time are not well established. However there is increasing evidence that the early postnatal period is critical for pancreatic development. At this time a complex set of signals appears to influence pancreatic development and β cell survival. This has implications both in terms of acute glucose control but also relative insulin deficiency is likely to play a role in poor postnatal growth, which has been associated with later motor and cognitive impairment, and fewer β cells are linked to risk of type 2 diabetes later in life.

Methods

A multi-centre, randomised controlled trial of early insulin replacement in very low birth weight babies (VLBW, birth weight < 1500 g). 500 infants will be recruited from 10 centres in the UK and Europe. Babies will be randomised to receive a continuous insulin infusion (0.05 units/kg/h) or to receive standard neonatal care from the first day of life and for the next 7 days. If blood glucose (BG) levels fall infants will receive 20% dextrose titrated to maintain normoglycaemia (4–8 mmol/l). If BG is consistently above 10 mmol/l babies will receive standard treatment with additional insulin infusion. The primary end point will be mortality on or before expected date of delivery, secondary end points will be markers of morbidity and include episodes of sepsis, severity of retinopathy, chronic lung disease and growth.

Trial Registration

Current Controlled Trials ISRCTN78428828. EUDRACT Number 2004-002170-34

Developmental pharmacokinetics of opioids in neonates

Recognition and treatment of pain are now important indicators of the quality of care being delivered to neonates. However, population-specific characteristics have to be considered, necessitating an integrated, population-specific approach. Such an approach starts with a systematic evaluation ofpain, using a validated pain-assessment instrument, and should be followed by effective interventions, mainly based on appropriate, i.e., safe and effective, administration of analgesics. We will illustrate the impact of age on the pharmacokinetics and metabolism of opioids using recently collected and reported observations of tramadol disposition in early neonatal life. Although distribution volume and clearance display age-dependent maturation, it is important to recognize that important, unexplained interindividual variability in drug metabolism is still observed. Research questions in the field of developmental pharmacokinetics of opioids should focus on covariables of relevance in the interindividual variability of both pharmacokinetics and pharmacodynamics of opioids in neonates and on long-term outcomes in preterm and term neonates to whom opioids were administered, with regard to behavioral consequences and effects on pain thresholds.

O-demethylation of tramadol in the first months of life

OBJECTIVE

Assess in vivo O-demethylation activity in the first months of life.

METHODS

Time-concentration profiles of tramadol (M) and O-demethyl tramadol (M1) in plasma and urine were simultaneously collected in the first 24 h of continuous intravenous tramadol administration in neonates and young infants. M and M1 were determined by high performance liquid chromatography. Correlations between perinatal characteristics [postnatal age (PNA), postmenstrual age (PMA)] and the contribution of metabolites (M, M1) to overall tramadol elimination and to the plasma and urine log M/M1 were calculated.

RESULTS

Plasma samples were available in 20/29 and complete 24-h urine collections were available in 25/29 neonates (25-53 weeks PMA). Mean plasma log M/M1 value (>4 h, n=86) was 0.8 (SD 0.4). A significant correlation between plasma log M/M1 and PMA (r=-0.73, P<0.0001) and PNA (r=-0.58, P<0.005) was observed. In a multiple regression model, only PMA remained an independent variable. Mean urine log M/M1 was 0.94 (SD 0.7). Significant correlations of the urine log M/M1 ratio with PMA (r=-0.73, P<0.0001) and PNA (r=-0.56, P=0.0035) were observed. In a multiple regression model with the urine log M/M1 ratio as dependent variable, only PMA remained an independent variable. The maturational half-life of the log M/M1 ratio in early neonatal life in the age range evaluated is about 12-16 weeks without plateau.

CONCLUSIONS

O-demethylation activity was already observed in early neonatal life. A significant correlation with PMA was documented, but PMA can only partially explain the observed variability in O-demethylation activity. Polymorphism therefore likely already contributes to the interindividual variability observed in neonates.

Nonselective cyclo-oxygenase inhibitors and glomerular filtration rate in preterm neonates

The adverse effects of nonselective cyclo-oxygenase (COX) inhibitors on the immature kidney have been described in newborn rabbits, but it is much more laborious and difficult to study its relative impact on renal function in human neonates. Amikacin clearance was therefore used as surrogate marker to study the impact of nonselective COX-inhibitors on glomerular filtration rate. Clinical characteristics and amikacin clearance of infants on respiratory support were retrospectively collected. Results in neonates in whom either ibuprofen-lysine or acetylsalicylic acid was administered prophylactically to induce closure of a patent asymptomatic ductus arteriosus were compared to infants not cotreated with any COX-inhibitor (Mann-Whitney U-, chi-square tests). Amikacin clearance was calculated in 142 infants, of whom 50 were cotreated with ibuprofen and 33 with acetylsalicylic acid. There were no significant differences in clinical characteristics between the three groups. Compared to controls (0.52, range 0.09-2.33 ml/kg/min), a significant similar decrease in amikacin clearance in infants cotreated with ibuprofen (0.38, range 0.13-0.80 ml/kg/min, p<0.01) or acetylsalicylic acid (0.38, range 0.13-0.78 ml/kg/min, p<0.01) was demonstrated. Using amikacin clearance as marker, a significant and similar reduction in glomerular filtration rate was documented in preterm infants cotreated with ibuprofen or acetylsalicylic acid.