Early dexamethasone therapy in preterm infants: a follow-up study

Corticosteroids in the prevention and management of bronchopulmonary dysplasia

Corticosteroids were first prescribed for preterm neonates to treat respiratory distress syndrome, but they were found to have no beneficial effect in this disorder. About 20 years ago, dexamethasone was first used to treat infants with bronchopulmonary dysplasia who were ventilator dependent after the age of 3 weeks. There were short-term benefits, with an improvement in lung function and a facilitation of endotracheal extubation. During the 1990s, corticosteroid treatment, mainly with dexamethasone in relatively high doses, became very common in neonatal intensive care units. Towards the end of the decade, however, follow-up studies provided evidence of abnormal neurodevelopment, especially in infants treated early (<4 days) with dexamethasone. The precise cause of these neurodevelopmental problems is unclear, but until further evidence has been obtained, the early use of dexamethasone cannot be recommended for preterm infants. This review attempts to provide evidence-based guidelines for postnatal steroid therapy in the management of chronic lung disease.

Inhaled versus systemic corticosteroids for preventing chronic lung disease in ventilated very low birth weight preterm neonates

BACKGROUND

Chronic lung disease (CLD) remains an important cause of mortality and morbidity in preterm infants despite the administration of antenatal corticosteroids, surfactant replacement therapy and other advances in neonatal intensive care. There is increasing evidence from cellular and biochemical research that inflammation plays an important role in the pathogenesis of CLD. Thus, interventions aimed at reducing or modulating the inflammatory process may reduce the incidence or severity of CLD. Theoretically, the use of inhaled corticosteroids may allow for beneficial effects on the pulmonary system without concomitant high systemic concentrations and less risk of adverse effects.

OBJECTIVES

To compare the effectiveness of inhaled versus systemic corticosteroids, started within the first two weeks of life, in preventing CLD in ventilated very low birth weight infants.

SEARCH STRATEGY

Randomized and quasi-randomized trials were identified by searching the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 - September 2002), EMBASE (1980 - September 2002), CINAHL (1982 - September 2002), reference lists of published trials and abstracts published in Pediatric Research (1990 - April 2002) from the Society of Pediatric Research/ Pediatric Academic Society's annual meetings.

SELECTION CRITERIA

Randomized or quasi-randomized clinical trials comparing inhaled versus systemic corticosteroid therapy (regardless of the dose and duration of therapy), started in first two weeks of life in very low birth weight preterm infants receiving assisted ventilation.

DATA COLLECTION AND ANALYSIS

Data regarding clinical outcomes including CLD at 28 days or 36 weeks corrected gestational age (CGA), mortality, combined outcome of death or CLD at 28 days or 36 weeks CGA, other pulmonary outcomes and adverse effects were evaluated. All data were analyzed using RevMan 4.1. When appropriate, meta-analysis was performed using relative risk (RR), risk difference (RD), and weighted mean difference (WMD) along with their 95% confidence intervals (CI). If RD was significant, number needed to treat (NNT) or number needed to harm (NNH) was calculated.

MAIN RESULTS

Two trials qualified for inclusion in this review. There was an increase in the incidence of CLD at 36 weeks CGA in the inhaled steroid group amongst all randomized infants, which was of borderline statistical significance: [RR 1.45 (95% CI 0.99, 2.11); RD 0.11 (95% CI 0.00, 0.21), p = 0.05, 1 trial and n = 278]. There was no statistically significant difference in the incidence of CLD at 36 weeks amongst all survivors [RR 1.34 (95% CI 0.94, 1.90); RD 0.11(95% CI -0.02, 0.24), 1 trial and n = 206]. There were no statistically significant differences for oxygen dependency at 28 days (2 trials and n = 294), death by 28 days (2 trials and n = 294) or 36 weeks (2 trials and n = 294) and the combined outcome of death or CLD by 28 days (2 trials and n = 294) or 36 weeks CGA (1 trial and n = 278). The duration of mechanical ventilation was statistically significantly longer in the inhaled as compared to the systemic steroid group (WMD 3.89 days, 95% CI 0.24, 7.55; 2 trials and n = 294). The duration of supplemental oxygen was statistically significantly longer in the inhaled as compared to the systemic steroid group (WMD 11.10 days, 95% CI 1.97, 20.22; 2 trials and n = 294). There was a significantly lower incidence of hyperglycemia in the group receiving inhaled steroids (RR 0.52, 95% CI 0.39,0.71; RD -0.25, 95% CI -0.37, -0.14; 1 trial and n = 278). The NNT was 4.0 (95% CI 2.7, 7.14) to avoid one infant experiencing hyperglycemia. There was a statistically significant increase in the rate of patent ductus arteriosus (RR 1.64, 95% CI 1.23, 2.17; RD 0.21, 95% CI 0.10, 0.33; 1 trial and n = 278) in the group receiving inhaled steroids. The NNH was 4.8, 95% CI 3, 10. There were decreases of borderline statistical significance in the incidences of gastrointestinal hemorrhage and gastrointestinal perforation in the inhaled as compared to systemic steroid group: for gastrointestinal hemorrhage, RR 0.40, 95% CI 0.16, 1.02; RD -0.06, 95% CI -0.12, 0.00, p = 0.05 (1 trial and n = 278); for gastrointestinal perforation, RR 0.16, 95% CI 0.02, 1.29; RD -0.04, 95% CI -0.07, 0.00, p = 0.05 (1 trial and n = 278). The incidence of other side effects was not statistically significantly different in the two groups. No information was available on long term neurodevelopmental outcomes.

REVIEWER'S CONCLUSIONS

This review found no evidence that early inhaled steroids confer important advantages over systemic steroids in the management of ventilator dependent preterm infants. Neither inhaled steroids, nor systemic steroids, can be recommended as a part of standard practice for ventilated preterm infants. Because they might have fewer adverse effects than systemic steroids, further randomized controlled trials of inhaled steroids are needed which address risk/benefit ratio of different delivery techniques, dosing schedules and long term effects, with particular attention to neurodevelopmental outcome.

Early postnatal (<96 hours) corticosteroids for preventing chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) remains a major problem in neonatal intensive care units. Persistent inflammation in the lungs is the most likely underlying pathogenesis. Corticosteroids have been used to either prevent or treat CLD because of their potent anti-inflammatory effects.

OBJECTIVES

To determine if postnatal corticosteroid treatment is of benefit in the prevention of chronic lung disease (CLD) in the preterm infant. This review examines the outcome of trials where preterm infants at risk of CLD were given postnatal steroids within 96 hours after birth.

SEARCH STRATEGY

Randomised controlled trials of postnatal corticosteroid therapy were sought from the Oxford Database of Perinatal Trials, the Cochrane Controlled Trials Register, MEDLINE (1966 - October 2002), hand searching paediatric and perinatal journals, examining previous review articles and information received from practising neonatologists. Authors of all studies were contacted, where possible, to confirm details of reported follow-up studies, or to obtain any information about long-term follow-up where none had been reported.

SELECTION CRITERIA

Randomised controlled trials of postnatal corticosteroid treatment within 96 hours of birth (early) in high risk preterm infants were selected for this review.

DATA COLLECTION AND ANALYSIS

Data regarding clinical outcomes including mortality, CLD (including late rescue with corticosteroids, and need for home oxygen therapy), death or CLD, failure to extubate, complications during the primary hospitalisation (including infection, hyperglycaemia, hypertension, pulmonary air leak, patent ductus arteriosus (PDA), severe intraventricular haemorrhage (IVH), periventricular leucomalacia (PVL), necrotising enterocolitis (NEC), gastrointestinal bleeding, intestinal perforation, severe retinopathy of prematurity (ROP), and long-term outcome (including blindness, deafness, cerebral palsy and major neurosensory disability) were abstracted and analysed using RevMan 4.1.

MAIN RESULTS

Twenty-one randomised controlled trials enrolling a total of 3072 participants were eligible for inclusion in this review. A meta-analysis of these trials demonstrated significant benefits as regards earlier extubation and decreased risks of CLD at both 28 days and 36 weeks, death or CLD at 28 days and 36 weeks, PDA and severe ROP. There were no significant differences in the rates of neonatal or subsequent mortality, infection, severe IVH, PVL, NEC or pulmonary haemorrhage. Gastrointestinal bleeding and intestinal perforation were important adverse effects and the risks of hyperglycaemia and hypertension were also increased. In the nine trials which have reported late outcomes, several adverse neurological effects were found at follow-up examinations of survivors treated with early steroids: developmental delay (not defined), cerebral palsy and abnormal neurological exam. However, major neurosensory disability was not significantly increased, either overall in the 4 studies where this outcome could be determined, or in the 2 individual studies where the rate of cerebral palsy and abnormal neurological exam were significantly increased. Moreover, the rate of the combined outcome of death or major neurosensory disability was not significantly increased.

REVIEWER'S CONCLUSIONS

The benefits of early postnatal corticosteroid treatment (< 96 hours) may not outweigh the known or potential adverse effects of this treatment. Although early steroid treatment facilitates extubation and reduces the risk of chronic lung disease, it causes short-term adverse effects including gastrointestinal bleeding, intestinal perforation, hyperglycaemia, hypertension, hypertrophic cardiomyopathy and growth failure. Long-term follow-up studies report an increased risk of abnormal neurological exam and cerebral palsy. However, the methodological quality of the studies determining the long-term outcome is limited in some cases, the children have been assessed predominantly before school age, and no study has been sufficiently powered to detect important adverse long-term neurosensory outcomes. There is a compelling need for the long term follow-up and reporting of late outcomes, especially neurological and developmental outcomes, among surviving infants who participated in all randomised trials of early postnatal corticosteroid treatment. The role of inhaled steroids remains to be elucidated.

Inhaled versus systemic corticosteroids for the treatment of chronic lung disease in ventilated very low birth weight preterm infants

BACKGROUND

Chronic lung disease (CLD) remains a serious and common problem among very low birth weight infants despite the use of antenatal steroids and postnatal surfactant therapy to decrease the incidence and severity of respiratory distress syndrome. Corticosteroids have been widely used to treat or prevent CLD due to their anti-inflammatory properties. However, the use of systemic steroids has been associated with serious short and long term adverse effects. Administration of corticosteroids topically through the respiratory tract might result in beneficial effects on the pulmonary system with fewer undesirable systemic side effects.

OBJECTIVES

To compare the effectiveness of inhaled versus systemic corticosteroids administered to ventilator dependent preterm neonates with birth weight </= 1500 grams or gestational age </= 32 weeks after two weeks of life for the treatment of evolving CLD.

SEARCH STRATEGY

Randomized and quasi-randomized trials were identified by searching the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 - September 2002), EMBASE (1980 - September 2002), CINAHL (1982 - September 2002), reference lists of published trials and abstracts published in Pediatric Research (1990 - April 2002) from the Society for Pediatric Research/Pediatric Academic Societies' Annual Meetings.

SELECTION CRITERIA

Randomized or quasi-randomized trials comparing inhaled versus systemic corticosteroid therapy (irrespective of the dose and duration of therapy) starting after the first two weeks of life in ventilator dependent very low birth weight preterm neonates.

DATA COLLECTION AND ANALYSIS

Data were extracted regarding clinical outcomes including CLD at 28 days or 36 weeks corrected gestational age (CGA), mortality, combined outcome of death or CLD at 28 days or 36 weeks CGA, other pulmonary outcomes and adverse effects. All data were analyzed using RevMan 4.1. When appropriate, meta-analysis was performed using relative risk (RR), risk difference (RD), and weighted mean difference (WMD) along with their 95% confidence intervals (CI). If RD was statistically significant, number needed to treat (NNT) was calculated.

MAIN RESULTS

Five trials comparing inhaled versus systemic corticosteroids in the treatment of CLD were identified. Two trials were excluded as both included non ventilator dependent patients. One trial is awaiting assessment and clarification of published data. Two trials qualified for inclusion in this review. Halliday et al (Halliday 2001a) randomized infants < 72 hours, while Suchomski et al (Suchomski 2002) randomized at 12-21 days. Although the steroids were commenced after the first 2 weeks of life in both the trials, the outcomes were measured over different time periods, from the age at randomization in each trial, making it inappropriate to combine results. In neither trial was there a statistically significant difference between the groups in the incidence of CLD at 36 weeks CGA amongst all randomized infants. The estimates for the trial by Halliday et al (Halliday 2001a) were RR 1.10 (95% CI 0.82, 1.47), RD 0.03 (95% CI -0.08, 0.15); number of infants (n) = 292 and for the trial by Suchomski et al (Suchomski 2002) RR 0.90 (95% CI 0.79, 1.02), RD -0.10 (95% CI -0.22, 0.02; n = 78 ). There were no statistically significant differences between the groups in either trial for oxygen dependency at 28 days, death by 28 days or 36 weeks, the combined outcome of death or CLD by 28 days or 36 weeks CGA, duration of intubation, duration of oxygen dependence, or adverse effects. Information on the long term neurodevelopmental outcomes was not available.

REVIEWER'S CONCLUSIONS

This review found no evidence that inhaled corticosteroids confer net advantages over systemic corticosteroids in the management of ventilator dependent preterm infants. Neither inhaled steroids, nor systemic steroids, can be recommended as standard treatment for ventilated preterm infants. There was no evidence of difference in effectiveness or side-effect profiles for inhaled versus systemic steroids. A better delivery system guaranteeing selective delivery of inhaled steroids to the alveoli might result in beneficial clinical effects without increasing side-effects. To resolve this issue, studies are needed to identify the risk/benefit ratio of different delivery techniques and dosing schedules for the administration of these medications. The long term effects of inhaled steroids, with particular attention to neurodevelopmental outcome, should be addressed in future studies.

Cognitive and behavioral deficits in premature graduates of intensive care

A substantial number of VLBW graduates of intensive care develop cognitive and behavioral problems, even in the absence of neuroimaging abnormalities. Although this article has highlighted the potential, important, contributing role of medical and stressful, neonatal, environmental conditions to the development of these deficits, it is not all-encompassing, and there are additional prenatal (ie, in utero stress, drug exposure) and neonatal (ie, infectious) contributing factors. The long-term, outcome data presented in this article are pertinent to the more mature, VLBW infant, and it remains unclear and critically important to delineate the long-term, neurobehavioral outcome of those extremely low birth-weight survivors born at the cutting limit of viability.

Cerebral palsy in very preterm infants: new epidemiological insights

The focus of this review is on new insights from recent epidemiological research on cerebral palsy in preterm infants. These include: 1) a better understanding of issues related to diagnosis and classification; 2) new information about the brain abnormalities underlying cerebral palsy in preterm infants; and 3) a better understanding of biological mechanisms that may underlie previously described epidemiological associations. Ongoing efforts to improve the diagnosis and classification of cerebral palsy have been enhanced by findings from serial examinations of cohorts of very preterm infants. Cranial ultrasonography through the anterior fontanelle of very preterm infants has provided information about grossly evident brain damage, found in about one-half of preterm infants who develop cerebral palsy. Insights into the pathophysiologic basis for certain epidemiologic associations have come from studies of experimental brain damage in animals and clinical studies of neurologic disorders in adults. Much of the current epidemiological research into the causes of cerebral palsy in preterm infants has focused on two potential mechanisms of brain damage. One mechanism involves insufficient cerebral perfusion; the other, cytokine-mediated damage, potentially triggered by events such as maternal infection (e.g., intrauterine or periodontal infection), neonatal infection (e.g., sepsis and necrotizing enterocolitis), and neonatal oxygen- or ventilator-induced lung injury. In addition to the preterm infant's increased exposure to such damaging factors, the high frequency of cerebral palsy in these infants might be due, in part, to insufficient levels of developmentally regulated protective substances, such as thyroid hormone and glucocorticoids. Models of causation currently are being investigated using recently developed methods for quantifying, with small quantities of blood, biomolecules that are suspected to either promote or protect against brain damage in the neonate. Clinical investigations now under way can be expected to identify strategies to be tested in clinical trials that could lower the risk of cerebral palsy in very preterm infants.

[Respiratory distress syndrome, early postnatal corticoid therapy and periventricular leukomalacia]

The aetiology of cavitating periventricular leukomalacia (cPVL) involves pre and perinatal factors. Early postnatal dexamethasone has been associated with an increase in cerebral palsy but its role in the development of PVL remains uncertain.

OBJECTIVES

(1) Reevaluate major factors associated with cPVL, (2) Evaluate the potential effect of early postnatal dexamethasone.

METHOD

This retrospective case-control study (matched for gestational age, birth weight, twin pregnancy and date of birth) compared 50 premature infants with cPVL diagnosed between D7 and D45 from 1995 to 2000 and 50 matched control newborns with normal serial neurosonograms. A data base with 97 selected perinatal variables was used to perform logistic regression analysis in controlling confounding variables, the results are expressed as adjusted Odds Ratio (OR) with 95% confidence interval.

RESULTS

The two populations were comparable for gestational age (median: 29.3 weeks, range: 24.4-34.7) and birth-weight (1297 g, 645-2130 g). The annual incidence of cPVL in preterm infants with a gestational age < 33 weeks varied from 1995 to 2000: 1.3%, 4.5%, 13.4%, 2.1%, 3%, 2.9%. Early postnatal dexamethasone was used in 23 of the newborns who developed cPVL (between november 1996 and march 1998). The only antenatal factor associated with cPVL was cardiac decelerations (28% vs 14%, OR = 3.4, 1.1-11.3). The postnatal risk factors were respiratory distress syndrome requiring the use of rescue surfactant (78% vs 38%, OR = 4.2, 1.4-11.9) and early postnatal dexamethasone at the time it was used (78% vs 17%, OR = 17.1, 3.9-73).

CONCLUSION

The use of rescue surfactant and of early postnatal dexamethasone in preterm infants with respiratory distress syndrome were independently associated with the subsequent occurrence of cPVL. Cardiac deceleration was the only antenatal factor associated with cPVL.

Intratracheal administration of glucocorticoids using surfactant as a vehicle

1. Glucocorticoids are an effective treatment in the amelioration of chronic lung disease in neonates. However, systemic administration of glucocorticoids to neonates is associated with significant side-effects that preclude them as an early intervention to prevent onset of the condition. Conversely, local intratracheal administration of glucocorticoids may prevent inflammatory insult to the lungs without the development of systemic side-effects. We therefore investigated whether local intratracheal delivery of corticosteroids could be facilitated using surfactant as a vehicle. 2. Addition of dexamethasone to either diluted or commercial artificial surfactant, Survanta (Abbott Industries, Sydney, NSW, Australia), did not alter the surface properties of the surfactant. 3. After intratracheal instillation to rats, radiolabelled dexamethasone in Survanta was well distributed throughout all four lobes of the lungs. A concentration gradient of the steroid was observed between the root and the peripheral sections of all lobes. 4. Our results suggest that surfactant is an effective vehicle for intratracheal delivery of glucocorticoids. Moreover, we propose that prophylactic intratracheal administration of glucocorticoids administered shortly after birth may prevent inflammatory insult to the lungs and thereby reduce the likelihood of chronic lung disease developing.

Association of antenatal and postnatal dexamethasone exposure with outcomes in extremely low birth weight neonates

BACKGROUND

Recent studies of preterm neonates have indicated that antenatal dexamethasone (ADX) may have adverse effects on cranial ultrasound findings at the time of hospital discharge, including periventricular leukomalacia. Furthermore, both ADX and postnatal dexamethasone (PDX) may have adverse effects on subsequent neurodevelopmental outcome.

OBJECTIVES

1) To assess the effects of ADX exposure on cranial ultrasound findings at the time of hospital discharge and 2) to evaluate the individual effects of ADX and/or PDX exposure on subsequent neurodevelopmental outcome in extremely low birth weight (ELBW) neonates in whom confounding risk factors known to influence outcome were controlled.

METHODS

One hundred seventy-three ELBW (< or =1000 g) neonates were studied using a prospectively collected database and hospital and clinic records. Study patients were assigned to 1 of 4 groups according to dexamethasone exposure: group I, no dexamethasone exposure; group II, ADX exposure to hasten fetal lung maturity; group III, PDX exposure for chronic lung disease; group IV, both ADX and PDX exposure. The 4 groups were compared using multinomial logistic regression or analysis of covariance to control for confounding variables. Primary outcome variables were cranial ultrasound findings at hospital discharge and results of developmental testing at 18 to 22 months' corrected age (Bayley Scales of Infant Development).

RESULTS

Cranial ultrasound results as well as Bayley Scales of Infant Development scores were similar in groups I and II and in groups III and IV. The likelihood of abnormal cranial ultrasound studies and lower scores on neurodevelopmental testing was greater in groups III and IV versus groups I and II. In this study, ADX did not seem to increase the risk of periventricular leukomalacia.

CONCLUSIONS

ADX exposure is not associated with an increase in abnormal cranial ultrasound findings in ELBW neonates. PDX exposure, but not ADX exposure, is associated with worse neurodevelopmental outcome in this population. These results are supportive of the recent statement by the American Academy of Pediatrics (Committee on Fetus and Newborn) and the Canadian Paediatric Society (Fetus and Newborn Committee) and emphasize that PDX should be used with caution in ELBW neonates.

Differential effect of dexamethasone and hydrocortisone on alveolar growth in rat pups

Glucocorticoids are widely used in perinatology, since they decrease the incidence of respiratory distress syndrome and chronic lung disease. However, evidence is now increasing that their use in this age group may result in impaired alveolar lung growth and general development. The aim of this study was to determine whether a low dose of hydrocortisone (1 mg/kg/day for 11 days) was deleterious to lung growth in rat pups, as compared to an equivalent dose of dexamethasone. While both dexamethasone and hydrocortisone increased alveolar diameter with thinning of the interairspace walls, only dexamethasone reduced the overall internal surface area of the lung available for respiratory exchange. Changes were more marked with dexamethasone as compared to hydrocortisone, which did not appear to affect alveolar septation. In conclusion, a prolonged course of low-dose hydrocortisone may be deleterious for alveolar lung growth in rat pups, but the changes are less marked than those caused by dexamethasone.

Controlled trial of early dexamethasone treatment for the prevention of chronic lung disease in preterm infants: a 3-year follow-up

OBJECTIVE

There is increasing concern in regard to the possible long-term adverse effects of postnatal dexamethasone treatment in preterm infants. The purpose of this study was to assess growth and neurodevelopmental outcome in preterm infants at high risk of chronic lung disease (CLD), treated with early (<96 hours) postnatal dexamethasone.

DESIGN

Three-year follow-up data of physical growth and neurodevelopmental outcome of preterm infants enrolled in a controlled trial to study the effectiveness of early postnatal dexamethasone administration for the prevention of CLD were reviewed. The original trial included 25 treated neonates who received dexamethasone intravenously from the fourth day of life for 7 days (0.5 mg/kg/d for the first 3 days, 0.25 mg/kg/d the next 3 days, and 0.125 mg/kg/d on the seventh day), and 25 untreated neonates as controls. Forty-five surviving infants (22 untreated and 23 treated) completed the 3-year follow-up.

RESULTS

At the end of follow-up, infants pertaining to both study groups had similar values for body weight, height, and head circumference, and a similar incidence of infants with anthropometrics data below the third percentile. Moreover, no differences were detected between the groups in regard to incidence of major cranial ultrasound abnormalities, cerebral palsy, major neurosensory impairment or IQ scores, and distribution.

CONCLUSIONS

Early (<96 hours) postnatal dexamethasone administration at the doses employed in this study did not impair physical or neurodevelopmental outcome in preterm infants at high risk of CLD. However, the small sample size of our study was not tailored to look for long-term outcomes and our results are not in agreement with those of larger trials and systematic reviews. The real risks of postnatal dexamethasone administration could be definitely assessed only when more well-designed trials using long-term neurodevelopmental assessment as the primary outcome will be reported.

A randomized trial of inhaled versus intravenous steroids in ventilator-dependent preterm infants

OBJECTIVE

Intravenous steroids improve the respiratory course in ventilator-dependent preterm infants but have adverse effects. We hypothesized that inhaled steroids would be as effective, but with less systemic effects.

STUDY DESIGN

We conducted a randomized, prospective trial comparing inhaled beclomethasone, either 400 or 800 microg/d, to intravenous dexamethasone in preterm infants dependent on conventional mechanical ventilation and supplemental oxygen at 2 weeks of age.

RESULTS

Seventy-eight infants were randomized. By day three of therapy, the intravenous steroid group had significantly decreased ventilator and oxygen requirements compared to either inhaled group. The inhaled 800-microg/d group trended toward more rapid decreases in ventilator and oxygen requirements than the 400-microg/d group. By day 14, all groups had similar reductions in ventilator and oxygen requirements. The incidence of adverse effects did not differ between groups.

CONCLUSIONS

In this small, randomized study, inhaled steroids conferred no advantages to intravenous steroids in the management of ventilator-dependent preterm infants.

Multiple courses of antenatal corticosteroids are associated with early severe lung disease in preterm neonates

OBJECTIVE

Determine whether the increased neonatal mortality following repeated courses of antenatal corticosteroids (ANCS), observed in the Thyrotropin-Releasing Hormone (TRH) Trial, was related to confounding maternal risk factors or specific preterm morbidities.

STUDY DESIGN

A post hoc analysis of 595 TRH trial neonates, 26 to 32 weeks' gestation, studied the association between > or =3 courses ANCS and mortality. Potential confounding maternal factors and preterm morbidities were evaluated using logistic regression and log likelihood modeling.

RESULTS

Mortality was 9.2% after > or =3 courses (13/141) vs. 4.8% after 1 or 2 courses (22/454). This association was not explained by maternal factors, or other common preterm morbidities. However, 15/141 infants receiving > or =3 courses (10.6%) had early severe lung disease (ESLD) with 10 deaths, compared to 16/454 of the 1- to 2-course infants (3.5%) with 7 deaths (odds ratio 3.5, p<0.001).

CONCLUSIONS

ESLD, but not maternal risk factors, was associated with increased mortality in preterm infants after > or =3 courses ANCS.

The effect of postnatal steroids on growth and development

Single courses of prenatal corticosteroids have many beneficial effects including reduction in respiratory distress syndrome, intraventricular hemorrhage and neonatal mortality. Postnatal corticosteroids, however, have both beneficial and harmful effects. The beneficial effects include shortened time on the ventilator and a reduction in chronic lung disease. Dexamethasone treatment started within the first 4 days of life is associated with an increased risk of abnormal neurodevelopment including cerebral palsy. Other adverse effects include metabolic disturbances, cardiac hypertrophy, reduced growth and gastrointestinal perforation. The risks of early dexamethasone treatment in currently used doses outweigh the benefits. Further research is needed to determine the optimal corticosteroid drug, its dose and timing of administration to maximize benefit and reduce risk to a minimum. Other non-drug interventions should be used to minimize the risk of chronic lung disease in very preterm infants.

[Bronchopulmonary dysplasia and corticosteroid therapy]

Inflammation plays a major role in the pathogenesis of bronchopulmonary dysplasia of preterm infants. Having a strong anti-inflammatory effect, corticosteroids have been proposed in the management of this disease. Antenatal steroids protect the newborn against its development. Postnatal systemic administration of steroids reduces the duration of mechanical ventilation and oxygen therapy, but is associated with short term and long term adverse effects. Early administration of dexamethasone (before 7 days of life) reduces the incidence and the severity of chronic lung disease at 28 days of life and 36 weeks of post-conceptional age. Inhaled steroids are associated with less adverse effects than dexamethasone administration, but they are also less effective.

Postnatal corticosteroids to treat or prevent chronic lung disease in preterm infants

This statement is intended for health care professionals caring for neonates and young infants. The objectives of this statement are to review the short- and long-term effects of systemic and inhaled postnatal corticosteroids for the prevention or treatment of evolving or established chronic lung disease and to make recommendations for the use of corticosteroids in infants with very low birth weight. The routine use of systemic dexamethasone for the prevention or treatment of chronic lung disease in infants with very low birth weight is not recommended.

A randomized trial of moderately early low-dose dexamethasone therapy in very low birth weight infants: dynamic pulmonary mechanics, oxygenation, and ventilation

OBJECTIVE

Dexamethasone is used in very low birth weight (VLBW) ventilator-dependent infants to prevent or decrease the severity of chronic lung disease. We reported a significant increase in respiratory compliance during a 7-day weaning course of moderately early dexamethasone therapy (0.5 mg/kg/d) in VLBW infants, along with a shorter duration of mechanical ventilation and O2 supplementation. Although 0.5 mg/kg/d has been the most commonly used dose in preterm infants, the use of a lower dose of dexamethasone may reduce potential adverse effects of steroid therapy. Quantification of dynamic pulmonary mechanics in VLBW infants who receive low-dose dexamethasone has not been reported. The objective of this study was to compare the effect of 2 dose regimens of dexamethasone on dynamic pulmonary mechanics, mean airway pressure (MAP), and fractional inspired oxygen concentration (Fio2) in intubated VLBW infants who were at risk for chronic lung disease.

METHODS

We studied 47 VLBW (birth weight: 550-1290 g; gestational age: 24-30 weeks) ventilator-dependent infants at 7 to 14 days of age. Twenty-three infants were randomized to receive dexamethasone at 0.5 mg/kg/d intravenously for 3 days (high dose), 0.25 mg/kg/d for 3 days, and 0.1 mg/kg/d during the 7th day; 24 infants received low-dose dexamethasone as 0.2 mg/kg/d for 3 days and 0.1 mg/kg/d for 4 days. Respiratory compliance (Crs) and resistance were measured before and on days 2, 5, and 7 of dexamethasone therapy. We recorded airway pressure, flow, and tidal volume, and mechanical breaths were analyzed.

RESULTS

Crs significantly increased during dexamethasone therapy in both groups of infants when compared with baseline (74% increase in the high-dose group and 66% increase in the low-dose group). Dexamethasone increased tidal volume and significantly reduced Fio2 and MAP in both groups of infants. A transient increase in blood pressure was noted in both groups.

CONCLUSIONS

Our findings indicate that 1) comparable significant increases in Crs are present in the low-dose dexamethasone as well as the high-dose dexamethasone groups on days 2, 5, and 7 of steroid therapy; and 2) MAP and Fio2 are significantly decreased during dexamethasone therapy in both groups of infants. We conclude that low-dose and high-dose dexamethasone, as used in this study, have comparable beneficial effects on dynamic pulmonary mechanics and subsequently on oxygen requirement and applied ventilatory support in VLBW infants.

Effects of tapering neonatal dexamethasone on rat growth, neurodevelopment, and stress response

Dexamethasone is commonly used to lessen the morbidity of chronic lung disease in premature infants, but little is known regarding neurological consequences of its prolonged use. To study neurological effects of dexamethasone, we have developed a rat model in which newborn pups are exposed to tapering doses of dexamethasone at a time corresponding neurodevelopmentally to human exposure in the neonatal intensive care unit. On postnatal day (PD) 2, litters were divided into three groups: 1) handled controls, 2) saline-injected animals, and 3) animals injected with tapering doses of intramuscular dexamethasone between PD 3 and 6. Somatic growth and brain weight were decreased in dexamethasone-treated animals. Dexamethasone-treated animals demonstrated delays in gross neurological development on PD 7 and 14 but not PD 20. In late adolescence (PD 33), dexamethasone-treated animals were less active in light and dark environments, while demonstrating a blunted serum corticosterone response to a novel stress. The dissociation between behavioral and hormonal stress responsiveness suggests that neonatal dexamethasone exposure permanently alters central nervous system function, particularly within the neuroendocrine stress axis. This may lead to increased risk for learning impairment and maladaptive responses to the environment.

Controversies in the use of postnatal steroids

This review evaluates and compares, by using the best available medical evidence, the risks and benefits of postnatal steroid use in very low birth weight infants. Systemic postnatal steroids are effective at reducing the risk of chronic lung disease in ventilated very low birth weight infants; they appear to be most effective when administered to ventilator-dependent infants at 7 to 14 days of age. The beneficial effects are accompanied by an increase in the risk of long-term neurologic sequelae in addition to a number of short-term complications. Whether these risks are justified is largely dependent on the relative value that a parent or caregiver would place on chronic lung disease as compared to the adverse neurologic sequelae.

The hypothalamic pituitary axis in the fetus and newborn

Glucocorticoid receptor activation in the fetal lung triggers maturation necessary for extra-uterine life. Antenatal treatment with betamethasone and dexamethasone has lowered severity of respiratory distress in very low birth weight infants, and dexamethasone given postnatally has resulted in short-term improvement in chronic lung disease. Recently, however, surfactant therapy has diminished the differential benefit of antenatal glucocorticoid treatment, and it has been difficult to show that postnatal dexamethasone therapy improves survival. Treated infants may have reduced weight gain, adrenal suppression, increased incidence of intestinal perforation and infection, and long-term developmental and metabolic problems. Recent data suggest that the fetal hypothalamic/pituitary/adrenal axis is active early and is precisely structured for an intricate sequence of specifically fetal developmental events, which may be deranged by dexamethasone therapy. We consider data suggesting that persistence of the fetal pattern in some premature infants constitutes adrenal insufficiency, and that therapy at stress replacement doses with less potent glucocorticoids might avoid side effects seen with traditional regimens.

Neurobehavioral deficits in premature graduates of intensive care--potential medical and neonatal environmental risk factors

There is growing evidence that a large number of very low birth weight infants are exhibiting neurobehavioral problems in the absence of cerebral palsy at follow-up that has extended into school age and adolescence. Many clinical factors (ie, chronic lung disease, recurrent apnea and bradycardia, transient hypothyroxemia of prematurity, hyperbilirubinemia, nutritional deficiencies, glucocorticoid exposure), as well as stressful environmental conditions, including infant-provider interaction, constant noise, and bright light, may act in combination to impact on the developing brain, even in the absence of overt hemorrhage and/or ischemia. Any potential intervention strategy designed to prevent cognitive and behavioral problems has to account for the numerous biological and clinical conditions and/or interventions, as well as postdischarge social and environmental influences.

Neurotoxic effects of fluorinated glucocorticoid preparations on the developing mouse brain: role of preservatives

Prenatal betamethasone (Celestene) therapy reduces the incidence of brain damage, whereas prenatal or neonatal dexamethasone (Soludecadron) increases the risk of brain lesions or neuromotor deficits. To determine whether this increase is ascribable to the sulfites used as preservatives in Soludecadron, we investigated the effects of 12 h of exposure to pure dexamethasone, Soludecadron, pure betamethasone, Celestene, and sulfites on in vitro and in vivo death of neurons cultured under basal conditions or with excitotoxic agents (N-methyl-D-aspartate or (S)-5-bromowillardiine) or hypoxia. Apoptotic features were quantitated using a fluorescent chromatin stain (Hoechst 33258). Neuronal viability was unaffected by pure dexamethasone, pure betamethasone, or Celestene. Soludecadron or sulfites significantly increased neuronal loss. Pure dexamethasone or pure betamethasone produced a 40-50% decrease in neuronal death induced by N-methyl-D-aspartate, (S)-5-bromowillardiine, or hypoxia, whereas Soludecadron had no effect and sulfites significantly increased the neurotoxicity of excitotoxic agents. In in vivo experiments involving terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling after several i.p. injections of fluorinated glucocorticoids, Soludecadron, but not pure dexamethasone, significantly increased the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-stained cells in neocortical layers and thalamus. These experimental findings suggest that injectable dexamethasone should be used with caution during the perinatal period.

The effects of repeated antenatal glucocorticoid therapy on the developing brain

Antenatal glucocorticoid (GC) therapy improves infant outcome following preterm birth. As approximately 50% of women given a first course of antenatal GCs remain undelivered 7-14 d later, many clinicians administer further courses. GCs are known to be neurotoxic and there is concern that exposure during early development may have adverse effects on the immature brain. The aim of this investigation was to compare magnetic resonance (MR) indices of brain maturation in infants exposed to repeated antenatal GC therapy and born at or close to term, with non-GC exposed control infants. MR images were obtained during quiet sleep without sedation. T1 weighted volume images were obtained in the sagittal plane and T1, T2 weighted spin echo and inversion recovery images in the transverse plane. Brain volume and surface area were calculated from segmented image slices, and a measure of the complexity of cortical folding, the whole cortex convolution index (WCCI), from computerized analysis of a vector coded contour following algorithm. Analysis of covariance was used to compare the two groups after allowing for the effect of postmenstrual age. There were 10 infants in the GC group (range of antenatal GC exposure, 3-11 courses) and 6 controls. Each GC course comprised two 12-mg IM doses of betamethasone 24 h apart. GC exposed infants had a significantly lower WCCI (p = 0.001) and smaller surface area (p = 0.02), after allowing for postmenstrual age. There was no significant difference in brain volume (p = 0.5). Repeated antenatal GC exposure results in measurable differences in brain maturation when compared with gestational age matched non-GC exposed controls. The clinical relevance of these observations is not known.

The outcome of extreme prematurity

Significant advances in perinatology and neonatology in the last decade have resulted in increased survival of extremely premature infants. Survival rates for infants born in tertiary perinatal and neonatal care centers in the United States in the 1990s increase with each week of gestational age from 22 through 26 weeks. Reported survival rates at 22 weeks range from 0% to 21% in the few reporting studies. Reported survival rates at 23 and 24 weeks range from 5% to 46% and from 40% to 59%, respectively. These may not be the maximum survival rates possible because at these gestational ages information is either insufficient to determine that obstetric and neonatal intensive care strategies to maximize neonatal survival were used or it is specified that such strategies were not used. Reported survival rates at 25 and 26 weeks range from 60% to 82% and from from 75% to 93%, respectively. The literature regarding the prevalence of major neurodevelopmental disabilities among extremely premature survivors in the last 25 years is heteogeneous, and the reported prevalances of major disability vary much more than do survival rates. However, the majority of extremely premature infants who survive will be free of major disability. Overall, approximately one fifth to one quarter of survivors have at least one major disability-impaired mental development, cerebral palsy, blindness, or deafness. Impaired mental development is the most prevalent disability (17%-21% [95% CI] of survivors affected), followed by cerebral palsy (12%-15% of survivors affected). Blindness and deafness are less common (5% to 8% and 3% to 5% of survivors affected, respectively). Approximately one half of disabled survivors have more than one major disability. Based on studies of infants less than 750 to 1,000 grams birth weight, it can be anticipated that approximately another half of all extremely premature survivors will have one or more subtle neurodevelopmental disabilities in the school and teenage years. There is little evidence to suggest that long-term neurodevelopmental outcome has changed from the late 1970s to the early 1990s or with increasing survival. Survival of individual extremely premature infants cannot be accurately predicted in the immediate perinatal period. Major disability cannot be accurately predicted for individual survivors during the course in the newborn intensive care unit.

Repeated ultrasound guided fetal injections of corticosteroid alter nervous system maturation in the ovine fetus

INTRODUCTION

Recent studies in sheep have shown that repeated maternal injections of betamethasone are associated with adverse effects within the nervous system. Repeated fetal injections of betamethasone achieve serial improvements in preterm lung function in sheep and are a possible alternative to repeated maternal therapy. We have evaluated the effect of repeated fetal administration of betamethasone on nervous system maturation in an ovine model.

METHODS

Date-mated ewes (n = 48) were randomized to receive ultrasound-guided fetal injections of betamethasone or saline between days 104 to 124 of gestation and were delivered by cesarean section on day 125 or 145 (term = 150). Optic and sciatic nerves were prepared for light and electronmicroscopy. Eye diameters were measured and transverse sections of retinae were evaluated. Data were analyzed using a mixed model analysis of variance.

RESULTS

Repeated fetal administration of corticosteroid did not significantly affect optic nerve myelination but resulted in significant delays in sciatic axonal growth (p < 0.02) and retinal maturation (p < 0.04). The process of performing repeated fetal injections also significantly affected some retinal parameters.

CONCLUSION

Repeated fetal administration of betamethasone alters some aspects of nervous system maturation in sheep. It is premature to plan trials of repeated fetal corticosteroid therapy in humans.

Perinatal glucocorticoid therapy and neurodevelopmental outcome: an epidemiologic perspective

A relatively brief course of antenatal glucocorticoids (ACS), given to reduce the severity of respiratory distress syndrome in preterm infants, improves survival and appears to protect against brain damage. In clinical trials as well as observational studies, ACS have been associated with a decreased risk of intraventricular haemorrhage and cerebral palsy. In observational studies a decreased risk of white-matter damage, identified with cranial ultrasound, has been observed. There is some evidence, from observational studies, that repeated courses of ACS (typically given at weekly intervals) can reduce the rate of fetal head growth, and experiments in animals provide further support for this possibility. In contrast to the effects of a brief course of ACS, postnatal glucocorticoids (PCS), given to preterm infants to reduce the severity of chronic lung disease have been associated with an increased risk of neurologic impairment. Available evidence suggests that PCS does not improve survival. Further study is needed of the neurodevelopmental consequences of both multiple courses of ACS, as well as PCS.

Postnatal glucocorticoid therapy for prevention of bronchopulmonary dysplasia: routes of administration compared

Postnatal systemic and inhaled glucocorticoid therapies continue to be used in the management of bronchopulmonary dysplasia (BPD). Systemic dexamethasone therapy has been studied longer than aerosolized glucocorticoid therapy. Several prophylactic trials of systemic dexamethasone therapy demonstrated a reduction in the incidence of BPD and neonatal mortality. However, evidence of potentially serious acute and long-term adverse effects has reduced enthusiasm for use of systemic dexamethasone therapy. Although no trial to date of inhaled glucocorticoid therapy showed a reduction in the incidence of BPD, some studies demonstrated secondary pulmonary benefits with few short-term adverse effects. This article compares the clinical efficacy and safety of these two routes of administration of glucocorticoid therapy.

Effect of antenatal corticosteroids on postmortem brain weight of preterm babies

OBJECTIVES

To investigate the effects of single and repeated courses of antenatal corticosteroids on brain growth in very preterm babies.

DESIGN

Retrospective study of 110 very preterm babies delivered at a single University Teaching Hospital between 1992 and 1999 who had a full necropsy including detailed examination of the brain.

RESULTS

Mean brain weight did not differ significantly between babies who received corticosteroids and those who did not 160 vs. 157 g, (p=0.82), nor was there a difference between mean brain weight of stillborn or liveborn babies in relation to steroid use 164 vs. 159 g, (p=0.84) and 156 vs. 152g (p=0.81). There was no apparent dose-response relationship between the total number of doses of corticosteroids or timing since the first dose of corticosteroids and brain weight, p=0.95 and p=0.87.

CONCLUSIONS

Single and multiple courses of antenatal corticosteroids had no significant effect on brain growth in babies delivered preterm who died but long-term follow-up studies are required to evaluate the functional neurological outcome of surviving children.

Effect of dexamethasone therapy on pulmonary function in chronic lung disease: a comparison of disease types

BACKGROUND

In the present study, we investigated the effect of dexamethasone (DEX) therapy on extubation and pulmonary function in patients with chronic lung disease (CLD) who required long-term mechanical ventilation. In addition, we compared the effects of DEX therapy among CLD types.

METHODS

Twenty-two CLD patients who were ventilator dependent for 28 days or longer received DEX therapy for the purposes of extubation. A tapering dose of DEX, starting from 0.5 mg/kg per day, was administered for 7 days. Pulmonary function was measured at initiation of administration and 4 days after initiation. We evaluated static respiratory system compliance (Crs) and static respiratory system resistance (Rrs) adjusted by bodyweight. Chronic lung disease types were categorized according to the classification of the Ministry of Health and Welfare Research Project. We compared the effect of DEX therapy among CLD types.

RESULTS

Dexamethasone therapy was started at a mean (+/-SD) 45 =/- 11 days after birth and 32.1 +/- 1.3 weeks of postconceptional age in infants with a mean bodyweight of 939 +/- 153 g. After DEX therapy, extubation was successful in all 22 patients. Following DEX administration, Crs was significantly increased from 0.69 +/- 0.13 to 1.17 +/- 0.21 mL/cm H2O per kg. In contrast, Rrs did not show any clear changes. Comparing CLD types, no difference was observed for Crs and Rrs in each disease type.

CONCLUSIONS

Dexamethasone was administered to CLD patients requiring long-term mechanical ventilation for the purposes of extubation and extubation was successful in all patients. It was found that Crs was increased in all patients following DEX, regardless of CLD type. The increase in Crs following DEX administration may have been related to successful extubation.

Risk factors for neurologic impairment among very low-birth-weight infants

Although cerebral palsy is the most common neurologic impairment among very low-birth-weight survivors, its etiology remains uncertain. Current research supports the role of both antenatal and neonatal factors in the pathogenesis of cerebral palsy among these extremely premature infants. Important antenatal risk factors include chorioamnionitis and multiple placental lesions. Maternal preeclampsia may provide neuroprotection. The major neonatal risk factors include severe cranial ultrasound abnormalities, chronic lung disease, hyperbilirubinemia, and possibly hypothyroxinemia.

Focal small bowel perforation: an adverse effect of early postnatal dexamethasone therapy in extremely low birth weight infants

OBJECTIVE

We tested the hypothesis that early postnatal dexamethasone (EPD) increases the risk of focal small bowel perforation (FSBP) in extremely low birth weight (ELBW) infants.

STUDY DESIGN

The techniques of meta-analysis were applied to studies evaluating EPD, which we identified through a systematic literature search. Studies were included if they were randomized, placebo-controlled trials of EPD, enrolled infants with birth weights < or =1000 g, and reported FSBP as an outcome variable. The Breslow-Day test was used to assess for homogeneity and a summary odds ratio was calculated using the Mantel-Haenszel exact method.

RESULTS

Four studies, with a pooled sample of 1383 infants, were included in the primary analysis. The Breslow-Day test showed a p-value of 0.61, indicating homogeneity among the studies. FSBP was significantly higher in EPD treated infants [odds ratio 1.91, 95% confidence interval (CI) 1.21, 3.07; p=0.004].

CONCLUSION

EPD increases the risk of FSBP in ELBW infants.

The adverse neuro-developmental effects of postnatal steroids in the preterm infant: a systematic review of RCTs

BACKGROUND

Recent reports have raised concerns that postnatal steroids may cause neuro-developmental impairment in preterm infants. This systematic review was performed with the objective of determining whether glucocorticoid therapy, to prevent or treat bronchopulmonary dysplasia, impairs neuro-developmental outcomes in preterm infants.

METHOD

A systematic review of the literature was performed. Medline was searched and articles retrieved using predefined criteria. Data from randomized controlled trials with adequate neuro-developmental follow up (to at least one year) were entered into a meta-analysis to determine the effects of postnatal treatment of preterm infants with glucocorticoids. Cerebral palsy rates, and neuro-developmental impairment (developmental score more than 2SD below the mean, or cerebral palsy or blindness) were analyzed. The studies were divided into 2 groups according to the extent of contamination of the results by treatment of controls with steroids after the initial study period, those with less than 30% contamination, and those with more than 30% contamination or size of contamination not reported.

RESULTS

Postnatal steroid therapy is associated with an increase in cerebral palsy and neuro-developmental impairment. The studies with less contamination show a greater effect of the steroids, consistent with a real direct toxic effect of steroids on the developing central nervous system. The typical relative risk for the development of cerebral palsy derived from studies with less than 30% contamination is 2.86 (95% CI 1.95, 4.19). The typical relative risk for the development of neuro-developmental disability among followed up infants from studies with less than 30% contamination is 1.66 (95% CI 1.26, 2.19). From this subgroup of studies, the number of premature infants who need to be treated to have one more infant with cerebral palsy (number needed to harm, NNH) is 7; to have one more infant with neuro-developmental impairment the NNH is 11.

CONCLUSIONS

Postnatal pharmacologic steroid treatment for prevention or treatment of bronchopulmonary dysplasia is associated with dramatic increases in neuro-developmental impairment. As there is no clear evidence in the literature of long term benefit, their use for this indication should be abandoned.

The clinical, morphologic, and molecular changes in the ileum associated with early postnatal dexamethasone administration: from the baby's bowel to the researcher's bench

Focal small bowel perforation (FSBP) is a life-threatening event that predominantly affects extremely low birth weight (ELBW) infants. Histopathology from surgical specimens of ileum with FSBP shows a healthy mucosa overlying a thinned muscularis with segmental degeneration. Clinical data strongly support an association between early postnatal administration of dexamethasone (EPD) and FSBP. Additional risk factors, including gestational age, administration of prophylactic indomethacin, and severity of illness, may be synergistic with EPD for the pathogenesis of perforations. Animal models of dexamethasone administration show morphologic changes in the ileum, similar to those seen in ELBW infants, including increased mucosal maturation and thinning of the muscularis. These tissue-specific differences may be mediated by a perturbation in growth factor expression or accumulation. In support of this hypothesis, dexamethasone has been associated with increased IGF-I immunolocalization in the mucosa and decreased immunolocalization in the muscularis. The known growth-promoting functions of IGF-I are consistent with the observed dexamethasone-associated changes within both the mucosa and the muscularis. Ongoing studies in this animal model are exploring the potential mechanisms by which dexamethasone might affect IGF-I availability.

Neonatal dexamethasone treatment induces long-lasting changes in T-cell receptor vbeta repertoire in rats

Glucocorticoids are frequently administered for the prevention of chronic lung disease in infants with respiratory distress syndrome. However, neonatal treatment may have consequences for immune functioning in the long-term. Here we demonstrate that neonatal glucocorticoid treatment has long-lasting effects on mRNA expression of several Vbeta genes within the CD4 and CD8 T cell subset in rats. Changes in the peripheral T cell Vbeta repertoire may be a consequence of altered intrathymic selection events in which corticosterone plays an important role. Indeed, here we show that neonatal glucocorticoid treatment affects corticosterone production by thymic epithelial cells during neonatal life. In conclusion, changes in T cell Vbeta repertoire after neonatal glucocorticoid treatment may contribute to altered immune reactivity in later life.

Inhaled nitric oxide: current and future uses in neonates

Inhaled nitric oxide (iNO), a selective pulmonary vasodilator, is available for treatment of persistent pulmonary hypertension of the newborn in term and near-term neonates. iNO decreases pulmonary vascular resistance leading to diminished extrapulmonary shunt and also has a microselective effect which improves ventilation/perfusion matching. Clinical trials indicate the need for extracorporeal membrane oxygenation (ECMO) is diminished by iNO. Information suggests a 20 ppm starting dose; doses greater than 40 ppm offer no advantage. The typical duration of therapy in responders is less than one week. Several approaches to weaning have been successful. Abrupt discontinuation should be avoided. Ventilatory management remains important when parenchymal lung disease accompanies pulmonary hypertension of the newborn; HFOV used to optimize lung inflation facilitates the action of iNO. Non-ECMO centers should be able to provide iNO during transport to an ECMO center. Data suggest a possible role for iNO in preterms with hypoxemic respiratory failure and studies in this group should proceed.

Antenatal steroids and the developing brain

Randomised clinical trials show that two injections of corticosteroid into the mother before preterm delivery reduce respiratory distress syndrome, neonatal mortality, and intraventricular haemorrhage. However, repeated courses of antenatal steroid are not backed by such evidence of safety and efficacy. Animal studies have shown that maternal corticosteroid delays myelination and reduces the growth of all fetal brain areas particularly the hippocampus. Corticosteroids may reduce or enhance hypoxic-ischaemic injury to the developing brain depending on timing and dosage. Clinical trials of maternally administered corticosteroid show no evidence of increased disability on follow up but numbers are small. Postnatal trials of dexamethasone when brain maturity is still preterm show a significant increase in later disability in the dexamethasone treated groups. There is evidence from randomised trials, retrospective data, experiments on pregnant mice, and the chemical make up of the preparations that betamethasone may be safer and more protective of the immature brain than dexamethasone. Single course corticosteroid treatment before preterm delivery must still be recommended as a life saving and cost effective intervention, but clinicians may wish to change from using dexamethasone to betamethasone. In view of the animal and postnatal data, clinicians should be cautious with repeated courses of antenatal corticosteroids and repetition may be unnecessary for lung maturity.

Effects of dexamethasone treatment on bone and collagen turnover in preterm infants with chronic lung disease

Dexamethasone is used commonly in the treatment of chronic lung disease of prematurity, but there are concerns about possible deleterious effects on growth and bone. Our aim in this study was to examine the effects of dexamethasone treatment on bone and collagen turnover in preterm infants. Bone-specific alkaline phosphatase, the C-terminal propeptide of type I collagen (PICP, reflecting whole-body type I collagen synthesis), and the N-terminal propeptide of type III procollagen (P3NP, reflecting soft tissue collagen turnover), together with the C-terminal telopeptide of type I collagen (ICTP), urinary pyridinoline (Pyd), and deoxypyridinoline (all markers of collagen breakdown) were measured at weekly intervals over the first 12 wk of life in 14 preterm infants with chronic lung disease treated with dexamethasone. Results were expressed as SD scores relative to preterm control infants not treated with dexamethasone. PICP, P3NP, ICTP, and Pyd all showed marked decreases (-2.1 to -3.7 SD scores) during the first week of treatment (p < 0.001), returning to pretreatment levels after stopping dexamethasone. In the group as a whole, these collagen markers were negatively correlated with dexamethasone dose (p < 0.0001); negative correlations were also seen in most individual babies, although the slopes of individual regression lines varied by a factor of 2. Weight gain at 12 wk was correlated with PICP, expressed as the mean SD score over 12 wk for each baby, (r = 0.69, p < 0.01) but not with other markers or cumulative dose of dexamethasone. We conclude that dexamethasone markedly suppressed collagen turnover in preterm infants in a dose-dependent fashion, although some babies were more affected than others. The degree of suppression of type I collagen synthesis was a strong independent predictor of overall weight gain over the first 12 wk of life.