Transient adrenocortical insufficiency of prematurity and systemic hypotension in very low birthweight infants

Perinatal endocrinology: common endocrine disorders in the sick and premature newborn

Endocrine disorders are common in infants in the neonatal ICU. They often are associated with prematurity, low birth weight or very low birth weight, and small size for gestational age. They also frequently occur in infants who are critically ill or stressed. This article describes the most common conditions and current knowledge regarding management.

Early systemic hypotension and vasopressor support in low birth weight infants: impact on neurodevelopment

BACKGROUND

The duration and severity of systemic hypotension have been related with altered neurodevelopment. Cerebral circulation is pressure-passive in low birth weight infants with early systemic hypotension who receive cardiovascular support. The treatment of early systemic hypotension is controversial, because it has been associated with short-term and long-term morbidity in retrospective studies. However, there has been no prospective information on cardiovascular support for hypotension and morbidity.

OBJECTIVE

Our goal for this prospective study was to evaluate the effect on neurodevelopment resulting from the use of vasopressors/inotropes for early systemic hypotension.

METHODS

Low birth weight infants with early systemic hypotension (<24 hours of life; study group) were assigned randomly to receive dopamine (2.5-10 microg/kg per minute) or epinephrine (0.125-0.5 microg/kg per minute) in progressively larger doses until target blood pressure was attained (treatment-success subgroup). Hemodynamically stable patients who did not receive cardiovascular support were the control group. Outcome measures were serial cranial ultrasound up to 40 weeks, structured neurologic evaluation (every 3 months), and neurodevelopmental test at 2 to 3 years of age.

RESULTS

One hundred thirty patients were included (study = 60; treatment success = 38; controls = 70). Study-group patients had lower birth weight, gestational age, and 5-minute Apgar score, higher rates of premature rupture of membranes, need for cardiorespiratory resuscitation at birth, and sickness shortly after birth than the control group. The patients in the study group also had significantly higher serum troponin I levels at birth. Initial cranial ultrasound findings did not differ between groups, but the final cranial ultrasounds revealed higher rates of severe periventricular hemorrhage in the study group and higher rates of normal cranial ultrasounds in the control group. Only the latter remained when the treatment-success subgroup and control group were compared. Multivariate analysis did not detect any association between final cranial ultrasounds and the use of vasopressors/inotropes. Sixteen infants died and 103 were followed up (90% survival rate). No differences between groups were found in the rates of abnormal neurologic status, developmental delay, or combined adverse outcome (death or cerebral palsy or severe neurodevelopmental delay).

CONCLUSIONS

Cautious use of cardiovascular support to treat early systemic hypotension in low birth weight infants seems to be safe. The question of whether raising systemic blood pressure to within a normal range will improve outcome should be examined by using appropriate study designs.

High versus low dose of initial thyroid hormone replacement for congenital hypothyroidism

BACKGROUND

Congenital hypothyroidism (CHT) affects approximately one in 3000 to 4000 infants. CHT is one of the most common preventable causes of learning difficulties. Optimal management of CHT requires early diagnosis and prompt treatment to avoid abnormal neurodevelopmental outcome. One of the main issues in the management of CHT relates to the initial dose of levothyroxine to be used in order to achieve optimal results in terms of intellectual development. Currently, it remains unclear whether high dose thyroid hormone replacement is more effective than low dose in the treatment of CHT. Further research is required to determine an appropriate dose that improves mental and psychomotor developmental outcomes.

OBJECTIVES

To determine the effects of high versus low dose of initial thyroid hormone replacement for congenital hypothyroidism.

SEARCH STRATEGY

Randomised controlled trials were identified by searching The Cochrane Library, MEDLINE and EMBASE and reference lists of published papers.

SELECTION CRITERIA

Randomised controlled clinical trials investigating the effects of high versus low dose of initial thyroid hormone replacement for congenital hypothyroidism were included.

DATA COLLECTION AND ANALYSIS

Both authors independently selected trials, assessed risk of bias and extracted data.

MAIN RESULTS

The initial search identified 1014 records which identified 13 publications for further examination. After screening the full text of the 13 selected papers, only one study evaluating 47 babies finally met the inclusion criteria. Using the same cohort at two different time periods, the study investigated the effects of high versus low dose thyroid hormone replacement in relation to (1) time taken to achieve euthyroid status and (2) neurodevelopmental outcome. The study reported that a high dose is more effective in rising serum thyroxine and free thyroxine concentrations to the target range and earlier normalisation of thyroid stimulating hormone compared to a lower dose. Similarly, full scale intelligence quotient was noted to be significantly higher in children who received the high dose compared to the lower dose. However, the verbal intelligence quotient and performance intelligence quotient were similar in both groups. Growth and adverse effects were not reported in the included trial.

AUTHORS' CONCLUSIONS

There is currently only one randomised controlled trial evaluating the effects of high versus low dose of initial thyroid hormone replacement for CHT. There is inadequate evidence to suggest that a high dose is more beneficial compared to a low dose initial thyroid hormone replacement in the treatment of CHT.

Thyroid system immaturities in very low birth weight premature infants

Continuing advances in the care of premature infants has contributed to the increased survival of very low birth weight premature infants. These infants are characterized by a variety of organ and physiological systems immaturities predisposing to deficiencies of postnatal adaptation and a high prevalence of neonatal morbidities. These morbidities have a major impact on postnatal mental and neurological outcomes. Thyroid hormones play a critical role in central nervous system development and function, and thyroid system immaturities as well as morbidity-related thyroid dysfunction (the nonthyroidal illness syndrome) contribute to the transient hypothyroxinemia of premature infants (THOP). Several studies have demonstrated a correlation of THOP with subsequent low IQ and neurologic sequelae in very low birth weight premature infants, and there is suggestive evidence that thyroid hormone supplementation in very low birth weight infants can improve mental outcome. Here, we review normal fetal thyroid system development and the system immaturities contributing to THOP and predisposing to nonthyroidal illness in very low birth weight infants.

Brain cooling for preterm infants

There is strong evidence that prolonged, moderate cerebral hypothermia initiated within a few hours after severe hypoxia-ischemia and continued until resolution of the acute phase of delayed cell death can reduce neuronal loss and improve behavioral recovery in term infants and adults after cardiac arrest. This review examines the evidence that mild to moderate hypothermia is protective after hypoxia-ischemia in models of preterm brain injury and evaluates the potential risks. Induced hypothermia likely has potential to significantly reduce disability. Cautious, systematic trials are essential before hypothermia can be used in these vulnerable infants.

Do cortisol concentrations predict short-term outcomes in extremely low birth weight infants?

OBJECTIVE

Relative adrenal insufficiency in extremely low birth weight infants may contribute to significant morbidity and death. Our objective was to evaluate the relationship between cortisol concentrations and short-term outcomes.

METHODS

Cortisol concentrations were obtained for 350 intubated, extremely low birth weight infants at postnatal age of 12 to 48 hours and at day 5 to 7, as part of a multicenter, randomized trial of hydrocortisone treatment for prophylaxis of relative adrenal insufficiency. Death and short-term morbidity were monitored prospectively. Cortisol levels at each time point were divided into quartiles. The incidence rates of outcomes were determined for each quartile and for infants with cortisol values of <10th percentile or >90th percentile. RESULTS. Median cortisol values were 16.0 microg/dL at baseline and 13.1 microg/dL on day 5 to 7 in the placebo group. Outcomes did not differ in each quartile between treatment and placebo groups. Low cortisol values at baseline or day 5 to 7 were not associated with increased morbidity or mortality rates and were not predictive of open-label hydrocortisone use. In fact, vasopressor use was lower for infants with lower cortisol values at baseline. Severe intraventricular hemorrhage was more frequent in infants with cortisol levels in the upper quartile at baseline, and values of >90th percentile were significantly associated with higher rates of death, severe intraventricular hemorrhage, periventricular leukomalacia, gastrointestinal perforation, and severe retinopathy of prematurity.

CONCLUSIONS

Low cortisol concentrations were not predictive of adverse short-term outcomes, but high cortisol concentrations were associated with severe intraventricular hemorrhage, and extremely elevated values were associated with morbidity and death. Low cortisol concentrations alone at these 2 time points did not identify the infants at highest risk for adverse outcomes. In contrast, high cortisol values were associated with increased morbidity and mortality rates.

17-Hydroxyprogesterone in premature infants as a marker of intrauterine stress

AIMS

Amniotic infection (AI) and preeclampsia (PE), which are commonly the reason for prematurity, inflict stress of different duration on immature fetuses. Whether chronic stress, as reflected by intrauterine growth retardation, influences the level of 17-OH progesterone (17-OHP), was not previously examined.

METHODS

We analyzed 17-OHP and TSH levels during neonatal screenings in the first hours of life of 90 premature infants born between 25 and 33 weeks of gestation in infants with AI (n=37) or with PE (n=53). Control of acute stress parameters was derived from umbilical arterial cord blood pH and base excess (BE).

RESULTS

Mean 17-OHP levels of infants born to mothers with PE were 85.7 nmol/L compared to 54.6 nmol/L (P<0.001) in AI infants. 17-OHP was even higher when intrauterine growth restriction was present (99.8 nmol/L). Antenatal steroids and mode of delivery did not significantly affect 17-OHP levels.

CONCLUSIONS

Stress of relatively long duration, as in cases of PE, leads to a significant increase of 17-OHP level in preterm infants. The postnatal 17-OHP level may be considered as a measure for severity of intrauterine stress and might be used as an individualized indicator for earlier intensive care.

Hypothyroxinemia of prematurity: cause, diagnosis and management

Infants born at extreme prematurity are at a high risk of developmental disability. A major risk factor for disability is having a low level of thyroid hormone, described as hypothyroxinemia, which is recognized to be a frequent phenomenon in these infants. At present, there is uncertainty among clinicians regarding the most appropriate method of managing hypothyroxinemia of prematurity. The literature suggests that some, but not all, forms of thyroid supplementation may reduce the incidence of disability in infants born at extreme prematurity. There is a pressing need to confirm the benefit of treatment and to establish the optimal way to treat transient hypothyroxinemia in these infants.

The plasma angiotensin II level increases in very low-birth weight infants with neonatal chronic lung disease

BACKGROUND

Angiotensin II (AII) has been reported to play an important role in organ fibrosis, and a local renin-angiotensin-system (RAS) has been demonstrated in the lungs. However, the relationship of the RAS to chronic lung disease of the newborn (CLD) remains obscure.

OBJECTIVE

To investigate the plasma AII levels throughout the neonatal period in very low-birth weight (VLBW) infants and examine the possible factors that might affect the AII levels.

STUDY DESIGN

The study includes 20 VLBW infants. Blood samples were collected on days 0, 7, 21 and 35 and plasma AII levels were assayed using an enzyme immunoassay. The data were analyzed by a multiple linear regression analysis with the plasma AII level as the dependent variable and significant factors determined based on a univariate analysis as independent variables.

RESULTS

The geometric mean of the plasma AII concentrations on days 0, 7, 21 and 35 was 51 pg/mL, 86 pg/mL, 132 pg/mL, and 50 pg/mL, respectively. On day 21, only CLD (p<0.01) had a highly significant association with the plasma AII level. On day 35, birth weight (p<0.05) and CLD (p<0.01) had a highly significant association with the plasma AII level. This analysis confirmed CLD to be the most significant factor associated with plasma AII level on days 21 and 35.

CONCLUSION

These findings suggest that higher levels of plasma AII in VLBW infants appear to be related to the development of CLD.

Comparison of serum cortisol concentrations in preterm infants with or without late-onset circulatory collapse due to adrenal insufficiency of prematurity

A recent survey found that approximately 4% of very low birth weight infants in Japan were treated with glucocorticoids postnatally for circulatory collapse thought to be caused by late-onset adrenal insufficiency. We identified 11 preterm infants with clinical signs compatible with this diagnosis (hypotension, oliguria, hyponatremia, lung edema, and increased demand for oxygen treatment) and matched them for gestational age with 11 infants without such signs. Blood samples were obtained for cortisol and its precursors from the patient group before the administration of hydrocortisone, and from the control group during the same postnatal week. All samples were analyzed using a gas chromatography-mass spectrometry system. Cortisol concentrations did not differ between the two groups (6.6 +/- 4.5 vs 3.4 +/- 2.7 microg/dL); however, the total concentration of precursors in the pathway to cortisol production was significantly higher in the patient group (72.2 +/- 50.3 vs 25.0 +/- 28.5 microg/dL; p < 0.05). We conclude that the clinical picture of late-onset adrenal insufficiency in preterm infants is not a result of an absolute deficiency of cortisol production, but may be a result of a limited ability to synthesize sufficient cortisol for the degree of clinical stress.

Late-onset circulatory dysfunction of premature infants and late-onset periventricular leukomalacia

BACKGROUND

The sudden appearance of hypotension and oliguria without obvious cause following stable circulation and respiration in preterm infants is frequent in Japan. Such episodes are referred to as late-onset circulatory dysfunction of premature infants (LCD). Volume expanders and inotropic agents are often ineffective against this condition, whereas i.v. steroids are significantly effective. A major problem is that cystic periventricular leukomalacia (PVL) often develops a few weeks after an episode. The aim of the present study was to clarify the risk factors, including LCD, related to cystic PVL.

METHODS

A case-control study was performed for preterm infants who were delivered at <33 weeks of gestation and admitted to seven neonatal intensive care units in Japan. Cystic PVL infants were stratified into early-onset PVL diagnosed within 28 days of age and late-onset PVL diagnosed after more than 28 days of age. The reported and new risk factors for PVL, for each group of PVL infants, and for all PVL infants, were compared with controls.

RESULTS

Thirty-two infants were diagnosed with cystic PVL (17 early-onset and 15 late-onset). All PVL infants significantly differed from controls on Apgar score, number of abortions and pregnancies, intraventricular hemorrhage, and LCD. LCD was diagnosed in 28.1% of both PVL groups compared with 6.3% of controls (P = 0.02). Multivariate analysis demonstrated significant association between late-onset PVL and LCD.

CONCLUSION

LCD was significantly associated with cystic PVL, especially late-onset PVL. Elucidating the cause of LCD might reduce the incidence of PVL and improve the neurological prognosis of preterm infants.

TIPIT: A randomised controlled trial of thyroxine in preterm infants under 28 weeks' gestation

BACKGROUND

Infants born at extreme prematurity (below 28 weeks' gestation) are at high risk of developmental disability. A major risk factor for disability is having a low level of thyroid hormone which is recognised to be a frequent phenomenon in these infants. At present it is unclear whether low levels of thyroid hormone are a cause of disability, or a consequence of concurrent adversity.

METHODS

We propose an explanatory multi-centre double blind randomised controlled trial of thyroid hormone supplementation in babies born below 28 weeks' gestation. All infants will receive either levothyroxine or placebo until 32 weeks' corrected gestational age. The primary outcome will be brain growth. This will be assessed by the width of the sub-arachnoid space measured using cranial ultrasound and head circumference at 36 weeks' corrected gestational. The secondary outcomes will be (a) thyroid hormone concentrations measured at increasing postnatal age, (b) status of the hypothalamic pituitary axis, (c) auxological data between birth and 36 weeks' corrected gestational age, (d) thyroid gland volume, (e) volumes of brain structures (measured by magnetic resonance imaging), (f) determination of the extent of myelination and white matter integrity (measured by diffusion weighted MRI) and brain vessel morphology (measured by magnetic resonance angiography) at expected date of delivery and (g) markers of morbidity including duration of mechanical ventilation and chronic lung disease.We will also examine how activity of the hypothalamic-pituitary-adrenal axis modulates the effects of thyroid supplementation. This will contribute to decisions about which confounding variables to assess in large-scale studies.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN89493983.

Effect of cerebral hypothermia on cortisol and adrenocorticotropic hormone responses after umbilical cord occlusion in preterm fetal sheep

The hypothalamic-pituitary-adrenal (HPA) axis is essential for adaptation to stress. In the present study, we examined the hypothesis that head cooling with mild systemic hypothermia would adversely affect fetal adrenocorticotropic hormone (ACTH) and cortisol responses to an asphyxial insult. Chronically instrumented preterm fetal sheep (104 d of gestation, term is 147 d) were allocated to sham occlusion (n = 7), 25 min of complete umbilical cord occlusion (n = 7), or occlusion and head cooling with mild systemic hypothermia (n = 7, mean +/- SEM esophageal temperature 37.6 +/- 0.3 degrees C vs 39.0 +/- 0.2 degrees C; p < 0.05) from 90 min to 70 h after occlusion, followed by spontaneous rewarming. During umbilical cord occlusion, there was a rapid rise in ACTH and cortisol levels, with further increases after release of cord occlusion. ACTH levels returned to sham control values after 10 h in both occlusion groups. In contrast, plasma cortisol levels remained elevated after 48 h in both occlusion groups and were still significantly elevated in the hypothermia-occlusion group 2 h after rewarming, at 72 h, compared with the normothermia-occlusion and sham groups. In conclusion, hypothermia does not affect the overall HPA responses to severe asphyxia in the preterm fetus but does prolong the cortisol response.

A comparison of albumin-bolus therapy versus normal saline-bolus therapy for hypotension in neonates

OBJECTIVE

We compared responses to bolus infusion of 5% albumin (ALB) or normal saline (NS) for hypotension in neonates.

STUDY DESIGN

Hypotensive infants were given 10 ml kg(-1) of NS or ALB. A second bolus was given for persistent hypotension. Dopamine therapy was started for hypotension after the second bolus. The primary response was increase in arterial blood pressure toward normal range 1 h postinfusion. Secondary measures included duration of normotension, meeting criteria for second bolus, meeting criteria for vasopressor support and cost comparison.

RESULT

Those receiving ALB (N=49 ALB and 52 NS) were more likely to achieve a normotensive state (ALB=57.1%, NS=32.1% P=0.01) 1 h following the initial bolus therapy. Subsequently, the NS group was also more likely to qualify for vasopressor infusion (ALB=24.5%, NS=44.2% P=0.02). Overall cost for either therapy was equivalent.

CONCLUSION

In hypotensive neonates, ALB results in a greater likelihood of achieving normotension and decreased subsequent use of vasopressors when compared to NS.

Hydrocortisone and indomethacin negatively modulate EGF-R signaling in human fetal intestine

Concomitant use of hydrocortisone and the nonspecific cyclo-oxygenase (COX)-inhibitor indomethacin increases the risk for intestinal perforations in preterm infants. We determined whether this was associated with insufficient epidermal growth factor receptor (EGF-R) signaling. We tested the effect of EGF, hydrocortisone, and indomethacin on its activation, cell proliferation and migration, COX-2 expression, and prostaglandin E2 (PGE2) production. Human small intestine epithelial cell line FHsInt74 and EGF-R-deficient mice [EGF-R (-/-)] were used as models. The data revealed that EGF-R signaling had a bimodal positive effect on fetal enterocyte: 1) it increased cell proliferation and migration synergistically with hydrocortisone and 2) up-regulated COX-2 mRNA expression and subsequent PGE2 production. Correlating with this, COX-2 protein expression was down-regulated in EGF-R (-/-) intestine. Despite a positive effect on cell proliferation with EGF, hydrocortisone blunted the stimulatory effect of EGF on COX-2 expression and PGE2 production. Addition of indomethacin even further inhibited the EGF-stimulated PGE2 synthesis. The data suggest that concomitant use of indomethacin and hydrocortisone on preterm infants, who physiologically synthesize only low levels of EGF-R ligands, may lead to intestinal problems related to failure in cytoprotective and regenerative events.

Growth and neurodevelopmental outcomes after early low-dose hydrocortisone treatment in extremely low birth weight infants

BACKGROUND

Low cortisol concentrations in premature infants have been correlated with increased severity of illness, hypotension, mortality, and development of bronchopulmonary dysplasia. A total of 360 mechanically ventilated infants with a birth weight of 500 to 999 g were enrolled in a randomized, multicenter trial of prophylaxis of early adrenal insufficiency to prevent bronchopulmonary dysplasia. Mortality and bronchopulmonary dysplasia were decreased in the hydrocortisone-treated patients exposed to chorioamnionitis. We now report outcomes at 18 to 22 months' corrected age.

PATIENTS AND METHODS

Surviving infants were evaluated with standardized neurologic examination and Bayley Scales of Infant Development-II. Neurodevelopmental impairment was defined as a Mental Developmental Index or Psychomotor Developmental Index of <70, cerebral palsy, blindness or deafness.

RESULTS

A total of 252 (87%) of 291 survivors were evaluated. Cerebral palsy was diagnosed in 13% of hydrocortisone-treated versus 14% of placebo-treated infants. Fewer hydrocortisone-treated infants had a Mental Development Index <70, and more of the hydrocortisone-treated infants showed evidence of awareness of object permanence. Incidence of neurodevelopmental impairment was not different (39% [hydrocortisone] vs 44% [placebo]). There were no differences in physical growth measures. Chorioamnionitis-exposed infants treated with hydrocortisone were shorter and weighed less than controls but had no evidence of neurodevelopmental impairment. Among infants not exposed to chorioamnionitis, hydrocortisone-treated patients were less likely to have a Mental Development Index of <70 or to be receiving glucocorticoids at follow-up.

CONCLUSIONS

Early, low-dose hydrocortisone treatment was not associated with increased cerebral palsy. Treated infants had indicators of improved developmental outcome. Together with the short-term benefit previously reported, these data support additional studies of hydrocortisone treatment of adrenal insufficiency in extremely premature infants.

Cord blood cortisol level is lower in growth-restricted newborns

AIM

To establish the difference in plasma cortisol concentrations between newborns with intrauterine growth-restricted (IUGR) and appropriate for gestational age (AGA) birthweights.

SUBJECTS AND METHODS

We measured plasma cortisol concentrations in the umbilical venous cord blood of 68 IUGR newborns and 71 AGA birthweight newborns. All newborns were delivered in term, vaginally, in the morning, within 8 hours and had APGAR scores greater or equal to eight.

RESULTS

There was no significant difference between compared groups according to maternal age, parity, gestational age and neonatal gender. Neonatal plasma cortisol levels were significantly lower in the IUGR (median: 312.3 mmol/L, min-max: 158.9-588.1 mmol/L) compared to the AGA group (median: 458.7 mmol/L, min-max: 314.5-718.5 mmol/L) (Mann-Whitney U-test; P<0000). The probability of having a cortisol plasma level greater than or equal to 458.7 mmol/L for IUGR newborns was only 1:12, and to have cortisol plasma level less than or equal to 312.3 mmol/L for AGA newborns was much lower (0:34). In the range of plasma cortisol level between 312.3 mmol/L and 458.7 mmol/L, no statistically significant difference in the plasma cortisol level between IUGR and AGA newborns was found.

CONCLUSIONS

Neonatal plasma cortisol level is lower in the IUGR compared to the AGA group. Our results suggest that endocrine relationships seem to be lost in a specific group of the IUGR newborns. Although we usually tend to simplify the problem and declare only one cause, this time it is impossible. It is probable that the cause is hidden in small and insufficient placenta with deranged auto-regulation of placental 11beta-HSD-2 mechanism.

Changes in myocardial function and hemodynamics after ligation of the ductus arteriosus in preterm infants

OBJECTIVE

To characterize the changes in systemic hemodynamics and systolic, diastolic, and global myocardial performance after patent ductus arteriosus (PDA) ligation in very-low-birth-weight infants.

STUDY DESIGN

Echocardiograms were performed on 23 neonates (mean gestational age, 26.2 +/- 2.2 weeks) at 2.3 +/- 2.0 hours before PDA ligation (n = 23) and at 2.0 +/- 1.4 hours (n = 23) and 23.5 +/- 2.5 hours after (n = 11) PDA ligation.

RESULTS

Mean blood pressure, heart rate, load-independent contractility, shortening fraction, left ventricular (LV) afterload, and diastolic function did not change. Preload (early and atrial mitral inflow velocities) decreased immediately after ligation but remained unchanged thereafter. LV output decreased and systemic vascular resistance increased after surgery. The LV myocardial performance index (MPI), a measure of global myocardial performance, deteriorated acutely after ligation but improved by 23.5 hours after surgery. Changes in LV MPI were most closely correlated with changes in LV output.

CONCLUSIONS

After PDA ligation, LV output and MPI decrease, due primarily to a decrease in LV preload, although LV contractility and diastolic function do not change. However, the changes in LV MPI after ligation also reflect an acute deterioration followed by an improvement in global cardiac function, because LV loading conditions remained unchanged after surgery and thus cannot explain the improvement in MPI by 24 hours after ligation.

Maternal stress and behavior modulate relationships between neonatal stress, attention, and basal cortisol at 8 months in preterm infants

There is evidence that the developmental trajectory of cortisol secretion in preterm infants is altered, with elevated basal cortisol levels observed postnatally through at least 18 months corrected age (CA). This alteration is possibly due to neonatal pain-related stress. High cortisol levels might contribute to greater risk of impaired neurodevelopment. Since maternal factors are important for the regulation of infant stress responses, we investigated relationships between infant (neonatal pain-related stress, attention, cortisol) and maternal (stress, interactive behaviors) factors at age 8 months CA. We found that interactive maternal behaviors buffered the relationship between high neonatal pain-related stress exposure and poorer focused attention in mothers who self-reported low concurrent stress. Furthermore, in preterm infants exposed to high concurrent maternal stress and overwhelming interactive maternal behaviors, higher basal cortisol levels were associated with poor focused attention. Overall, these findings suggest that maternal factors can influence the cognitive resilience at 8 months of preterm infants exposed to early life stress.

Pituitary-adrenal axis during human development

Investigation of early human fetal tissue has helped us elucidate the onset of the activation of the pituitary-adrenal axis during human development. Adrenal steroidogenesis and ACTH secretion from the pituitary starts at 7–8 weeks postconception, providing the rationale for prenatal treatment using dexamethasone offered to fetuses at risk of 21-hydroxylase deficiency (21-OHD). Fluctuation of 3beta-hydroxysteroid dehydrogenase (HSD3B2) in human fetal adrenal has several significant meanings. Its activity during early gestation is essential for inhibiting androgen production in the adrenal and safeguarding normal female sexual development. The enzyme may be reduced during mid-gestation in order to maintain pregnancy and to prevent preterm labor. Its reappearance in late gestation is also crucial for fetal maturation and parturition at term. Late-onset circulation failure observed in extremely low birth weight newborns may be associated with the paucity of HSD3B2 in their adrenals. In fetuses with 21-OHD, a proportion of increased 17alpha-hydroxyprogesterone may be converted to dihydrotestosterone through the backdoor pathway and contribute to the virilization of female fetuses.

Adrenal insufficiency: still a cause of morbidity and death in childhood

Adrenal insufficiency is relatively rare in childhood and adolescence. Signs and symptoms may be nonspecific; therefore, the diagnosis may not be suspected early in the course. If unrecognized, adrenal insufficiency may present with life-threatening cardiovascular collapse. Adrenal crisis continues to occur in children with known primary or secondary adrenal insufficiency during intercurrent illness because of failure to increase glucocorticoid dosage. In this article, current knowledge of the incidence, diagnosis, and treatment of adrenal insufficiency in children and factors precipitating adrenal crisis are summarized. Suggestions for prevention of adrenal crisis in patients at risk are provided for health care professionals and families.

Early low-dose hydrocortisone in very preterm infants: a randomized, placebo-controlled trial

BACKGROUND

Several reports indicate a decreased cortisol response to adrenocorticotropic hormone in preterm infants developing chronic lung disease and in preterm infants with refractory hypotension. Low-dose hydrocortisone (HC) may allow for beneficial effects.

OBJECTIVE

Our aim was to assess whether HC is able to increase survival without chronic lung disease.

METHODS

We performed a double-blind, randomized, placebo-controlled trial. Fifty mechanically ventilated infants (birth weight: 500-1,249 g) were randomized to receive treatment (HC 0.5 mg/kg/12 h for 9 days, then HC 0.5 mg/kg/24 h for 3 days) or placebo. Major outcome was survival without oxygen dependence at 36 weeks of postconceptional age (O(2)-free survival).

RESULTS

The basic characteristics were similar between the two groups. O(2)-free survival was higher in the HC group (64 vs. 32%). The advantage was particularly evident among infants without antenatal steroids. The mortality rate was 16% in the HC group versus 40% in the control group (difference not significant). Hypotension after recruitment was reduced by HC (0 vs. 30%). The incidence of gastrointestinal perforation and other adverse effects was similar between the two groups.

CONCLUSIONS

HC prophylaxis improved O(2)-free survival and early cardiocirculatory function in our population, without important short-term effects. The neurodevelopmental outcome will be assessed at 2 years.

Anti-inflammatory therapy in the neonatal intensive care unit: present and future

Inflammation has been linked to numerous adverse outcomes in newborns. This paper reviews several major sources of inflammation, methods to reduce exposure, current anti-inflammatory drug therapy and future research directions. The first major source of inflammation--chorioamnionitis--is often present long before delivery; postnatal interventions may not alter outcomes. Reducing the exposure of preterm infants to postnatal inflammatory stimuli such as mechanical ventilation and sepsis may be more effective than anti-inflammatory drug therapy in improving outcomes. If anti-inflammatory drug therapy is considered necessary, the only drug currently proven to decrease extubation failure and bronchopulmonary dsyplasia (BPD) is dexamethasone, which is associated with numerous side effects. Erythromycin treatment of Ureaplasma urealyticum has been ineffective in reducing BPD; are trials of azythromycin planned. Research may improve future outcomes by tailoring glucocorticoid dosage, duration and formulation in targeted populations and by developing agents to inhibit specific pro-inflammatory mechanisms.

Hemodynamic changes after low-dosage hydrocortisone administration in vasopressor-treated preterm and term neonates

OBJECTIVE

We sought to investigate whether the increase in blood pressure and decrease in vasopressor support after hydrocortisone administration are associated with changes in systemic hemodynamics in neonates who receive high-dosage dopamine to maintain blood pressure at the lowest acceptable levels.

METHODS

In this prospective, observational study, preterm and term neonates who required dopamine > or = 15 microg/kg per minute to maintain minimum acceptable blood pressure received intravenous hydrocortisone 2 mg/kg followed by up to 4 doses of 1 mg/kg every 12 hours. Fifteen preterm and 5 term neonates without a patent ductus arteriosus composed the study population. Echocardiograms and vascular Doppler studies were performed immediately before the first dose of hydrocortisone and at 1, 2, 6 to 12, 24, and 48 hours thereafter.

RESULTS

In the 15 preterm infants, during the first 12 hours of hydrocortisone treatment, the 28% increase in blood pressure paralleled that in the systemic vascular resistance without changes in stroke volume or cardiac output, whereas dopamine dosage decreased. By 24 hours, the dosage of dopamine continued to decrease, whereas stroke volume increased without additional changes in systemic vascular resistance. By 48 hours, dopamine dosage decreased by 72%; blood pressure and stroke volume increased by 31% and 33%, respectively; and systemic vascular resistance and cardiac output tended to be higher (14% and 21%, respectively) compared with baseline. Contractility, global myocardial function, and Doppler indices of blood flow in the middle cerebral and renal artery remained normal and unchanged. The findings in the 5 term infants showed a similar pattern for changes in cardiac function, systemic hemodynamics, and organ blood flow after hydrocortisone administration.

CONCLUSIONS

In preterm and term neonates who require high-dosage dopamine to maintain blood pressure at the lowest acceptable levels, hydrocortisone improves blood pressure without compromising cardiac function, systemic perfusion, or cerebral and renal blood flow.

Management of hypotension and low systemic blood flow in the very low birth weight neonate during the first postnatal week

Systemic hypotension during the first postnatal week is associated with increased mortality and morbidity in the very low birth weight (VLBW) neonate. Hypotension is generally defined as blood pressure below the fifth percentile of the gestational- and postnatal-age dependent blood pressure norms. Recent studies indicate that in most VLBW neonates, cerebral blood flow autoregulation is indeed lost when blood pressure reaches the fifth percentile. Treatment of the circulatory compromise should address the primary pathogenic factor(s) of the condition (hypovolemia, myocardial compromise, failure of vasoregulation or a combination of factors). Recent findings also suggest that vasopressor resistance can be treated with a brief course of low-dose hydrocortisone. However, due to the short- and potential long-term side effects of early hydrocortisone treatment, its use should be restricted to neonates with vasopressor-resistant hypotension. Finally, concomitant administration of hydrocortisone with indomethacin should be avoided due to the increased incidence of gastrointestinal perforations.

Which inotrope for which baby?

While we know a lot about blood pressure (BP) responses to various inotropes and a bit about systemic and organ blood flow responses, we know almost nothing about how different inotropes affect clinical outcomes. Low systemic blood flow (SBF) is common in the first 24 h after birth in very preterm babies (and more mature babies with severe respiratory problems) and is not always reflected by low BP. The causes of this low SBF are complex but may relate to maladaptation to high extrauterine systemic (and sometimes pulmonary) vascular resistance. After day 1, hypotensive babies are more likely to have normal or high SBF reflecting vasodilatation. Empirically, inotropes that reduce afterload (such as dobutamine) may be more appropriate in the transitional period, while those with more vasoconstrictor actions (such as dopamine) may be more appropriate later on. Defining the haemodynamic in an individual baby needs both BP and echocardiographic measures of SBF. Research in this area needs to move beyond just demonstrating changes in physiological variables to showing improvements in important clinical outcomes.

Placental 11beta-HSD2 activity, early postnatal clinical course, and adrenal function in extremely low birth weight infants

The placental enzyme 11beta-hydroxysteroid dehydrogenase-2 (11beta-HSD2) transforms maternal cortisol to inactive cortisone. Fetal glucocorticoid excess due to reduced 11beta-HSD2 activity could make small preterm infants susceptible to early adrenal insufficiency when the maternal cortisol source is no longer sustained. We assessed whether placental 11beta-HSD2 activity is related to early adrenal insufficiency and postnatal clinical course in extremely low birth weight (<1000 g) infants. Mean gestational age of the 44 infants was 26.6 wk (range, 23.7-32.0), birth weight was 747 g (440-981), and relative birth weight was -1.9 SD (-4.9 to 1.0). We determined placental 11beta-HSD2 activity, baseline, and ACTH-stimulated cortisol and assessed illness severity by the Score of Neonatal Acute Physiology (SNAP). One standard deviation decrease in placental 11beta-HSD2 activity corresponded to a 1.85 (95% CI 0.55 to 3.14; p = 0.006) unit increase in SNAP score and 2.9 mm Hg decrease in minimum mean arterial pressure (95% CI 0.3 to 5.6 mm Hg; p = 0.03). Placental 11beta-HSD2 activity was not associated with cortisol concentrations, although the confidence interval of the ACTH-stimulated cortisol was close to zero: 1 SD increase corresponded to 17% (-18% to 49%) increase in ACTH-stimulated cortisol. Moreover, a 1 SD decrease in enzyme activity was associated with a hazard ratio for postnatal glucocorticoid treatment of 1.63 (95% CI 1.00 to 2.65); p = 0.05. In ELBW infants, lower placental 11beta-HSD2 activity is associated with more severe early postnatal illness and hypotension. Although an association with baseline or ACTH-stimulated cortisol was not seen, possible relationships with other components of the hypothalamic-pituitary-adrenal axis remain to be determined.

Prospective evaluation of postnatal steroid administration: a 1-year experience from the California Perinatal Quality Care Collaborative

OBJECTIVE

Postnatal steroids (PNSs) are used frequently to prevent or treat chronic lung disease (CLD) in the very low birth weight (VLBW) infant, and their use continues despite concerns regarding an increased incidence of longer-term neurodevelopmental abnormalities in such infants. More recently, there has been a suggestion that corticosteroids may be a useful alternative therapy for hypotension in VLBW infants, but there have been no prospective reports of such use for a current cohort of VLBW infants.

METHODS

The California Perinatal Quality Care Collaborative (CPQCC) requested members to supplement their routine Vermont Oxford Network data collection with additional information on any VLBW infant treated during their hospital course with PNS, for any indication. The indication, actual agent used, total initial daily dose, age at treatment, type of respiratory support, mean airway pressure, fraction of inspired oxygen, and duration of first dosing were recorded.

RESULTS

From April 2002 to March 2003 in California, 22 of the 62 CPQCC hospitals reported supplemental data, if applicable, from a cohort of 1401 VLBW infants (expanded data group [EDG]), representing 33.2% of the VLBW infants registered with the CPQCC during the 12-month period. PNSs for CLD were administered to 8.2% of all VLBW infants in 2003, 8.6% of infants in the 42 hospitals that did not submit supplemental data (routine data-set group, compared with 7.6% in EDG hospitals). Of the 1401 VLBW infants in the EDG, 19.3% received PNSs; 3.6% received PNSs for only CLD, 11.8% for only non-CLD indications, and 4.0% for both indications. At all birth weight categories, non-CLD use was significantly greater than CLD use. The most common non-CLD indication was hypotension, followed by extubation stridor, for which 36 (16.3%) infants were treated. For hypotension, medications used were hydrocortisone followed by dexamethasone. Infants treated with PNSs exclusively for hypotension had a significantly higher incidence of intraventricular hemorrhage, periventricular leukomalacia, and death when compared with infants treated only for CLD or those who did not receive PNSs.

CONCLUSIONS

The common early use of hydrocortisone for hypotension and the high morbidity and mortality in children receiving such treatment has not been recognized previously and prospective trials evaluating the short- and long-term risk/benefit of such treatment are urgently required.

Cardiovascular Effects of Low-Dose Dexamethasone in Very Low Birth Weight Neonates with Refractory Hypotension

BACKGROUND

Administration of hydrocortisone and relatively high doses of dexamethasone increase blood pressure in volume- and pressor-resistant hypotensive preterm infants. However, little is known about the temporal relationship of dexamethasone administration and the improvement in blood pressure and the weaning of pressors/inotropes. Furthermore, there are no sufficient data available on whether a smaller dose of dexamethasone would also be effective in treating refractory hypotension.

OBJECTIVE

To study the cardiovascular responses to low-dose dexamethasone in very low birth weight neonates with volume- and pressor-resistant hypotension.

METHODS

Retrospective database review. Twenty-four preterm neonates (gestational age 26 (23-34) weeks; birth weight 801 (457-1,180) g; postnatal age 2 (1-24) days, medians (ranges)) who remained hypotensive despite volume administration and combined dopamine and dobutamine treatment at >or=30 microg/kg/min received dexamethasone 0.1 mg/kg followed by 0.05 mg/kg intravenously every 12 h for 5 additional doses if still on pressors >or=8 microg/kg/min.

RESULTS

Two hours after the first dose of dexamethasone the mean blood pressure increased from 30 +/- 5 to 34 +/- 6 mm Hg (p < 0.001) and remained elevated at 4, 6, 12, and 24 h after treatment was started (p < 0.001). Six hours after the initial dose of dexamethasone the pressor/inotrope requirement decreased from 34 +/- 9 to 24 +/- 13 microg/kg/min (p = 0.001) and continued to decrease at 12 and 24 h (p < 0.001). Urine output also increased significantly during the first 6 h after dexamethasone (p < 0.001).

CONCLUSIONS

Low-dose dexamethasone rapidly increases blood pressure and decreases pressor requirements in very low birth weight neonates with volume- and pressor-resistant hypotension.

A double-blind, randomized, controlled study of a "stress dose" of hydrocortisone for rescue treatment of refractory hypotension in preterm infants

OBJECTIVE

To assess the effectiveness of a "stress dose" of hydrocortisone for rescue treatment of refractory hypotension and adrenocortical insufficiency of prematurity in very low birth weight (VLBW) infants. We hypothesized that significantly more VLBW infants who were receiving dopamine > or =10 microg/kg per min could wean off vasopressor support 72 hours after treatment with hydrocortisone.

METHODS

A double-blind, randomized, controlled study was conducted in a university neonatal center. Forty-eight VLBW infants who had refractory hypotension and required dopamine > or =10 microg/kg per min were randomly assigned to receive a stress dose of hydrocortisone (1 mg/kg every 8 hours for 5 days; n = 24) or an equivalent volume of the placebo solution (isotonic saline; n = 24).

RESULTS

The baseline clinical characteristics were similar between the groups. Serum cortisol concentrations were very low immediately before randomization in both groups of infants. Significantly more VLBW infants who were treated with hydrocortisone weaned off vasopressor support 72 hours after starting treatment. The use of volume expander, cumulative dose of dopamine, and dobutamine were significantly less in hydrocortisone-treated infants compared with control infants. In addition, the median duration of vasopressor treatment was halved in hydrocortisone-treated patients. Two versus 11 infants in the hydrocortisone and control groups required a second vasopressor for treatment of refractory hypotension. The trend (linear and quadratic) of the mean arterial blood pressure was also significantly and consistently higher in hydrocortisone-treated infants.

CONCLUSIONS

A stress dose of hydrocortisone was effective in treating refractory hypotension in VLBW infants. Although routine and prophylactic use of systemic corticosteroids could not be recommended because of their potential adverse effects, this relatively low dose of hydrocortisone would probably be preferable to high-dose dexamethasone for treatment of refractory hypotension in emergency and life-threatening situations.

Neonatal Thyroxine Supplementation for Transient Hypothyroxinemia of Prematurity

Extremely low birth-weight newborns (<1000g) experience low levels of thyroid hormone that vary inversely with the severity of neonatal illness and the extent of developmental immaturity with levels reaching a nadir at approximate, equals7 days after birth; this phenomenon can persist for several weeks. In the absence of transplacental passage, 30-50% of these neonates cannot generate sufficient quantities of thyroid hormone to meet postnatal demands, placing them at an increased risk for developmental delay and cerebral palsy. Population surveys and interventional trials suggest that a therapeutic opening exists during a 'window of opportunity' corresponding to this period of diminished capacity. Variables to consider before intervention focus on the consideration that supplementation of both the substrate thyroxine and the active hormone triiodothyronine may be necessary in quantities that do not suppress thyroid-stimulating hormone release, yet overcome the persistence of increased conversion to 3,3'5'-triodo-L-thyronine, terminal deiodination, and activity of the sulfation inactivation pathways, as well as the diminished capacity of the newborn to accommodate postnatal physiologic changes. Single daily replacement doses may suppress levels of converting enzymes in the brain, suggesting that physiologic 'mimicry' provided by a constant infusion may be the preferred dosing option. Properly powered clinical trials targeting long-term developmental outcomes are needed to discern whether these interventions will do more than simply elevate blood levels of thyroid hormones to the target values of either the fetus or developing neonate. Identifying the appropriate indications for supplementation may alleviate individual pain and distress due to disability for several hundred extremely low birth-weight neonates each year in the US alone, and save society a pro-rated lifetime cost of nearly $US1 million per child.

Cortisol, contingency learning, and memory in preterm and full-term infants

Cortisol plays an important role in learning and memory. An inverted-U shaped function has been proposed to account for the positive and negative effects of cortisol on cognitive performance and memory in adults, such that too little or too much impair but moderate amounts facilitate performance. Whether such relationships between cortisol and mental function apply to early infancy, when cortisol secretion, learning, and memory undergo rapid developmental changes, is unknown. We compared relationships between learning/memory and cortisol in preterm and full-term infants and examined whether a greater risk for adrenal insufficiency associated with prematurity produces differential cortisol-memory relationships. Learning in three-month old (corrected for gestational age) preterm and full-term infants was evaluated using a conjugate reinforcement mobile task. Memory was tested by repeating the same task 24h later. Salivary cortisol samples were collected before and 20 min after the presentation of the mobile. We found that preterm infants had lower cortisol levels and smaller cortisol responses than full-term infants. This is consistent with relative adrenal insufficiency reported in the neonatal period. Infants who showed increased cortisol levels from 0 to 20 min on Day 1 had significantly better memory, regardless of prematurity, than infants who showed decreased cortisol levels.

Risk of high blood pressure among young men increases with the degree of immaturity at birth

BACKGROUND

Survivors of preterm birth constitute a new generation of young adults, but little is known about their long-term health. We investigated the association between gestational age (GA) and risk of high blood pressure (HBP) in young Swedish men and whether GA modified the risk of HBP; ie, whether HBP was related to being born small for gestational age (SGA).

METHODS AND RESULTS

This population-based cohort study included 329 495 Swedish men born in 1973 to 1981 who were conscripted for military service in 1993 to 2001. Multivariate linear- and logistic-regression analyses were performed. Main outcome measures were systolic and diastolic BPs at conscription. Linear-regression analyses showed that systolic BP increased with decreasing GA (regression coefficient -0.31 mm Hg/wk, P<0.001). Systolic and diastolic BPs both increased with decreasing birth weight for GA, but the association with systolic BP was most evident (regression coefficient -0.67 mm Hg per SD score in birth weight for GA, P<0.001). Compared with men born at term (GA, 37 to 41 weeks), the adjusted odd ratios (95% confidence intervals [CIs]) for high systolic BP (> or =140 mm Hg) were as follows: moderately preterm (33 to 36 weeks), 1.25 (1.19 to 1.30); very preterm (29 to 32 weeks), 1.48 (1.30 to 1.68); and extremely preterm (24 to 28 weeks), 1.93 (1.34 to 2.76). Being SGA was associated only with an increased risk of high systolic BP among men born at 33 weeks or later. The risk estimates for high diastolic BP (> or =90 mm Hg) increased with decreasing GA, but the risk reached significance only among men born moderately preterm.

CONCLUSIONS

Preterm birth, a common pregnancy complication, is a risk factor for HBP in young men. The risk of high systolic BP associated with birth weight for GA is modified by GA, suggesting that perinatal contributions to BP elevation later in life may be induced by different biological pathways.

Cortisol and ACTH responses to severe asphyxia in preterm fetal sheep

It has been hypothesized that the hypothalamic-pituitary-adrenal (HPA) axis is immature in the preterm fetus and that this compromises their ability to adapt to hypoxic stress; however, there are few direct data. We therefore examined the effects of asphyxia on HPA responses in chronically instrumented preterm fetal sheep (104 days of gestation; term is 147 days), allocated to a sham control group (n = 7) or 25 min of complete umbilical cord occlusion (n = 8), followed by recovery for 72 h. During umbilical cord occlusion there was a rapid rise in ACTH levels (230.4 +/- 63.5 versus 14.1 +/- 1.8 ng ml(-1) in sham controls, 16-fold) and cortisol levels (7.4 +/- 4.9 versus 0.2 +/- 0.1 ng ml(-1), 31-fold), with further increases after release of cord occlusion. ACTH levels were normalized by 24 h, while plasma cortisol levels returned to sham control values 72 h after asphyxia. Fetal arterial blood pressure was elevated in the first 36 h, with a marked increase in femoral vascular resistance, and correlated positively with cortisol levels after asphyxia (P = 0.05). In conclusion, the preterm fetus shows a brisk, substantial HPA response to severe hypoxia.

Pathophysiology of newborn hypotension outside the transitional period

Hypotension is a common diagnosis in neonatal intensive care units. Although there are epidemiological data for normative blood pressure values in preterm and term infants, the ranges of normal blood pressure where adequate organ perfusion is ensured for different gestational and postnatal ages remain unclear. An understanding of the developmentally regulated differences in the physiology and pathophysiology of the neonatal cardiovascular system in comparison to that of mature subjects is important to formulate an appropriate treatment strategy in neonates with circulatory compromise. This article reviews the current understanding of pathophysiology of hypotension and shock in the neonate beyond the transitional period, focusing on hypovolemia, myocardial dysfunction, abnormal peripheral vasoregulation, and relative or absolute adrenal insufficiency with potentially associated down regulation of adrenergic receptors.

Pretreatment cortisol values may predict responses to hydrocortisone administration for the prevention of bronchopulmonary dysplasia in high-risk infants

OBJECTIVES

To investigate the effect of hydrocortisone treatment on survival without bronchopulmonary dysplasia (BPD) and to study whether serum cortisol concentrations predict the response.

STUDY DESIGN

We performed a randomized, placebo-controlled trial on infants with gestation < or =30 weeks, body weight of 501 to 1250 g, and respiratory failure. Hydrocortisone was started before 36 hours of age and given for 10 days at doses from 2.0 to 0.75 mg/kg per day. Shortly before hydrocortisone treatment, basal and stimulated (ACTH, 0.1 microg/kg) serum cortisols were measured.

RESULTS

The study was discontinued early, because of gastrointestinal perforations in the hydrocortisone group (4/25 vs 0/26, P = .05); 3 of the 4 had received indomethacin/ibuprofen. The incidence of BPD (28% vs placebo 42%, P = 0.28) tended to be lower, and patent ductus arteriosus (36% vs 73%, P = .01) was lower in the hydrocortisone group. The hydrocortisone-treated infants with serum cortisol concentrations above the median had a high risk of gastrointestinal perforation. In infants with cortisol values below the median, hydrocortisone treatment increased survival without BPD.

CONCLUSIONS

Serum cortisol concentrations measured shortly after birth may identify those very high-risk infants who may benefit from hydrocortisone supplementation.

Glucose homeostasis in the newborn

Hepatic glucose production by glycogenolysis and gluconeogenesis is essential to maintain blood glucose levels, and the glucose-6-phosphatase system catalyses the terminal step of both pathways. Developmental delays in the postnatal up-regulation of hepatic glucose-6-phosphatase enzyme activity are common in preterm infants. Two groups of infants have been identified with failure of developmental regulation of glucose homeostasis. Firstly, up to 20% of preterm infants about to be discharged home are at risk of hypoglycaemia if a feed is delayed. Cortisol, corticotrophin and epinephrine levels are higher in the infants with severe and persistent hypoglycaemia, but insulin, glucagon and human growth hormone do not differ from normoglycaemic infants. Secondly, preterm infants with an inadequate glycaemic response to glucagon (30% at the time of discharge home) have relative fasting hyperglycaemia, hyperinsulinaemia, increased insulin:glucagon ratios and a lower insulin sensitivity index. Hormonal dysfunctions in preterm infants may contribute to failures in postnatal expression of hepatic enzymes.

Prophylaxis of early adrenal insufficiency to prevent bronchopulmonary dysplasia: a multicenter trial

BACKGROUND

Infants developing bronchopulmonary dysplasia (BPD) show decreased cortisol response to adrenocorticotropic hormone. A pilot study of low-dose hydrocortisone therapy for prophylaxis of early adrenal insufficiency showed improved survival without BPD at 36 weeks' postmenstrual age, particularly in infants exposed to histologic chorioamnionitis.

METHODS

Mechanically ventilated infants with birth weights of 500 to 999 g were enrolled into this multicenter, randomized, masked trial between 12 and 48 hours of life. Patients received placebo or hydrocortisone, 1 mg/kg per day for 12 days, then 0.5 mg/kg per day for 3 days. BPD at 36 weeks' postmenstrual age was defined clinically (receiving supplemental oxygen) and physiologically (supplemental oxygen required for O2 saturation > or =90%).

RESULTS

Patient enrollment was stopped at 360 patients because of an increase in spontaneous gastrointestinal perforation in the hydrocortisone-treated group. Survival without BPD was similar, defined clinically or physiologically, as were mortality, head circumference, and weight at 36 weeks. For patients exposed to histologic chorioamnionitis (n = 149), hydrocortisone treatment significantly decreased mortality and increased survival without BPD, defined clinically or physiologically. After treatment, cortisol values and response to adrenocorticotropic hormone were similar between groups. Hydrocortisone-treated infants receiving indomethacin had more gastrointestinal perforations than placebo-treated infants receiving indomethacin, suggesting an interactive effect.

CONCLUSIONS

Prophylaxis of early adrenal insufficiency did not improve survival without BPD in the overall study population; however, treatment of chorioamnionitis-exposed infants significantly decreased mortality and improved survival without BPD. Low-dose hydrocortisone therapy did not suppress adrenal function or compromise short-term growth. The combination of indomethacin and hydrocortisone should be avoided.