Refractory hypotension in preterm infants with adrenocortical insufficiency

Corticosteroid use in neonatal hypotension: A survey of Canadian neonatologists

OBJECTIVE

To assess prescribing practices and perspectives regarding the use of corticosteroids in the management of neonatal hypotension.

METHODS

Cross-sectional questionnaire-based electronic survey of neonatologists (n = 206) practicing at tertiary neonatal intensive care units across 30 academic centres in Canada.

RESULTS

The overall response rate was 33% (72/206), with a completion rate was 94%. Most (48/72, 64%) worked in a unit that covered both inborn and outborn infants, and 53% (37/70) worked in units with >100 very low birth weight infants admitted annually. Among the 72 respondents, 39% use a loading dose, of whom most (57%) use 2 mg/kg. Dosing ranges were variable, most using either 0.5 mg/kg or 1 mg/kg, q6h. Among the 56% (40/72) of neonatologists who reported measuring cortisol before initiation of hydrocortisone, cut-offs for initiation of hydrocortisone varied from <100 to <500 nmol/L, most of whom (48%) used <100 nmol/L. Of 71 respondents, 92% (65) indicated that a randomized control trial examining the use of corticosteroids in neonatal hypotension is needed, of whom 52% (37) indicated that the intervention group should receiving hydrocortisone after one vasopressor/inotrope.

CONCLUSIONS

This survey provides insight into the prescribing practices of tertiary neonatologists with regards to the use of corticosteroids in neonatal hypotension. While corticosteroids are frequently prescribed, there is variability in the indication, dosing, and duration of corticosteroid use. The findings from this survey can be used to inform further research, including a clinical trial, regarding the practice in the management of neonatal hypotension.

Impact of postnatal steroids on peripheral avascular retina and severity of retinopathy of prematurity

BACKGROUND

We investigated the role of postnatal steroids on the severity of retinopathy of prematurity (ROP) and its impact on peripheral avascular retina (PAR).

METHODS

A retrospective cohort study of infants born at ≤32 weeks gestation and/or birth weight ≤1500 g. Demographics, the dose and duration of steroid treatment, and age when full retinal vascularization occurred were collected. The primary outcomes were the severity of ROP and time to full vascularization of the retina.

RESULTS

A total of 1695 patients were enrolled, 67% of whom received steroid therapy. Their birth weight was 1142 ± 396 g and gestational age was 28.6 ± 2.7 weeks. The total hydrocortisone-equivalent dose prescribed was 28.5 ± 74.3 mg/kg. The total days of steroid treatment were 8.9 ± 35.1 days. After correction for major demographic differences, infants who received a higher cumulative dose of steroids for a longer duration had a significantly increased incidence of severe ROP and PAR (P < 0.001). For each day of steroid treatment, there was a 3.2% increase in the hazard of the severe form of ROP (95% CI: 1.022-1.043) along with 5.7% delay in achieving full retinal vascularization (95% CI: 1.04-1.08) (P < 0.001).

CONCLUSION

Cumulative dose and duration of postnatal steroid use were independently associated with the severity of ROP and PAR. Thus, postnatal steroids should be used very prudently.

IMPACT

We report ROP outcomes in a large cohort of infants from two major healthcare systems where we have studied the impact of postnatal steroids on the severity of ROP, growth, and development of retinal vessels. After correcting our data for three major outcome measures, we show that high-dose postnatal steroids used for a prolonged duration of time are independently associated with severe ROP and delay in retinal vascularization. Postnatal steroids impact the visual outcomes of VLBW infants significantly, so their clinical use needs to be moderated.

Hemodynamic dysfunction in neonatal sepsis

Cardiovascular disturbances are a frequent occurrence in neonatal sepsis. Preterm and term infants are particularly vulnerable due to the unique features of their cardiovascular function and reserve, compared to older children and adults. The clinical manifestations of neonatal sepsis are a product of the variable inflammatory pathways involved (warm vs. cold shock physiology), developmental state of the cardiovascular system, and hormonal responses. Targeted neonatal echocardiography has played an important role in advancing our knowledge, may help delineate specific hemodynamic phenotypes in real-time, and supports an individualized physiology-based management of sepsis-associated cardiovascular dysfunction. IMPACT: Cardiovascular dysfunction is a common sequela of sepsis. This review aims to highlight the pathophysiological mechanisms involved in hemodynamic disturbance in neonatal sepsis, provide insights from targeted neonatal echocardiography-based clinical studies, and suggest its potential incorporation in day-to-day management.

Antenatal Glucocorticoids Reduce the Incidence of Refractory Hypotension in Low Birthweight Infants during the Early Neonatal Period, but Do Not Affect It beyond This Time

OBJECTIVE

This study aimed to clarify the effect of antenatal glucocorticoids (AGs) on the incidence of refractory hypotension (RH) in very low birthweight (VLBW) infants after the first week of life.

STUDY DESIGN

We included VLBW infants born at a gestational age of <30 weeks and divided them into three groups: the complete group (born within 7 days of completing a single course [two doses] of AGs), the incomplete group (born without complete course), and the late delivery group (born at ≥8 days after a single course). We compared the incidence and period of onset of RH among the three groups.

RESULTS

A total of 115 infants were enrolled. The incidence of RH in the first week of life was significantly lower in the complete group than in the other groups. However, there was no significant difference in the incidence of RH after the first week of life among the groups.

CONCLUSION

AGs contribute to circulatory stabilization during the first week of life, but this effect does not last after 1 or 2 weeks of administration. In infants who receive AGs, physicians should consider that the risk of RH after the first week of life is not low.

Development and Validation of a Dynamic Nomogram to Predict the Risk of Neonatal White Matter Damage

Purpose

White matter damage (WMD) was defined as the appearance of rough and uneven echo enhancement in the white matter around the ventricle. The aim of this study was to develop and validate a risk prediction model for neonatal WMD.

Materials and Methods

We collected data for 1,733 infants hospitalized at the Department of Neonatology at The First Affiliated Hospital of Zhengzhou University from 2017 to 2020. Infants were randomly assigned to training (n = 1,216) or validation (n = 517) cohorts at a ratio of 7:3. Multivariate logistic regression and least absolute shrinkage and selection operator (LASSO) regression analyses were used to establish a risk prediction model and web-based risk calculator based on the training cohort data. The predictive accuracy of the model was verified in the validation cohort.

Results

We identified four variables as independent risk factors for brain WMD in neonates by multivariate logistic regression and LASSO analysis, including gestational age, fetal distress, prelabor rupture of membranes, and use of corticosteroids. These were used to establish a risk prediction nomogram and web-based calculator (https://caowenjun.shinyapps.io/dynnomapp/). The C-index of the training and validation sets was 0.898 (95% confidence interval: 0.8745-0.9215) and 0.887 (95% confidence interval: 0.8478-0.9262), respectively. Decision tree analysis showed that the model was highly effective in the threshold range of 1-61%. The sensitivity and specificity of the model were 82.5 and 81.7%, respectively, and the cutoff value was 0.099.

Conclusion

This is the first study describing the use of a nomogram and web-based calculator to predict the risk of WMD in neonates. The web-based calculator increases the applicability of the predictive model and is a convenient tool for doctors at primary hospitals and outpatient clinics, family doctors, and even parents to identify high-risk births early on and implementing appropriate interventions while avoiding excessive treatment of low-risk patients.

Corticosteroids for Neonatal Hypotension

Several limitations and controversies surround the definition of hypotension; however, it remains one of the most common problems faced by neonates. Approximately 15% to 30% of neonates with hypotension fail to respond to volume and/or vasopressor or inotropes. They are considered to have refractory hypotension. Although it is thought to have multiple causes, absolute and relative adrenal insufficiency is considered as the main reason for refractory hypotension. This article focuses on the role of adrenal insufficiency in causing refractory hypotension in preterm and term infants, the different options of corticosteroids available, and their risk/benefit profiles.

Cortisol production in preterm infants with or without late-onset adrenal insufficiency of prematurity: A prospective observational study

BACKGROUND

Immature adrenocortical function in preterm infants may cause inadequate production of cortisol under stress, resulting in adrenal insufficiency of prematurity (AOP). The objective of this study is to compare cortisol production in preterm infants with and without late-onset AOP.

METHODS

Of 27 preterm infants born at less than 32 weeks gestation, cortisol production was analyzed in those who did (patients, group P) and did not (controls, group C) eventually develop late-onset AOP. Blood samples were prospectively collected every two weeks after birth, and steroid hormone concentrations in the pathway to cortisol production were measured retrospectively.

RESULTS

We restricted the initial subjects to infants with gestation less than 29 weeks to adjust for confounding factors, culminating in matched infants in groups P (n = 8) and C (n = 11). The cortisol concentrations did not differ between the groups before AOP onset (P = 0.20), but the total concentrations of precursors for cortisol were higher in group P (P < 0.0001). The total concentrations of precursors in group C were inversely correlated with postmenstrual age (ρ = -0.38, P < 0.01). The pattern of changes in total concentrations of precursors differed between the groups (P < 0.05).

CONCLUSION

Adrenal cortex maturity in preterm infants develops in parallel with postmenstrual age. Infants with late-onset AOP have undeveloped maturation of adrenocortical function after birth.

CLINICAL TRIAL REGISTRATION

UMIN000022453.

Future perspectives on the use of deformation analysis to identify the underlying pathophysiological basis for cardiovascular compromise in neonates

The assessment of the wellbeing of the cardiovascular status in premature infants has come to the forefront in recent years. There is an increasing realisation that myocardial performance, systemic blood flow and end-organ perfusion (particularly during the transitional period) play an important role in determining short and long-term outcomes in this population. The recent open access series on Neonatologist Performed Echocardiography (NPE) published in this journal outline the necessary techniques for image acquisition and analysis and provide a framework for the potential clinical applications of NPE in neonatal, and specifically preterm care. In this "Future Perspectives" review, we describe the important determinants of adequate cellular metabolism and myocardial performance (e.g. loading conditions, intrinsic contractility and morphological change), we discuss the maladaptive state of the preterm cardiovascular system, and highlight the emerging role that non-invasive echocardiography techniques, such as deformation analysis, serve in identifying the underlying physiological basis for cardiovascular instability.

Novel method of measuring chronic stress for preterm infants: Skin cortisol

BACKGROUND AND OBJECTIVES

Infants who begin life in the medicalized environment of the neonatal intensive care unit (NICU) do so under stressful conditions. Environmental exposures are often abrasive to vulnerable infants, while invasive and noninvasive lifesaving interventions provide additional pain and/or stress. The most commonly selected biomarker to measure stress is cortisol. The skin is the barrier between the external environment and communicates with our neurological, endocrine and immune regulatory networks. To examine if skin cortisol may be a reliable biomarker of stress, NICU stress exposure and repeated measurements of skin cortisol in very preterm infants were examined retrospectively during the first 6 weeks of life. The temporal relationship between skin cortisol and NICU stress exposure was also analyzed.

MATERIALS AND METHODS

Participants included 82 preterm infants born weighing less than 1500 g, admitted to a level III NICU, with a mean gestational age of 28.5 weeks. Infants were studied from birth through 6 weeks of life. NICU stress data was collected using the Neonatal Infant Stressor Scale. Skin samples were collected using d-squame tape as soon after birth as possible and every two weeks thereafter.

RESULTS

On average, infants experienced approximately 43 stressful events per day during the first 6 weeks of life in the NICU. Stress level and cortisol reactivity varied by gestation age. Higher stress resulted in higher cortisol for infant >28 weeks; lower stress scores were associated with higher stress for infants <28 weeks. Stress exposure during 7 days prior to cortisol sampling yielded the highest AUC for the 2 groups. A statistically significant interaction was identified between gestational age and stress exposure during the previous 7 days (p < 0.01).

CONCLUSION

This is the first study to demonstrate skin cortisol as a preterm infant biomarker of chronic stress exposure. For infants with appropriate skin maturation, this non-invasive sampling method provides several benefits. Importantly, this method may be less intrusive and disruptive for preterm infants.

Hyperdehydroepiandrosterone in neonates with hypoxic ischemic encephalopathy and circulatory collapse

BACKGROUND

Circulatory collapse is a very common complication of the critical illnesses in neonates including neonates with hypoxic ischemic encephalopathy; it can be the end result and cause of death of several conditions. Often, despite treatment with fluid resuscitation and vasopressor agents, circulatory collapse persist, and blood pressure can remain critically low, compromising adequate blood flow to vital organs and brain. Low blood pressure has been associated with increased mortality.

METHOD

To investigate adrenal function in newborn infants who suffer from circulatory collapse during hypoxic ischemic encephalopathy. A total of 30 infants were analyzed in the study: 15 neonates in group A (neonates had hypoxic ischemic encephalopathy with vasopressor resistant hypotension) and 15 neonates in group B (neonates with hypoxic ischemic encephalopathy without vasopressor resistant hypotension). All the studied patients were subjected to history, examinations and laboratory investigation including serum cortisol concentrations and cortisol precursor's levels.

RESULTS

The cortisol concentrations did not differ significantly between the two groups: (12.9 ± 4.3) μg/dL and (12.1 ± 2.4) μg/dL in group A and group B, respectively. There are highly significant differences between groups A and B regarding Dehydroepiandrosterone (342.1 ± 101.3) μg/dL, (33.4 ± 16.5) μg/dL, respectively.

CONCLUSION

In this study, we noticed that cortisol concentrations did not differ between both groups in contrast to the expectation that neonates with critical illnesses should have higher cortisol concentrations than normal neonates. However, the marked increase in dehydroepiandrosterone DHEA may cause decrease cortisol function, so those neonates having accumulation of dehydroepiandrosterone may suffer from manifestation of adrenal insufficiency and vasopressor resistant hypotension in spite of normal cortisol level.

Management of Neonatal Hypotension

Hypotension is a common problem in neonates with complex underlying pathophysiology. Although treatment of low blood pressure is common, clinicians must use all available information to target neonates with compromised perfusion. Pharmacotherapy should be tailored to the specific physiologic perturbations of the individual neonate. Dopamine is the most commonly utilized agent and may be the most appropriate agent for septic shock with low diastolic blood pressure. However, alternative therapies should be considered for other etiologies of hypotension, including milrinone and vasopressin for persistent pulmonary hypertension of the newborn and dobutamine for patent ductus arteriosus. Additional studies are required to refine the approach to neonatal hypotension and document the long-term outcomes of treated neonates.

Cortisol precursors in neonates with vasopressor-resistant hypotension in relationship to demographic characteristics

OBJECTIVE

To correlate between cortisol precursors in neonates with vasopressor resistant hypotension and demographic characteristics.

METHODS

We investigated 48 neonates with vasopressor-resistant hypotension. Gestation at birth ranged from 34 to 42 weeks and postnatal age from 4 to 14 days. Cortisol and precursor steroids were measured soon after the onset of volume expansion and inotropes for treatment of shock. Their concentrations were determined using liquid chromatography/mass spectrometry.

RESULTS

In neonates with vasopressor-resistant hypotension, the serum levels of cortisol were within normal nonstress range. There was a strong negative linear association between postnatal age and dehydroepiandrosterone level (r = -0.50, p < .01), which decreased with neonatal age. In addition, there was a significant positive association between gestational age at birth and 17-hydroxy-pregnenolone (r = 0.33, p = .02). No further significant associations were evident between the neonatal weight, duration of gestation or gender and of the levels of cortisol or the other steroids (p > .05). The cause of therapy-resistant hypotension did not appear to influence the steroid levels.

CONCLUSIONS

Cortisol stress response is absent in these severely ill late preterm and term infants. This may be due to inhibition of the distal pathway of cortisol synthesis.

Hemodynamic Assessment and Monitoring of Premature Infants

The management of the hemodynamic status of critically ill preterm infants, particularly around the periviable period, remains a significant challenge in the neonatal intensive care unit for a multitude of reasons. The causes of hemodynamic compromise in this population are heterogeneous and usually superimposed on the complex physiologic processes that occur during transition from fetal to neonatal life. This review outlines the unique nature of low blood flow states in this population and present an overview of the current methods for identification and assessment of hemodynamic compromise.

Late-onset circulatory collapse of prematurity

Late-onset circulatory collapse (LCC) is a refractory hypotension occurring after the early neonatal period (>day 7), in very low-birthweight infants. Typically, infants stabilized within the early neonatal period develop sudden onset of circulatory collapse after the early neonatal period. The underlying pathophysiology of LCC is considered to be relative adrenal insufficiency, which is well known in Japan, but is not widely accepted in North America or Europe. The current increase in LCC in Japan suggests that the principal trigger is related to recent trends in neonatal medicine and/or newly introduced treatments for preterm infants, but the pathophysiology has not been fully elucidated. In this review, based on current knowledge regarding LCC, the pathophysiology is discussed.

Adrenocortical insufficiency and refractory hypotension in preterm infants

Preterm, very low birthweight (VLBW) infants are prone to life-threatening hypotension secondary to hypothalamic-pituitary-adrenal axis immaturity, resulting in adrenocortical insufficiency. Clinical presentations of inotrope-resistant refractory hypotension are usually evident, but interpretation of serum cortisol may pose much difficulty to front-line neonatologists. This review examines the salient pathophysiology of adrenocortical insufficiency in the immediate postnatal period, characterises its endocrinological abnormalities, and describes the typical and variant clinical presentations. Based on existing evidence, a practical scheme is proposed for logical interpretation of circulating cortisol levels and management of inotrope-resistant refractory hypotension in VLBW infants.

Term neonates with infection and shock display high cortisol precursors despite low levels of normal cortisol

AIM

Neonatal therapy-resistant septic shock is a common problem in middle and low-income countries. We investigated whether newborn infants with infection and therapy-resistant hypotension showed evidence of abnormal levels of cortisol or cortisol precursors.

METHODS

A total of 60 term or near term neonates with evidence of infection were enrolled after informed consent. Of these, 30 had an infection and refractory shock and 30 had an infection without shock. There were no detectable differences between the groups in the length of gestation, birth weight or gender distribution. Serum was obtained during days four and 14 after birth. Cortisol and cortisol precursor concentrations were analysed using liquid chromatography-tandem mass spectrometry.

RESULTS

The cortisol concentrations were low considering the expected responses to stress and they did not differ between the groups. The infants with infection and shock had higher serum dehydroepiandrosterone (DHEA) levels than those without shock (319.0 ± 110.3 μg/dL, versus 22.3 ± 18.3 μg/dL; p < 0.0001) and they also had higher 17-hydroxy-pregnenolone, pregnenolone and progesterone concentrations. There were no detectable differences in the levels of 17-hydroxy-progesterone, 11-deoxy-cortisol, cortisol or cortisone.

CONCLUSION

Septic newborn infants with therapy-resistant hypotension had very high DHEA levels, suggesting that 3-beta-hydroxysteroid dehydrogenase activity limited the rate of cortisol synthesis.

Steroids Improve Hemodynamics in Infants With Adrenal Insufficiency After Cardiac Surgery

OBJECTIVE

To investigate whether steroid replacement therapy improved hemodynamics in infants after surgery for congenital heart disease only when they develop adrenal insufficiency. The authors retrospectively investigated adrenal function and evaluated hemodynamic responses to steroid replacement therapy in infants after surgery for congenital heart disease.

DESIGN

Retrospective, cohort study.

SETTING

Intensive care unit in the National Cerebral and Cardiovascular Center Hospital in Japan.

PATIENTS

Thirty-two neonates and infants<3 months old who underwent cardiovascular surgery.

INTERVENTIONS

The patients were divided into 2 groups based on corticotropin stimulation test results: group AI with adrenal insufficiency (baseline cortisol<15 µg/dL or incremental increase after testing of<9 µg/dL, with baseline cortisol of 15-34 µg/dL); and group N with normal adrenal function. The corticotropin stimulation test was performed by injecting 3.5 µg/kg of tetracosactide acetate. Hydrocortisone (1 mg/kg) was administered every 6 hours, and hemodynamics were compared before and after steroid administration between the groups.

MEASUREMENTS AND MAIN RESULTS

Seven patients were classified into group AI, and demonstrated a mean blood pressure increase from 53±8 mmHg before treatment to 68±9 mmHg 18 hours after steroid administration (p<0.01). Urine output also increased, from 2.7±1.0 mL/kg/h to 4.8±1.9 mL/kg/h (p<0.05). In group N, neither mean blood pressure nor urine output increased after steroid administration.

CONCLUSIONS

After surgery for congenital heart disease, one-fifth of infants developed adrenal insufficiency. Steroid replacement therapy improved hemodynamics only in the subgroup with adrenal insufficiency.

Adrenal and thyroid function in the fetus and preterm infant

Adrenal and thyroid hormones are essential for the regulation of intrauterine homeostasis, and for the timely differentiation and maturation of fetal organs. These hormones play complex roles during fetal life, and are believed to underlie the cellular communication that coordinates maternal-fetal interactions. They serve to modulate the functional adaptation for extrauterine life during the perinatal period. The pathophysiology of systemic vasopressor-resistant hypotension is associated with low levels of circulating cortisol, a result of immaturity of hypothalamic-pituitary-adrenal axis in preterm infants under stress. Over the past few decades, studies in preterm infants have shown abnormal clinical findings that suggest adrenal or thyroid dysfunction, yet the criteria used to diagnose adrenal insufficiency in preterm infants continue to be arbitrary. In addition, although hypothyroidism is frequently observed in extremely low gestational age infants, the benefits of thyroid hormone replacement therapy remain controversial. Screening methods for congenital hypothyroidism or congenital adrenal hyperplasia in the preterm neonate are inconclusive. Thus, further understanding of fetal and perinatal adrenal and thyroid function will provide an insight into the management of adrenal and thyroid function in the preterm infant.

Postnatal epigenetic modification of glucocorticoid receptor gene in preterm infants: a prospective cohort study

OBJECTIVE

To examine the environmental effects on cytosine methylation of preterm infant's DNA, because early life experiences are considered to influence the physiological and mental health of an individual through epigenetic modification of DNA.

DESIGN

A prospective cohort study, comparison of epigenetic differences in the glucocorticoid receptor (GR) gene between healthy term and preterm infants.

SETTING

Neonatal Intensive Care Unit in a Japanese University Hospital.

PARTICIPANTS

A cohort of 40 (20 term and 20 preterm) infants was recruited on the day of birth, and peripheral blood was obtained from each infant at birth and on postnatal day 4.

MAIN OUTCOME MEASURES

The methylation rates in the 1-F promoter region of the GR gene using the Mquant method.

RESULTS

The methylation rate increased significantly between postnatal days 0 and 4 in preterm infants but remained stable in term infants. Thus, the methylation rate was significantly higher in preterm than in term infants at postnatal day 4. Several perinatal parameters were significantly correlated with this change in the methylation rate. Logistic regression analysis revealed that methylation rates at postnatal day 4 predicted the occurrence of later complications that required glucocorticoid administration during the neonatal period. No gene polymorphism was detected within the GR promoter region analysed.

CONCLUSIONS

Although further large-scale studies are needed to detect the environmental factors that explain the difference in epigenetic modification among infants after birth, our data show that the postnatal environment influences epigenetic programming of GR expression through methylation of the GR gene promoter in premature infants, which may result in relative glucocorticoid insufficiency during the postnatal period.

Hypotension following patent ductus arteriosus ligation: the role of adrenal hormones

OBJECTIVE

To test the hypothesis that an impaired adrenal response to stress might play a role in the hypotension that follows patent ductus arteriosus (PDA) ligation.

STUDY DESIGN

We performed a multicenter study of infants born at <32 weeks' gestation who were about to undergo PDA ligation. Serum adrenal steroids were measured 3 times: before and after a cosyntropin (1.0 μg/kg) stimulation test (performed before the ligation), and at 10-12 hours after the ligation. A standardized approach for diagnosis and treatment of postoperative hypotension was followed at each site. A modified inotrope score (1 × dopamine [μg/kg/min] + 1 × dobutamine) was used to monitor the catecholamine support an infant received. Infants were considered to have catecholamine-resistant hypotension if their greatest inotrope score was >15.

RESULTS

Of 95 infants enrolled, 43 (45%) developed hypotension and 14 (15%) developed catecholamine-resistant hypotension. Low postoperative cortisol levels were not associated with the overall incidence of hypotension after ligation. However, low cortisol levels were associated with the refractoriness of the hypotension to catecholamine treatment. In a multivariate analysis: the OR for developing catecholamine-resistant hypotension was OR 36.6, 95% CI 2.8-476, P = .006. Low cortisol levels (in infants with catecholamine-resistant hypotension) were not attributable to adrenal immaturity or impairment; their cortisol precursor concentrations were either low or unchanged, and their response to cosyntropin was similar to infants without catecholamine-resistant hypotension.

CONCLUSION

Infants with low cortisol concentrations after PDA ligation are likely to develop postoperative catecholamine-resistant hypotension. We speculate that decreased adrenal stimulation, rather than an impaired adrenal response to stimulation, may account for the decreased production.

Using in vitro high throughput screening assays to identify potential endocrine-disrupting chemicals

BACKGROUND

Over the past 20 years, an increased focus on detecting environmental chemicals that pose a risk of adverse effects due to endocrine disruption has driven the creation of the U.S. Environmental Protection Agency (EPA) Endocrine Disruptor Screening Program (EDSP). Thousands of chemicals are subject to the EDSP; thus, processing these chemicals using current test batteries could require millions of dollars and decades. A need for increased throughput and efficiency motivated the development of methods using in vitro high throughput screening (HTS) assays to prioritize chemicals for EDSP Tier 1 screening (T1S).

OBJECTIVE

In this study we used U.S. EPA ToxCast HTS assays for estrogen, androgen, steroidogenic, and thyroid-disrupting mechanisms to classify compounds and compare ToxCast results to in vitro and in vivo data from EDSP T1S assays.

METHOD

We implemented an iterative model that optimized the ability of endocrine-related HTS assays to predict components of EDSP T1S and related results. Balanced accuracy was used as a measure of model performance.

RESULTS

ToxCast estrogen receptor and androgen receptor assays predicted the results of relevant EDSP T1S assays with balanced accuracies of 0.91 (p < 0.001) and 0.92 (p < 0.001), respectively. Uterotrophic and Hershberger assay results were predicted with balanced accuracies of 0.89 (p < 0.001) and 1 (p < 0.001), respectively. Models for steroidogenic and thyroid-related effects could not be developed with the currently published ToxCast data.

CONCLUSIONS

Overall, results suggest that current ToxCast assays can accurately identify chemicals with potential to interact with the estrogenic and androgenic pathways, and could help prioritize chemicals for EDSP T1S assays.

Challenges in understanding the impact of blood pressure management on cerebral oxygenation in the preterm brain

Systemic hypotension in preterm infants has been related to increased mortality, cerebrovascular lesions, and neurodevelopmental morbidity. Treatment of hypotension with inotropic medications aims at preservation of end organ perfusion and oxygen delivery, especially the brain. The common inotropic medications in preterm infants include dopamine, dobutamine, adrenaline, with adjunctive use of corticosteroids in cases of refractory hypotension. Whether maintenance of mean arterial blood pressure (MAP) by use of inotropic medication is neuroprotective or not remains unclear. This review explores the different inotropic agents and their effects on perfusion and oxygenation in the preterm brain, in clinical studies as well as in animal models. Dopamine and adrenalin, because of their α-adrenergic vasoconstrictor actions, have raised concerns of reduction in cerebral blood flow (CBF). Several studies in hypotensive preterm infants have shown that dopamine elevates CBF together with increased MAP, in keeping with limited cerebro-autoregulation. Adrenaline is also effective in raising cerebral perfusion together with MAP in preterm infants. Experimental studies in immature animals show no cerebro-vasoconstrictive effects of dopamine or adrenaline, but demonstrate the consistent findings of increased cerebral perfusion and oxygenation with the use of dopamine, dobutamine, and adrenaline, alongside with raised MAP. Both clinical and animal studies report the transitory effects of adrenaline in increasing plasma lactate, and blood glucose, which might render its use as a 2nd line therapy. To investigate the cerebral effects of inotropic agents in long-term outcome in hypotensive preterm infants, carefully designed prospective research possibly including preterm infants with permissive hypotension is required. Preterm animal models would be useful in investigating the relationship between the physiological effects of inotropes and histopathology outcomes in the developing brain.

Corticosteroids for treating hypotension in preterm infants

BACKGROUND

Systemic hypotension is a relatively common complication of preterm birth and is associated with periventricular haemorrhage, periventricular white matter injury and adverse neurodevelopmental outcome. Corticosteroid treatment has been used as an alternative or an adjunct to conventional treatment with volume expansion and vasopressor/inotropic therapy.

OBJECTIVES

To determine the effectiveness and safety of corticosteroids used either as primary treatment of hypotension or for the treatment of refractory hypotension in preterm infants.

SEARCH METHODS

Randomized or quasi-randomised controlled trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2011), MEDLINE (1996 to Jan 2011), EMBASE (1974 to Jan 2011), CINAHL (1981 to 2011), reference lists of published papers and abstracts from the Pediatric Academic Societies and the European Society for Pediatric Research meetings published in Pediatric Research (1995 to 2011).

SELECTION CRITERIA

We included all randomised or quasi-randomised controlled trials investigating the effect of corticosteroid therapy in the treatment of hypotension in preterm infants (< 37 weeks gestation) less than 28 days old. Studies using corticosteroids as primary treatment were included as well as studies using corticosteroids in babies with hypotension resistant to inotropes/pressors and volume therapy. We included studies comparing oral/intravenous corticosteroids with placebo, other drugs used for providing cardiovascular support or no therapy in this review.

DATA COLLECTION AND ANALYSIS

Methodological quality of eligible studies was assessed according to the methods used for minimising selection bias, performance bias, attrition bias and detection bias. Studies that evaluated corticosteroids (1) as primary treatment for hypotension or (2) for refractory hypotension unresponsive to prior use of inotropes/pressors and volume therapy, were analysed using separate comparisons. Data were analysed using the standard methods of the Neonatal Review Group using Rev Man 5.1.2. Treatment effect was analysed using relative risk, risk reduction, number needed to treat for categorical outcomes and weighted mean difference for outcomes measured on a continuous scale, with 95% confidence intervals.

MAIN RESULTS

Four studies were included in this review enrolling a total of 123 babies. In one study, persistent hypotension was more common in hydrocortisone treated infants as compared to those who received dopamine as primary treatment for hypotension (RR 8.2, 95% CI 0.47 to 142.6; RD 0.19, 95% CI 0.01 to 0.37). In two studies comparing steroid versus placebo, persistent hypotension (defined as a continuing need for inotrope infusion) was less common in steroid treated infants as compared to controls who received placebo for refractory hypotension (RR 0.35, 95% CI 0.19 to 0.65; RD -0.47, 95% CI - 0.68 to - 0.26; NNT = 2.1, 95% CI 1.47, 3.8). There were no statistically significant effects on any other short or long-term outcome. A further two studies that have only been published in abstract form to date, may be eligible for inclusion in a future update of this review.

AUTHORS' CONCLUSIONS

Hydrocortisone may be as effective as dopamine when used as a primary treatment for hypotension. But the long term safety data on the use of hydrocortisone in this manner is unknown.Steroids are effective in treatment of refractory hypotension in preterm infants without an increase in short term adverse consequences. However, long term safety or benefit data is lacking. With long term benefit or safety data lacking steroids cannot be recommended routinely for the treatment of hypotension in preterm infants.

Effects of low-dose hydrocortisone therapy on immune function in neonatal horses

Low-dose hydrocortisone (LDHC) therapy modulates inflammatory responses in adults and improves outcomes in some septic adults and neonates, but its immunologic effects have not been evaluated in neonates. The objective of this study was to evaluate effects of LDHC therapy on ex vivo immune function in neonatal horses (foals). We hypothesized that LDHC treatment would dampen proinflammatory responses without impairing neutrophil function. Hydrocortisone (1.3 mg/kg/d i.v.) was administered to foals in a tapering 3.5 d course. Peripheral blood leukocytes were collected from foals before, during, and after hydrocortisone treatment. A separate group of age-matched untreated foals served as controls. Endotoxin-induced peripheral blood mononuclear cell gene expression of inflammatory cytokines was measured by real-time quantitative RT-PCR. Neutrophils were incubated with labeled, killed Staphylococcus aureus or Escherichia coli for assessment of phagocytosis, and with phorbol myristate acetate, zymosan, or endotoxin for measurement of reactive oxygen species (ROS) production. Neutrophil phagocytosis and ROS production were similar in both groups. Foals receiving hydrocortisone had significantly decreased endotoxin-induced expression of TNF-α, IL-6, IL-8, and IL-1β. These data suggest that this LDHC treatment regimen ameliorates endotoxin-induced proinflammatory cytokine expression in neonatal foals without impairing innate immune responses needed to combat bacterial infection.

A prospective longitudinal study to estimate the "adjusted cortisol percentile" in preterm infants

The normal range of serum cortisol concentrations and the appropriate levels of circulating cortisol in different clinical situations in preterm infants are not well defined. This study aimed to evaluate the impact of perinatal factors on circulating cortisol levels in preterm infants and to create a quantitative model that could estimate the "adjusted cortisol percentile." Serial serum cortisol concentrations were measured in 209 infants ≤ 32 wk gestation on d 1, 4, 7, 14, and 21 of life. Seven perinatal factors or conditions that could affect circulating cortisol level were identified. Serum cortisol levels were higher on d 4 (p = 0.007) and d 7 (p = 0.007) but lower on d 21 (p = 0.001) compared with d 1. Serum cortisol was also higher in infants on nasal continuous positive airway pressure (p = 0.003); requiring a second vasopressor (p < 0.001); with intraventricular hemorrhage (≥ grade 3; p < 0.001); with histologic chorioamnionitis (p = 0.007); with severe lung disease (p = 0.046); and with decreasing GA (p < 0.001). A mathematical equation was proposed based on factors derived in this preliminary study for estimating the adjusted cortisol percentile. Frontline neonatologists could now access the equation on our Web site (http://www.sta.cuhk.edu.hk/pswong/ACortP.html) to calculate the adjusted cortisol percentile, which could potentially improve the interpretation of circulating cortisol in different clinical situations.

Effect of stress on the hypothalamic-pituitary-adrenal axis in the fetus and newborn

The hypothalamic-pituitary-adrenal (HPA) axis is essential for maintaining homeostasis in the fetus and newborn. A proportion of extremely preterm infants suffer from transient adrenocortical insufficiency of prematurity. Although these infants have suboptimal adrenocortical response to stress in the first week of life, the HPA axis adapts rapidly, and most exhibit an adequate response by day 14. An attenuated cortisol response in preterm infants might be protective against intracranial bleeding. Severe hypoxic-ischemic encephalopathy is a potent stimulus to the HPA axis. Chronic intrauterine hypoxemia can up-regulate the setpoint of the HPA axis and augments adrenal steroidogenic production, resulting in sustained elevation of circulating cortisol levels.

Adrenal function in newborns undergoing surgery

OBJECTIVE

To measure cortisol, adrenocorticotropic hormone (ACTH)-stimulated cortisol and ACTH values in the newborn intensive care unit-admitted newborn infants within 48 h before surgery and to describe the relationship of these values to measures of clinical illness before and after surgery.

STUDY DESIGN

In this prospective observational study, we measured baseline and ACTH-stimulated cortisol concentrations within 48 h before surgery in newborn infants <44 weeks postmenstrual age and examined the relationship of these values to measures of illness severity both before and after surgery, including the score for neonatal acute physiology (SNAP) and use of vasopressors. ACTH concentrations were measured in a subset of the infants.

RESULT

Twenty-five infants were enrolled and had median (25th to 75th percentile) baseline and ACTH-stimulated cortisol values of 7.1 (3.5 to 11.1) and 40.4 mcg per 100 ml (22.6 to 50.6). Preterm infants had significantly lower ACTH-stimulated cortisol values (median 21.6 vs 44.7 mcg per 100 ml). There was no correlation between any of these values and either the presurgical or postsurgical measures of illness severity, nor the increase in SNAP after surgery. Infants receiving vasopressors perioperatively had lower median ACTH-stimulated cortisol values (22.6 vs 44.7 mcg per 100 ml).

CONCLUSION

Presurgical cortisol values do not predict clinical response to surgical stress as measured by severity of illness scores but lower values were associated with vasopressor therapy. Further investigation would be required to determine how cortisol values are related to outcome and whether perioperative glucocorticoid supplementation would be beneficial in this population.

Clinical characterization and long-term prognosis of neurological development in preterm infants with late-onset circulatory collapse

OBJECTIVE

To characterize the risk factors for late-onset circulatory collapse (LCC) in preterm infants responsive to corticosteroid therapy and evaluate the long-term neurological prognosis.

STUDY DESIGN

A retrospective case-control study for preterm infants (≤32 weeks' gestation) admitted to our neonatal intensive care unit from 1994 through 2002.

RESULT

Sixty-five infants (11%) were diagnosed with LCC. Infants with a shorter gestation and lower birth weight had a higher incidence of LCC. LCC infants had a significantly lower 1-min Apgar score, significantly higher incidence of severe intraventricular hemorrhage, chronic lung disease, and postnatal periventricular leukomalacia, and significantly longer duration of ventilation use, oxygen use, and hospital stay. Somatic growth at 36 weeks' postmenstrual age was poorer in infants with LCC than without LCC (controls). LCC infants were significantly more likely than controls to have cerebral palsy at 3 years.

CONCLUSION

LCC is associated with poor neurodevelopmental outcomes. Prevention of LCC can lead to improved neurological prognoses.

Serum cortisol values, superior vena cava flow and illness severity scores in very low birth weight infants

OBJECTIVE

Recent evidence suggests that high cortisol concentrations are associated with increased morbidity and mortality in very low birth weight (VLBW) infants. Neonatal illness severity and mortality risk scores are reliable in predicting morbidity and mortality. The objectives were (i) to assess the correlation between serum cortisol levels and clinical assessment of multi-organ dysfunction/illness severity scores (CRIB II, SNAPPE-II and neonatal multiple organ dysfunction score (NEOMOD)) in first 24 h in VLBW infants and (ii) to assess the relationship between surrogates of end organ blood flow and serum cortisol levels.

STUDY DESIGN

A prospective observational cohort study. Neonates with birth weight <1500 g were eligible for enrollment. Echocardiography evaluation of superior vena cava (SVC) flow was carried out in the first 24 h life. Cortisol levels were measured simultaneously and appropriate clinical scores were calculated.

RESULT

A total of 54 VLBW neonates were enrolled following parental consent. Two patients were excluded because of congenital malformations. In 14 babies the cortisol value was not simultaneously obtained. The mean birth weight was 1.08 kg, mean gestational age was 27.8 weeks. There was a significant correlation between cortisol and NEOMOD score (P=0.006). There was no correlation between cortisol and CRIB II score (P=0.34), SVC flow (P=0.49) and mean arterial blood pressure respectively (P=0.35).

CONCLUSION

There was no correlation between SVC flow and cortisol values or between cortisol and mean blood pressure values. There was a significant correlation between cortisol levels and neonatal organ dysfunction score evaluated suggesting that stressed VLBW infants do mount a cortisol response.

Pathophysiology and treatment of septic shock in neonates

Neonatal septic shock is a devastating condition associated with high morbidity and mortality. Definitions for the sepsis continuum and treatment algorithms specific for premature neonates are needed to improve studies of septic shock and assess benefit from clinical interventions. Unique features of the immature immune system and pathophysiologic responses to sepsis, particularly those of extremely preterm infants, necessitate that clinical trials consider them as a separate group. Keen clinical suspicion and knowledge of risk factors will help to identify those neonates at greatest risk for development of septic shock. Genomic and proteomic approaches, particularly those that use very small sample volumes, will increase our understanding of the pathophysiology and direct the development of novel agents for prevention and treatment of severe sepsis and shock in the neonate. Although at present antimicrobial therapy and supportive care remain the foundation of treatment, in the future immunomodulatory agents are likely to improve outcomes for this vulnerable population.

Hydrocortisone for hypotension and vasopressor dependence in preterm neonates: a meta-analysis

BACKGROUND

A full consensus has not been reached about the hemodynamic efficacy of hydrocortisone administration in hypotensive and vasopressor-dependent preterm neonates.

OBJECTIVE

To examine the efficacy of hydrocortisone for treatment of hypotension and reduction of vasopressor requirements in preterm infants.

METHOD

Standard meta-analytic techniques, including random and fixed effects models, were used to calculate combined effect size correlations and significance levels.

RESULT

Random effects meta-analysis showed that hydrocortisone increases blood pressure (seven studies; N=144; r=0.71, 95%CI=0.18 to 0.92) and reduces vasopressor requirement (five studies; N=93; r=0.74, 95%CI=0.0084 to 0.96). The number of new or unretrieved studies averaging null results required to increase the overall p to 0.05 is k=78 for blood pressure increase and k=47 for vasopressor requirement reduction.

CONCLUSION

The effects of hydrocortisone on increasing blood pressure and decreasing vasopressor requirements in preterm infants are robust with a large tolerance for future null results. Actual clinical benefits of increasing blood pressure and decreasing vasopressor requirements, however, remain unknown. Long-term sequelae of hydrocortisone administration have yet to be fully elucidated.

Transient adrenal insufficiency in the premature newborn

PURPOSE OF REVIEW

Relative adrenal insufficiency is a controversial phenomenon described in adults and children with critical illness, especially septic shock. In the past 2 decades, relative adrenal insufficiency has also been reported in the critically ill premature as well as term newborn. The present study will review the initial and more recent studies addressing adrenal insufficiency in the premature infant.

RECENT FINDINGS

Studies suggest that 'relative adrenal insufficiency' is a contributing factor to hemodynamic instability in the sick preterm newborn. Many ill preterm newborns have inappropriately low serum cortisol concentrations and respond to steroid administration. Adrenal insufficiency is transient and likely reflects normal adrenal physiology at younger gestational ages. There is no general consensus on its diagnosis, effective minimum dose for treatment and duration of treatment.

SUMMARY

More large scale, multicenter, randomized, double-blind studies are needed to make the diagnosis of relative adrenal insufficiency and to determine the indication, dose, complications and outcome of glucocorticoid therapy.

Adrenocortical response in infants undergoing cardiac surgery with cardiopulmonary bypass and circulatory arrest

OBJECTIVE

To detail changes in adrenocorticotropic hormone (ACTH), cortisol, and aldosterone levels following cardiac surgery and to test the hypothesis that postcardiotomy infants requiring excessively high-dose vasopressor support will demonstrate adrenal insufficiency which will be proportional to cardiopulmonary bypass (CPB)/circulatory arrest times and vasopressor requirements.

DESIGN

Prospective observational pilot study.

SETTING

A tertiary care pediatric cardiac intensive care unit.

PATIENTS

Prospectively enrolled infants were divided into three subgroups: CPB, CPB with deep hypothermic circulatory arrest (DHCA), and control subjects.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A representative patient sample from each surgical group underwent preoperative synthetic ACTH testing. Postoperative serum samples for cortisol, ACTH, and inotrope score (IS) were collected at discrete intervals over 48 hrs along with patient demographics, surgical procedure, and CPB/DHCA times. Fifty-eight patients were classified by subgroup: 31 CPB, 22 DHCA, and 5 controls. Ten patients with DHCA, analyzed separately, received intraoperative steroids. Tested patients demonstrated preoperative adrenal competence. Cortisol peaked within 2 hrs of surgery without differences among groups. ACTH inversely correlated with bypass time in patients with DHCA (p = .03) but not with circulatory arrest time. Peak cortisol level did not correlate with simultaneous IS. Although not noted in any DHCA-steroid patients, nine patients had increased ACTH/cortisol ratios in association with elevated ISs suggesting inadequate adrenal responsiveness to endogenous ACTH.

CONCLUSIONS

The majority of infants with congenital heart disease and intact hypothalamic-pituitary-adrenal axes demonstrated an appropriate adrenocortical stress response to cardiac surgery. Peak serum cortisol was unrelated to CPB/DHCA time and did not predict the level of inotrope support. However, a subset of patients with elevated ACTH/cortisol ratios seemed to have a clinical status consistent with adrenal insufficiency and may be a target group for early postoperative steroid therapy.

Relative adrenal insufficiency in the preterm and term infant

Cortisol release in the face of illness or stress is vital for survival. Relative adrenal insufficiency occurs when a patient's cortisol response is inadequate for the degree of illness or stress. Numerous studies have documented the existence of relative adrenal insufficiency in critically ill adults, and its association with increased morbidity and mortality. There is increasing evidence that relative adrenal insufficiency may be an etiology for hemodynamic instability and hypotension in the critically ill newborn, but compared with the adult population, there is still a paucity of data in this population. Randomized controlled trials are needed to evaluate the efficacy and safety of glucocorticoids for the treatment of cardiovascular insufficiency due to relative adrenal insufficiency in ill preterm and term newborn infants.

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.

Steroid replacement therapy for severe heart failure after Norwood procedure

A 15-day-old neonate demonstrated severe heart failure and capillary leak syndrome after undergoing a Norwood procedure for hypoplastic left heart syndrome. Because she developed severe subcutaneous edema and baseline blood cortisol was low, we suspected relative adrenal insufficiency. After 18 days of dexamethasone administration, her hemodynamics and respiratory function improved, and she was successfully extubated and discharged from hospital. When hemodynamics are unstable in neonates after major cardiac surgery, relative adrenal insufficiency and steroid replacement should be considered.

Altered basal cortisol levels at 3, 6, 8 and 18 months in infants born at extremely low gestational age

OBJECTIVE

Little is known about the developmental trajectory of cortisol levels in preterm infants after hospital discharge.

STUDY DESIGN

In a cohort of 225 infants (gestational age at birth <33 weeks) basal salivary cortisol levels were compared in infants born at extremely low gestational age (ELGA, 23-28 weeks), very low gestational age (29-32 weeks), and term (37-42 weeks) at 3, 6, 8, and 18 months corrected age (CA). Infants with major neurosensory or motor impairment were excluded.

RESULTS

At 3 months CA, salivary cortisol levels were lower in both preterm groups compared with the term infants (P = .003). Conversely, at 8 and 18 months CA, the ELGA infants had significantly higher basal cortisol levels than the very low gestational age and term infants (P = .016 and P = .006, respectively).

CONCLUSIONS

In ELGA infants, the shift from low basal cortisol levels at 3 months to significantly high levels at 8 and 18 months CA suggests long-term "resetting" of endocrine stress systems. Multiple factors may contribute to these higher cortisol levels in the ELGA infants, including physiological immaturity at birth, cumulative stress related to multiple procedures, and mechanical ventilation during lengthy hospitalization. Prolonged elevation of the cortisol "set-point" may have negative implications for neurodevelopment and later health.

Corticosteroids for treating hypotension in preterm infants

BACKGROUND

Systemic hypotension is a relatively common complication of preterm birth and is associated with periventricular haemmorhage, periventricular white matter injury and adverse neurodevelopmental outcome. Corticosteroid treatment has been used as an alternative, or an adjunct, to conventional treatment with volume expansion and vasopressor/inotropic therapy.

OBJECTIVES

To determine the effectiveness and safety of corticosteroids used either as primary treatment of hypotension or for the treatment of refractory hypotension in preterm infants.

SEARCH STRATEGY

Randomized or quasi-randomized controlled trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2005), MEDLINE (1996 - June 2005), EMBASE (1974 - June 2005), reference lists of published papers and abstracts from the Pediatric Academic Societies and the European Society for Pediatric Research meetings published in Pediatric Research (1995 - 2004).

SELECTION CRITERIA

We included all randomised or quasi-randomised controlled trials investigating the effect of corticosteroid therapy in the treatment of hypotension in preterm infants (< 37 weeks gestation) less than 28 days old. Studies using corticosteroids as primary treatment were included as well as studies using corticosteroids in babies with hypotension resistant to inotropes/pressors and volume therapy. We included studies comparing oral/intravenous corticosteroids with placebo, other drugs used for providing cardiovascular support or no therapy in this review.

DATA COLLECTION AND ANALYSIS

Methodological quality of eligible studies was assessed according to the methods used for minimising selection bias, performance bias, attrition bias and detection bias. Studies that evaluated corticosteroids (1) as primary treatment for hypotension or (2) for refractory hypotension unresponsive to prior use of inotropes/pressors and volume therapy, were analysed using separate comparisons. Data were analysed using the standard methods of the Neonatal Review Group using Rev Man 4.2.7. Treatment effect was analysed using relative risk, risk reduction, number needed to treat for categorical outcomes and weighted mean difference for outcomes measured on a continuous scale, with 95% confidence intervals.

MAIN RESULTS

Two studies were included in this review enrolling a total of 57 babies. In the first study, persistent hypotension was more common in hydrocortisone treated infants as compared to those who received dopamine as primary treatment for hypotension (RR 8.2, 95% CI 0.47 to 142.6; RD 0.19, 95% CI 0.01 to 0.37). In the second study, persistent hypotension (defined as a continuing need for epinephrine infusion) was less common in dexamethasone treated infants as compared to controls who received placebo for refractory hypotension (RR 0.42 , 95% CI 0.17 to 1.06; RD -0.51, 95% CI - 0.91 to - 0.12). There were no statistically significant effects on any other short or long-term outcome. It was not considered appropriate to perform a meta-analysis. A further two studies that have only been published in abstract form to date, may be eligible for inclusion in a future update of this review.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the routine use of steroids in the treatment of primary or refractory neonatal hypotension. Hydrocortisone may be as effective as dopamine in treating primary hypotension, but there are no data regarding the long-term safety of steroids used for this indication.A single dose of dexamethasone may be effective in treating preterm infants with refractory hypotension receiving epinephrine. However, given the lack of data on long-term safety dexamethasone cannot be recommended for routine use in preterm hypotension.

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.

Adrenal insufficiency in the critically ill neonate and child

PURPOSE OF REVIEW

Adrenal insufficiency, common in critically ill patients of all ages, has recently gained prominence as a significant pathologic entity in pediatrics. This review describes the current diagnostic approach to detecting adrenal insufficiency and the clinical consequences in critically ill children and infants. It also discusses the current therapeutic approach to adrenal insufficiency in critically ill patients.

RECENT FINDINGS

Relative adrenal insufficiency and its clinical implications have recently come into focus with observational studies demonstrating a high prevalence in pediatric septic shock patients and a significant associated morbidity. Neonatal studies have clarified diagnostic testing and defined clinical outcomes associated with adrenal insufficiency in preterm infants. Comparisons of bioavailable and total cortisol levels demonstrate the utility of total cortisol testing in pediatric septic shock patients.

SUMMARY

Adrenal insufficiency contributes to morbidity in critically ill neonates and children. Diagnostic testing by adrenocorticotropin stimulation tests should be done in patients unresponsive to standard treatment of shock. Prospective, randomized clinical trials in critically ill neonates and children with adrenal insufficiency are required to determine if these populations will benefit from glucocorticoid replacement therapy.

Early neonatal hypotension in premature infants born to preeclamptic mothers

BACKGROUND

Early neonatal hypotension (ENH) is common in premature infants and has been claimed to occur more frequently in infants born to mothers with severe preeclampsia. Previous studies that showed a relationship between maternal preeclampsia and neonatal hypotension did not control for potential confounding factors such as birth weight and maternal treatment with magnesium sulfate (MgSO4).

OBJECTIVE

To determine whether maternal preeclampsia is an independent risk factor for ENH.

STUDY DESIGN

We conducted a retrospective review of all viable singleton infants with gestational age of 23 to 30 weeks who were admitted to the neonatal intensive care unit over a 2-year period. ENH was defined as the persistence of the mean arterial pressure lower than the gestational age in weeks requiring volume expansion and inotropic support in the first 24 h of life.

RESULTS

One hundred and eighty four infants were enrolled. Seventy-five (41%) infants met the diagnostic criteria for ENH. Maternal preeclampsia, the presence of labor, maternal treatment with MgSO4, Apgar scores, birth weight, gestational age and respiratory distress syndrome were significantly associated with ENH by univariate analysis. Only gestational age and maternal preeclampsia were significantly associated with ENH by multiple logistic regression.

CONCLUSION

Gestational age and maternal preeclampsia were independent risk factors for ENH in our population of premature infants.

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.