Postnatal betamethasone vs dexamethasone in premature infants with bronchopulmonary dysplasia: a pilot study

Comparing low-dose (DART) and enhanced low-dose dexamethasone regimens in preterm infants with bronchopulmonary dysplasia

Introduction

Determining the optimal dexamethasone dosage for facilitating extubation in extremely low birth weight (ELBW) infants with bronchopulmonary dysplasia (BPD) remains uncertain. This study aims to compare the effectiveness of low-dose (DART) and enhanced low-dose dexamethasone regimens in achieving successful extubation in these infants.

Methods

We conducted a retrospective cohort study at the Women's Wellness and Research Center (WWRC) involving ELBW infants who received dexamethasone for BPD prevention or treatment, or for extubation between January 1st, 2015, and December 31st, 2019. Our goal was to assess successful extubation within various time points of treatement.

Results

A total of 77 patients, matched in gestational age and BW, were enrolled in the study, receiving a total of 121 dexamethasone courses. Low-dose dexamethasone courses were administered 75 times to 49 infants, while 46 courses of enhanced low-dose were given to 28 infants. Treatment commenced at 30.8 ± 3.4 weeks post-menstrual age, compared to 32.1 ± 2.5 weeks in the enhanced low-dose group (p = 0.014). The median (IQR) course duration was seven (3-10) days in the low-dose group, while it was 10 (8-14) days in the enhanced low-dose group (p < 0.001). The median (IQR) course dose was 0.73 (0.53-0.86) mg/kg in the low-dose group and 1.27 (0.97-2.05) mg/kg in the enhanced low-dose group (p < 0.001). There were no differences in extubation success at any time point between the two groups at 72 h and seven days after treatment initiation, by course completion, and within seven days after treatment completion. However, regression analysis identified several predictors of successful extubation; baseline FiO2, course duration, and duration of invasive mechanical ventilation were negatively associated with successful extubation at various time points, while received dose per kg and cumulative dose positively correlated with successful extubation at different time points. No significant differences were observed in secondary outcomes, including death or BPD.

Conclusion

The choice between low-dose and enhanced low-dose dexamethasone regimens may not significantly impact extubation success. However, careful consideration of dosing, ventilation status, and treatment duration remains crucial in achieving successful extubation. This study highlights the need for personalized dexamethasone therapy in ELBW infants.

Systemic corticosteroid regimens for prevention of bronchopulmonary dysplasia in preterm infants

BACKGROUND

Systematic reviews showed that systemic postnatal corticosteroids reduce the risk of bronchopulmonary dysplasia (BPD) in preterm infants. However, corticosteroids have also been associated with an increased risk of neurodevelopmental impairment. It is unknown whether these beneficial and adverse effects are modulated by differences in corticosteroid treatment regimens related to type of steroid, timing of treatment initiation, duration, pulse versus continuous delivery, and cumulative dose.

OBJECTIVES

To assess the effects of different corticosteroid treatment regimens on mortality, pulmonary morbidity, and neurodevelopmental outcome in very low birth weight infants.

SEARCH METHODS

We conducted searches in September 2022 of MEDLINE, the Cochrane Library, Embase, and two trial registries, without date, language or publication- type limits. Other search methods included checking the reference lists of included studies for randomized controlled trials (RCTs) and quasi-randomized trials.

SELECTION CRITERIA

We included RCTs comparing two or more different treatment regimens of systemic postnatal corticosteroids in preterm infants at risk for BPD, as defined by the original trialists. The following comparisons of intervention were eligible: alternative corticosteroid (e.g. hydrocortisone) versus another corticosteroid (e.g. dexamethasone); lower (experimental arm) versus higher dosage (control arm); later (experimental arm) versus earlier (control arm) initiation of therapy; a pulse-dosage (experimental arm) versus continuous-dosage regimen (control arm); and individually-tailored regimens (experimental arm) based on the pulmonary response versus a standardized (predetermined administered to every infant) regimen (control arm). We excluded placebo-controlled and inhalation corticosteroid studies.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed eligibility and risk of bias of trials, and extracted data on study design, participant characteristics and the relevant outcomes. We asked the original investigators to verify if data extraction was correct and, if possible, to provide any missing data. We assessed the following primary outcome: the composite outcome mortality or BPD at 36 weeks' postmenstrual age (PMA). Secondary outcomes were: the components of the composite outcome; in-hospital morbidities and pulmonary outcomes, and long-term neurodevelopmental sequelae. We analyzed data using Review Manager 5 and used the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

We included 16 studies in this review; of these, 15 were included in the quantitative synthesis. Two trials investigated multiple regimens, and were therefore included in more than one comparison. Only RCTs investigating dexamethasone were identified. Eight studies enrolling a total of 306 participants investigated the cumulative dosage administered; these trials were categorized according to the cumulative dosage investigated, 'low' being < 2 mg/kg, 'moderate' being between 2 and 4 mg/kg, and 'high' > 4 mg/kg; three studies contrasted a high versus a moderate cumulative dose, and five studies a moderate versus a low cumulative dexamethasone dose. We graded the certainty of the evidence low to very low because of the small number of events, and the risk of selection, attrition and reporting bias. Overall analysis of the studies investigating a higher dose versus a lower dosage regimen showed no differences in the outcomes BPD, the composite outcome death or BPD at 36 weeks' PMA, or abnormal neurodevelopmental outcome in survivors assessed. Although there was no evidence of a subgroup difference for the higher versus lower dosage regimens comparisons (Chi2 = 2.91, df = 1 (P = 0.09), I2 = 65.7%), a larger effect was seen in the subgroup analysis of moderate-dosage regimens versus high-dosage regimens for the outcome cerebral palsy in survivors. In this subgroup analysis, there was an increased risk of cerebral palsy (RR 6.85, 95% CI 1.29 to 36.36; RD 0.23, 95% CI 0.08 to 0.37; P = 0.02; I² = 0%; NNTH 5, 95% CI 2.6 to 12.7; 2 studies, 74 infants). There was evidence of subgroup differences for higher versus lower dosage regimens comparisons for the combined outcomes death or cerebral palsy, and death and abnormal neurodevelopmental outcomes (Chi2 = 4.25, df = 1 (P = 0.04), I2 = 76.5%; and Chi2 = 7.11, df = 1 (P = 0.008), I2 = 85.9%, respectively). In the subgroup analysis comparing a high dosage regimen of dexamethasone versus a moderate cumulative-dosage regimen, there was an increased risk of death or cerebral palsy (RR 3.20, 95% CI 1.35 to 7.58; RD 0.25, 95% CI 0.09 to 0.41; P = 0.002; I² = 0%; NNTH 5, 95% CI 2.4 to 13.6; 2 studies, 84 infants; moderate-certainty evidence), and death or abnormal neurodevelopmental outcome (RR 3.41, 95% CI 1.44 to 8.07; RD 0.28, 95% CI 0.11 to 0.44; P = 0.0009; I² = 0%; NNTH 4, 95% CI 2.2 to 10.4; 2 studies, 84 infants; moderate-certainty evidence). There were no differences in outcomes between a moderate- and a low-dosage regimen. Five studies enrolling 797 infants investigated early initiation of dexamethasone therapy versus a moderately early or delayed initiation, and showed no significant differences in the overall analyses for the primary outcomes. The two RCTs investigating a continuous versus a pulse dexamethasone regimen showed an increased risk of the combined outcome death or BPD when using the pulse therapy. Finally, three trials investigating a standard regimen versus a participant-individualized course of dexamethasone showed no difference in the primary outcome and long-term neurodevelopmental outcomes. We assessed the GRADE certainty of evidence for all comparisons discussed above as moderate to very low, because the validity of all comparisons is hampered by unclear or high risk of bias, small samples of randomized infants, heterogeneity in study population and design, non-protocolized use of 'rescue' corticosteroids and lack of long-term neurodevelopmental data in most studies.

AUTHORS' CONCLUSIONS

The evidence is very uncertain about the effects of different corticosteroid regimens on the outcomes mortality, pulmonary morbidity, and long term neurodevelopmental impairment. Despite the fact that the studies investigating higher versus lower dosage regimens showed that higher-dosage regimens may reduce the incidence of death or neurodevelopmental impairment, we cannot conclude what the optimal type, dosage, or timing of initiation is for the prevention of BPD in preterm infants, based on current level of evidence. Further high quality trials would be needed to establish the optimal systemic postnatal corticosteroid dosage regimen.

Glucocorticoid-Induced Hyperinsulinism in a Preterm Neonate with Inherited ABCC8 Variant

Glucose homeostasis is a real challenge for extremely preterm infants (EPIs) who have both limited substrate availability and immature glucose metabolism regulation. In the first days of life, EPIs frequently develop transient glucose intolerance, which has a complex pathophysiology that associates unregulated gluconeogenesis, immature insulin secretion, and peripheral insulin resistance. In this population, glucocorticoid therapy is frequently administrated to prevent severe bronchopulmonary dysplasia. During this treatment, glucose intolerance classically increases and may lead to hyperglycemia. We report a case of neonatal hypoglycemia that was concomitant to a glucocorticoids administration, and that led to a congenital hyperinsulinism diagnosis in an EPI with a heterozygous ABCC8 variant. The variant was inherited from his mother, who had developed monogenic onset diabetes of the youth (MODY) at the age of 23. ABCC8 encodes a beta-cell potassium channel unit and causes congenital hyperinsulinism or MODY depending on the mutation location. Moreover, some mutations have been observed in the same patient to cause both hyperinsulinism in infancy and MODY in adulthood. In our case, the baby showed repeated and severe hypoglycemias, which were undoubtedly time-associated with the betamethasone intravenous administration. This hyperinsulinism was transient, and the infant has not yet developed diabetes at three years of age. We take the opportunity presented by this unusual clinical presentation to provide a review of the literature, suggesting new insights regarding the pathophysiology of the beta-pancreatic cells’ insulin secretion: glucocorticoids may potentiate basal insulin secretion in patients with ABCC8 mutation.

Pharmacotherapy in Bronchopulmonary Dysplasia: What Is the Evidence?

Bronchopulmonary Dysplasia (BPD) is a multifactorial disease affecting over 35% of extremely preterm infants born each year. Despite the advances made in understanding the pathogenesis of this disease over the last five decades, BPD remains one of the major causes of morbidity and mortality in this population, and the incidence of the disease increases with decreasing gestational age. As inflammation is one of the key drivers in the pathogenesis, it has been targeted by majority of pharmacological and non-pharmacological methods to prevent BPD. Most extremely premature infants receive a myriad of medications during their stay in the neonatal intensive care unit in an effort to prevent or manage BPD, with corticosteroids, caffeine, and diuretics being the most commonly used medications. However, there is no consensus regarding their use and benefits in this population. This review summarizes the available literature regarding these medications and aims to provide neonatologists and neonatal providers with evidence-based recommendations.

Dexamethasone, Prednisolone, and Methylprednisolone Use and 2-Year Neurodevelopmental Outcomes in Extremely Preterm Infants

IMPORTANCE

Practice variability exists in the use of corticosteroids to treat or prevent bronchopulmonary dysplasia in extremely preterm infants, but there is limited information on longer-term impacts.

OBJECTIVE

To describe the use of corticosteroids in extremely preterm infants and evaluate the association with neurodevelopmental outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was a secondary analysis of data from the Preterm Erythropoietin Neuroprotection (PENUT) randomized clinical trial, conducted at 19 participating sites and 30 neonatal intensive care units (NICUs) in the US. Inborn infants born between 24 0/7 and 27 6/7 weeks gestational age between December 2013 and September 2016 were included in analysis. Data analysis was conducted between February 2021 and January 2022.

EXPOSURES

Cumulative dose of dexamethasone and duration of therapy for dexamethasone and prednisolone or methyl prednisolone were evaluated.

MAIN OUTCOMES AND MEASURES

Demographic and clinical characteristics were described in infants who did or did not receive corticosteroids of interest and survived to discharge. Neurodevelopmental outcomes at 2 years of age were evaluated using the Bayley Scales of Infant Development-Third Edition (BSID-III) at corrected age 2 years.

RESULTS

A total of 828 extremely preterm infants (403 [49%] girls; median [IQR] gestational age, 26 [25-27] weeks) born at 19 sites who survived to discharge were included in this analysis, and 312 infants (38%) were exposed to at least 1 corticosteroid of interest during their NICU stay, including 279 exposed to dexamethasone, 137 exposed to prednisolone or methylprednisolone, and 79 exposed to both. Exposed infants, compared with nonexposed infants, had a lower birth weight (mean [SD], 718 [168] g vs 868 [180] g) and were born earlier (mean [SD] gestational age, 25 [1] weeks vs 26 [1] weeks). The median (IQR) start day was 29 (20-44) days for dexamethasone and 53 (30-90) days for prednisolone or methylprednisolone. The median (IQR) total days of exposure was 10 (5-15) days for dexamethasone and 13 (6-25) days for prednisolone or methylprednisolone. The median (IQR) cumulative dose of dexamethasone was 1.3 (0.9-2.8) mg/kg. After adjusting for potential confounders, treatment with dexamethasone for longer than 14 days was associated with worse neurodevelopmental outcomes, with mean scores in BSID-III 7.4 (95% CI, -12.3 to -2.5) points lower in the motor domain (P = .003) and 5.8 (95% CI, -10.9 to -0.6) points lower in the language domain (P = .03), compared with unexposed infants.

CONCLUSIONS AND RELEVANCE

These findings suggest that long duration and higher cumulative dose of dexamethasone were associated with worse neurodevelopmental scores at corrected age 2 years. Potential unmeasured differences in the clinical conditions of exposed vs unexposed infants may contribute to these findings. Improved standardization of treatment and documentation of indications would facilitate replication studies.

L’administration postnatale de corticostéroïdes pour prévenir ou traiter la dysplasie bronchopulmonaire chez les nouveau-nés prématurés

Les corticostéroïdes ont longtemps été administrés pendant la période postnatale pour prévenir et traiter la dysplasie bronchopulmonaire (DBP), une cause importante de morbidité et de mortalité chez les nouveau-nés prématurés. L’administration préventive de dexaméthasone pendant la première semaine de vie est liée à une augmentation du risque de paralysie cérébrale, et l’administration précoce de corticostéroïdes inhalés semble être associée à une hausse du risque de mortalité. À l’heure actuelle, aucune de ces deux approches n’est recommandée pour prévenir la DBP. Selon de nouvelles données probantes, un traitement prophylactique d’hydrocortisone à des doses physiologiques, entrepris avant 48 heures de vie sans ajout d’indométacine, améliore la survie sans DBP, et n’a pas d’effets neurodéveloppementaux indésirables à l’âge de deux ans. Les cliniciens peuvent envisager ce traitement pour les nouveau-nés les plus à risque de DBP. Il n’est pas recommandé d’entreprendre un traitement systématique de dexaméthasone pour tous les nouveau-nés sous assistance respiratoire, mais après la première semaine de vie, les cliniciens peuvent envisager un court traitement de dexaméthasone à faible dose (0,15 mg/kg/jour à 0,2 mg/kg/jour) pour certains nouveau-nés à haut risque de DBP ou atteints d’une DBP évolutive. Aucune donnée probante n’indique que l’hydrocortisone remplace la dexaméthasone avec efficacité ou innocuité dans le traitement d’une DBP évolutive ou établie. Les données à jour n’appuient pas l’administration de corticostéroïdes inhalés pour traiter la DBP.

Postnatal corticosteroids to prevent or treat bronchopulmonary dysplasia in preterm infants

Historically, postnatal corticosteroids have been used to prevent and treat bronchopulmonary dysplasia (BPD), a significant cause of morbidity and mortality in preterm infants. Administering dexamethasone to prevent BPD in the first 7 days post-birth has been associated with increasing risk for cerebral palsy, while early inhaled corticosteroids appear to be associated with an increased risk of mortality. Neither medication is presently recommended to prevent BPD. New evidence suggests that prophylactic hydrocortisone, when initiated in the first 48 hours post-birth, at a physiological dose, and in the absence of indomethacin, improves survival without BPD, with no adverse neurodevelopmental effects at 2 years. This therapy may be considered by clinicians for infants at highest risk for BPD. Routine dexamethasone therapy for all ventilator-dependent infants is not recommended, but after the first week post-birth, clinicians may consider a short course of low-dose dexamethasone (0.15 mg/kg/day to 0.2 mg/kg/day) for individual infants at high risk for, or with evolving, BPD. There is no evidence that hydrocortisone is an effective or safe alternative to dexamethasone for treating evolving or established BPD. Current evidence does not support inhaled corticosteroids for the treatment of BPD.

Postnatal glucocorticoid-induced hypomyelination, gliosis, and neurologic deficits are dose-dependent, preparation-specific, and reversible

Postnatal glucocorticoids (GCs) are widely used in the prevention of chronic lung disease in premature infants. Their pharmacologic use is associated with neurodevelopmental delay and cerebral palsy. However, the effect of GC dose and preparation (dexamethasone versus betamethasone) on short and long-term neurological outcomes remains undetermined, and the mechanisms of GC-induced brain injury are unclear. We hypothesized that postnatal GC would induce hypomyelination and motor impairment in a preparation- and dose-specific manner, and that GC receptor (GR) inhibition might restore myelination and neurological function in GC-treated animals. Additionally, GC-induced hypomyelination and neurological deficit might be transient. To test our hypotheses, we treated prematurely delivered rabbit pups with high (0.5mg/kg/day) or low (0.2mg/kg/day) doses of dexamethasone or betamethasone. Myelin basic protein (MBP), oligodendrocyte proliferation and maturation, astrocytes, transcriptomic profile, and neurobehavioral functions were evaluated. We found that high-dose GC treatment, but not low-dose, reduced MBP expression and impaired motor function at postnatal day 14. High-dose dexamethasone induced astrogliosis, betamethasone did not. Mifepristone, a GR antagonist, reversed dexamethasone-induced myelination, but not astrogliosis. Both GCs inhibited oligodendrocyte proliferation and maturation. Moreover, high-dose dexamethasone altered genes associated with myelination, cell-cycle, GR, and mitogen-activated protein kinase. Importantly, GC-induced hypomyelination, gliosis, and motor-deficit, observed at day 14, completely recovered by day 21. Hence, high-dose, but not low-dose, postnatal GC causes reversible reductions in myelination and motor functions. GC treatment induces hypomyelination by GR-dependent genomic mechanisms, but astrogliosis by non-genomic mechanisms. GC-induced motor impairment and neurodevelopmental delay might be transient and recover spontaneously in premature infants.

Postnatal steroids in extremely low birth weight infants: betamethasone or hydrocortisone?

AIM

To compare the efficacy and tolerance of betamethasone (BTM) and hydrocortisone (HC) in weaning extremely low birth weight (ELBW) infants with bronchopulmonary dysplasia (BPD) from the ventilator.

METHODS

Monocentric, retrospective, cohort analysis based on prospective, standardized collection of data between 2005 and 2011 in ELBW receiving postnatal steroids (PS) after the second week of life. We used BTM for the first 4 years, and thereafter HC. We compared extubation rates, growth, glycaemia and blood pressure.

RESULTS

Sixty-seven infants received PS: 35 BTM and 32 HC. Most infants (83% BTM vs. 72% HC) were extubated during treatment (p = 0.281). During PS, the need for insulin was similar. Mean arterial blood pressure was similar at day 3 of PS, but was significantly lower in infants treated by BTM 30 days after the end of treatment. The z-scores for body weight and head circumference indicated significantly greater loss in BTM than HC group. This persisted only for body weight after adjustment for differences in energy intake and corticosteroid dose.

CONCLUSION

Our study suggests that HC may be as efficient as BTM in facilitating the extubation of ELBW infants, without short-term adverse effects. Blood pressure monitoring and investigation of long-term neurodevelopment are nevertheless needed.

Postnatal corticosteroids for prevention and treatment of chronic lung disease in the preterm newborn

Despite significant progress in the treatment of preterm neonates, bronchopulmonary dysplasia (BPD) continues to be a major cause of neonatal morbidity. Affected infants suffered from long-term pulmonary and nonpulmonary sequel. The pulmonary sequels include reactive airway disease and asthma during childhood and adolescence. Nonpulmonary sequels include poor coordination and muscle tone, difficulty in walking, vision and hearing problems, delayed cognitive development, and poor academic achievement. As inflammation seems to be a primary mediator of injury in pathogenesis of BPD, role of steroids as antiinflammatory agent has been extensively studied and proven to be efficacious in management. However, evidence is insufficient to make a recommendation regarding other glucocorticoid doses and preparations. Numerous studies have been performed to investigate the effects of steroid. The purpose of this paper is to evaluate these studies in order to elucidate the beneficial and harmful effects of steroid on the prevention and treatment of BPD.

[The use of postnatal corticosteroid therapy in premature infants to prevent or treat bronchopulmonary dysplasia: current situation and recommendations]

In the last few years, several studies related to the benefit/risk balance of postnatal corticosteroids administered to premature neonates for prevention or treatment of bronchopulmonary dysplasia (BPD) have been published. These data encourage caution, given the risk of long-term adverse neurodevelopmental outcomes. In the meantime, the clinical profile of BPD has been altered based on the progress made in the pre- and postnatal care of premature infants. In 2006, a survey conducted in France in neonatal centers showed that corticosteroids were still frequently used (57% of the centers) following various protocols in very preterm-born infants for respiratory impairment. To promote safer practices and rational use of corticosteroids in the prevention and treatment of BPD in preterm-born neonates, we reviewed the available data in order to establish recommendations. Systemic administration of corticosteroids for prevention or treatment of BPD: (i) should not be used during the first 4 days of life; (ii) is not indicated in the first 3 weeks of life nor (iii) in extubated infants (nasal ventilation or oxygen therapy). The systemic administration of steroids can only be considered after the first 3 weeks of life in very preterm-born ventilator-dependent infants to facilitate extubation (or prevent reintubation related to the severity of BPD). Postnatal dexamethasone administration studied in several randomized clinical trials was shown to have an unfavorable benefit/risk profile, mainly because of the long-term adverse neurocognitive outcomes. Very few studies have been conducted with betamethasone in the postnatal period. According to sparse data, this drug might be as efficacious as dexamethasone, but its long-term risk profile is unknown. It should be noted that following prenatal administration, the benefit/risk profile of betamethasone is better than that of dexamethasone, especially with regard to neurocognitive development. Intravenous hydrocortisone administered at an early stage for the prevention of BPD is being evaluated and should not be administered in this indication, except within clinical trials approved by the ethics committee. No other corticosteroids have been evaluated in the postnatal period in respiratory indications. In conclusion, in the situations described above for which systemic corticosteroids could be justified, the use of betamethasone (or hydrocortisone) appears to be better. As usual, the lowest possible dose of corticosteroids should be administered for the shortest possible duration. The betamethasone-equivalent dose of 0.125 mg/kg/day for 3 days is deemed adequate. If inhaled, corticosteroid therapy may facilitate extubation. Neither its efficacy in respiratory diseases nor its long-term risk profile has been so far established.

Staging perspectives in neurodevelopmental aspects of neuropsychiatry: agents, phases and ages at expression

Neurodevelopmental risk factors have assumed a critical role in prevailing notions concerning the etiopathogenesis of neuropsychiatric disorders. Staging, diagnostic elements at which phase of disease is determined, provides a means of conceptualizing the degree and extent of factors affecting brain development trajectories, but is concurrently specified through the particular interactions of genes and environment unique to each individual case. For present purposes, staging perspectives in neurodevelopmental aspects of the disease processes are considered from conditions giving rise to neurodevelopmental staging in affective states, adolescence, dopamine disease states, and autism spectrum disorders. Three major aspects influencing the eventual course of individual developmental trajectories appear to possess an essential determinant influence upon outcome: (i) the type of agent that interferes with brain development, whether chemical, immune system activating or absent (anoxia/hypoxia), (ii) the phase of brain development at which the agent exerts disruption, whether prenatal, postnatal, or adolescent, and (iii) the age of expression of structural and functional abnormalities. Clinical staging may be assumed at any or each developmental phase. The present perspective offers both a challenge to bring further order to diagnosis, intervention, and prognosis and a statement regarding the extreme complexities and interwoven intricacies of epigenetic factors, biomarkers, and neurobehavioral entities that aggravate currents notions of the neuropsychiatric disorders.

Antenatal and postnatal corticosteroid and resuscitation induced lung injury in preterm sheep

Background

Initiation of ventilation using high tidal volumes in preterm lambs causes lung injury and inflammation. Antenatal corticosteroids mature the lungs of preterm infants and postnatal corticosteroids are used to treat bronchopulmonary dysplasia.

Objective

To test if antenatal or postnatal corticosteroids would decrease resuscitation induced lung injury.

Methods

129 d gestational age lambs (n = 5-8/gp; term = 150 d) were operatively delivered and ventilated after exposure to either 1) no medication, 2) antenatal maternal IM Betamethasone 0.5 mg/kg 24 h prior to delivery, 3) 0.5 mg/kg Dexamethasone IV at delivery or 4) Cortisol 2 mg/kg IV at delivery. Lambs then were ventilated with no PEEP and escalating tidal volumes (V_T) to 15 mL/kg for 15 min and then given surfactant. The lambs were ventilated with V_T 8 mL/kg and PEEP 5 cmH₂0 for 2 h 45 min.

Results

High V_T ventilation caused a deterioration of lung physiology, lung inflammation and injury. Antenatal betamethasone improved ventilation, decreased inflammatory cytokine mRNA expression and alveolar protein leak, but did not prevent neutrophil influx. Postnatal dexamethasone decreased pro-inflammatory cytokine expression, but had no beneficial effect on ventilation, and postnatal cortisol had no effect. Ventilation increased liver serum amyloid mRNA expression, which was unaffected by corticosteroids.

Conclusions

Antenatal betamethasone decreased lung injury without decreasing lung inflammatory cells or systemic acute phase responses. Postnatal dexamethasone or cortisol, at the doses tested, did not have important effects on lung function or injury, suggesting that corticosteroids given at birth will not decrease resuscitation mediated injury.