Managing established bronchopulmonary dysplasia without using routine blood gas measurements

OBJECTIVE

Routine blood gas measurements are common in infants with severe bronchopulmonary dysplasia (sBPD) and are a noxious stimulus. We developed a guideline-driven approach to evaluate the care of infants with sBPD without routine blood gas sampling in the chronic phase of NICU care (after diagnosis at 36 weeks PMA).

STUDY DESIGN

We examined blood gas utilization and outcomes in our sBPD inpatient care unit using data collected between 2014 and 2020.

RESULTS

485 sBPD infants met inclusion criteria, and 303 (62%) never had a blood gas obtained after 36 weeks PMA. In infants who had blood gas measurements, the median number of total blood gases per patient was only 4 (IQR 1-10). We did not identify adverse effects on hospital outcomes in patients without routine blood gas measurements.

CONCLUSIONS

We found that patients with established BPD could be managed without routine blood gas analyses after 36 weeks PMA.

Approaches to Interdisciplinary Care for Infants with Severe Bronchopulmonary Dysplasia: A Survey of the Bronchopulmonary Dysplasia Collaborative

OBJECTIVE

 Bronchopulmonary dysplasia (BPD) remains the most common late morbidity for extremely premature infants. Care of infants with BPD requires a longitudinal approach from the neonatal intensive care unit to ambulatory care though interdisciplinary programs. Current approaches for the development of optimal programs vary among centers.

STUDY DESIGN

 We conducted a survey of 18 academic centers that are members of the BPD Collaborative, a consortium of institutions with an established interdisciplinary BPD program. We aimed to characterize the approach, composition, and current practices of the interdisciplinary teams in inpatient and outpatient domains.

RESULTS

 Variations exist among centers, including composition of the interdisciplinary team, whether the team is the primary or consult service, timing of the first team assessment of the patient, frequency and nature of rounds during the hospitalization, and the timing of ambulatory visits postdischarge.

CONCLUSION

 Further studies to assess long-term outcomes are needed to optimize interdisciplinary care of infants with severe BPD.

KEY POINTS

· Care of infants with BPD requires a longitudinal approach from the NICU to ambulatory care.. · Benefits of interdisciplinary care for children have been observed in other chronic conditions.. · Current approaches for the development of optimal interdisciplinary BPD programs vary among centers..

The challenge of accurately describing the epidemiology of bronchopulmonary dysplasia (BPD) based on the various current definitions of BPD

Despite marked improvements in the survival of extremely low birth weight preterm infants, bronchopulmonary dysplasia (BPD) remains a prevalent morbidity. BPD has evolved pathologically and epidemiologically but the definition has failed to keep up. The majority of the definitions of BPD still use the respiratory support provided to the infants at a single timepoint. The lack of a uniform definition of BPD presently reflects the changing BPD pathogenesis and phenotype and limits defining the epidemiology. To address the epidemiology of BPD, the definition should be clarified; even the newer definitions have not been validated entirely. The definition needs to be meaningful clinically and be predictive of long-term respiratory outcomes. We believe the definition should have a composite assessment like a score (quantitative measurement) and include the different phenotypes (qualitative measurements) so that optimally they can be applied to the different phases of BPD and at different timepoints. Furthermore, the definitions need to be easy to measure and assess so that generalizability is enhanced.

Prostanoids and their analogues for the treatment of pulmonary hypertension in neonates

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) is a disease entity that describes a physiology in which there is persistence of increased pulmonary arterial pressure. PPHN is characterised by failure to adapt to a functional postnatal circulation with a fall in pulmonary vascular resistance. PPHN is responsible for impairment in oxygenation and significant neonatal mortality and morbidity. Prostanoids and their analogues may be useful therapeutic interventions due to their pulmonary vasodilatory and immunomodulatory effects.

OBJECTIVES

Primary objective• To determine the efficacy and safety of prostanoids and their analogues (iloprost, treprostinil, and beraprost) in decreasing mortality and the need for extracorporeal membrane oxygenation (ECMO) among neonates with PHSecondary objective• To determine the efficacy and safety of prostanoids and their analogues (iloprost, treprostinil, and beraprost) in decreasing neonatal morbidity (necrotizing enterocolitis (NEC), chronic lung disease (CLD), retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), length of hospital stay, and duration of mechanical ventilation) and improving neurodevelopmental outcomes among neonates with PHComparisons• Prostanoids and their analogues at any dosage or duration used to treat PPHN versus 'standard treatment without these agents', placebo, or inhaled nitric oxide (iNO) therapy• Prostanoids and their analogues at any dosage or duration used to treat refractory PPHN as an 'add-on' therapy to iNO versus iNO alone SEARCH METHODS: We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 9), MEDLINE via PubMed (1966 to 16 September 2018), Embase (1980 to 16 September 2018), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 16 September 2018). We also searched clinical trials databases, conference proceedings of the Pediatric Academic Societies (1990 to 16 September 2018), and the reference lists of retrieved articles for randomized controlled trials and quasi-randomized trials. We contacted authors who have published in this field as discerned from the reference lists of identified clinical trials and review authors' personal files.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials evaluating prostanoids or their analogues (at any dose, route of administration, or duration) used in neonates at any gestational age less than 28 days' postnatal age for confirmed or suspected PPHN.

DATA COLLECTION AND ANALYSIS

We used the standard methods of Cochrane Neonatal to conduct a systematic review and to assess the methodological quality of included studies (neonatal.cochrane.org/en/index.html). Three review authors independently assessed the titles and abstracts of studies identified by the search strategy and obtained full-text versions for assessment if necessary. We designed forms for trial inclusion or exclusion and for data extraction. We planned to use the GRADE approach to assess the quality of evidence.

MAIN RESULTS

We did not identify any eligible neonatal trials evaluating prostanoids or their analogues as sole agents in the treatment of PPHN.

AUTHORS' CONCLUSIONS

Implications for practiceCurrently, no evidence shows the use of prostanoids or their analogues as pulmonary vasodilators and sole therapeutic agents for the treatment of PPHN in neonates (age 28 days or less).Implications for researchThe safety and efficacy of different preparations and doses and routes of administration of prostacyclins and their analogues in neonates must be established. Well-designed, adequately powered, randomized, multi-center trials are needed to address the efficacy and safety of prostanoids and their analogues in the treatment of PPHN. These trials should evaluate long-term neurodevelopmental and pulmonary outcomes, in addition to short-term outcomes.

Evaluating the efficacy of Seattle-PAP for the respiratory support of premature neonates: study protocol for a randomized controlled trial

BACKGROUND

At birth, the majority of neonates born at <30 weeks of gestation require respiratory support to facilitate transition and ensure adequate gas exchange. Although the optimal approach to the initial respiratory management is uncertain, the American Academy of Pediatrics endorses noninvasive respiratory support with nasal continuous positive airway pressure (nCPAP) for premature neonates with respiratory insufficiency. Despite evidence for its use, nCPAP failure, requiring intubation and mechanical ventilation, is common. Recently, investigators have described a novel method to deliver bubble nCPAP, termed Seattle-PAP. While preclinical and pilot studies are encouraging regarding the potential value of Seattle-PAP, a large trial is needed to compare Seattle-PAP directly with the current standard of care for bubble nCPAP (Fisher & Paykel CPAP or FP-CPAP).

METHODS/DESIGN

We designed a multicenter, non-blinded, randomized controlled trial that will enroll 230 premature infants (22^0/7 to 29^6/7 weeks of gestation). Infants will be randomized to receive Seattle-PAP or FP-CPAP. The primary outcome is respiratory failure requiring intubation and mechanical ventilation. Secondary outcomes include measures of short- and long-term respiratory morbidity and cost-effectiveness.

DISCUSSION

This trial will assess whether Seattle-PAP is more efficacious and cost-effective than FP-CPAP in real-world practice among premature neonates.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03085329 . Registered on 21 March 2017.

Short term evaluation of respiratory effort by premature infants supported with bubble nasal continuous airway pressure using Seattle-PAP and a standard bubble device

Background

Almost one million prematurely born infants die annually from respiratory insufficiency, predominantly in countries with limited access to respiratory support for neonates. The primary hypothesis tested in the present study was that a modified device for bubble nasal continuous positive airway pressure (Bn-CPAP) would provide lower work of spontaneous breathing, estimated by esophageal pressure-rate products.

Methods

Infants born <32 weeks gestation and stable on Bn-CPAP with FiO₂ <0.30 were studied within 72 h following delivery. Esophageal pressures during spontaneous breathing were measured during 2 h on standard Bn-CPAP, then 2 h with Bn-CPAP using a modified bubble device presently termed Seattle-PAP, which produces a different pattern of pressure fluctuations and which provided greater respiratory support in preclinical studies, then 2 h on standard Bn-CPAP.

Results

All 40 infants enrolled completed the study and follow-up through 36 wks post menstrual age or hospital discharge, whichever came first. No infants were on supplemental oxygen at completion of follow-up. No infants developed pneumothoraces or nasal trauma, and no adverse events attributed to the study were observed. Pressure-rate products on the two devices were not different, but effort of breathing, assessed by areas under esophageal pressure-time curves, was lower with Seattle-PAP than with standard Bn-CPAP.

Conclusion

Use of Seattle-PAP to implement Bn-CPAP lowers the effort of breathing exerted even by relatively healthy spontaneously breathing premature neonates. Whether the lower effort of breathing observed with Seattle-PAP translates to improvements in neonatal mortality or morbidity will need to be determined by studies in appropriate patient populations.

A novel multimodal computational system using near-infrared spectroscopy predicts the need for ECMO initiation in neonates with congenital diaphragmatic hernia

BACKGROUND/PURPOSE

The purpose of this study was to develop a computational algorithm that would predict the need for ECMO in neonates with congenital diaphragmatic hernia (CDH).

METHODS

CDH patients from August 2010 to 2016 were enrolled in a study to continuously measure cerebral tissue oxygen saturation (cStO2) of left and right cerebral hemispheres. NIRS devices utilized were FORE-SIGHT, CASMED and INVOS 5100, Somanetics. Using MATLAB©, a data randomization function was used to deidentify and blindly group patient's data files as follows: 12 for the computational model development phase (6 ECMO and 6 non-ECMO) and the remaining patients for the validation phase.

RESULTS

Of the 56 CDH patients enrolled, 22 (39%) required ECMO. During development of the algorithm, a difference between right and left hemispheric cerebral oxygenation via NIRS (ΔHCO) was noted in CDH patients that required ECMO. Using ROC analysis, a ΔHCO cutoff >10% was predictive of needing ECMO (AUC: 0.92; sensitivity: 85%; and specificity: 100%). The algorithm predicted need for ECMO within the first 12h of life and at least 6h prior to the clinical decision for ECMO with 88% sensitivity and 100% specificity.

CONCLUSION

This computational algorithm of cerebral NIRS predicts the need for ECMO in neonates with CDH.

LEVEL OF EVIDENCE

II.

Continuous Positive Airway Pressure Strategies with Bubble Nasal Continuous Positive Airway Pressure: Not All Bubbling Is the Same: The Seattle Positive Airway Pressure System

Premature neonates are predisposed to complications, including bronchopulmonary dysplasia (BPD). BPD is associated with long-term pulmonary and neurodevelopmental consequences. Noninvasive respiratory support with nasal continuous positive airway pressure (CPAP) has been recommended strongly by the American Academy of Pediatrics. However, CPAP implementation has shown at least a 50% failure rate. Enhancing nasal CPAP effectiveness may decrease the need for mechanical ventilation and reduce the incidence of BPD. Bubble nasal CPAP is better than nasal CPAP using mechanical devices and the bubbling provides air exchange in distal respiratory units. The Seattle PAP system reduces parameters that assess work of breathing.

An evaluation of the role of concomitant anomalies on the outcomes of fetuses with congenital diaphragmatic hernia

PURPOSE

The purpose of this study was to evaluate the impact of various types of associated anomalies on CDH mortality and morbidity.

METHODS

All CDH patients at a tertiary care center from January 2004 to January 2014 were reviewed retrospectively. Isolated CDH was defined as CDH without any associated anomalies. Cardiac anomalies were stratified into minor and major based on the Risk Adjustment for Congenital Heart Surgery-1 (RACHS-1) scoring system. Other anatomic anomalies requiring intervention in the perinatal period were classified as major anomalies. The outcomes of interest were 6-month mortality as well as pulmonary and gastrointestinal morbidity.

RESULTS

Of 189 CDH patients, 93 (49%) had isolated CDH. Others had: cardiac anomalies alone (n=47, 25%), genetic anomalies (n=28, 15%), structural anomalies alone (n=18, 10%), and both cardiac and genetic anomalies (n=20, 11%). Fifty (26.5%) patients were dead before six months of age. Mortality rate at 6months was higher in patients with genetic and major cardiac anomalies. A major cardiac anomaly was independently associated with a 102-fold increased risk of mortality at 6months (95%CI: 3.1-3402). Pulmonary morbidity was increased in patients with genetic, major cardiac, and major structural anomalies, while gastrointestinal morbidity was higher in patients with major structural anomalies alone.

CONCLUSION

Major cardiac and genetic anomalies were associated with increased 6-month mortality in CDH patients. However, the association with minor cardiac anomalies and/or structural anomalies did not affect mortality and morbidity of CDH patients. The presence of minor anomalies should not adversely impact their perinatal management or consideration for in-utero therapy.

Space occupying lesions in the presence of congenital diaphragmatic hernia

INTRODUCTION

Previous reports describe lung malformations and other chest lesions in association with congenital diaphragmatic hernia (CDH), yet little is known how these lesions affect outcomes. We sought to evaluate the incidence and outcomes of patients diagnosed with chest lesions in association with CDH.

METHODS

The charts of all infants treated for CDH in a single tertiary center from January 2004 to January 2015 were reviewed. The outcomes of those with space occupying lesions (SOLs) in association with CDH were compared to those with isolated CDH. Statistical analysis was performed using Student's t-test and Mann-Whitney U test for continuous variables and Fisher's exact for categorical variables.

RESULTS

Of the 214 infants treated, 20 had an associated SOL (4 had>1 lesion). SOLs were confirmed by pathological examination and included: bronchopulmonary sequestration (n=10; 4.7%), ectopic liver (n=9; 4.2%), foregut duplication cyst (n=2; 1%), and other lesions (n=3; 1.4%). No statistical difference was noted in the long-term outcomes of patients with SOL in comparison to those with isolated CDH.

CONCLUSION

SOLs are not uncommon in neonates with CDH. Despite theoretical concerns, there is no evidence that SOLs are associated with worse outcomes, a finding which is helpful during prenatal counseling of families.

Gene Expression Profiling Identifies Cell Proliferation and Inflammation as the Predominant Pathways Regulated by Aryl Hydrocarbon Receptor in Primary Human Fetal Lung Cells Exposed to Hyperoxia

Exposure to hyperoxia contributes to the development of bronchopulmonary dysplasia (BPD) in premature infants. We observed that aryl hydrocarbon receptor (AhR) signaling protects newborn mice and primary fetal human pulmonary microvascular endothelial cells (HPMECs) against hyperoxic injury. Additionally, a recent genome-wide transcriptome study in a newborn mouse model of BPD identified AhR as a key regulator of hyperoxia-induced gene dysregulation. Whether the AhR similarly deregulates genes in HPMEC is unknown. Therefore, the objective of this study was to characterize transcriptome level gene expression profile in AhR-sufficient and -deficient HPMEC exposed to normoxic and hyperoxic conditions. Global gene expression profiling was performed using Illumina microarray platform and selected genes were validated by real-time RT-PCR. AhR gene expression and hyperoxia independently affected the expression of 540 and 593 genes, respectively. Two-way ANOVA further identified 85 genes that were affected by an interaction between AhR expression and exposure to hyperoxia. Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology, and Reactome pathway analysis identified cell proliferation, immune function, cytokine signaling, and organ development as the major pathways affected in AhR-deficient cells. The biological processes that were significantly enriched by hyperoxia included metabolic process, stress response, signal transduction, cell cycle, and immune regulation. Cell cycle was the predominant pathway affected by the combined effect of AhR knockdown and hyperoxia. Functional analysis of cell cycle showed that AhR-deficient cells had decreased proliferation compared with AhR-sufficient cells. These findings suggest that AhR modulates hyperoxic lung injury by regulating the genes that are necessary for cell proliferation and inflammation.

Risk-stratification of severity for infants with CDH: Prenatal versus postnatal predictors of outcome

PURPOSE

The purpose of this study was to compare the predication accuracy of a newly described postnatally-based clinical prediction model to fetal imaging-based predictors of mortality for infants with CDH.

METHODS

We performed a retrospective review of all CDH patients treated at a comprehensive fetal care center from January 2004 to January 2014. Prenatal data reviewed included lung-to-head ratio (LHR), observed/expected-total fetal lung volume (O/E-TFLV), and percent liver herniation (%LH). Based on the postnatal prediction model, neonates were categorized as low, intermediate, and high risk of death. The primary outcome was 6-month mortality.

RESULTS

Of 176 CDH patients, 58 had a major cardiac anomaly, and 28 had a genetic anomaly. Patients with O/E-TFLV <35% and %LH >20% were at increased risk for mortality (44% and 36%, respectively). There was a significant difference in mortality between low, intermediate, and high-risk groups (4% vs. 22% vs. 51%; p<0.001). On multivariate regression, the O/E-TFLV and postnatal-based mortality risk score were the two independent predictors of 6-month mortality.

CONCLUSION

The CDH Study Group postnatal predictive model provides good discrimination among three risk groups in our patient cohort. The prenatal MRI-based O/E-TFLV is the strongest prenatal predictor of 6-month mortality in infants with CDH and will help guide prenatal counseling and discussions regarding fetal intervention and perinatal management.

A novel multimodal computational system using near-infrared spectroscopy to monitor cerebral oxygenation during assisted ventilation in CDH patients

BACKGROUND/PURPOSE

The aim of this study was to create a computational simulator to serve as an early alert system for cerebral hypoxemia prior to the onset of clinical symptoms.

METHODS

Neonates with congenital diaphragmatic hernia (Jan 2010-Dec 2014) were recruited to collect continuous measurements of cerebral tissue oxygen saturation (cStO2) using a near-infrared spectroscopy (NIRS) device (FORE-SIGHT®, CASMED). Clinicians were blinded to NIRS data and treated infants based on pre-established clinical protocols. Charts were reviewed retrospectively to identify clinical events of hypoxemia (spontaneous, sustained decrease in preductal SpO2<85% leading to ventilator changes). We developed a computational algorithm that determined baseline values, variability and event data for each patient.

RESULTS

Twenty-three of 36 patients enrolled met data criteria. The algorithm anticipated an event at least 15 minutes prior to the event in 77% of cases, with an average pre-event detection of 47 minutes (range 16-122 minutes). Post-event StO2 (SpO2<85%) was determined to be 63.7% ± 11.7. In this computational model, the sensitivity to distinguish low states of cerebral perfusion was 94% with a specificity of 96%.

CONCLUSION

We have developed a computational algorithm with an early warning system that has the potential of being translated into a real-time clinical interface that may improve management of neonates.

The effect of supplemental parenteral nutrition on outcomes of necrotizing enterocolitis in premature, low birth weight neonates

BACKGROUND

We hypothesized that supplemental parenteral nutrition (PN) decreases the need for surgery and mortality associated with necrotizing enterocolitis (NEC).

METHODS

Single institution retrospective review of all premature, low birth weight infants with NEC from January 2006 to December 2013 was conducted.

RESULTS

NEC was identified in 114 premature, low birth weight infants, 59 (51.8%) of which required surgical management. Surgical NEC infants were born younger (25.8 ± 4.0 vs 27.8 ± 3.3 weeks, P = .005) and weighed less at birth (829 ± 281 vs 938 ± 271 g, P = .038) than those managed medically. There was no difference in the use of PN (37.7% vs 31.4%, P = .541) between surgical and medical NEC patients. There was no statistically significant difference in mortality at discharge between patients who had PN at NEC onset and those who did not (31.4% vs 42.6%, P = .294) CONCLUSION: In this single-center study, supplemental PN at NEC onset does not appear to significantly improve outcomes as demonstrated by rates of surgical intervention and in-hospital mortality.

Omeprazole Attenuates Pulmonary Aryl Hydrocarbon Receptor Activation and Potentiates Hyperoxia-Induced Developmental Lung Injury in Newborn Mice

Hyperoxia contributes to the development of bronchopulmonary dysplasia (BPD) in human preterm infants and a similar lung phenotype characterized by alveolar simplification in newborn mice. Omeprazole (OM) is a proton pump inhibitor that is used to treat humans with gastric acid related disorders. OM-mediated aryl hydrocarbon receptor (AhR) activation attenuates acute hyperoxic lung injury (HLI) in adult mice. Whether OM activates pulmonary AhR and protects C57BL/6J newborn mice against hyperoxia-induced developmental lung (alveolar and pulmonary vascular simplification, inflammation, and oxidative stress) injury (HDLI) is unknown. Therefore, we tested the hypothesis that OM will activate pulmonary AhR and mitigate HDLI in newborn mice. Newborn mice were treated daily with i.p. injections of OM at doses of 10 (OM10) or 25 (OM25) mg/kg while being exposed to air or hyperoxia (FiO2 of 85%) for 14 days, following which their lungs were harvested to determine alveolarization, pulmonary vascularization, inflammation, oxidative stress, vascular injury, and AhR activation. To our surprise, hyperoxia-induced alveolar and pulmonary vascular simplification, inflammation, oxidative stress, and vascular injury were augmented in OM25-treated animals. These findings were associated with attenuated pulmonary vascular endothelial growth factor receptor 2 expression and decreased pulmonary AhR activation in the OM25 group. We conclude that contrary to our hypothesis, OM decreases functional activation of pulmonary AhR and potentiates HDLI in newborn mice. These observations are consistent with our previous findings, which suggest that AhR activation plays a protective role in HDLI in newborn mice.

Persistent hypercarbia after resuscitation is associated with increased mortality in congenital diaphragmatic hernia patients

BACKGROUND

Within congenital diaphragmatic hernia (CDH) care, there have been attempts to identify clinical parameters associated with patient survival, including markers of postnatal pulmonary gas exchange. This study aimed to identify whether postnatal pulmonary gas exchange parameters correlated with CDH patient survival.

METHODS

A retrospective review was performed of isolated CDH neonates treated at a single institution from 1/2007 to 12/2013. Patient demographics, prenatal imaging, and postnatal clinical parameters, including arterial blood gas values within the first 24hours of life, were collected.

RESULTS

Seventy-four patients with isolated CDH were identified. Fifty-seven had fetal MRI. Overall, 30-day patient survival was 85%. Sixteen infants (22%) required ECMO within 24hours. Mean initial PaCO2 in nonsurvivors was higher, and infants who remained hypercarbic postresuscitation (72±19mmHg) had a worse prognosis than those who resuscitated to a normal PaCO2 (39±1.6mmHg) (p<0.001). Prenatal fetal lung volumes measured by MRI were not strongly correlated with PaCO2 levels.

CONCLUSION

CDH nonsurvivors are unable to maintain sufficient pulmonary gas exchange during the first 24hours of resuscitation. Furthermore, prenatal fetal lung volumes are weakly correlated with actual pulmonary gas exchange. These data may be useful for patient counseling during the resuscitative phase of CDH care.

Disruption of cytochrome P4501A2 in mice leads to increased susceptibility to hyperoxic lung injury

Hyperoxia contributes to acute lung injury in diseases such as acute respiratory distress syndrome. Cytochrome P450 (CYP) 1A enzymes have been implicated in hyperoxic lung injury, but the mechanistic role of CYP1A2 in pulmonary injury is not known. We hypothesized that mice lacking the gene Cyp1a2 (which is predominantly expressed in the liver) will be more sensitive to lung injury and inflammation mediated by hyperoxia and that CYP1A2 will play a protective role by attenuating lipid peroxidation and oxidative stress in the lung. Eight- to ten-week-old WT (C57BL/6) or Cyp1a2(-/-) mice were exposed to hyperoxia (>95% O2) or maintained in room air for 24-72 h. Lung injury was assessed by determining the ratio of lung weight/body weight (LW/BW) and by histology. Extent of inflammation was determined by measuring the number of neutrophils in the lung as well as cytokine expression. The Cyp1a2(-/-) mice under hyperoxic conditions showed increased LW/BW ratios, lung injury, neutrophil infiltration, and IL-6 and TNF-α levels and augmented lipid peroxidation, as evidenced by increased formation of malondialdehyde- and 4-hydroxynonenal-protein adducts and pulmonary isofurans compared to WT mice. In vitro experiments showed that the F2-isoprostane PGF2-α is metabolized by CYP1A2 to a dinor metabolite, providing evidence for a catalytic role for CYP1A2 in the metabolism of F2-isoprostanes. In summary, our results support the hypothesis that hepatic CYP1A2 plays a critical role in the attenuation of hyperoxic lung injury by decreasing lipid peroxidation and oxidative stress in vivo.

Revisiting outcomes of right congenital diaphragmatic hernia

BACKGROUND

Studies comparing outcomes of right- and left-sided congenital diaphragmatic hernia (R-CDH and L-CDH) have yielded conflicting results. We hypothesized that R-CDH is associated with higher short-term pulmonary morbidity than L-CDH.

METHODS

We reviewed all CDH patients at a tertiary children's hospital over 10 y. In prenatally diagnosed CDH, the observed-to-expected total fetal lung volume and percentage liver herniation (%LH) were calculated using fetal magnetic resonance imaging-based measurements. Outcomes were compared in patients with isolated CDH. Patients were subsequently matched by %LH to compare outcomes.

RESULTS

Of 189 CDH patients, 37 (20.1 %) were R-CDH and 147 (79.9%) were L-CDH. Those with R-CDH were prenatally diagnosed at a significantly lower rate (40.5% versus 73.5%; P < 0.001) and later gestational age (26.5 ± 7.7 versus 22.6 ± 5.65 wk; P = 0.062). There was no difference in observed-to-expected total fetal lung volume between those with R-CDH and L-CDH (30.2 ± 11.1% versus 33.1 ± 14.2%; P = 0.471). Fetuses with R-CDH had a higher %LH than those with L-CDH (37.5 ± 14.1% versus 18.6 ± 12.2%; P < 0.001). Patients with isolated R-CDH had a higher need for extracorporeal membrane oxygenation than L-CDH (48% versus 27%; P = 0.055). There was no difference in duration of tracheal intubation, hospital stay, need for supplemental oxygen at 30-d of life or 6-mo mortality between groups. There was no difference in mortality and pulmonary morbidity when patients were matched by %LH.

CONCLUSIONS

Compared to those with L-CDH, fetuses with R-CDH are less likely to be diagnosed prenatally and have a higher need for extracorporeal membrane oxygenation. The sidedness of the hernia defect was not associated with differences in short-term pulmonary morbidity in this large, contemporary single-institution experience of neonates with CDH.

Respiratory severity score on day of life 30 is predictive of mortality and the length of mechanical ventilation in premature infants with protracted ventilation

OBJECTIVE

We tested the hypothesis that Respiratory Severity Score (RSS) on day of life 30 is predictive of mortality and length of mechanical ventilation in premature infants on prolonged mechanical ventilation.

METHODS

A retrospective chart review was performed using the Nationwide Children's Hospital medical record and Vermont-Oxford Network databases. The primary outcome variable was survival to hospital discharge and the secondary outcome was length of mechanical ventilation after day of life 30.

RESULTS

We identified 199 neonates admitted to Nationwide Children's Hospital between 2004 and 2007 with birth weight less than 1,500 g that received prolonged mechanical ventilation in the first 30 days of their life. A total of 184 infants were included in the analysis, excluding 14 patients with congenital anomalies and one infant with incomplete data. RSS on day of life 30 was significantly greater in the group of infants that died compared to those that survived (P = 0.003, 95% CI = [0.08, 0.40]). Further analysis demonstrated that the maximum difference in mortality was obtained with a threshold RSS of 6. Of the 109 patients who had RSS less than 6 on day of life 30, mortality rate was 4.6% (5/109) while those greater than or equal to 6 had a mortality rate of 21.3% (16/75). Both Kaplan-Meier survival curves comparing mortality and length of mechanical ventilation in infants with RSS < 6 versus those with RSS ≥ 6 demonstrated strong associations between RSS on day of life 30 and survival (P = 0.002) and length of ventilation after day of life 30 (P < 0.001).

CONCLUSION

RSS ≥ 6 on day of life 30 is associated with higher mortality and longer period of mechanical ventilation in premature infants requiring mechanical ventilation through 30 days of life.

Aryl hydrocarbon receptor is necessary to protect fetal human pulmonary microvascular endothelial cells against hyperoxic injury: Mechanistic roles of antioxidant enzymes and RelB

Hyperoxia contributes to the development of bronchopulmonary dysplasia (BPD) in premature infants. Activation of the aryl hydrocarbon receptor (AhR) protects adult and newborn mice against hyperoxic lung injury by mediating increases in the expression of phase I (cytochrome P450 (CYP) 1A) and phase II (NADP(H) quinone oxidoreductase (NQO1)) antioxidant enzymes (AOE). AhR positively regulates the expression of RelB, a component of the nuclear factor-kappaB (NF-κB) protein that contributes to anti-inflammatory processes in adult animals. Whether AhR regulates the expression of AOE and RelB, and protects fetal primary human lung cells against hyperoxic injury is unknown. Therefore, we tested the hypothesis that AhR-deficient fetal human pulmonary microvascular endothelial cells (HPMEC) will have decreased RelB activation and AOE, which will in turn predispose them to increased oxidative stress, inflammation, and cell death compared to AhR-sufficient HPMEC upon exposure to hyperoxia. AhR-deficient HPMEC showed increased hyperoxia-induced reactive oxygen species (ROS) generation, cleavage of poly(ADP-ribose) polymerase (PARP), and cell death compared to AhR-sufficient HPMEC. Additionally, AhR-deficient cell culture supernatants displayed increased macrophage inflammatory protein 1α and 1β, indicating a heightened inflammatory state. Interestingly, loss of AhR was associated with a significantly attenuated CYP1A1, NQO1, superoxide dismutase 1(SOD1), and nuclear RelB protein expression. These findings support the hypothesis that decreased RelB activation and AOE in AhR-deficient cells is associated with increased hyperoxic injury compared to AhR-sufficient cells.

Are all pulmonary hypoplasias the same? A comparison of pulmonary outcomes in neonates with congenital diaphragmatic hernia, omphalocele and congenital lung malformation

INTRODUCTION

Patients with congenital diaphragmatic hernias (CDH), omphaloceles, and congenital lung malformations (CLM) may have pulmonary hypoplasia and experience respiratory insufficiency. We hypothesize that given equivalent lung volumes, the degree of respiratory insufficiency will be comparable regardless of the etiology.

METHODS

Records of all fetuses with CDH, omphalocele, and CLM between January 2000 and June 2013 were reviewed. MRI-based observed-to-expected total fetal lung volumes (O/E-TFLV) were calculated. An analysis of outcomes in patients with O/E-TFLV between 40% and 60%, the most inclusive range, was performed.

RESULTS

285 patients were evaluated (161, CDH; 24, omphalocele; 100, CLM). Fetuses with CDH had the smallest mean O/E-TFLV. CDH patients were intubated for longer and had a higher incidence of pulmonary hypertension. Fifty-six patients with the three diagnoses had an O/E-TFLV of 40%-60%. The need for ECMO, supplemental oxygen at 30days of life, and 6-month mortality were similar among groups. CDH patients had a significantly longer duration of intubation and higher incidence of pulmonary hypertension than the other two diagnoses.

CONCLUSION

Given equivalent lung volumes (40%-60% of expected), CDH patients require more pulmonary support initially than omphalocele and CLM patients. In addition to lung volumes, disease-specific factors, such as pulmonary hypertension in CDH, also contribute to pulmonary morbidity and overall outcome.

Mice deficient in the gene for cytochrome P450 (CYP)1A1 are more susceptible than wild-type to hyperoxic lung injury: evidence for protective role of CYP1A1 against oxidative stress

Hyperoxia contributes to acute lung injury in diseases such as acute respiratory distress syndrome in adults and bronchopulmonary dysplasia in premature infants. Cytochrome P450 (CYP)1A1 has been shown to modulate hyperoxic lung injury. The mechanistic role(s) of CYP1A1 in hyperoxic lung injury in vivo is not known. In this investigation, we hypothesized that Cyp1a1(-/-) mice would be more susceptible to hyperoxic lung injury than wild-type (WT) mice, and that the protective role of CYP1A1 is in part due to CYP1A1-mediated decrease in the levels of reactive oxygen species-mediated lipid hydroperoxides, e.g., F2-isoprostanes/isofurans, leading to attenuation of oxidative damage. Eight- to ten-week-old male WT (C57BL/6J) or Cyp1a1(-/-) mice were exposed to hyperoxia (>95% O2) or room air for 24-72 h. The Cyp1a1(-/-) mice were more susceptible to oxygen-mediated lung damage and inflammation than WT mice, as evidenced by increased lung weight/body weight ratio, lung injury, neutrophil infiltration, and augmented expression of IL-6. Hyperoxia for 24-48 h induced CYP1A expression at the mRNA, protein, and enzyme levels in liver and lung of WT mice. Pulmonary F2-isoprostane and isofuran levels were elevated in WT mice after hyperoxia for 24 h. On the other hand, Cyp1a1(-/-) mice showed higher levels after 48-72 h of hyperoxia exposure compared to WT mice. Our results support the hypothesis that CYP1A1 protects against hyperoxic lung injury by decreasing oxidative stress. Future research could lead to the development of novel strategies for prevention and/or treatment of acute lung injury.

Fetal MRI lung volumes are predictive of perinatal outcomes in fetuses with congenital lung masses

PURPOSE

The purpose of this study was to evaluate fetal magnetic resonance imaging (MRI) as a modality for predicting perinatal outcomes and lung-related morbidity in fetuses with congenital lung masses (CLM).

METHODS

The records of all patients treated for CLM from 2002 to 2012 were reviewed retrospectively. Fetal MRI-derived lung mass volume ratio (LMVR), observed/expected normal fetal lung volume (O/E-NFLV), and lesion-to-lung volume ratio (LLV) were calculated. Multivariate regression and receiver operating characteristic analyses were applied to determine the predictive accuracy of prenatal imaging.

RESULTS

Of 128 fetuses with CLM, 93% (n=118) survived. MRI data were available for 113 fetuses. In early gestation (<26weeks), MRI measurements of LMVR and LLV correlated with risk of fetal hydrops, mortality, and/or need for fetal intervention. In later gestation (>26weeks), LMVR, LLV, and O/E-NFLV correlated with neonatal respiratory distress, intubation, NICU admission and need for neonatal surgery. On multivariate regression, LMVR was the strongest predictor for development of fetal hydrops (OR: 6.97, 1.58-30.84; p=0.01) and neonatal respiratory distress (OR: 12.38, 3.52-43.61; p≤0.001). An LMVR >2.0 predicted worse perinatal outcome with 83% sensitivity and 99% specificity (AUC=0.94; p<0.001).

CONCLUSION

Fetal MRI volumetric measurements of lung masses and residual normal lung are predictive of perinatal outcomes in fetuses with CLM. These data may assist in perinatal risk stratification, counseling, and resource utilization.

Fetal MRI improves diagnostic accuracy in patients referred to a fetal center for suspected esophageal atresia

PURPOSE

The purpose of this study was to describe prenatal imaging characteristics and outcomes of fetuses with suspected esophageal atresia (EA) in order to improve prenatal diagnosis, counseling, and management.

METHODS

The medical records of all patients referred to our multidisciplinary fetal center for suspected EA from January 2003 to April 2013 were reviewed retrospectively.

RESULTS

Thirty-three patients were referred with a prenatal diagnosis of possible EA. Following fetal center evaluation with MRI, EA was deemed unlikely in 6 (18%) fetuses. Of 27 fetuses in whom EA could not be excluded, EA was confirmed postnatally in 15 (56%), excluded in 7 (26%), and unconfirmed in 5 (3 fetal losses; 2 lost to follow-up). Imaging characteristics on fetal MRI associated with the highest positive predictive values (PPV) were an esophageal pouch (100%) and a small stomach (75%). The finding of polyhydramnios had high sensitivity (93%) but low specificity (31%) and PPV (61%) for a diagnosis of EA.

CONCLUSION

Prenatal imaging and fetal center evaluation correctly identify the presence or absence of esophageal atresia in 78% of patients referred on suspicion of this condition. The presence of an esophageal pouch on fetal MRI has significant predictive value for EA. These data may assist with evidence-based prenatal family counseling.

Prenatal MRI fetal lung volumes and percent liver herniation predict pulmonary morbidity in congenital diaphragmatic hernia (CDH)

PURPOSE

The purpose of this study was to determine whether prenatal imaging parameters are predictive of postnatal CDH-associated pulmonary morbidity.

METHODS

The records of all neonates with CDH treated from 2004 to 2012 were reviewed. Patients requiring supplemental oxygen at 30 days of life (DOL) were classified as having chronic lung disease (CLD). Fetal MRI-measured observed/expected total fetal lung volume (O/E-TFLV) and percent liver herniation (%LH) were recorded. Receiver operating characteristic (ROC) curves and multivariate regression were applied to assess the prognostic value of O/E-TFLV and %LH for development of CLD.

RESULTS

Of 172 neonates with CDH, 108 had fetal MRIs, and survival was 76%. 82% (89/108) were alive at DOL 30, 46 (52%) of whom had CLD. Neonates with CLD had lower mean O/E-TFLV (30 vs.42%; p=0.001) and higher %LH (21.3±2.8 vs.7.1±1.8%; p<0.001) compared to neonates without CLD. Using ROC analysis, the best cutoffs in predicting CLD were an O/E-TFLV<35% (AUC=0.74; p<0.001) and %LH>20% (AUC=0.78; p<0.001). On logistic regression, O/E-TFLV<35% and a %LH>20% were highly associated with indicators of long-term pulmonary sequelae. On multivariate analysis, %LH was the strongest predictor of CLD in patients with CDH (OR: 10.96, 95%CI: 2.5-48.9, p=0.002).

CONCLUSION

Prenatal measurement of O/E-TFLV and %LH is predictive of CDH pulmonary morbidity and can aid in establishing parental expectations of postnatal outcomes.

Lung development alterations in newborn mice after recovery from exposure to sublethal hyperoxia

Exposure of newborn mice to hyperoxia arrests lung development, with resultant pathological characteristics similar to bronchopulmonary dysplasia in infants born prematurely. We tested the hypothesis that aberrations in lung development caused by 14 days of sublethal hyperoxia would be reversed during 14 days of recovery to room air (RA) when the concentration of oxygen exposure was weaned gradually. Newborn FVB mice were exposed to 85% oxygen or RA for 14 days. Weaning from hyperoxia was by either transfer directly into RA or a decrease in the concentration of oxygen by 10% per days. At 28 days, pups were euthanized, and the lungs were inflation fixed and assessed. At postnatal day 28, lungs of mice weaned abruptly from hyperoxia had fewer (6 ± 0.6 versus 10 ± 0.7; P < 0.001) alveoli per high-powered field and larger alveoli (4050 ± 207 versus 2305 ± 182 μm(2)) than animals weaned gradually; both hyperoxia-exposed groups were different from lungs obtained from air-breathing controls (20 ± 0.5 alveoli per high-powered field; P < 0.001). The results are consistent with the absence of catch-up alveolarization in this model and indicate that the long-term consequences of early exposures to hyperoxia merit closer examination. The effects of abrupt weaning to RA observed further suggest that weaning should be considered in experimental models of newborn exposure to hyperoxia.

Increased susceptibility to hyperoxic lung injury and alveolar simplification in newborn rats by prenatal administration of benzo[a]pyrene

Maternal smoking is one of the risk factors for preterm birth and for the development of bronchopulmonary dysplasia (BPD). In this study, we tested the hypothesis that prenatal exposure of rats to benzo[a]pyrene (BP), a component of cigarette smoke, will result in increased susceptibility of newborns to oxygen-mediated lung injury and alveolar simplification, and that cytochrome P450 (CYP)1A and 1B1 enzymes and oxidative stress mechanistically contribute to this phenomenon. Timed pregnant Fisher 344 rats were administered BP (25 mg/kg) or the vehicle corn oil (CO) on gestational days 18, 19 and 20, and newborn rats were either maintained in room air or exposed to hyperoxia (85% O2) for 7 or 14 days. Hyperoxic newborn rats prenatally exposed to the vehicle CO showed lung injury and alveolar simplification, and inflammation, and these effects were potentiated in rats that were prenatally exposed to BP. Prenatal exposure to BP, followed by hyperoxia, also resulted in significant modulation of hepatic and pulmonary cytochrome P450 (CYP)1A and 1B1 enzymes at PND 7-14. These rats displayed significant oxidative stress in lungs at postnatal day (PND) 14, as evidenced by increased levels of the F2-isoprostane 8-iso-PGF2α. Furthermore, these animals showed BP-derived DNA adducts and oxidative DNA adducts in the lung. In conclusion, our results show increased susceptibility of newborns to oxygen-mediated lung injury and alveolar simplification following maternal exposure to BP, and our results suggest that modulation of CYP1A/1B1 enzymes, increases in oxidative stress, and BP-DNA adducts contributed to this phenomenon.

Repair of congenital diaphragmatic hernias on Extracorporeal Membrane Oxygenation (ECMO): does early repair improve patient survival?

INTRODUCTION

The optimal timing of repair for congenital diaphragmatic hernia (CDH) patients that require ECMO is controversial. Early repair on ECMO theoretically allows for restoration of normal thoracic anatomy but entails significant bleeding risks. The purpose of this study was to examine the institutional outcomes of early CDH repair on ECMO.

METHODS

The records of infants with CDH placed on ECMO from 2001 to 2011 were reviewed. Since 2009, a protocol was instituted for early repair while on ECMO. For this study, three cohorts were analyzed: early repair (<72 h), late repair (>72 h), and post-decannulation. These groups were compared for outcomes regarding morbidity and survival.

RESULTS

Forty-six CDH patients received ECMO support with an overall survival of 53%. Twenty-nine patients (11 early/18 late) were repaired on ECMO, while 17 patients had repair post-decannulation. Survival was 73%, 50%, and 64% for those repaired early, late, or post-decannulation, respectively. Despite significantly worse prenatal factors, patients repaired early on ECMO had a similar survival. When comparing patients repaired on ECMO, the early group patients were decannulated 6 days earlier (p-value=0.009) and had significantly lower circuit complications (p=0.03).

CONCLUSION

In conclusion, early repair on ECMO was associated with decreased ECMO duration, decreased circuit complications, and a trend towards improved survival.

Usefulness of routine head ultrasound scans before surgery for congenital heart disease

OBJECTIVE

The purpose of this study was to assess the utility of preoperative head ultrasound scan (HUS) in a cohort of newborns also under going preoperative MRI as part of a prospective research study of brain injury in infants having surgery for congenital heart disease(CHD).

METHODS

A total of 167 infants diagnosed with CHD were included in this 3-center study. None of the patients had clinical signs or symptoms of preoperative brain injury, and all patients received both HUS and brain MRI before undergoing surgical intervention. HUS and MRI results were reported by experienced neuroradiologists who were blinded to any specific clinical details of the study participants. The findings of the individual imaging modes were compared to evaluate for the presence of brain injury.

RESULTS

Preoperative brain injury was present on HUS in 5 infants(3%) and on MRI in 44 infants (26%) (P , .001). Four of the HUS showed intraventricular hemorrhage not seen on MRI, suggesting false-positive results, and the fifth showed periventricular leukomalacia. The predominant MRI abnormality was white matter injury (n = 32). Other findings included infarct (n = 16) and hemorrhage (n = 5).

CONCLUSIONS

Preoperative brain injury on MRI was present in 26% of infants with CHD, but only 3% had any evidence of brain injury on HUS.Among positive HUS, 80% were false-positive results. Our findings suggest that routine HUS is not indicated in asymptomatic term or near-term neonates undergoing surgery for CHD, and MRI may bea preferable tool when the assessment of these infants is warranted.

Usefulness of routine head ultrasound scans before surgery for congenital heart disease

OBJECTIVE

The purpose of this study was to assess the utility of preoperative head ultrasound scan (HUS) in a cohort of newborns also undergoing preoperative MRI as part of a prospective research study of brain injury in infants having surgery for congenital heart disease (CHD).

METHODS

A total of 167 infants diagnosed with CHD were included in this 3-center study. None of the patients had clinical signs or symptoms of preoperative brain injury, and all patients received both HUS and brain MRI before undergoing surgical intervention. HUS and MRI results were reported by experienced neuroradiologists who were blinded to any specific clinical details of the study participants. The findings of the individual imaging modes were compared to evaluate for the presence of brain injury.

RESULTS

Preoperative brain injury was present on HUS in 5 infants (3%) and on MRI in 44 infants (26%) (P < .001). Four of the HUS showed intraventricular hemorrhage not seen on MRI, suggesting false-positive results, and the fifth showed periventricular leukomalacia. The predominant MRI abnormality was white matter injury (n = 32). Other findings included infarct (n = 16) and hemorrhage (n = 5).

CONCLUSIONS

Preoperative brain injury on MRI was present in 26% of infants with CHD, but only 3% had any evidence of brain injury on HUS. Among positive HUS, 80% were false-positive results. Our findings suggest that routine HUS is not indicated in asymptomatic term or near-term neonates undergoing surgery for CHD, and MRI may be a preferable tool when the assessment of these infants is warranted.

Outcomes of fetuses with lower urinary tract obstruction treated with vesicoamniotic shunt: a single-institution experience

PURPOSE

The purpose of this manuscript was to examine the outcomes of patients with lower urinary tract obstruction (LUTO) treated with vesicoamniotic shunt (VAS) to improve the quality of prenatal consultation and therapy.

METHODS

The medical records of all patients diagnosed with LUTO at our center between January 2004 and March 2012 were reviewed retrospectively.

RESULTS

Of 14 male fetuses with LUTO, all with characteristic ultrasound findings, 11 underwent intervention. One patient received vesicocentesis alone, while 10 had VAS. Two fetuses additionally underwent cystoscopy (one with attempted valve ablation), and two had peritoneoamniotic shunts. Of 16 total VAS, 13 were placed successfully, 8 dislodged (median 7 days), and 1 obstructed (84 days). Two fetuses suffered in utero demise, and two have unknown outcomes. LUTO was confirmed in six of eight live-born fetuses. One patient died in the neonatal period, while seven survived. All six available at follow-up (median 3.7 years), had significant genitourinary morbidity. Five patients had chronic kidney disease, but only one has required dialysis and transplant. Three had respiratory insufficiency, and one required a tracheostomy.

CONCLUSION

Despite significant perinatal and long-term morbidity, VAS offers patients faced with a poor prognosis an improved chance of survival. Our results underscore the need for further research into the diagnosis and treatment of LUTO.

Tracheostomy placement in infants with bronchopulmonary dysplasia: safety and outcomes

Optimizing the timing and safety for the placement of a tracheostomy in infants with bronchopulmonary dysplasia (BPD) has not been determined. The purpose of the present study was to describe the data from a single institution about the efficacy and safety of tracheostomy placement in infants with BPD needing long-term respiratory support. We established a service line for the comprehensive care of infants with BPD and we collected retrospective clinical data from this service line. We identified patients that had a trachostomy placed using the local Vermont-Oxford database, and obtained clinical data from chart reviews. We identified infants who had a tracheostomy placed for the indication of severe BPD only. Safety and respiratory efficacy was assessed by overall survival to discharge and the change in respiratory supportive care from just before placement to 1-month post-placement. Twenty-two patients (750 ± 236 g, 25.4 ± 2.1 weeks gestation) had a tracheostomy placed on day of life 177 ± 74 which coincided with a post-conceptual age of 51 ± 10 weeks. At placement these infants were on high settings to support their lung disease. The mean airway pressure (MAP) was 14.3 ± 3.3 cmH(2) O, the peak inspiratory pressure was 43.7 ± 8.0 cmH(2) O, and the FiO(2) was 0.51 ± 0.13. The mean respiratory severity score (MAP × FiO(2) ) 1 month after tracheostomy was significantly (P = 0.03) lower than prior to tracheostomy. Survival to hospital discharge was 77%. All patients with tracheostomies that survived were discharged home on mist collar supplemental oxygen. In conclusion, the high survival rate in these patients with severe BPD and the decreased respiratory support after placement of a tracheostomy suggests that high ventilatory pressures should not be a deterrent for placement of a tracheostomy. Future research should be aimed at determining optimal patient selection and timing for tracheostomy placement in infants with severe BPD.

The use of ECMO for persistent pulmonary hypertension of the newborn: a decade of experience

PURPOSE

Despite improvements in the management of persistent pulmonary hypertension of the newborn (PPHN), a number of infants with inadequate gas exchange are treated with extracorporeal membrane oxygenation (ECMO). The objectives of this study were to use the Extracorporeal Life Support Organization Registry to review the outcomes of neonates with PPHN receiving ECMO, and to identify pre-ECMO variables that may be associated with increased mortality.

MATERIALS AND METHODS

The study is a retrospective analysis of all patients with PPHN supported with ECMO and reported to the Extracorporeal Life Support Organization registry from 2000 to 2010. Prematurity was defined as <37 wk gestation. Univariate analysis was performed using Student's t-test or Fisher's exact test. Variables found to be statistically significant underwent multivariate analysis by logistic regression. Kaplan-Meier survival curves were generated to analyze the relationship between duration of ECMO support and patient survival.

RESULTS

A total of 1569 neonates with PPHN received ECMO support during the study period, at an average age of 3.1 d of life and for a duration of 6.9 d. Survival among neonates with PPHN receiving ECMO support was 81%, and those receiving support for 7, 10, 14, and 21 d survived at rates of 88%, 78%, 55%, and 25%, respectively. By logistic regression, prematurity (P < 0.01), pre-ECMO pH ≤7.2 (P = 0.02), pre-ECMO SaO(2) ≤65% (P = 0.01), and duration of ECMO ≥7 d (P < 0.001) were independent predictors of death in this group. An average of 2.2 complications occurred per patient, with cardiovascular, mechanical, and renal complications being the most common.

CONCLUSIONS

Neonates with PPHN have high survival rates with ECMO support. Prematurity, acidosis, and profound hypoxemia are independently associated with increased mortality. Furthermore, prolonged ECMO support (>7 d) is associated with a higher risk of mortality in this cohort than in patients supported for <1 wk.

Plasma lipid metabolites are associated with gestational age but not bronchopulmonary dysplasia

AIM

To test the hypothesis that plasma lipid metabolite levels in premature infants are associated with the development of bronchopulmonary dysplasia (BPD). The studies also tested a secondary hypothesis that plasma lipid metabolite levels were correlated with gestational age.

METHODS

Infants born <32 weeks' gestation were enrolled during the first 72 h of life. Plasma samples were obtained and lipid levels were measured by LC-MS/MS. Clinical data were collected to determine infant outcomes and BPD diagnosis.

RESULTS

Following adjustment for confounders, lipid levels were not associated with BPD; however, levels of specific lipid metabolites were correlated with gestational age.

CONCLUSION

Immature lipid metabolism pathways in premature infants may contribute to the pathogenesis of BPD and other diseases.

Prenatal inflammation exacerbates hyperoxia-induced functional and structural changes in adult mice

Maternally derived inflammatory mediators, such as IL-6 and IL-8, contribute to preterm delivery, low birth weight, and respiratory insufficiency, which are routinely treated with oxygen. Premature infants are at risk for developing adult-onset cardiac, metabolic, and pulmonary diseases. Long-term pulmonary consequences of perinatal inflammation are unclear. We tested the hypothesis that a hostile perinatal environment induces profibrotic pathways resulting in pulmonary fibrosis, including persistently altered lung structure and function. Pregnant C3H/HeN mice injected with LPS or saline on embryonic day 16. Offspring were placed in room air (RA) or 85% O(2) for 14 days and then returned to RA. Pulmonary function tests, microCTs, molecular and histological analyses were performed between embryonic day 18 and 8 wk. Alveolarization was most compromised in LPS/O(2)-exposed offspring. Collagen staining and protein levels were increased, and static compliance was decreased only in LPS/O(2)-exposed mice. Three-dimensional microCT reconstruction and quantification revealed increased tissue densities only in LPS/O(2) mice. Diffuse interstitial fibrosis was associated with decreased micro-RNA-29, increased transforming growth factor-β expression, and phosphorylation of Smad2 during embryonic or early fetal lung development. Systemic maternal LPS administration in combination with neonatal hyperoxic exposure induces activation of profibrotic pathways, impaired alveolarization, and diminished lung function that are associated with prenatal and postnatal suppression of miR-29 expression.

Venovenous cannulation for extracorporeal membrane oxygenation using a bicaval dual-lumen catheter in neonates

PURPOSE

Venovenous extracorporeal membrane oxygenation (VV-ECMO) has been used as a management strategy for neonates with refractory pulmonary failure. However, VV-ECMO has been limited in neonates secondary to cannula design and patient size. Herein, we describe the use of a bicaval dual-lumen catheter for VV-ECMO in neonates.

METHODS

The medical records of all neonates cannulated for ECMO support with a bicaval dual-lumen 13F catheter from 2008 to 2010 were reviewed.

RESULTS

Nine neonates cannulated with this dual-lumen catheter were identified. The median gestational age was 38 weeks (range, 31-40 weeks), the median weight was 3.4 kg (range, 2.2-5.5 kg), the median age at cannulation was 2 days (range, 1-64 days), and the median duration of ECMO support was 7 days (range, 5-23 days). There were no VV-to-VA conversions. The median pump flow both at 4 and 24 hours postcannulation was 300 mL/min (range, 240-370 mL/min). One patient developed cannula thrombosis, and one required cannula repositioning because of flow recirculation. Overall survival was 56%.

CONCLUSION

The dual-lumen bicaval catheter can be safely used in neonates with minimal complications and is our preferred method for VV-ECMO support in the neonatal population.

Omeprazole attenuates hyperoxic injury in H441 cells via the aryl hydrocarbon receptor

Hyperoxia contributes to the development of bronchopulmonary dysplasia in premature infants. Earlier we observed that aryl hydrocarbon receptor (AhR)-deficient mice are more susceptible to hyperoxic lung injury than AhR-sufficient mice, and this phenomenon was associated with a lack of expression of cytochrome P450 1A enzymes. Omeprazole, a proton pump inhibitor used in humans with gastric acid-related disorders, activates AhR in hepatocytes in vitro. However, the effects of omeprazole on AhR activation in the lungs and its impact on hyperoxia-induced reactive oxygen species (ROS) generation and inflammation are unknown. In this study, we tested the hypothesis that omeprazole attenuates hyperoxia-induced cytotoxicity, ROS generation, and expression of monocyte chemoattractant protein-1 (MCP-1) in human lung-derived H441 cells via AhR activation. Experimental groups included cells transfected with AhR small interfering RNA (siRNA). Hyperoxia resulted in significant increases in cytotoxicity, ROS generation, and MCP-1 production, which were significantly attenuated with the functional activation of AhR by omeprazole. The protective effects of omeprazole on cytotoxicity, ROS production, and MCP-1 production were lost in H441 cells whose AhR gene was silenced by AhR siRNA. These findings support the hypothesis that omeprazole protects against hyperoxic injury in vitro via AhR activation that is associated with decreased ROS generation and expression of MCP-1.

Maternal docosahexaenoic acid supplementation decreases lung inflammation in hyperoxia-exposed newborn mice

DHA is a long-chain fatty acid that has potent antiinflammatory properties. Whereas maternal DHA dietary supplementation has been shown to improve cognitive development in infants fed DHA-supplemented milk, the antiinflammatory effects of maternal DHA supplementation on the developing fetus and neonate have not been extensively explored. Pregnant C3H/HeN dams were fed purified control or DHA-supplemented diets (~0.25% of total fat) at embryonic d 16 and consumed these diets throughout the study. At birth, the nursing mouse pups were placed in room air (RA; 21% O(2)) or >95% O(2) (hyperoxia) for up to 7 d. These studies tested the hypothesis that maternal DHA supplementation would decrease inflammation and improve alveolarization in the lungs of newborn mouse pups exposed to hyperoxia. Survival, inflammatory responses, and lung growth were compared among control diet/RA, DHA/RA, control/O(2), and DHA/O(2) pups. There were fewer neutrophils and macrophages in lung tissues from pups nursed by DHA-supplemented dams than in those nursed by dams fed the control diet at 7 d of hyperoxia exposure (P < 0.015). Although differences due to hyperoxia exposure were observed, maternal diet did not affect keratinocyte-derived chemokine, macrophage inflammatory protein-2, IL-1β, or TNFα mRNA levels in pup tissues. Hyperoxia also induced NF-κB activity, but maternal diet did not affect NF-κB or PPARγ activities. In mice, DHA supplementation decreases leukocyte infiltration in the offspring exposed to hyperoxia, suggesting a potential role for DHA supplementation as a therapy to reduce inflammation in preterm infants.

Riboflavin supplementation does not attenuate hyperoxic lung injury in transgenic (spc-mt)hGR mice

The aims of this study were to test the hypothesis that mice expressing mitochondrially targeted human glutathione reductase (GR) driven by a surfactant protein C promoter ((spc-mt)hGR) are functionally riboflavin deficient and that this deficiency exacerbates hyperoxic lung injury. The authors further hypothesized that dietary supplementation with riboflavin (FADH) will improve the bioactivity of GR, thus enhancing resistance to hyperoxic lung injury. Transgenic (mt-spc)hGR mice and their nontransgenic littermates were fed control or riboflavin-supplemented diets upon weaning. At 6 weeks of age the mice were exposed to either room air (RA) or >95% O(2) for up to 84 hours. GR activities (with and without exogenous FADH) and GR protein levels were measured in lung tissue homogenates. Glutathione (GSH) and glutathione disulfide (GSSG) concentrations were assayed to identify changes in GR activity in vivo. Lung injury was assessed by right lung to body weight ratios and bronchoalveolar lavage protein concentrations. The data showed that enhanced GR activity in the mitochondria of lung type II cells does not protect adult mice from hyperoxic lung injury. Furthermore, the addition of riboflavin to the diets of (spc-mt)hGR mice neither enhances GR activities nor offers protection from hyperoxic lung injury. The results indicated that modulation of mitochondrial GR activity in lung type II cells is not an effective therapy to minimize hyperoxic lung injury.

Thioredoxin-interacting protein inhibits hypoxia-inducible factor transcriptional activity

Vascular endothelial growth factor (VEGF) is required for proper lung development and is transcriptionally regulated in alveolar epithelial cells by hypoxia-inducible factor (HIF). Previous findings in a newborn mouse model of bronchopulmonary dysplasia (BPD) suggest that thioredoxin-interacting protein (Txnip) is a novel regulator of VEGF expression. The present studies were designed to test the hypothesis that Txnip negatively regulates VEGF through effects on HIF-mediated gene expression. To test this hypothesis, we first examined the levels of VEGF and Txnip protein in the lungs of 1-day-old newborn mice and E19 embryos and detected a significant inverse correlation. To elucidate the mechanisms underlying this relationship, we studied the effects of Txnip overexpression on HIF-mediated transcription using murine lung epithelial (MLE-12) cells. Overexpression of Txnip inhibited HIF-mediated reporter activity in both hypoxia and room air. Suppression of HIF activity by Txnip seemed to be independent of the ability of Txnip to bind to thioredoxin. Thus, our studies support a model in which Txnip is a potentially critical regulator of HIF-mediated gene transcription in the murine lung. Alterations in Txnip expression could alter lung VEGF expression in prematurely born human infants and contribute to the development of BPD.

Deficits in lung alveolarization and function after systemic maternal inflammation and neonatal hyperoxia exposure

Systemic maternal inflammation contributes to preterm birth and is associated with development of bronchopulmonary dysplasia (BPD). Infants with BPD exhibit decreased alveolarization, diffuse interstitial fibrosis with thickened alveolar septa, and impaired pulmonary function. We tested the hypothesis that systemic prenatal LPS administration to pregnant mice followed by postnatal hyperoxia exposure is associated with prolonged alterations in pulmonary structure and function after return to room air (RA) that are more severe than hyperoxia exposure alone. Timed-pregnant C3H/HeN mice were dosed with LPS (80 microg/kg) or saline on gestation day 16. Newborn pups were exposed to RA or 85% O2 for 14 days and then to RA for an additional 14 days. Data were collected and analyzed on postnatal days 14 and 28. The combination of prenatal LPS and postnatal hyperoxia exposure generated a phenotype with more inflammation (measured as no. of macrophages per high-power field) than either insult alone at day 28. The combined exposures were associated with a diffuse fibrotic response [measured as hydroxyproline content (microg)] but did not induce a more severe developmental arrest than hyperoxia alone. Pulmonary function tests indicated that hyperoxia, independent of maternal exposure, induced compliance decreases on day 14 that did not persist after RA recovery. Either treatment alone or combined induced an increase in resistance on day 14, but the increase persisted on day 28 only in pups receiving the combined treatment. In conclusion, the combination of systemic maternal inflammation and neonatal hyperoxia induced a prolonged phenotype of arrested alveolarization, diffuse fibrosis, and impaired lung mechanics that mimics human BPD. This new model should be useful in designing studies of specific mechanisms and interventions that could ultimately be utilized to define therapies to prevent BPD in premature infants.

Inhaled nitric oxide decreases leukocyte trafficking in the neonatal mouse lung during exposure to >95% oxygen

Chronic lung injury in the neonate is termed bronchopulmonary dysplasia (BPD). These patients generally require supplemental oxygen therapy, and hyperoxia has been implicated in the pathogenesis of BPD. The concomitant use of oxygen and inhaled NO (iNO) may result in the generation of reactive nitrogen species or may have an anti-inflammatory effect in the neonatal lung. We tested the hypothesis that exposure to >95% O2 in neonatal mice would increase trafficking of leukocytes into the lung and that the addition of iNO to >95% O2 would decrease this leukocyte trafficking. Hyperoxia resulted in fewer alveoli, increased presence of neutrophils and macrophages, and decreased number of mast cells within the lung parenchyma. Adding iNO to hyperoxia prevented the hyperoxia-induced changes and resulted in the numbers of alveoli, neutrophils, macrophages, and mast cells approximating those found in controls (room air exposure). Intercellular adhesion molecule (ICAM) and monocyte chemotactic protein-1 (MCP-1), two factors responsible for leukocyte recruitment, were up-regulated by hyperoxic exposure, but the addition of iNO to the hyperoxic exposure prevented the hyperoxia-induced up-regulation of ICAM and MCP-1. These data demonstrate that iNO alters the hyperoxia-induced recruitment of leukocytes into the lung.

Implementation of a multidisciplinary guideline-driven approach to the care of the extremely premature infant improved hospital outcomes

AIM

To test the hypothesis that implementing guidelines for the standardized care of the extremely premature infant (<27 weeks) in the first week of life would improve patient outcomes in an all referral NICU.

METHODS

Data were collected on all infants <27 weeks gestational age and <7 days of age on admission cared for using these small baby guidelines (SBG), as well as on all age-matched infants admitted the year prior (comparison).

RESULTS

Thirty-seven patients were cared for utilizing the SBG and 40 patients were in the comparison group. There were no differences between the groups in gestational age, birthweight or age on admission. There was no difference in survival to discharge (73% SBG, 70% comparison). The mean length of stay for survivors was 112 +/- 38 days SBG and 145 +/- 76 days (p < 0.05) comparison group. Survival without BPD was greater in the SBG group (24%) than in the comparison group (9%; p < 0.05), and survival without severe IVH was greater in the SBG group (65%) than in the comparison group (38%; p < 0.01).

CONCLUSIONS

These data demonstrate that applying a unified approach to the care of the extremely premature infant in the first week of life resulted in a decrease in the length of hospitalization and improved patient outcomes.