Association between mechanical ventilation and neurodevelopmental disorders in a nationwide cohort of extremely low birth weight infants

Cerebral Palsy and Motor Impairment After Extreme Prematurity: Prediction of Diagnoses at Ages 2 and 10 Years

OBJECTIVE

To identify perinatal factors in children born extremely preterm (EP) that were associated with motor impairment (MI) at 2 and 10 years of age and develop a predictive algorithm to estimate the risk of MI during childhood.

STUDY DESIGN

Participants of the Extremely Low Gestational Age Newborns Study (ELGANS) were classified as: no MI, MI only at 2 years, MI only at 10 years, and MI at both 2 and 10 years, based on a standardized neurological examination at 2 and the Gross Motor Function Classification System (GMFCS) at 10 years of age. Least Absolute Shrinkage and Selection Operator (LASSO) regression was used to develop the final predictive model.

RESULTS

Of the 849 study participants, 64 (7.5%) had a diagnosis of MI at both 2 and 10 years and 63 (7.4%) had a diagnosis of MI at 1 visit but not the other. Of 22 total risk factors queried, 4 variables most reliably and accurately predicted MI: gestational age, weight z-score growth trajectory during neonatal intensive care unit (NICU) stay, ventriculomegaly, and cerebral echolucency on head ultrasound. By selecting probability thresholds of 3.5% and 7.0% at ages 2 and 10, respectively, likelihood of developing MI can be predicted with a sensitivity and specificity of 71.2%/72.1% at age 2 and 70.7%/70.7% at age 10.

CONCLUSION

In our cohort, the diagnosis of MI at 2 years did not always predict a diagnosis of MI at 10 years. Specific risk factors are predictive of MI and can estimate an individual infant's risk at NICU discharge of MI at age 10 years.

Genetic pathways in cerebral palsy: a review of the implications for precision diagnosis and understanding disease mechanisms

ABSTRACT

Cerebral palsy is a diagnostic term utilized to describe a group of permanent disorders affecting movement and posture. Patients with cerebral palsy are often only capable of limited activity, resulting from non-progressive disturbances in the fetal or neonatal brain. These disturbances severely impact the child's daily life and impose a substantial economic burden on the family. Although cerebral palsy encompasses various brain injuries leading to similar clinical outcomes, the understanding of its etiological pathways remains incomplete owing to its complexity and heterogeneity. This review aims to summarize the current knowledge on the genetic factors influencing cerebral palsy development. It is now widely acknowledged that genetic mutations and alterations play a pivotal role in cerebral palsy development, which can be further influenced by environmental factors. Despite continuous research endeavors, the underlying factors contributing to cerebral palsy remain are still elusive. However, significant progress has been made in genetic research that has markedly enhanced our comprehension of the genetic factors underlying cerebral palsy development. Moreover, these genetic factors have been categorized based on the identified gene mutations in patients through clinical genotyping, including thrombosis, angiogenesis, mitochondrial and oxidative phosphorylation function, neuronal migration, and cellular autophagy. Furthermore, exploring targeted genotypes holds potential for precision treatment. In conclusion, advancements in genetic research have substantially improved our understanding of the genetic causes underlying cerebral palsy. These breakthroughs have the potential to pave the way for new treatments and therapies, consequently shaping the future of cerebral palsy research and its clinical management. The investigation of cerebral palsy genetics holds the potential to significantly advance treatments and management strategies. By elucidating the underlying cellular mechanisms, we can develop targeted interventions to optimize outcomes. A continued collaboration between researchers and clinicians is imperative to comprehensively unravel the intricate genetic etiology of cerebral palsy.

Evaluation of Autism Spectrum Disorder Risk in Infants With Intraventricular Hemorrhage

Background This study evaluates the long-term risk of autism spectrum disorder (ASD) in infants with intraventricular hemorrhage (IVH) using the Modified Checklist for Autism in Toddlers-Revised with Follow-Up (M-CHAT-R/F) screening tool. Methods This retrospective cohort study compared IVH (exposed) infants across all gestational age groups with no-IVH (non-exposed) infants admitted to level IV neonatal intensive care unit (NICU). The M-CHAT-R/F screening tool was used to assess the ASD risk at 16-30 months of age. Discharge cranial ultrasound (CUS) findings also determined the ASD risk. Descriptive statistics comprised median and interquartile range for skewed continuous data and frequencies and percentages for categorical variables. Comparisons for non-ordinal categorical measures in bivariate analysis were carried out using the χ2 test or Fisher exact test. Results Of the 334 infants, 167 had IVH, and 167 had no IVH. High ASD risk (43% vs. 20%, p = 0.044) and cerebral palsy (19% vs. 5%, p = 0.004) were significantly associated with severe IVH. Infants with CUS findings of periventricular leukomalacia had 3.24 odds of developing high ASD risk (odds ratios/OR: 3.24, 95% confidence interval/CI: 0.73-14.34), and those with hydrocephalus needing ventriculoperitoneal (VP) shunt had 4.75 odds of developing high ASD risk (OR: 4.75, 95% CI: 0.73-30.69). Conclusion Severe IVH, but not mild IVH, increased the risk of ASD and cerebral palsy. This study demonstrates the need for timely screening for ASD in high-risk infants. Prompt detection leads to earlier treatment and better outcomes.

A Family-Centered, Multidisciplinary Clinic for Early Diagnosis of Neurodevelopmental Impairment and Cerebral Palsy in China-A Pilot Observation

BACKGROUND

Comprehensive multidisciplinary assessment of neurodevelopmental outcomes of high-risk neonates may have significant challenges in low- and middle-income countries, in addition to socio-cultural barriers. We aimed to compare the time to diagnosis of neurodevelopmental impairment (NDI) and cerebral palsy (CP) in preterm neonates (<29 weeks) at a multidisciplinary assessment and care (MDAC) clinic with that of a conventional high-risk infant follow-up clinic in China.

METHODS

All eligible surviving very preterm neonates born at <29 weeks gestation at the University of Hong Kong-Shenzhen Hospital between January 2015 and December 2019 were followed up in conventional (2015-2017) and MDAC (2018-2020) clinics up to 2 years corrected age with clinical demographic information collected in a prospective database. The MDAC team used standardized developmental assessments. The rates and timing of diagnosing NDI and CP in two epochs were compared.

RESULTS

The rates of NDI and CP were not different in two epochs [NDI: 12 (50%) vs. 12 (41%); CP: 3 (12%) vs. 2 (7%) of 24 and 29 surviving infants assessed in conventional and MDAC clinics, respectively]. Infants in the MDAC clinic were diagnosed with NDI and CP earlier than those in the pre-MDAC epoch (6 vs. 14 months corrected age, respectively, P < 0.05).

CONCLUSION

High-risk preterm neonates can be followed more effectively in a family-centered, child-friendly multidisciplinary clinic, leading to an earlier diagnosis of NDI and CP. Early counseling and interventions could be implemented accordingly.

Changes in Use of Respiratory Support for Preterm Infants in the US, 2008-2018

IMPORTANCE

In preterm infants, mechanical ventilation (MV) is associated with adverse pulmonary and neurodevelopmental outcomes. Multiple randomized clinical trials over the past 2 decades have shown the effectiveness of early noninvasive ventilation (NIV) in decreasing the use of MV in preterm infants. The epidemiologic factors associated with respiratory support in US preterm infants and any temporal changes after these trials is unknown.

OBJECTIVE

To evaluate temporal changes in MV and noninvasive respiratory support in US preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

In a cohort design, 2 large national data sets (Pediatrix Clinical Data Warehouse for the clinical cohort and National Inpatient Sample for the national cohort) were used to collect data on preterm infants (<35 weeks' gestation) without congenital anomalies who received active intensive care and were discharged home or died in the birth hospital from January 1, 2008, to December 31, 2018. Data analysis was conducted from December 10, 2019, to December 16, 2020.

EXPOSURE

Discharge year.

MAIN OUTCOME AND MEASURES

In the clinical cohort, detailed respiratory support data were generated, including days of MV and NIV modalities, and temporal trends were evaluated using multivariable modified Poisson or negative binomial regression models with discharge year as a continuous variable. In the national cohort, observed and expected national MV use were calculated.

RESULTS

Among 259 311 infants (47.2% female) in 359 neonatal intensive care units in the clinical cohort, decreases were noted in the use (from 29.4% of infants in 2008 to 18.5% in 2018, relative risk for annual change, 0.96; 95% CI, 0.95-0.96) and duration (mean days, from 10.3 in 2008 to 9.7 in 2018; rate ratio for annual change, 0.98; 95% CI, 0.97-0.98) of MV. Noninvasive ventilation use increased from 57.9% of infants in 2008 to 67.4% in 2018 (adjusted relative risk for annual change, 1.02; 95% CI, 1.02-1.03), and mean NIV duration increased by 3.2 days (95% CI, 2.9-3.6 days). With increased use of continuous positive airway pressure and nasal intermittent positive-pressure ventilation as the main factors in the increase, the mean duration of respiratory support increased from 13.8 to 15.4 days (adjusted rate ratio for annual change, 1.03; 95% CI, 1.02-1.04) from 2008 to 2018. Among 1 169 441 infants in the national cohort, MV use decreased from 22.0% in 2008 to 18.5% in 2018, with an estimated 29 700 fewer ventilated infants and 142 000 fewer days of MV than expected during this period.

CONCLUSIONS AND RELEVANCE

These findings suggest that preterm respiratory support changed significantly from 2008 to 2018, with decreased use and duration of MV, increased use and duration of NIV, and an overall increase in respiratory support duration.

Association of time of day and extubation success in very low birthweight infants: a multicenter cohort study

OBJECTIVE

To determine the association of overnight extubation (OE) with extubation success.

STUDY DESIGN

Retrospective cohort study in three NICUs from 2016 to 2020. Infants without congenital anomalies, less than 1500 grams at birth, who were ventilated and received an extubation attempt were included. Primary exposure was OE (7:00 pm-6:59 am) and outcome was extubation success defined as no mechanical ventilation for at least 7 days after extubation.

RESULTS

A total of 76/379 (20%) infants received OE. Infants extubated during the daytime were older and had higher illness severity markers. Extubation success rates did not differ for overnight (57/76, 75%) versus daytime extubations (231/303, 76%) after adjusting for confounders (adjusted relative risk 0.95, 95% CI 0.82-1.11).

CONCLUSION

Though infants in our cohort undergoing daytime and OE were dissimilar, extubation success rates did not differ. Larger multicenter studies are needed to test our findings and identify markers of extubation readiness in preterm infants.

Respiratory Support of the Preterm Neonate: Lessons About Ventilation-Induced Brain Injury From Large Animal Models

Many preterm neonates require mechanical ventilation which increases the risk of cerebral inflammation and white matter injury in the immature brain. In this review, we discuss the links between ventilation and brain injury with a focus on the immediate period after birth, incorporating respiratory support in the delivery room and subsequent mechanical ventilation in the neonatal intensive care unit. This review collates insight from large animal models in which acute injurious ventilation and prolonged periods of ventilation have been used to create clinically relevant brain injury patterns. These models are valuable resources in investigating the pathophysiology of ventilation-induced brain injury and have important translational implications. We discuss the challenges of reconciling lung and brain maturation in commonly used large animal models. A comprehensive understanding of ventilation-induced brain injury is necessary to guide the way we care for preterm neonates, with the goal to improve their neurodevelopmental outcomes.

Developing routinely recorded clinical data from electronic patient records as a national resource to improve neonatal health care: the Medicines for Neonates research programme

Background

Clinical data offer the potential to advance patient care. Neonatal specialised care is a high-cost NHS service received by approximately 80,000 newborn infants each year.

Objectives

(1) To develop the use of routinely recorded operational clinical data from electronic patient records (EPRs), secure national coverage, evaluate and improve the quality of clinical data, and develop their use as a national resource to improve neonatal health care and outcomes. To test the hypotheses that (2) clinical and research data are of comparable quality, (3) routine NHS clinical assessment at the age of 2 years reliably identifies children with neurodevelopmental impairment and (4) trial-based economic evaluations of neonatal interventions can be reliably conducted using clinical data. (5) To test methods to link NHS data sets and (6) to evaluate parent views of personal data in research.

Design

Six inter-related workstreams; quarterly extractions of predefined data from neonatal EPRs; and approvals from the National Research Ethics Service, Health Research Authority Confidentiality Advisory Group, Caldicott Guardians and lead neonatal clinicians of participating NHS trusts.

Setting

NHS neonatal units.

Participants

Neonatal clinical teams; parents of babies admitted to NHS neonatal units.

Interventions

In workstream 3, we employed the Bayley-III scales to evaluate neurodevelopmental status and the Quantitative Checklist of Autism in Toddlers (Q-CHAT) to evaluate social communication skills. In workstream 6, we recruited parents with previous experience of a child in neonatal care to assist in the design of a questionnaire directed at the parents of infants admitted to neonatal units.

Data sources

Data were extracted from the EPR of admissions to NHS neonatal units.

Main outcome measures

We created a National Neonatal Research Database (NNRD) containing a defined extract from real-time, point-of-care, clinician-entered EPRs from all NHS neonatal units in England, Wales and Scotland (n = 200), established a UK Neonatal Collaborative of all NHS trusts providing neonatal specialised care, and created a new NHS information standard: the Neonatal Data Set (ISB 1595) (see http://webarchive.nationalarchives.gov.uk/±/http://www.isb.nhs.uk/documents/isb-1595/amd-32–2012/index_html; accessed 25 June 2018).

Results

We found low discordance between clinical (NNRD) and research data for most important infant and maternal characteristics, and higher prevalence of clinical outcomes. Compared with research assessments, NHS clinical assessment at the age of 2 years has lower sensitivity but higher specificity for identifying children with neurodevelopmental impairment. Completeness and quality are higher for clinical than for administrative NHS data; linkage is feasible and substantially enhances data quality and scope. The majority of hospital resource inputs for economic evaluations of neonatal interventions can be extracted reliably from the NNRD. In general, there is strong parent support for sharing routine clinical data for research purposes.

Limitations

We were only able to include data from all English neonatal units from 2012 onwards and conduct only limited cross validation of NNRD data directly against data in paper case notes. We were unable to conduct qualitative analyses of parent perspectives. We were also only able to assess the utility of trial-based economic evaluations of neonatal interventions using a single trial. We suggest that results should be validated against other trials.

Conclusions

We show that it is possible to obtain research-standard data from neonatal EPRs, and achieve complete population coverage, but we highlight the importance of implementing systematic examination of NHS data quality and completeness and testing methods to improve these measures. Currently available EPR data do not enable ascertainment of neurodevelopmental outcomes reliably in very preterm infants. Measures to maintain high quality and completeness of clinical and administrative data are important health service goals. As parent support for sharing clinical data for research is underpinned by strong altruistic motivation, improving wider public understanding of benefits may enhance informed decision-making.

Future work

We aim to implement a new paradigm for newborn health care in which continuous incremental improvement is achieved efficiently and cost-effectively by close integration of evidence generation with clinical care through the use of high-quality EPR data. In future work, we aim to automate completeness and quality checks and make recording processes more ‘user friendly’ and constructed in ways that minimise the likelihood of missing or erroneous entries. The development of criteria that provide assurance that data conform to prespecified completeness and quality criteria would be an important development. The benefits of EPR data might be extended by testing their use in large pragmatic clinical trials. It would also be of value to develop methods to quality assure EPR data including involving parents, and link the NNRD to other health, social care and educational data sets to facilitate the acquisition of lifelong outcomes across multiple domains.

Study registration

This study is registered as PROSPERO CRD42015017439 (workstream 1) and PROSPERO CRD42012002168 (workstream 3).

Funding

The National Institute for Health Research Programme Grants for Applied Research programme (£1,641,471). Unrestricted donations were supplied by Abbott Laboratories (Maidenhead, UK: £35,000), Nutricia Research Foundation (Schiphol, the Netherlands: £15,000), GE Healthcare (Amersham, UK: £1000). A grant to support the use of routinely collected, standardised, electronic clinical data for audit, management and multidisciplinary feedback in neonatal medicine was received from the Department of Health and Social Care (£135,494).

Early caloric deprivation in preterm infants affects Bayley-III scales performance at 18-24 months of corrected age

BACKGROUND

Adequate nutrition is essential for optimal neurodevelopment to preterm infants. Our aim was to evaluate the impact of caloric deprivation on Bayley-III scales performance at 18-24 months of corrected age, in a cohort of preterm infants.

METHODS

We prospectively enrolled infants with gestational age <30 weeks and birth weight <1500 g. Apart from a whole cohort analysis, we performed a subgroup analysis between infants received inadequate calories (<85 Kcal/kg/day) during the first two weeks of age, compared to a standard nutrition group. All infants underwent a Bayley-III assessment at 18-24 months of corrected age.

RESULTS

From the 63 preterm infants analysed, 25% had caloric deprivation compared to 75% with adequate nutrition. Caloric deprived infants were of lower gestational age and birth weight, and received a lower amount of enteral feeding during the first 14 days of age. There were no differences between the two groups regarding the common neonatal co-morbidities. Caloric deprived infants had significantly lower composite index scores at 18-24 months of corrected age. Caloric deprivation, late onset sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia were significant risk factors of neurodevelopmental impairment.

CONCLUSIONS

Several neonatal factors affect the neurodevelopmental outcome of preterm infants, and nutrition may pose an important role.

The complex aetiology of cerebral palsy

Cerebral palsy (CP) is the most prevalent, severe and costly motor disability of childhood. Consequently, CP is a public health priority for prevention, but its aetiology has proved complex. In this Review, we summarize the evidence for a decline in the birth prevalence of CP in some high-income nations, describe the epidemiological evidence for risk factors, such as preterm delivery and fetal growth restriction, genetics, pregnancy infection and other exposures, and discuss the success achieved so far in prevention through the use of magnesium sulfate in preterm labour and therapeutic hypothermia for birth-asphyxiated infants. We also consider the complexities of disentangling prenatal and perinatal influences, and of establishing subtypes of the disorder, with a view to accelerating the translation of evidence into the development of strategies for the prevention of CP.

Research Review: The role of obstetric and neonatal complications in childhood attention deficit and hyperactivity disorder - a systematic review

BACKGROUND

Attention deficit and hyperactivity disorder (ADHD) is a developmental disorder characterized by an inability to sustain attention, activity levels and impulse control, and, according to the latest studies, the prevalence is about 8% and in some countries less than 1%. Currently, it is well-known that complications during the perinatal period have significant implications on child's physical and mental health. Purpose of the present paper is to review the literature about the association between perinatal complications and future risk of an ADHD diagnosis.

METHODS

A research in the main database sources has been conducted to obtain a systematic review on the perinatal risk factors of ADHD.

RESULTS

Among perinatal complications, available data indicate low birth weight (LBW) (Cohen's d effect size range: 0.31-1.64-small effect size) and preterm birth (PB) (range d: 0.41-0.68) as the most important factors associated with a future diagnosis of ADHD.

CONCLUSIONS

PB and LBW children should be carefully monitored for an early diagnosis of ADHD limiting the impact of the disease in life span. A systematic review focusing on these risk factors have not been published until now, in the next future preventive strategies should be developed in order to minimize ADHD onset.

Clinical profile of newborns undergoing physical therapy in a neonatal intensive care unit

Abstract Introduction: In neonatal therapy units, physical therapy is directed toward integral baby care. Objective: To describe the profile of newborns (NBs) hospitalized in a Neonatal Intensive Care Unit (NICU). Methods: Retrospective documentary study with data collection from medical records from July 2011 to July 2013. The sample consisted of NBs who performed motor and respiratory therapy. Data were grouped into five categories according to birth weight (≤ 1000g, 1001-1500g, 1501-2000g, 2001-2500g, ≥ 2501g). Results: total of 1,884 newborns were admitted to the NICU within the stipulated period, 168 (13.9%) underwent physical therapy. Of the 168 NBs who underwent physical therapy, 137 were born in the hospital (81.5%) and 31 were transferred there (18.5%); 17 of these babies died during the neonatal hospital stay (10.1%). All newborns of the extremely low birth weight group (≤ 1000g) required mechanical ventilation, 72.7% non-invasive ventilation and 16.6% high-frequency oscillatory ventilation. The occurrence of pneumothorax in the extremely low birth weight group was 13.8% and 16% in the group with birth weight 1001-1500g. Conclusion: Infants with low birth weight (<2500g) constituted the profile of NBs who underwent physical therapy, which was directly related to higher incidence of death and pneumothorax, as well as increased use of mechanical and non-invasive ventilation.

Head Lag in Infancy: What Is It Telling Us?

OBJECTIVE

To investigate changes in head lag across postmenstrual age and define associations between head lag and (1) perinatal exposures and (2) neurodevelopment.

METHOD

Sixty-four infants born ≤ 30 wk gestation had head lag assessed before and at term-equivalent age. Neurobehavior was assessed at term age. At 2 yr, neurodevelopmental testing was conducted.

RESULTS

Head lag decreased with advancing postmenstrual age, but 58% (n = 37) of infants continued to demonstrate head lag at term. Head lag was associated with longer stay in the neonatal intensive care unit (p = .009), inotrope use (p = .04), sepsis (p = .02), longer endotracheal intubation (p = .01), and cerebral injury (p = .006). Head lag was related to alterations in early neurobehavior (p < .03), but no associations with neurodevelopment were found at 2 yr.

CONCLUSION

Head lag was related to medical factors and early neurobehavior, but it may not be a good predictor of outcome when used in isolation.

Angiogenesis induced by prenatal ischemia predisposes to periventricular hemorrhage during postnatal mechanical ventilation

BACKGROUND

Three risk factors are associated with hemorrhagic forms of encephalopathy of prematurity (EP): (i) prematurity, (ii) in utero ischemia (IUI) or perinatal ischemia, and (iii) mechanical ventilation. We hypothesized that IUI would induce an angiogenic response marked by activation of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9), the latter degrading vascular basement membrane and increasing vulnerability to raised intravenous pressure during positive pressure mechanical ventilation.

METHODS

We studied a rat model of hemorrhagic-EP characterized by periventricular hemorrhages in which a 20-min episode of IUI is induced at E19, pups are born naturally at E21-22, and on P0, are subjected to a 20-min episode of positive pressure mechanical ventilation. Tissues were studied by H&E staining, immunolabeling, immunoblot, and zymography.

RESULTS

Mechanical ventilation of rat pups 2-3 d after 20-min IUI caused widespread hemorrhages in periventricular tissues. IUI resulted in upregulation of VEGF and MMP-9. Zymography confirmed significantly elevated gelatinase activity. MMP-9 activation was accompanied by severe loss of MMP-9 substrates, collagen IV and laminin, in microvessels in periventricular areas.

CONCLUSION

Our findings are consistent with the hypothesis that positive pressure mechanical ventilation of the newborn in the context of recent prenatal ischemia/hypoxia can predispose to periventricular hemorrhages.

Parenteral nutrition compromises neurodevelopment of preterm pigs

BACKGROUND

Despite advances in nutritional support and intensive care, preterm infants are at higher risk of compromised neurodevelopment.

OBJECTIVE

This study evaluated the contribution of total parenteral nutrition (PN) to compromised neurodevelopment after preterm birth.

METHODS

Preterm pigs were provided PN or enteral nutrition (EN) for 10 d. Neurodevelopment was assessed by observations of motor activity and evaluation of sensory/motor reflexes, brain weight, MRI, and cerebellar histology.

RESULTS

Despite similar gains in body weight, PN pigs had smaller brains (32 ± 0.4 vs. 35 ± 0.6 g; P = 0.0002) including the cerebellum, as well as reduced motor activity (P = 0.005), which corresponded to underdeveloped myelination (P = 0.004) measured by diffusion tensor imaging. PN resulted in lower serum triglycerides (17 ± 5.9 vs. 27 ± 3.1 mg/dL; P = 0.05), total cholesterol (31 ± 9.6 vs. 85 ± 8.1 mg/dL; P = 0.04), VLDL cholesterol (3.7 ± 1.2 vs. 5.7 ± 0.7 mg/dL; P = 0.04), and HDL cholesterol (16 ± 4.6 vs. 57 ± 7.3 mg/dL; P = 0.03) and nonsignificantly lower LDL cholesterol (10.7 ± 4.4 vs. 22.7 ± 2.9 mg/dL; P = 0.09).

CONCLUSIONS

The compromised neurodevelopment caused by total PN is a novel finding, was independent of confounding variables (disease, inconsistent gestational ages, diverse genetics, extrauterine growth retardation, and inconsistent neonatal intensive care unit protocols), and highlights a need to improve current PN solutions. The preterm pig is a translational animal model for improving nutrition support to enhance neurodevelopment of preterm infants requiring PN.

A preterm pig model of lung immaturity and spontaneous infant respiratory distress syndrome

Respiratory distress syndrome (RDS) and bronchopulmonary dysplasia remain the leading causes of preterm infant morbidity, mortality, and lifelong disability. Research to improve outcomes requires translational large animal models for RDS. Preterm pigs delivered by caesarian section at gestation days (GD) 98, 100, 102, and 104 were provided 24 h of neonatal intensive care, monitoring (pulse oximetry, blood gases, serum biomarkers, radiography), and nutritional support, with or without intubation and mechanical ventilation (MV; pressure control ventilation with volume guarantee). Spontaneous development of RDS and mortality without MV are inversely related with GD at delivery and correspond with inadequacy of tidal volume and gas exchange. GD 98 and 100 pigs have consolidated lungs, immature alveolar architecture, and minimal surfactant protein-B expression, and MV is essential at GD 98. Although GD 102 pigs had some alveoli lined by pneumocytes and surfactant was released in response to MV, blood gases and radiography revealed limited recruitment 1-2 h after delivery, and mortality at 24 h was 66% (35/53) with supplemental oxygen provided by a mask and 69% (9/13) with bubble continuous positive airway pressure (8-9 cmH2O). The lungs at GD 104 had higher densities of thin-walled alveoli that secreted surfactant, and MV was not essential. Between GD 98 and 102, preterm pigs have ventilation inadequacies and risks of RDS that mimic those of preterm infants born during the saccular phase of lung development, are compatible with standards of neonatal intensive care, and are alternative to fetal nonhuman primates and lambs.