Perinatal factors associated with long-term respiratory sequelae in extremely low birthweight infants

Association of hyaluronan and proteoglycan link protein 1 gene with the need of home oxygen therapy in premature Japanese infants with bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) has a lasting effect on the respiratory function of infants, imposing chronic health burdens. BPD is influenced by various prenatal, postnatal, and genetic factors. This study explored the connection between BPD and home oxygen therapy (HOT), and then we examined the association between HOT and a specific single-nucleotide polymorphism (SNP) in the hyaluronan and proteoglycan link protein 1 (HAPLN1) gene among premature Japanese infants.

MATERIALS AND METHODS

Prenatal and postnatal data from 212 premature infants were collected and analyzed by four SNPs (rs975563, rs10942332, rs179851, and rs4703570) around HAPLN1 using the TaqMan polymerase chain reaction method. The clinical characteristics and genotype frequencies of HAPLN1 were assessed and compared between HOT and non-HOT groups.

RESULTS

Individuals with AA/AC genotypes in the rs4703570 SNP exhibited significantly higher HOT rates at discharge than those with CC homozygotes (odds ratio, 1.20, 95% confidence interval, 1.07-1.35, p = .038). A logistic regression analysis determined that CC homozygotes in the rs4703570 SNP did not show a statistically significant independent association with HOT at discharge.

CONCLUSIONS

Although our study did not reveal a correlation between HAPLN1 and the onset of BPD, we observed that individuals with CC homozygosity at the rs4703570 SNP exhibit a reduced risk of HOT.

Chorioamnionitis and respiratory outcomes in prematurely born children: a systematic review and meta analysis

INTRODUCTION

To conduct a systematic review and meta-analysis of the association between chorioamnionitis and respiratory outcomes of prematurely born children.

CONTENT

Pubmed, Medline and Embase were searched for relevant studies. Studies were included if they assessed prematurely born children, who had been exposed to chorioamnionitis and had either lung function testing or assessment of wheeze or asthma following NICU discharge. Two reviewers independently screened the search results, applied inclusion criteria and assessed methodological quality. One reviewer extracted the data and these were checked by a second reviewer.

SUMMARY

1,237 studies were identified, but only eight which included 35,000 infants, fulfilled the inclusion criteria. One study looked at both lung function results and wheeze or asthma in childhood. Four of five studies found an association between wheeze/asthma in childhood and exposure to chorioamnionitis: the overall Odds Ratio (OR) for developing wheeze/asthma in childhood was OR 1.71 (95 % CI: 1.55-1.89). Four studies looked at lung function in childhood, three of which showed no statistically significant association between chorioamnionitis exposure and altered lung function. One study found lower lung function in those exposed to chorioamnionitis and lower expiratory flows with increasing levels of chorioamnionitis (forced expiratory flow at 50 % of exhaled forced vital capacity (=FEF50) p=0.012, forced expiratory flow at 25-75 % of the forced vital capacity is exhaled (=FEF25-75) p=0.014).

OUTLOOK

There was a significant association between chorioamnionitis and the development of wheeze or asthma in childhood, but overall not in impairment of lung function.

Changes in Lung Function Among Infants Born Extremely Preterm over a 20-Year Period in the Post-Surfactant Era: A Retrospective Study

Lung function was assessed at 8 years in 308 infants born extremely preterm between 1994 and 2013. Although lung function of those infants born at 22 through 25 weeks remained unchanged, those who were born at 26-27 weeks showed a significant improvement over the past 2 decades.

Urine Desmosine as a Novel Biomarker for Bronchopulmonary Dysplasia and Postprematurity Respiratory Disease in Extremely Preterm or Low Birth Weight Infants

OBJECTIVE

This study aimed to evaluate whether elevated urine desmosine levels at 3 weeks of age were associated with severe radiological findings, bronchopulmonary dysplasia (BPD), and post-prematurity respiratory disease (PRD) in extremely preterm (EP) or extremely low birth weight (ELBW) infants.

STUDY DESIGN

This study recruited 37 EP (22-27 completed weeks) or ELBW (<1,000 g) infants. Urine was collected between 21 and 28 postnatal days, and desmosine was measured using an enzyme-linked immunosorbent assay kit; the urine creatinine level was also measured. Bubbly/cystic lungs were characterized by emphysematous chest X-rays on postnatal day 28. Furthermore, provision of supplemental oxygen or positive-pressure respiratory support at 40 weeks' postmenstrual age defined BPD, and increased medical utilization at 18 months of corrected age defined PRD. The desmosine/creatinine threshold was determined by receiver operating characteristic analysis. The adjusted risk and 95% confidence interval (CI) for elevated urine desmosine/creatinine levels were estimated by logistic regression analysis.

RESULTS

Elevated urine desmosine/creatinine levels higher than the threshold were significantly associated with bubbly/cystic lungs (8/13 [61.5%] vs. 2/24 [8.3%], p = 0.001), BPD (10/13 [76.9%] vs. 8/24 [33.3%], p = 0.02), and PRD (6/13 [46.2%] vs. 2/24 [8.3%], p = 0.01). After adjusting for gestational age, birth weight, and sex, the urine desmosine/creatinine levels were significantly higher in those who were highly at risk of bubbly/cystic lungs (odds ratio [OR], 13.2; 95% CI, 1.67-105) and PRD (OR, 13.8; 95% CI, 1.31-144).

CONCLUSION

Elevated urine desmosine/creatinine levels on the third postnatal week were associated with bubbly/cystic lungs on day 28 and PRD at 18 months of corrected age in EP or ELBW infants.

KEY POINTS

· Urine desmosine was prospectively measured in 3-week-old EP/ELBW infants.. · Elevated urine desmosine levels were associated with emphysematous radiological findings on day 28, PRD at 18 months of corrected age.. · Urine desmosine may be a promising biomarker indicating lung damage in EP/ELBW infants..

Increasing airway obstruction through life following bronchopulmonary dysplasia: a meta-analysis

Background

Few studies exist investigating lung function trajectories of those born preterm; however growing evidence suggests some individuals experience increasing airway obstruction throughout life. Here we use the studies identified in a recent systematic review to provide the first meta-analysis investigating the impact of preterm birth on airway obstruction measured by the forced expiratory volume in 1 s (FEV1) to forced vital capacity (FVC) ratio.

Methods

Cohorts were included for analysis if they reported FEV1/FVC in survivors of preterm birth (<37 weeks' gestation) and control populations born at term. Meta-analysis was performed using a random effect model, expressed as standardised mean difference (SMD). Meta-regression was conducted using age and birth year as moderators.

Results

55 cohorts were eligible, 35 of which defined groups with bronchopulmonary dysplasia (BPD). Compared to control populations born at term, lower values of FEV1/FVC were seen in all individuals born preterm (SMD -0.56), with greater differences seen in those with BPD (SMD -0.87) than those without BPD (SMD -0.45). Meta-regression identified age as a significant predictor of FEV1/FVC in those with BPD with the FEV1/FVC ratio moving -0.04 sds away from the term control population for every year of increased age.

Conclusions

Survivors of preterm birth have significantly increased airway obstruction compared to those born at term with larger differences in those with BPD. Increased age is associated with a decline in FEV1/FVC values suggesting increased airway obstruction over the life course.

Neonatal respiratory support related to lung function abnormalities in school-age children with bronchopulmonary dysplasia

OBJECTIVE

To elucidate the relationship between abnormal lung function (LF) at school age and neonatal respiratory support in very low birth weight children with bronchopulmonary dysplasia (BPD).

STUDY DESIGN

We retrospectively examined 78 BPD children whose LF was evaluated at 8-9 years. LF abnormalities were defined by reduced values of spirometric parameters. Adjusted odds ratios (aORs) for abnormal LF by the type and postmenstrual age (PMA) of respiratory support were calculated using logistic regression analysis after controlling perinatal factors.

RESULTS

Overall, 24 (31%) patients had LF abnormalities. Antenatal steroid use was associated with a decreased risk of abnormal LF [aOR, 0.31; 95% CI, 0.09-0.92]. Requiring positive-pressure support at 37 weeks' PMA correlated with abnormal LF [aOR, 4.58; 95% CI, 1.15-21.90]; whereas only low-flow oxygen at any PMA did not.

CONCLUSION

Requiring positive-pressure support at 37 weeks' PMA could be an indicator of abnormal LF at school age.

Bronchopulmonary Dysplasia in Extremely Premature Infants: A Scoping Review for Identifying Risk Factors

BACKGROUND

Over the years, bronchopulmonary dysplasia (BPD) affects the pulmonary function of infants, resulting in chronic health burdens for infants and their families. The aim of this scoping review was to screen available evidence regarding perinatal risk factors associated with the development and severity of BPD.

METHODS

The eligibility criteria of the studies were year of publication between 2016 and 2021; setting of a developed country; English or Japanese as the study language; and randomized controlled, cohort, or case-control design. The titles and abstracts of the studies were screened by independent reviewers.

RESULTS

Of 8189 eligible studies, 3 were included for severe BPD and 26 were included for moderate BPD. The risk factors for severe BPD were male sex, iatrogenic preterm birth, maternal hypertensive disorders of pregnancy (HDP), low gestational age, small-for-gestational-age (SGA) birth weight, mechanical ventilation on day 1, and need for patent ductus arteriosus (PDA) management. The risk factors for moderate or severe BPD included male sex, premature rupture of membranes, clinical chorioamnionitis, maternal HDP, SGA birth weight, bubbly/cystic appearance on X-ray, and PDA management.

CONCLUSIONS

We identified several risk factors for BPD. We plan to confirm the validity of the new classification using the existing dataset.

Inhaled Nitric Oxide Therapy in the Post-Acute Phase in Extremely Preterm Infants: A Japanese Cohort Study

OBJECTIVE

To determine the trends in inhaled nitric oxide (iNO) utilization in the late phase of hospitalization in a large Japanese cohort of extremely preterm infants and evaluate its benefit on long-term outcomes.

STUDY DESIGN

This was a retrospective multicenter cohort study of 15 977 extremely preterm infants born at <28 weeks of gestational age between 2003 and 2016, in the Neonatal Research Network, Japan. Demographic characteristics, morbidity, and mortality were compared between extremely preterm infants with and without post-acute iNO therapy. Multivariable logistic analysis was performed to determine factors associated with post-acute iNO and its impact on neurodevelopmental outcomes at 3 years of age.

RESULTS

Post-acute iNO utilization rates increased from 0.3% in 2009 to 1.9% in 2016, even under strict insurance coverage rules starting in 2009. Gestational age (1-week increment; aOR 0.82, 95% CI 0.76-0.88), small for gestational age (1.47, 1.08-1.99), histologic chorioamnionitis (1.50, 1.21-1.86), 5-minute Apgar score <4 (1.51, 1.10-2.07), air leak (1.92, 1.30-2.83), and bubbly/cystic appearance on chest X-Ray (1.68, 1.37-2.06) were associated with post-acute iNO. Post-acute iNO was not associated with neurodevelopmental outcomes at 3 years of age.

CONCLUSIONS

The increasing post-acute iNO utilization rate among extremely preterm infants has been concurrent with improved survival rates of extremely preterm infants in Japan. Infants treated with post-acute iNO had more severe disease and complications than the comparison group, but there were no differences in neurodevelopmental outcome at 3 years. This suggests post-acute iNO may benefit extremely preterm infants.

Intrauterine Ureaplasma is associated with small airway obstruction in extremely preterm infants

BACKGROUND

The long-term follow-up of lung function (LF) in extremely preterm (EP) infants with bronchopulmonary dysplasia (BPD) has shown a worldwide increase in small airway obstructions (SAO).

OBJECTIVES

We investigated the relationships between intrauterine Ureplasma infection in EP infants and bubbly/cystic lung, BPD, and SAO at school age.

METHODS

Placental pathology, placental Ureaplasma DNA (pU-DNA), and cord blood immunoglobulin M (IgM) (C-IgM) were investigated in 360 EP infants born from 1981 to 2004. Maternal amniotic inflammatory response (M-AIR) scores and hemosiderin deposition (HD) were estimated in the chorioamnion. The study subjects were divided into groups based on their M-AIR scores. Their LF at school age was compared with those of 33 healthy siblings.

FINDINGS

pU-DNA and C-IgM were significantly related to SAO at school age (p < 0.012). M-AIR score 3 and pU-DNA >1000 units had an odds ratio (OR) of 35 (95% confidence interval: 10-172) and 18 (5.6-67) for bubbly/cystic lung, and 11 (3.1 - 43) and 31 (4.5-349) for severe BPD, and 5.3 (2.1-11) and 12 (2.4-74) for SAO, respectively. The ORs of surfactant treatment, BPD grade III, O₂ at 40 weeks, HD, and C-IgM >30 mg/dl for SAO were 0.21 (0.075-0.58), 5.3 (2.1-15), 2.5 (1.4-4.6), 3.6 (1.5-9.1) and 2.5 (1.0-5.2). 84% (90/107) SAO infants showed no or mild BPD in infancy, and 61% of infants had no severe CAM.

CONCLUSION

Our long-term cohort study of LF in EP infants revealed that intrauterine Ureaplasma was associated with bubbly/cystic lung, severe BPD, and SAO at school age.

Sports participation and preterm birth: a nationwide birth cohort in Japan

BACKGROUND

Children born preterm may be less physically active than children born term because of neurocognitive problems, reduced lung function, and poor physical fitness. We evaluated sports participation of children and adolescents who had been born preterm (<37 weeks) and early term (37-38 weeks) in 2001.

METHODS

Data from a nationwide longitudinal survey (n = 47,015, including 2375 children born preterm) were analyzed. As indicators of sports participation, we used responses to questions about participation in sports clubs at 7 and 10 years old and in extracurricular school sports at 15 years old.

RESULTS

Children born very preterm (25-31 weeks) and moderately to late preterm (32-36 weeks) were less likely to participate in sports clubs at 7, 10, and 15 years old than children born full term (39-41 weeks). Compared with children born full term, the adjusted risk ratios for participation in extracurricular school sports at 15 years old were 0.86 (95% confidence interval: 0.75-0.98) for children born very preterm, 0.92 (0.88-0.97) for children born moderately to late preterm, and 1.00 (0.98-1.02) for children born early term.

CONCLUSIONS

Our findings suggest that preterm birth is associated with less participation in organized sports during childhood and adolescence than full-term birth.

IMPACT

Research investigating associations between preterm birth and physical activity among children born in the 2000s is limited. This study shows that preterm birth was associated with less participation in organized sports during childhood and adolescence than full-term birth, especially in boys, and the participation in organized sports of children born preterm decreased as gestation shortened. During childhood, boys born early term were also less likely to participate in organized sports than boys born full term, suggesting a continuum with preterm births. These findings offer important additional insights into the limited evidence available for predicting future health outcomes for preterm infants.

Severe bronchopulmonary dysplasia in extremely premature infants: a scoping review protocol for identifying risk factors

INTRODUCTION

The remarkable improvement in the long-term prognosis of extremely premature infants has led to an increase in the number of cases of bronchopulmonary dysplasia (BPD). BPD affects pulmonary function and developmental outcomes, resulting in high chronic health burdens for infants and their families over the years. Therefore, identifying its risk factors in the early period of life and exploring better prophylactics and treatment strategies are important.The objectives of our scoping review are to screen available evidence, identify perinatal risk factors involved in the development and severity of BPD and devise a novel disease classification system that can predict long-term prognosis.

METHODS AND ANALYSIS

Eligibility criteria are as follows: articles published from 2002 to 2021; studies conducted in developed countries; articles written in English (PubMed) or Japanese (Ichushi); randomised controlled trials, prospective/retrospective cohort studies or case-control studies; extremely premature infants born before 28 weeks of gestational age; and articles in which endpoint was severe BPD as classified by the National Institute of Child Health and Human Development.We will screen the titles and abstracts of studies identified by independent reviewers using the population-concept-context framework. After a full-text review and data charting, we will provide the perinatal risk factors for severe BPD along with the risk ratio or odds ratio, 95% confidence interval and p values.

ETHICS AND DISSEMINATION

Institutional review board approval is not required due to the nature of the study. The results of this review will be disseminated through peer-reviewed publications and presentations at relevant conferences.Protocol V.1, 22 September 2021 TRIAL REGISTRATION NUMBER: UMIN000045529.

The status of chronic lung disease diagnosis in Japan: Secondary publication

BACKGROUND

In Japan, the definition and classification of neonatal chronic lung disease (CLD) used for its diagnosis are a combination of those used in Japan and abroad.

METHODS

To clarify the current state of CLD diagnosis, a questionnaire survey was conducted.

RESULTS

Half of the patients of the medical centers included in the study were diagnosed with CLD in real time, while the other half were diagnosed after discharge. In addition, in approximately 70% of the facilities, diagnosis was made after discussions various among medical teams. In approximately 80% of the centers, the chest radiography used for CLD diagnosis were evaluated by multiple doctors. Furthermore, some centers used chest X-rays that were taken at approximately 28 days of age for CLD diagnosis, whereas at other facilities, diagnosis was made regardless of time at which the chest radiography were obtained. Only a small number of centers have established criteria for determining the necessity of oxygen at the corrected age of 36 weeks, and the target saturation of peripheral oxygen levels also tend to vary for each facility. Whether the conditions wherein the patient receives respiratory support for apnea or respiratory tract diseases should be considered as CLD also differed among the facilities.

CONCLUSIONS

It is necessary to reassess the definition and classification of CLD in Japan to accurately evaluate and improve the quality of respiratory management based on the long-term prognosis.

Clinical Characteristics and Outcomes Until 2 Years of Age in Preterm Infants With Typical Chest Imaging Findings of Bronchopulmonary Dysplasia: A Propensity Score Analysis

Objective: The goal of the current study was to assess the associations of typical chest imaging findings of bronchopulmonary dysplasia (BPD) in preterm infants with clinical characteristics and outcomes until 2 years of age. Method: This retrospective cohort study enrolled 256 preterm infants with BPD who were admitted between 2014 and 2018. A propensity score analysis was used to adjust for confounding factors. The primary outcomes were the severity of BPD, home oxygen therapy (HOT) at discharge and mortality between 28 days after birth and 2 years of age. A multivariate logistic regression analysis was performed to identify related variables of mortality. Results: Seventy-eight patients with typical chest imaging findings were enrolled, of which 50 (64.1%) were first found by CXR, while 28 (35.9%) were first found by CT. In addition, 85.9% (67/78) were discovered before 36 weeks postmenstrual age (PMA) (gestational age [GA] < 32 weeks) or before 56 days after birth (GA > 32 weeks). After propensity score matching, the matched groups consisted of 58 pairs of patients. Those with typical imaging findings had a remarkably higher mortality rate (29.3 vs. 12.1%, p = 0.022, OR 3.021), higher proportion of severe BPD (32.8 vs. 12.1%, p = 0.003, OR 4.669) and higher rate of HOT at discharge (74.1 vs. 46.6%, p = 0.002, OR 3.291) than those without typical imaging findings. The multivariate logistic regression analysis showed that typical imaging findings ≤ 7 days and typical typical imaging findings >7 days were independent risk factors for mortality in preterm infants with BPD (OR 7.794, p = 0.004; OR 4.533, p = 0.001). Conclusions: More attention should be given to chest imaging findings of BPD, especially in the early stage (within 7 days). Early recognition of the development of BPD helps early individualized treatment of BPD. Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT04163822.

Present and Future of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common respiratory disorder among infants born extremely preterm. The pathogenesis of BPD involves multiple prenatal and postnatal mechanisms affecting the development of a very immature lung. Their combined effects alter the lung's morphogenesis, disrupt capillary gas exchange in the alveoli, and lead to the pathological and clinical features of BPD. The disorder is ultimately the result of an aberrant repair response to antenatal and postnatal injuries to the developing lungs. Neonatology has made huge advances in dealing with conditions related to prematurity, but efforts to prevent and treat BPD have so far been only partially effective. Seeing that BPD appears to have a role in the early origin of chronic obstructive pulmonary disease, its prevention is pivotal also in long-term respiratory outcome of these patients. There is currently some evidence to support the use of antenatal glucocorticoids, surfactant therapy, protective noninvasive ventilation, targeted saturations, early caffeine treatment, vitamin A, and fluid restriction, but none of the existing strategies have had any significant impact in reducing the burden of BPD. New areas of research are raising novel therapeutic prospects, however. For instance, early topical (intratracheal or nebulized) steroids seem promising: they might help to limit BPD development without the side effects of systemic steroids. Evidence in favor of stem cell therapy has emerged from several preclinical trials, and from a couple of studies in humans. Mesenchymal stromal/stem cells (MSCs) have revealed a reparatory capability, preventing the progression of BPD in animal models. Administering MSC-conditioned media containing extracellular vesicles (EVs) have also demonstrated a preventive action, without the potential risks associated with unwanted engraftment or the adverse effects of administering cells. In this paper, we explore these emerging treatments and take a look at the revolutionary changes in BPD and neonatology on the horizon.

Bubbly and cystic appearance on chest radiograph of extremely preterm infants with bronchopulmonary dysplasia is associated with wheezing disorder

AIM

Bubbly/cystic appearance on chest X-ray (CXR) is an important factor in cases of severe bronchopulmonary dysplasia (BPD). We aimed to determine whether CXR -based BPD classifications obtained in extremely preterm infants with oxygen dependency at 28 days after birth (BPD28) is associated with wheezing disorders.

METHODS

This was a multicentre retrospective cohort study of population data from infants (body weight, <1500 g) enrolled in the Neonatal Research Network of Japan. Of the 15 480 infants born at <28 weeks of gestation between 2003 and 2012, 8979 met the BPD28 criteria, and 4007 were classified as the no BPD28 group. BPD28 infants were classified according to the bubbly/cystic or no bubbly/cystic appearance on CXR at postnatal ≧28 days. The effects on wheezing disorder at 3 years of age were analysed.

RESULTS

Bubbly/cystic BPD28 infants showed higher rates of wheezing disorders compared with no BPD28 infants. Bubbly/cystic BPD28 (odds ratio 1.7; 95% confidence interval, 1.3-2.2) was a significant independent factor for wheezing disorders.

CONCLUSION

A bubbly/cystic appearance on CXR with BPD28 was a potential risk factor of wheezing disorders at 3 years of age. This may be a useful early diagnostic tool at ≧28 postnatal days in extremely preterm infants.

Reduced Lung Function at Preschool Age in Survivors of Very Low Birth Weight Preterm Infants

Background: Survivors of preterm birth are at risk of long-term respiratory consequences. The objective of this prospective study was to assess pulmonary function at preschool age of former very low birth weight (VLBW) preterm children. Methods: Lung function of children born preterm and term controls aged 5-6 years were assessed by spirometry. The results were converted to z-scores. A questionnaire regarding respiratory symptoms was completed. Associations to gestational age (GA), birth weight (BW), bronchopulmonary dysplasia (BPD), and perinatal factors were assessed. Results: In total, 85 VLBW preterm children and 29 term controls were studied. Of the preterm children, the mean GA was 28.6 ± 2.6 weeks and the mean BW was 1,047 ± 273 gm. Preterm children had significantly lower z-scores of forced expiratory volume in 1 s (FEV₁), FEV₁/forced vital capacity (FVC) ratio, and forced expiratory flow rate between 25-75% of FVC (FEF_25-75), compared with term controls (-0.73 vs. 0.04, p = 0.002; -0.22 vs. 0.39, p = 0.003; -0.93 vs. 0.0, p < 0.001; respectively). Further segregation of the preterm group revealed significantly impaired FEV₁, FEF_25-75 in children at earlier gestation (≤ 28 weeks, n = 45), lighter at birth (≤ 1,000 g, n = 38), or with BPD (n = 55) compared with term controls (p < 0.05). There were significant negative relationships between the severity of BPD with FEV₁, FVC, and FEF_25-75 (p < 0.05). However, no correlation between lung function measurements and respiratory symptoms was found. Conclusions: VLBW preterm infants have reduced lung function at preschool age, especially among those with younger GA, lower BW, and BPD. Additional long-term follow-up of respiratory outcomes are needed for this vulnerable population.

Perinatal factors associated with bubbly/cystic appearance in bronchopulmonary dysplasia: a nationwide, population-based cohort study in Japan

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains one of the most serious morbidities associated with preterm birth. Previous study reported that bubbly/cystic appearance on chest X-rays in the neonatal period is the strongest determinant of impaired lung function at school age in BPD patients.

AIMS

To determine perinatal risk factors for bubbly/cystic appearance on chest X-rays in extremely premature infants with BPD exposed to histological chorioamnionitis histological chorioamnionitis (hCAM).

STUDY DESIGN

Multicenter retrospective cohort study.

SUBJECTS

We analyzed 1369 extremely premature infants with severe hCAM who were admitted to the neonatal intensive care units participating in the Neonatal Research Network, Japan (NRNJ) Neonatal research network Japan.

OUTCOME MEASURES

Perinatal characteristics were compared and logistic regression analysis was performed for multivariate risk factor assessment.

RESULT

Infants with bubbly/cystic appearance on chest X-rays underwent longer duration of invasive mechanical ventilation and required inhaled nitric oxide and home oxygen therapy more frequently. Low gestational age (odds ratio 1.244; 95% confidence interval 1.139-1.359) and preterm premature rupture of membranes (odds ratio 1.507; 95% confidence interval 1.200-1.893) were significant risk factors.

CONCLUSION

Low gestational age and preterm premature rupture of membranes were independent risk factors for bubbly/cystic appearance in extremely premature infants with BPD following exposure to severe hCAM.

Oxygen saturation/FIO2 ratio at 36 weeks' PMA in 1005 preterm infants: Effect of gestational age and early respiratory disease patterns

OBJECTIVE

To assess oxygen diffusion at 36 weeks' post-menstrual age in preterm infants by means of the non-invasive oxygen saturation/fraction of inspired oxygen ratio (36w-SFR) and to identify factors associated with 36w-SFR - ie, gestational age (GA) and early respiratory disease patterns (ERP).

METHODS

Retrospective analysis of prospectively collected data.

SETTING

Neonatal Intensive Care Unit.

PATIENTS

1005 preterm infants born below 32 weeks' GA.

INTERVENTIONS

36w-SFR was the mean of SFR values over 24 h on the day infants reached 36 weeks' PMA.

MAIN OUTCOME MEASURES

36w-SFR.

STATISTICS

descriptive statistics, univariate, and multivariate analysis to study associations of 36w-SFR, including GA and ERP.

RESULTS

36w-SFR was significantly different between infants with and without bronchopulmonary dysplasia (BPD) (371 vs 467, P < 0.001), and according to ERP (LowFIO2 466, pulmonary improvement-PI 460, pulmonary deterioration-PD 405, early persistent pulmonary deterioration-EPPD 344, P < 0.001). Significant differences were found either in BPD and in non-BPD patients according to ERP (P < 0.001). Patients without BPD had significant differences in 36w-SFR according to GA (P < 0.001), while infants with BPD and increasing GA at birth had a non-significant trend for increased 36w-SFR (P = 0.621). Factors associated with 36w-SFR were GA, being small for GA, sepsis, human milk feeding, and ERP.

CONCLUSIONS

Preterm infants without BPD had a spectrum of oxygen diffusion impairment that was inversely associated with GA at birth. Infants with different patterns of ERP had significant differences in 36w-SFR.

Impact of chest radiography-based definition of bronchopulmonary dysplasia

BACKGROUND

Bubbly/cystic appearance on chest radiograph is an important factor in severe-type bronchopulmonary dysplasia (BPD) in Japan. The aim of this study was to determine the perinatal characteristics and neonatal complications of the bubbly/cystic(+) group in extremely preterm infants with BPD, that is, oxygen dependency at day 28 after birth (BPD28).

METHODS

This was a multicenter retrospective cohort study of population data from infants (birthweight, <1,500 g) enrolled in the Neonatal Research Network of Japan. Of the 15 480 infants born at <28 weeks' gestational age (GA) between 2003 and 2012, 8,979 met the BPD28 criteria. The BPD28 infants were classified according to bubbly/cystic appearance on radiograph (±) at >28 postnatal days.

RESULTS

The bubbly/cystic(+) group had lower GA and birthweight and required longer mechanical ventilation and oxygen dependency than the bubbly/cystic(-) group. After adjustment for confounding factors, bubbly/cystic appearance was an independent risk factor for home oxygen therapy at discharge.

CONCLUSION

Bubbly/cystic appearance on chest radiograph was a predictor of short-term respiratory outcomes in infants with BPD28, which is diagnosed much earlier (≥28 postnatal days), and has a potentially different etiology to BPD36 (oxygen and/or positive pressure respiratory support dependency at 36 weeks' postmenstrual age).

Physical fitness of non-disabled school-aged children born with extremely low birth weights

BACKGROUND

The assessment of long-term outcomes in survivors born with extremely low birth weights (ELBWs) has become increasingly important. However, little has been reported on the physical fitness of non-disabled school-aged children born with ELBWs.

AIMS

To assess the physical fitness of non-disabled school-aged children born with ELBWs.

STUDY DESIGN

Retrospective cohort study.

SUBJECTS

We analyzed 169 ELBW infants without cerebral palsy or intellectual disability (based on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) Full Scale intelligence quotient (IQ) test < 70).

OUTCOME MEASURES

Physical fitness was assessed using the grip strength, sit-up repetitions, sit & reach, side steps, standing long jump, and softball throw tests. T-scores were calculated using national survey data.

RESULTS

The T-scores for the grip strength, sit-up repetitions, sit & reach, side steps, standing long jump, softball throw tests, and the overall T-score were 43.7 ± 7.5, 44.2 ± 10.5, 46.0 ± 9.7, 40.9 ± 8.0, 40.0 ± 9.8, 42.4 ± 8.1, and 42.9 ± 5.5, respectively. After adjusting for other age-related factors, the height (SD score), WISC-III Performance IQ score, and percent predicted forced vital capacity (FVC) independently predicted the overall T-scores. Their standardized partial regression coefficients (β) were 0.334 (p = 0.009), 0.190 (p = 0.022), and 0.187 (p = 0.032), respectively.

CONCLUSIONS

Our cohort's physical fitness at approximately 8 years of age was significantly impaired compared to average Japanese children of the same age. Height, FVC, and Performance IQ independently predicted physical fitness, with height being the strongest predictor.

Longitudinal impairment of lung function in school-age children with extremely low birth weights

OBJECTIVES

To assess lung function and long-term respiratory outcomes in extremely low birth weight (ELBW) survivors.

WORKING HYPOTHESIS

ELBW, especially with respiratory complications in the neonatal period, affects lung function at a later age.

STUDY DESIGN

Longitudinal retrospective study.

PATIENT-SUBJECT SELECTION

Lung function was evaluated in 89 ELBW survivors (at ages 8 and 12) with or without a history of bronchopulmonary dysplasia (BPD) or a bubbly/cystic lung appearance in the neonatal period.

METHODOLOGY

FVC, FEV₁ , FEF₅₀ , and FEF₇₅ were measured using spirometry. Two-way repeated-measures ANOVA was used to compare lung function and deterioration time course from 8 to 12 years of age.

RESULTS

Lung function variables were significantly and positively correlated between 8 and 12 years: %FVC (R²  = 0.558), %FEV₁ (R²  = 0.539), %FEF₅₀ (R²  = 0.412), and %FEF₇₅ (R²  = 0.429). Lung function values were lower than Japanese reference values, especially in children with a history of severe BPD or a bubbly/cystic appearance. %FEV₁ and FEV₁ /FVC ratio worsened from 8 to 12 years of age: 83.0 ± 17.0% versus 76.6 ± 17.8% (mean difference, 95%CI: -6.43, -9.10 to -3.75) and 84.0 ± 10.1% versus 78.2 ± 13.4% (mean difference, 95%CI: -5.82, -8.56 to -3.08), regardless of whether or not there was a history of neonatal respiratory disease.

CONCLUSIONS

In ELBW survivors, the obstructive pattern of lung function impairment deteriorated from 8 to 12 years of age, independent of the presence of severe BPD or bubbly/cystic appearance in the neonatal period.

New Insights on Early Patterns of Respiratory Disease among Extremely Low Gestational Age Newborns

BACKGROUND

The analysis of early patterns of lung disease among preterm infants may help to identify predictors of pulmonary deterioration.

OBJECTIVES

To analyze FIO2 requirement in the first 14 days of life among preterm infants and to find predictors of bronchopulmonary dysplasia (BPD).

METHODS

Retrospective cohort study.

SETTING

3 Italian level III NICUs.

POPULATION

infants born between 240/7 and 276/7 weeks' gestational age (GA) who survived to 14 days. A consecutive sample of 588 infants was analyzed. Daily mode FIO2 in the first 2 weeks of life were analyzed according to the criteria defined by Laughon et al. [Pediatrics 2009;123:1124-1131], who found 3 early respiratory patterns: consistently low FIO2 (LowFIO2), pulmonary deterioration (PD), and early persistent pulmonary deterioration (EPPD). Factors associated with pulmonary deterioration were studied by univariate and multivariate analysis.

RESULTS

Forty percent of infants had low FIO2, 18% had pulmonary deterioation, 21% had early persistent pulmonary deterioration, and 21% had a previously unreported pattern (pulmonary improvement, PI). The prevalence of BPD was 7% in the LowFIO2 group, 28% in the PI group, 44% in the PD group, and 62% in the EPPD group (p = 0.000). Infants with lung deterioration were more frequently males (OR = 2.019, CI: 1.319-3.090, p = 0.001), had lower GA (OR = 0.945, CI: 0.915-0.975, p = 0.000), higher incidence of severe respiratory distress syndrome (OR = 2.956, CI: 1.430-6.112, p = 0.003), and lack of postnatal caffeine (OR = 0.167, CI: 0.052-0.541, p = 0.003).

CONCLUSIONS

We report 4 distinct patterns of early respiratory disease associated with significantly different prevalence of BPD and discuss risk factors for lung deterioration.

Early inhaled steroid use in extremely low birthweight infants: a randomised controlled trial

OBJECTIVE

We hypothesised that a prophylactic inhaled steroid would prevent the progression of bronchopulmonary dysplasia (BPD) in extremely low birthweight infants (ELBWIs).

DESIGN

This study was a multicentre, randomised, double-blinded, placebo-controlled trial.

SETTING

This investigation was conducted in 12 level III neonatal intensive care units (NICUs).

PATIENTS

A total of 211 ELBWIs requiring ventilator support were enrolled.

INTERVENTION

Starting within 24 h of birth and continuing until 6 weeks of age or extubation, two doses of 50 μg fluticasone propionate (FP) or placebo were administered every 24 h.

MAIN OUTCOME MEASUREMENT

The primary outcome measure used to indicate the morbidity of severe BPD incidence was death or oxygen dependence at discharge from the NICU. The secondary measures were neurodevelopmental impairments (NDIs) at 18 months of postmenstrual age and 3 years of age. We performed subgroup analyses based on gestational week (GW) and the presence of chorioamnionitis (CAM).

RESULTS

Infants were randomised into the FP (n=107) or placebo (n=104) groups. No significant differences were detected between the FP and placebo groups with respect to either the frequency of death or the oxygen dependence at discharge or NDIs. In subgroup analyses, the frequencies of death and oxygen dependence at discharge were significantly decreased in the FP group for infants born at 24-26 GWs and for infants with CAM, regardless of the GW at birth.

CONCLUSIONS

Inhaled steroids have no effect on the prevention of severe BPD or long-term NDI but might decrease the severity of BPD for ELBWIs with a risk factor.

TRIAL REGISTRATION NUMBER

UMIN-CTR C000000405.

Bubbly and cystic appearance in chronic lung disease: Is this diagnosed as Wilson-Mikity syndrome?

Wilson-Mikity syndrome (WMS) was first reported in 1960 by Wilson and Mikity. They described preterm infants who developed areas of cystic emphysema in the first month of life with subsequent progression to chronic lung disease (CLD) of infancy, although these infants did not exhibit early respiratory distress, such as respiratory distress syndrome (RDS). This condition was widely accepted over the next 20 years, but WMS is now rarely mentioned and is commonly considered an anachronism. In Japan, CLD is classified into six types according to the presence of RDS and/or intrauterine inflammation and appearance on chest X-ray. One type of CLD (type III, which accounts for 13.5% of all CLD) is defined as history of intrauterine inflammation and the typical bubbly and cystic appearance on chest X-ray described in the original report of WMS. There is insufficient evidence to determine whether WMS exists or whether WMS is relatively common only in Japan and not in other countries. It is important, however, to distinguish this type of CLD from other types because the strategy for the prevention or treatment of CLD should be different according to its origin, cause, and risk factors.