Lung function after extremely preterm birth-A population-based cohort study (EXPRESS)

Long-term lung function follow-up of preterm infants less than 32 weeks of gestational age

BACKGROUND

Preterm infants, particularly those with bronchopulmonary dysplasia (BPD), are at risk of lung development problems. Over the last decades, lung protective strategies have been used, decreasing the risk of chronic lung disease.

OBJECTIVE

To evaluate the pulmonary function test (PFT) of preterm infants born after the introduction of lung protective strategies and to assess perinatal determinants of impaired lung function in this population.

METHODS

A prospective, observational, single-center study was conducted in the neonatal unit of a high-complexity hospital. The study included newborns with less than 32 weeks gestational age born between 2012 and 2014, who were followed up until they reach school age. For the main outcome, two groups were stablished: no BPD or grade 1 BPD (no BPD/1) and grade 2 or 3 BPD (BPD 2/3).

RESULTS

Out of 327 patients, 116 were included. BPD was diagnosed in 49.1% (47), with 50.9% (29) classified as grade 1, 35.1% (20) as grade 2, and 14.0% (8) as grade 3. Mean age at PFT was 8.59 years (SD 0.90). Mean FEV1% was 95.36% (SD 13.21) and FEV1 z-score -0.36 (SD 1.12); FVC% 97.53% (SD 12.59) and FVC z-score -0.20 (SD 1.06); FEV1/FVC ratio 85.84% (SD 8.34) and z-score -0.24 (SD 1.34). When comparing patients with no BPD/1 and BPD 2/3, we observed differences in all pulmonary function parameters, which persisted after adjusting for gestational age. No differences in PFT were observed between patients without BPD and those with grade 1 BPD. Most patients (76.7%, 89) had normal spirometry pattern, with obstructive pattern observed in 12.9% (15), restrictive pattern in 9.5% (11), and mixed pattern in 0.9% (1) of patients.

CONCLUSION

Preterm infants with BPD 2/3 showed a decrease in all pulmonary function parameters compared to preterm infants with no BPD/1; an effect that was independent of gestational age. Among patients with BPD who had an altered PFT pattern, the most common pattern was obstructive, followed by restrictive and then, mixed.

Comparison of home-based spirometry and oscillometry measurements in school-age children with bronchopulmonary dysplasia

INTRODUCTION

This study compares home-based oscillometry and spirometry for characterizing respiratory system disease in school-aged children with bronchopulmonary dysplasia (BPD) in clinical research. We hypothesized higher rates of successful completion and abnormal cases identified through oscillometry, with correlations between device measurements.

METHODS

Participants 6-12 years old with BPD in the ongoing Air Quality, Environment and Respiratory Outcomes in BPD (AERO-BPD) study performed oscillometry followed by spirometry at two separate home visits. Parameters measured included airway resistance at 5 Hz(R5), resistance from 5 to 19 Hz(R5-19), resonance frequency(Fres), reactance at 5 Hz(X5), area under the curve between Fres and X5(AX), forced expiratory volume in 1 second(FEV1), forced vital capacity(FVC), and FEV1/FVC. Descriptive statistics identified the proportion of successful tests, correlation in measurements, and rate of lung disease for each device.

RESULTS

Among 76 subjects with 120 paired observations, 95% and 71% of participants successfully performed oscillometry and spirometry, respectively, at home visit one. 98% and 77% successfully performed oscillometry and spirometry, respectively, at home visit two. Odds ratios favored oscillometry (range 5.31-10.13, p < 0.01). FEV1 correlated with AX (correlation coefficient r = -0.27, p = 0.03); FEV1/FVC with AX (r = -0.32, p = 0.02); and FEV1/FVC with R5 (r = -0.37, p = 0.01). AX exhibited the highest prevalence of abnormality at 25%; other oscillometry parameters ranged from 5%-22%. Forty-five to sixty-four percent of participants had abnormal spirometry. Oscillometry assessments had significantly lower odds of capturing lung disease (odds ratios 0.07-0.24, p < 0.0001).

CONCLUSIONS

School-aged children with BPD demonstrated higher success rates in field-based oscillometry than spirometry. Spirometry exhibited higher rates of abnormality than oscillometry. Moderate correlation exists between device measurements.

Antenatal Endotoxin Induces Dysanapsis in Experimental Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, is characterized by impaired lung development with sustained functional abnormalities due to alterations of airways and the distal lung. Although clinical studies have shown striking associations between antenatal stress and BPD, little is known about the underlying pathogenetic mechanisms. Whether dysanapsis, the concept of discordant growth of the airways and parenchyma, contributes to late respiratory disease as a result of antenatal stress is unknown. We hypothesized that antenatal endotoxin (ETX) impairs juvenile lung function as a result of altered central airway and distal lung structure, suggesting the presence of dysanapsis in this preclinical BPD model. Fetal rats were exposed to intraamniotic ETX (10 μg) or saline solution (control) 2 days before term. We performed extensive structural and functional evaluation of the proximal airways and distal lung in 2-week-old rats. Distal lung structure was quantified by stereology. Conducting airway diameters were measured using micro-computed tomography. Lung function was assessed during invasive ventilation to quantify baseline mechanics, response to methacholine challenge, and spirometry. ETX-exposed pups exhibited distal lung simplification, decreased alveolar surface area, and decreased parenchyma-airway attachments. ETX-exposed pups exhibited decreased tracheal and second- and third-generation airway diameters. ETX increased respiratory system resistance and decreased lung compliance at baseline. Only Newtonian resistance, specific to large airways, exhibited increased methacholine reactivity in ETX-exposed pups compared with controls. ETX-exposed pups had a decreased ratio of FEV in 0.1 second to FVC and a normal FEV in 0.1 second, paralleling the clinical definition of dysanapsis. Antenatal ETX causes abnormalities of the central airways and distal lung growth, suggesting that dysanapsis contributes to abnormal lung function in juvenile rats.

Reduced pulmonary oxygen diffusion at 36 weeks of postmenstrual age in small-for-gestational-age preterm infants of less than 32 weeks without bronchopulmonary dysplasia

BACKGROUND

Small-for-gestational-age (SGA) preterm infants are at increased risk of developing bronchopulmonary dysplasia (BPD). There is limited information on pulmonary oxygen diffusion of SGA preterm infants, particularly in those without BPD.

OBJECTIVE

To compare the pulmonary oxygen diffusion of SGA to that of appropriate-for-gestational-age (AGA) preterm infants without BPD.

STUDY DESIGN

Preterm infants with a gestational age (GA) between 24.0 and 31.6 weeks were studied. The oxygen saturation (SpO2 ), fraction to inspired oxygen (FiO2 ), and the SpO2 to FiO2 ratio (SFR) were compared between SGA and AGA infants. The association between SGA and SFR at 36 weeks was assessed using a multiple regression analysis. In the subgroup without BPD, SGA were match-paired for GA and gender with AGA infants.

RESULTS

We analyzed 1189 infants surviving at 36 weeks: 194 (16%) were SGA and 995 (84%) AGA. The incidence of BPD was significantly higher in SGA than AGA infants (32% vs. 13%; p = .000). Out of the 995 infants without BPD, 132 (13%) were SGA and 863 (87%) AGA. SGA was negatively associated with the SFR value at 36 weeks, independently from BPD. SGA infants without BPD had significantly higher (better) SFR at birth, but lower (worse) SpO2 and SFR and from 33 to 36 weeks than their matched AGA counterpart. At 36 weeks, median SpO2 and SFR values were 97.7 versus 98.4 (p = .006) and 465 versus 468 (p = .010) in match-paired SGA and AGA, respectively.

CONCLUSION

Among preterm infants of less than 32 weeks and without BPD, SGA infants had a reduced pulmonary oxygen diffusion at 36 weeks in comparison with AGA infants.

Lung function deficits and bronchodilator responsiveness at 12 years of age in children born very preterm compared with controls born at term

INTRODUCTION

Very preterm birth is associated with lung function impairment later in life, but several aspects have not been studied. We aimed to comprehensively assess lung function at school age in very preterm infants and term controls, with special emphasis on bronchopulmonary dysplasia (BPD), sex, and bronchodilator response.

METHODS

At 12 years of age, 136 children born very preterm (85 with and 51 without BPD) and 56 children born at term performed spirometry, body plethysmography, impulse oscillometry, measurement of diffusion capacity, and multiple breath washout, before and after bronchodilator inhalation.

RESULTS

Airway symptoms and a diagnosis of asthma were more common in children born very preterm. These children had more airflow limitation, seen as lower forced expiratory volume in 1 s (FEV1 ) (p < .001), FEV1 /forced vital capacity (FVC) (p = .011), and mean forced expiratory flow between 25% and 75% of FVC (p < .001), and a higher total and peripheral airway resistance compared with term-born controls. There was no difference in total lung capacity but air trapping and lung clearance index were higher in children born very preterm. Diffusion capacity was lower in children born very preterm, especially in those with a diagnosis of BPD. In most other tests, the differences between preterm-born children with or without BPD were smaller than between children born preterm versus at term. Boys born preterm had more lung function deficits than preterm-born girls. In children born very preterm, airway obstruction was to a large extent reversible.

CONCLUSION

At 12 years of age, children born very preterm had lower lung function than children born at term in most aspects and there was only little difference between children with or without BPD. Airway obstruction improved markedly after bronchodilator inhalation.

Pulmonary phenotypes of bronchopulmonary dysplasia in the preterm infant

Bronchopulmonary dysplasia (BPD) remains the most common complication of premature birth, imposing a significant and potentially life-long burden on patients and their families. Despite advances in our understanding of the mechanisms that contribute to patterns of lung injury and dysfunctional repair, current therapeutic strategies remain non-specific with limited success. Contemporary definitions of BPD continue to rely on clinician prescribed respiratory support requirements at specific time points. While these criteria may be helpful in broadly identifying infants at higher risk of adverse outcomes, they do not offer any precise information regarding the degree to which each compartment of the lung is affected. In this review we will outline the different pulmonary phenotypes of BPD and discuss important features in the pathogenesis, clinical presentation, and management of these frequently overlapping scenarios.

Development and Disorders of the Airway in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD), a disorder characterized by arrested lung development, is a frequent cause of morbidity and mortality in premature infants. Parenchymal lung changes in BPD are relatively well-characterized and highly studied; however, there has been less emphasis placed on the role that airways disease plays in the pathophysiology of BPD. In preterm infants born between 22 and 32 weeks gestation, the conducting airways are fully formed but still immature and therefore susceptible to injury and further disruption of development. The arrest of maturation results in more compliant airways that are more susceptible to deformation and damage. Consequently, neonates with BPD are prone to developing airway pathology, particularly for patients who require intubation and positive-pressure ventilation. Airway pathology, which can be divided into large and small airways disease, results in increased respiratory morbidity in neonates with chronic lung disease of prematurity.

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.

Use of impulse oscillometry to assess lung function in prematurely born children and young people: Comparisons with spirometry

Premature birth is a risk factor for bronchopulmonary dysplasia (BPD); both of which are associated with obstructive airway disease throughout childhood. Impulse oscillometry (IOS) is an effort-independent, passive measure of tidal breathing, which could have benefits in assessing lung function amongst younger patients unable to perform valid spirometry. A literature search was conducted to investigate the use of IOS in prematurely born children and young people. IOS results correlate with those of spirometry. Reversibility of airway obstruction in children with BPD is variable. IOS could have benefits in assessing individual patient response and suitability for bronchodilator therapy. More work, however, is required to establish multi-ethnic reference ranges and standardise commercially available devices prior to its routine incorporation into clinical practice.

From neonatal lung function to lung function and respiratory morbidity at 6-year follow-up

BACKGROUND

Lung function is traceable from infancy to adulthood. Only a few studies have examined lung function from birth to childhood longitudinally in children born moderate to late preterm. We aimed to investigate how prematurity and lung function in the neonatal period are related to lung function and respiratory morbidity at age 6 in former moderate to late preterm children compared with children born at term.

METHODS

Lung function was measured in a cohort of moderately to late preterm (n = 48) and term-born (n = 53) infants in the neonatal period by FeNO, and tidal breathing flow-volume loops (TBFVL) and at age 6 (n = 52) by spirometry, whole-body plethysmograph and impulse oscillation combined with a respiratory symptom questionnaire.

RESULTS

Moderate to late preterm children had a higher T_PEF /T_E ratio neonatally (42.6% vs. 33.7%, p = 0.02) and a lower % predicted orced expiratory volume in the first second at age 6 (94.4% vs. 101.9%, p = 0.01) compared to term-born children. We found a significant association between the variability of neonatal tidal volume and effective airway resistance at age 6 (β = -0.34, p = 0.03). No association between neonatal FeNO or TBFVL and respiratory morbidity at 6-year follow-up was shown.

CONCLUSION

Children born moderate to late preterm had lower lung function at age 6 than term-born children. We did not find evidence for the use of neonatal tidal breathing parameters as a predictor for subsequent respiratory morbidity or lung function, however sample size was small.

Environmental and Behavioral Factors in Association with Lung Function Impairment in Children Living in Wuhan, China

Children’s lung function is a significant predictor of health status throughout their lifetime. This study aims to identify the prevalence of impaired lung function in children and the potential influencing factors in elementary school children of Wuhan, China. Children of 6−12 years old were enrolled from elementary schools in Wuhan, China, in 2018, on the basis of a cross-sectional study design. Information on personal behavior patterns and household characteristics, as well as parental factors, was collected based on a questionnaire survey. Spirometry was used to measure fifteen lung function indicators. Logistic regression models were used to estimate odds ratios of prevalence of impaired lung function with regard to socioeconomic, personal behavior patterns, household, and parental factors, respectively. Four lung function indicators such as FET and EVC in urban children had higher values than in the suburban children after adjusting for confounders (p < 0.05). A higher prevalence of impaired lung function (FEV6, FEV3, EVC, and VC) was found in the children from the rural area than in those from the urban area. A sex difference in FET impairment was observed, however, no significant difference in impairment in other lung function indicators were found between girls and boys. The elevated height and weight of the children was significantly associated with an increased and decreased prevalence of impaired lung function, respectively, particularly both for FEV6, FEV3, FIVC, and FIV1. Opening windows for a longer time in summer was significantly associated with a lower prevalence of impaired FEF25 and MVV, and an extended time of opening windows in winter was significantly associated with a lower prevalence of impaired FEV6. While, opening windows for a longer time in autumn was significantly associated with higher prevalence of impaired FEV6 and FEV1/VC. Home renovations, doing physical exercise for more than 30 min per day, air pollution exposure during commuting, sleeping in own rooms, height stunting, and preterm birth were significantly associated with an increased risk of impaired lung function. Breastfeeding, having a father with a white-collar profession and with a higher education level were positively associated with the lower prevalence of impaired lung function. Impaired lung function is commonly found in school children in Wuhan, nowadays. Breastfeeding, opening windows long-term in summer and winter, higher socioeconomics, and an urban living environment were protective factors for impaired lung function. However, opening windows long-term and using air conditioning short-term in autumn, as well as home renovations, doing physical exercise for more than 30 min per day, preterm birth, height stunting, and air pollution exposure during commuting were regarded as significant risk factors for impaired lung function. Promoting breastfeeding, lengthening window opening times in winter and summer, and controlling household renovation and air pollution exposure during commuting are recommended to reduce the risk of impaired lung function in children in Wuhan.

Comparative analysis of pulmonary function in children born preterm and full-term at 6–9 years of age

Abstract Objective: To compare pulmonary function parameters and the prevalence of altered pulmonary function in children born preterm and full-term, using the Global Lung Initiative reference values. Methods: This is a cross-sectional study with 6–9-year-old children submitted to measurement of airway resistance (Rint) and spirometry according to the American Thoracic Society and European Respiratory Society Technical Statement. The inclusion criteria were, among the preterm group: gestational age <37 weeks and birth weight <2000g; among the full-term group: schoolchildren born full-term with birth weight >2500g, recruited at two public schools in São Paulo, Brazil, matched by sex and age with the preterm group. As exclusion criteria, congenital malformations, cognitive deficit, and respiratory problems in the past 15 days were considered. Results: A total of 112 children were included in each group. Preterm children had gestational age of 30.8±2.8 weeks and birth weight of 1349±334g. Among them, 46.6% were boys, 46.4% presented respiratory distress syndrome, 19.6% bronchopulmonary dysplasia, and 65.2% were submitted to mechanical ventilation in the neonatal unit. At study entry, both groups were similar in age and anthropometric parameters. Parameters of pulmonary function (Z scores) in preterm and full-term groups were: Rint (0.13±2.24 vs. -1.02±1.29; p<0.001); forced vital capacity (FVC) (-0.39±1.27 vs. -0.15±1.03; p=0.106), forced expiratory volume in one second (FEV1)/FVC (-0.23±1.22 vs. 0.14±1.11; p=0.003), FEV1 (-0.48±1.29 vs. -0.04±1.08; p=0.071), and forced expiratory flow between 25% and 75% of vital capacity (FEF25-75) (1.16±1.37 vs. 2.08±1.26; p=0.005), respectively. The prevalence values of altered airway resistance (16.1 vs. 1.8%; p<0.001) and spirometry (26.8 vs. 13.4%, p=0.012) were higher in preterm infants than in full-term ones. Conclusions: Preterm children had higher prevalence of altered pulmonary function, higher Z scores of airway resistance, and lower Z scores of FEV1/FVC and FEF25-75 compared with those born full-term.

Airwave oscillometry and spirometry in children with asthma or wheeze

OBJECTIVE

Lung function testing is used in diagnosing asthma and assessing asthma control. Spirometry is most commonly used, but younger children can find performing this test challenging. Non-volitional tests such as airwave oscillometry (AOS) may be helpful in that population. We compared the success of spirometry and AOS in assessing bronchodilator responsiveness in children.

METHODS

AOS was conducted alongside routine lung function testing. Resistance at 5 Hz (R5), the difference between the resistance at 5 and 20 Hz (R5-20) and the area under the reactance curve (AX) were assessed. Patients between 5 and 16 years old attending clinic with wheeze or asthma were assessed. Patients performed AOS, followed by spirometry and were then given 400 µg salbutamol; the tests were repeated 15 minutes later.

RESULTS

Lung function testing was performed in 47 children of whom 46 (98%) and 32 (68%) performed acceptable baseline oscillometry and spirometry, respectively (p < 0.001). Children unable to perform acceptable spirometry were younger (7.35, range: 5.4-10.3 years) than those who could (10.4, range: 5.5-16.9 years), p < 0.001. The baseline z-scores of AOS R5 correlated with FEV₁ (r = 0.499, p = 0.004), FEF₇₅ (r = 0.617, p < 0.001), and FEV₁/FVC (r = 0.618, p < 0.001). There was a positive bronchodilator response assessed by spirometry (change in FEV₁ ≥ 12%) in eight children which corresponded to a change in R5 of 36% (range: 30%-50%) and a change in X5 of 39% (range: 15%-54%).

CONCLUSIONS

Oscillometry is a useful adjunct to spirometry in assessing young asthmatic children's lung function. The degree of airway obstruction, however, might affect the comparability of the results of the two techniques.

Geographical Differences and Temporal Improvements in Forced Expiratory Volume in 1 Second of Preterm-Born Children: A Systematic Review and Meta-analysis

Importance

Although preterm birth is associated with later deficits in lung function, there is a paucity of information on geographical differences and whether improvements occur over time, especially after surfactant was introduced.

Objective

To determine deficits in percentage predicted forced expiratory volume in 1 second (%FEV1) in preterm-born study participants, including those with bronchopulmonary dysplasia (BPD) in infancy, when compared with term-born control groups.

Data Sources

Eight databases searched up to December 2021.

Study Selection

Studies reporting spirometry for preterm-born participants with or without a term-born control group were identified.

Data Extraction and Synthesis

Data were extracted and quality assessed by 1 reviewer and checked by another. Data were pooled using random-effects models and analyzed using Review Manager and the R metafor package.

Main Outcomes and Measures

Deficits in %FEV1 between preterm-born and term groups. Associations between deficits in %FEV1 and year of birth, age, introduction of surfactant therapy, and geographical region of birth and residence were also assessed.

Results

From 16 856 titles, 685 full articles were screened: 86 with and without term-born control groups were included. Fifty studies with term controls were combined with the 36 studies from our previous systematic review, including 7094 preterm-born and 17 700 term-born participants. Of these studies, 45 included preterm-born children without BPD, 29 reported on BPD28 (supplemental oxygen dependency at 28 days), 26 reported on BPD36 (supplemental oxygen dependency at 36 weeks' postmenstrual age), and 86 included preterm-born participants. Compared with the term-born group, the group of all preterm-born participants (all preterm) had deficits of %FEV1 of -9.2%; those without BPD had deficits of -5.8%, and those with BPD had deficits of approximately -16% regardless of whether they had BPD28 or BPD36. As year of birth increased, there was a statistically significant narrowing of the difference in mean %FEV1 between the preterm- and term-born groups for the all preterm group and the 3 BPD groups but not for the preterm-born group without BPD. For the all BPD group, when compared with Scandinavia, North America and western Europe had deficits of -5.5% (95% CI, -10.7 to -0.3; P = .04) and -4.1% (95% CI, -8.8 to 0.5; P = .08), respectively.

Conclusions and Relevance

Values for the measure %FEV1 were reduced in preterm-born survivors. There were improvements in %FEV1 over recent years, but geographical region had an association with later %FEV1 for the BPD groups.

Multicentre randomised trial of invasive and less invasive surfactant delivery methods showed similar spirometry results at 5-9 years of age

AIM

We explored whether subnormal forced expiratory volume within one second (FEV₁ ) at 5-9 years of age was lower in children born preterm who received less invasive surfactant administration (LISA) rather than surfactant via an endotracheal tube.

METHODS

The multicentre, randomised Nonintubated Surfactant Application trial enrolled 211 preterm infants born at 23-26 weeks of gestation from 13 level III neonatal intensive care units from April 2009 to March 2012. They received surfactant via LISA (n=107) or after conventional endotracheal intubation (n=104). The follow-up assessments were carried out by a single team blinded to the group assignments. The main outcome was FEV₁ <80% of predicted values.

RESULTS

Spirometry was successful in 102/121 children. The other children died or were lost to follow up. Median FEV₁ was 93% (interquartile range 80-113%) of predicted values in the LISA group and 86% (interquartile range 77-102%) in the control group (p=0.685). Rates of FEV₁ < 80% were 11/57 (19%) and 15/45 (33 %) respectively, which was an absolute risk reduction of 14% (95% confidence interval -3.1% to 31.2%, p=0.235). There were no differences in other outcome measures.

CONCLUSION

The proportion of children aged 5-9 years with subnormal FEV₁ was not significantly different between the groups.

Neurodevelopmental disorders and somatic diagnoses in a national cohort of children born before 24 weeks of gestation

AIM

This study investigated childhood diagnoses in children born extremely preterm before 24 weeks of gestation.

METHODS

Diagnoses of neurodevelopmental disorders and selected somatic diagnoses were retrospectively retrieved from national Swedish registries for children born before 24 weeks from 2007 to 2018. Their individual medical files were also examined.

RESULTS

We studied 383 children born at a median of 23.3 (range 21.9-23.9) weeks, with a median birthweight of 565 (range 340-874) grams. Three-quarters (75%) had neurodevelopmental disorders, including speech disorders (52%), intellectual disabilities (40%), attention deficit hyperactivity disorder (30%), autism spectrum disorders (24%), visual impairment (22%), cerebral palsy (17%), epilepsy (10%) and hearing impairment (5%). More boys than girls born at 23 weeks had intellectual disabilities (45% vs. 27%, p < 0.01) and visual impairment (25% vs. 14%, p < 0.01). Just over half of the cohort (55%) received habilitation care. The majority (88%) had somatic diagnoses, including asthma (63%) and failure to thrive/short stature (39%).

CONCLUSION

Most children born before 24 weeks had neurodevelopmental disorders and/or additional somatic diagnoses in childhood and were referred to habilitation services. Clinicians should be aware of the multiple health and developmental problems affecting these children. Resources are needed to identify their long-term support needs at an early stage.

Management Practices During Perinatal Respiratory Transition of Very Premature Infants

The present review considers some controversial management practices during extremely premature perinatal transition. We focus on perinatal prevention and treatment of respiratory distress syndrome (RDS) in immature infants. New concerns regarding antenatal corticosteroid management have been raised. Many fetuses are only exposed to potential adverse effects of the drug. Hence, the formulation and the dosage may need to be modified. Another challenge is to increase the fraction of the high-risk fetuses that benefit from the drug and to minimize the harmful effects of the drug. On the other hand, boosting anti-inflammatory and anti-microbial properties of surfactant requires further attention. Techniques of prophylactic surfactant administration to extremely immature infants at birth may be further refined. Also, new findings suggest that prophylactic treatment of patent ductus arteriosus (PDA) of a high-risk population rather than later selective closure of PDA may be preferred. The TREOCAPA trial (Prophylactic treatment of the ductus arteriosus in preterm infants by acetaminophen) evaluates, whether early intravenous paracetamol decreases the serious cardiorespiratory consequences following extremely premature birth. Lastly, is inhaled nitric oxide (iNO) used in excess? According to current evidence, iNO treatment of uncomplicated RDS is not indicated. Considerably less than 10% of all very premature infants are affected by early persistence of pulmonary hypertension (PPHN). According to observational studies, effective ventilation combined with early iNO treatment are effective in management of this previously fatal disease. PPHN is associated with prolonged rupture of fetal membranes and birth asphyxia. The lipopolysaccharide (LPS)-induced immunotolerance and hypoxia-reperfusion-induced oxidant stress may inactivate NO-synthetases in pulmonary arterioles and terminal airways. Prospective trials on iNO in the management of PPHN are indicated. Other pulmonary vasodilators may be considered as comparison drugs or adjunctive drugs. The multidisciplinary challenge is to understand the regulation of pregnancy duration and the factors participating the onset of extremely premature preterm deliveries and respiratory adaptation. Basic research aims to identify deficiencies in maternal and fetal tissues that predispose to very preterm births and deteriorate the respiratory adaptation of immature infants. Better understanding on causes and prevention of extremely preterm births would eventually provide effective antenatal and neonatal management practices required for the intact survival.

Lifelong Lung Sequelae of Prematurity

The clinical, functional, and structural pattern of chronic lung disease of prematurity has changed enormously in last years, mirroring a better perinatal management and an increasing lung immaturity with the survival of increasingly premature infants. Respiratory symptoms and lung function impairment related to prematurity seem to improve over time, but premature birth increases the likelihood of lung function impairment in late childhood, predisposing to chronic obstructive pulmonary disease (COPD). It is mandatory to identify those individuals born premature who are at risk for developing long-term lung disease through a better awareness of physicians, the use of standardized CT imaging scores, and a more comprehensive periodic lung function evaluation. The aim of this narrative review was to provide a systematic approach to lifelong respiratory symptoms, lung function impairment, and lung structural anomalies in order to better understand the specific role of prematurity on lung health.

Endotypes of Prematurity and Phenotypes of Bronchopulmonary Dysplasia: Toward Personalized Neonatology

Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, is increasingly recognized as the consequence of a pathological reparative response of the developing lung to both antenatal and postnatal injury. According to this view, the pathogenesis of BPD is multifactorial and heterogeneous with different patterns of antenatal stress (endotypes) that combine with varying postnatal insults and might distinctively damage the development of airways, lung parenchyma, interstitium, lymphatic system, and pulmonary vasculature. This results in different clinical phenotypes of BPD. There is no clear consensus on which are the endotypes of prematurity but the combination of clinical information with placental and bacteriological data enables the identification of two main pathways leading to birth before 32 weeks of gestation: (1) infection/inflammation and (2) dysfunctional placentation. Regarding BPD phenotypes, the following have been proposed: parenchymal, peripheral airway, central airway, interstitial, congestive, vascular, and mixed phenotype. In line with the approach of personalized medicine, endotyping prematurity and phenotyping BPD will facilitate the design of more targeted therapeutic and prognostic approaches.

Bronchopulmonary dysplasia and expiratory airflow at 8 years in children born extremely preterm in the post-surfactant era

BACKGROUND

It is unclear if bronchopulmonary dysplasia (BPD) is independently associated with reduced expiratory airflow at school age.

OBJECTIVE

To determine the independent associations of moderate-severe BPD, mild BPD, gestational age and birth weight z-score with expiratory airflow in children born extremely preterm (EP; <28 weeks' gestation).

METHODS

All EP survivors born in Victoria, Australia, in three eras (1991-1992, n=225; 1997, n=151; and 2005, n=170) were recruited at birth and 418/546 (77%) had valid spirometry data at 8 years. BPD was classified as moderate-severe (oxygen requirement at 36 weeks' postmenstrual age), or mild (oxygen >28 days but not at 36 weeks' postmenstrual age). Expiratory airflow variables, including the forced expired volume in 1 s (FEV₁), were measured and values converted to z-scores.

RESULTS

Compared with no BPD (n=94), moderate-severe BPD (n=193) was associated with a substantial reduction in expiratory airflow (eg, zFEV₁ mean difference -0.69, 95% CI -0.97 to -0.41; p<0.001), but mild BPD (n=131) was not (zFEV₁ mean difference 0.01, 95% CI -0.28 to 0.31; p=0.93). On multivariable analysis, moderate-severe BPD remained strongly associated with reduced airflow (zFEV₁ mean difference -0.63, 95% CI -0.92 to -0.33; p<0.001), but mild BPD (zFEV₁ mean difference 0.04, 95% CI -0.26 to 0.34; p=0.27), gestational age (zFEV₁ 0.06 mean increase per week, 95% CI -0.05 to 0.17; p=0.29) and birth weight z-score (zFEV₁ 0.07 mean increase per SD, 95% CI -0.06 to 0.20; p=0.28) were not.

CONCLUSIONS

In children born EP, moderate-severe BPD, but not mild BPD was independently associated with reduced expiratory airflow at 8 years.

Respiratory support of infants born at 22-24 weeks of gestational age

Lung immaturity and acute respiratory failure are the major problems in the care of extremely preterm infants. Most infants with gestational age (GA) 22-24 weeks will need mechanical ventilation and many will depend on some type of respiratory support, invasive and non-invasive for extended periods. There is ongoing gap in knowledge regarding optimal respiratory support and applying strategies that are effective in more mature populations is not easy or even suitable because lung maturation differs in smaller infants. Better strategies on how to avoid lung damage and to promote growth and development of the immature lung are warranted since increased survival is accompanied by increasing rates of bronchopulmonary dysplasia and concerns over long-standing reductions in lung function. This review focuses on some aspects of respiratory care of infants born at 22-24 weeks of GA.

Respiratory Follow Up of the Premature Neonates-Rationale and Practical Issues

The aim of the review was to present the state of knowledge about the respiratory pathology in former premature neonates (children that were born preterm-before 37 weeks of gestation-and are examined and evaluated after 40 weeks corrected age) other than chronic lung disease, in order to provide reasons for a respiratory follow-up program for this category of patients. After a search of the current evidence, we found that premature infants are prone to long-term respiratory consequences due to several reasons: development of the lung outside of the uterus, leading to dysmaturation of the structures, pulmonary pathology due to immaturity, infectious agents or mechanical ventilation and deficient control of breathing. The medium- to long-term respiratory consequences of being born before term are represented by an increased risk of respiratory infections (especially viral) during the first years of life, a risk of recurrent wheezing and asthma and a decrease in pulmonary volumes and airway flows. Late preterm infants have risks of pulmonary long-term consequences similar to other former premature infants. Due to all the above risks, premature neonates should be followed in an organized fashion, being examined at regular time intervals from discharge from the maternity hospital until adulthood-this could lead to an early detection of the risks and preventive therapies in order to improve their prognosis and assure a normal and productive life. The difficulties related to establishing such programs are represented by the insufficient standardization of the data gathering forms, clinical examinations and lung function tests, but it is our belief that if more premature infants are followed, the experience will allow standards to be established in these fields and the methods of data gathering and evaluation to be unified.

Prematurity and Long-Term Respiratory Morbidity—What Is the Critical Gestational Age Threshold?

Respiratory morbidity is a hallmark complication of prematurity. Children born preterm are exposed to both short- and long-term respiratory morbidity. This study aimed to investigate whether a critical gestational age threshold exists for significant long-term respiratory morbidity. A 23-year, population-based cohort analysis was performed comparing singleton deliveries at a single tertiary medical center. A comparison of four gestational age groups was performed according to the WHO classification: term (≥37.0 weeks, reference group), moderate to late preterm (32.0–36.6 weeks), very preterm (28.0–31.6 weeks) and extremely preterm (24.0–27.6 weeks). Hospitalizations of the offspring up to the age of 18 years involving respiratory morbidities were evaluated. A Kaplan–Meier survival curve was used to compare cumulative hospitalization incidence between the groups. A Cox proportional hazards model was used to control for confounders and time to event. Overall, 220,563 singleton deliveries were included: 93.6% term deliveries, 6% moderate to late preterm, 0.4% very preterm and 0.1% extremely preterm. Hospitalizations involving respiratory morbidity were significantly higher in children born preterm (12.7% in extremely preterm children, 11.7% in very preterm, 7.0% in late preterm vs. 4.7% in term, p < 0.001). The Kaplan–Meier survival curve demonstrated a significantly higher cumulative incidence of respiratory-related hospitalizations in the preterm groups (log-rank, p < 0.001). In the Cox regression model, delivery before 32 weeks had twice the risk of long-term respiratory morbidity. Searching for a specific gestational age threshold, the slope for hospitalization rate was attenuated beyond 30 weeks’ gestation. In our population, it seems that 30 weeks’ gestation may be the critical threshold for long-term respiratory morbidity of the offspring, as the risk for long-term respiratory-related hospitalization seems to be attenuated beyond this point until term.

Pulmonary Magnetic Resonance Imaging of Ex-preterm Children with/without Bronchopulmonary Dysplasia

RATIONALE

Children born prematurely, particularly those with bronchopulmonary dysplasia, have persisting lung abnormalities requiring longitudinal monitoring. Pulmonary ultra-short echo time magnetic resonance imaging (MRI) measurements may provide sensitive markers of persisting lung abnormalities, and have not been evaluated in school-aged children born prematurely.

OBJECTIVE

To compare pulmonary MRI and pulmonary function test measurements in preterm-born school-aged children with and without bronchopulmonary dysplasia.

METHODS

Children aged 7-9 years, born extremely preterm, with and without bronchopulmonary dysplasia, were recruited from three centers. Participants underwent pulmonary ultra-short echo time MRI and pulmonary function tests. Primary outcomes included total proton density and proton density at full expiration, measured using MRI. Multiple linear regression analysis was performed, adjusting for gestational age and bronchopulmonary dysplasia. Associations between MRI and pulmonary function were tested.

RESULTS

Thirty-five children were included in the primary analysis (24 with bronchopulmonary dysplasia, 11 without); 29 completed pulmonary function tests, of whom 11 (38%) had airflow limitation. Children with bronchopulmonary dysplasia had 44% (CI: 10%, 66%) lower mean total proton density (mean ± SD: 3.6 ± 2.6) compared to those without (6.1 ± 4.0). Those with bronchopulmonary dysplasia had 25% (CI: 3%, 42%) lower proton density at full expiration than those without. Lower total proton density and proton density at full expiration were moderately correlated with greater residual volume, residual volume/total lung capacity, and lung clearance index (Spearman correlations for total proton density: -0.42, -0.57, and -0.53, respectively. Spearman correlations for proton density at full expiration: -0.28, -0.57, and -0.45, respectively).

CONCLUSIONS

School-aged preterm-born children with bronchopulmonary dysplasia have parenchymal tissue abnormalities measured using ultrashort MRI proton density, compared to those without. MRI proton density correlated with pulmonary function measures indicative of gas trapping. Clinical trial registered with ClinicalTrials.gov (NCT02921308).

Can birth weight predict offspring's lung function in adult age? Evidence from two Swedish birth cohorts

BACKGROUND

Associations between birth weight (BW) and adult lung function have been inconsistent and limited to early adulthood. We aimed to study this association in two population-based cohorts and explore if BW, adjusted for gestational age, predicts adult lung function. We also tested adult lung function impairment according to the mis-match hypothesis-small babies growing big as adults.

METHODS

We included 3495 individuals (aged 46.4 ± 5.4 years) from the Malmo Preventive Project (MPP), Sweden, born between 1921 and 1949, and 1401 young to middle-aged individuals (aged 28.6 ± 6.7 years) from the Malmo Offspring Study (MOS) with complete data on BW and gestational age. Adult lung function (forced vital capacity [FVC], forced expiratory volume in one second [FEV1] and the FEV1/FVC-ratio) were analysed as level of impairment (z-score), using multiple linear and logistic regressions.

RESULTS

BW (z-score) did not predict adult lung function in MPP, whereas BW was a significant (p = 0.003) predictor of FEV1 following full adjustment in MOS. For every additional unit increase in BW, children were 0.77 (95% CI 0.65-0.92) times less likely to have impaired adult lung function (FEV1). Moreover, adults born with lower BW (< 3510 g) showed improved lung function (FEV1 and FEV1/FVC in MOS and MPP, respectively) if they achieved higher adult body weight.

CONCLUSIONS

Adults born with lower birth weight, adjusted for gestational age, are more likely to have impaired lung function, seen in a younger birth cohort. Postnatal growth pattern may, however, compensate for low birth weight and contribute to better adult lung function.

Diagnosis and management of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in infants and is associated with increased mortality, respiratory morbidity, neurodevelopmental impairment, and increased healthcare costs. In parallel with advances made in the field of neonatal intensive care, the phenotype of BPD has evolved from a fibrocystic disease affecting late preterm infants to one of impaired parenchymal development and dysregulated vascular growth predominantly affecting infants born before 29 weeks' gestational age. BPD has been shown to have significant lifelong consequences. Adults with BPD have been found to have abnormal lung function tests, reduced exercise tolerance, and may be at increased risk for developing chronic obstructive pulmonary disease. Evidence shows that BPD occurs secondary to genetic-environmental interactions in an immature lung. In this review, we evaluate the various clinical definitions, imaging modalities, and biomarker data that are helpful in making an early diagnosis of BPD. In addition, we evaluate recent evidence about the prevention and treatment of BPD. We discuss the invasive and non-invasive ventilation strategies and pharmacological agents used in the early, evolving, and established phases of BPD.

Lung function between 8 and 15 years of age in very preterm infants with fetal growth restriction

BACKGROUND

The impact of intrauterine growth restriction (IUGR) on lung function in very preterm children is largely unknown as current evidence is mainly based on studies in children born small for gestational age but not necessarily with IUGR.

METHODS

Spirometry, transfer factor of the lung for carbon monoxide (TLco), and lung clearance index (LCI) were cross-sectionally evaluated at 8.0-15.0 years of age in children born <32 weeks of gestation with IUGR (n = 28) and without IUGR (n = 67). Controls born at term (n = 67) were also included.

RESULTS

Very preterm children with IUGR had lower mean forced expired volume in the first second (FEV₁) z-score than those with normal fetal growth (∆ -0.66, 95% confidence interval (CI) -1.12, -0.19), but not significant differences in LCI (∆ +0.24, 95% CI -0.09, 0.56) and TLco z-score (∆ -0.11, 95% CI -0.44, 0.23). The frequency of bronchopulmonary dysplasia (BPD) in the two groups was, respectively, 43% and 10% (P = 0.003). IUGR was negatively associated with FEV₁ (B = -0.66; P = 0.004), but the association lost significance (P = 0.05) when adjusting for BPD.

CONCLUSIONS

IUGR has an impact on conducting airways function of very preterm children at school age, with part of this effect being mediated by BPD. Ventilation inhomogeneity and diffusing capacity, instead, were not affected.

IMPACT

IUGR does not necessarily imply a low birthweight for gestational age (and vice versa). While a low birthweight is associated with worse respiratory outcomes, the impact of IUGR on lung function in premature children is largely unknown. IUGR affects conducting airways function in school-age children born <32 weeks with IUGR, but not ventilation inhomogeneity and diffusing capacity. The impact of IUGR on FEV₁ seems mainly related to the higher risk of BPD in this group.

Early Life Factors Associated with Preschool Wheezing in Preterm Infants

Advanced neonatal care has increased the survival of neonates born prematurely, and prematurity is a well-known risk factor for asthma/wheezing disorders. Thus, this prospective study aimed to determine the early life factors associated with preschool wheezing in premature neonates. Preterm neonates born between 2012 and 2017 were recruited, excluding those with bacterial infection within 7 days of life, maternal sepsis, and maternal chorioamnionitis. Birth and admission history, comorbidities, and maternal history were documented. Respiratory problems were followed-up at the neonatal outpatient department. Patients were divided into wheezing and non-wheezing groups. Data were analyzed using the Mann-Whitney test and Fisher's exact test, and multivariable logistic regression was used to define the risk factors of preschool wheezing/asthma. A total of 125 preterm infants were enrolled, including 19 in the wheezing group and 106 in the non-wheezing group. Patients in the wheezing group had longer duration of intubation (p = 0.025), higher rates for exclusive breast milk feeding (p = 0.012), and higher re-hospitalization rates for respiratory tract infections (p < 0.001), especially for respiratory syncytial virus (RSV) bronchiolitis (p = 0.045). The incidence of allergic rhinitis was also higher in the wheezing group (p = 0.005). After multivariable logistic regression, allergic rhinitis and re-hospitalization for respiratory tract infections were two significant risk factors for preschool wheezing/asthma in premature neonates. Close follow-up of premature infants at high risk for asthma susceptibility is recommended.

Medication utilization in children born preterm in the first two years of life

OBJECTIVE

To compare medications dispensed during the first 2 years in children born preterm and full-term.

STUDY DESIGN

Retrospective analysis of claims data from a commercial national managed care plan 2008-2019. 329,855 beneficiaries were enrolled from birth through 2 years, of which 25,408 (7.7%) were preterm (<37 weeks). Filled prescription claims and paid amount over 2 years were identified.

RESULTS

In preterm children, the number of filled prescriptions was 1.4 times and cost was 3.8 times that of full-term children. Number and cost of medications were inversely related to gestational age. Differences peak at 4-9 months and resolve by 19 months after discharge. Palivizumab, ranitidine, albuterol, lansoprazole, budesonide, and prednisolone had the greatest differences in utilization.

CONCLUSION

Prescription medication utilization among preterm children under 2 years is driven by palivizumab, anti-reflux, and respiratory medications, despite little evidence regarding efficacy for many medications and concern for harm with certain classes.

Air quality, Environment and Respiratory Outcomes in Bronchopulmonary Dysplasia, the AERO-BPD cohort study: design and adaptation during the SARS-CoV-2 pandemic

INTRODUCTION

Almost half of all school-age children with bronchopulmonary dysplasia (BPD) have asthma-like symptoms and more suffer from lung function deficits. While air pollution and indoor respiratory irritants are known to affect high-risk populations of children, few studies have objectively evaluated environmental contributions to long-term respiratory morbidity in this population. This study aimed to examine the role of indoor environmental exposures on respiratory morbidity in children with BPD.

METHODS AND ANALYSIS

The Air quality, Environment and Respiratory Ouctomes in BPD (AERO-BPD) study is a prospective, single-centre observational study that will enrol a unique cohort of 240 children with BPD and carefully characterise participants and their indoor home environmental exposures. Measures of indoor air quality constituents will assess the relationship of nitrogen dioxide (NO2), particulate matter (PM2.5), nitric oxide (NO), temperature and humidity, as well as dust concentrations of allergens, with concurrently measured respiratory symptoms and lung function.Adaptations to the research protocol due to the SARS-CoV-2 pandemic included remote home environment and participant assessments.

ETHICS AND DISSEMINATION

Study protocol was approved by the Boston Children's Hospital Committee on Clinical Investigation. Dissemination will be in the form of peer-reviewed publications and participant information products.

TRIAL REGISTRATION NUMBER

NCT04107701.

Early extubation to noninvasive respiratory support of former preterm lambs improves long-term respiratory outcomes

Invasive mechanical ventilation (IMV) and exposure to oxygen-rich gas during early postnatal life are contributing factors for long-term pulmonary morbidities faced by survivors of preterm birth and bronchopulmonary dysplasia. The duration of IMV that leads to long-term pulmonary morbidities is unknown. We compared two durations of IMV (3 h vs. 6 days) during the first 6-7 days of postnatal life in preterm lambs to test the hypothesis that minimizing the duration of IMV will improve long-term respiratory system mechanics and structural outcomes later in life. Moderately preterm (∼85% gestation) lambs were supported by IMV for either 3 h or 6 days before weaning from all respiratory support to become former preterm lambs. Respiratory system mechanics and airway reactivity were assessed monthly from 1 to 6 mo of chronological postnatal age by the forced oscillation technique. Quantitative morphological measurements were made for smooth muscle accumulation around terminal bronchioles and indices of alveolar formation. Minimizing IMV to 3 h led to significantly better (P < 0.05) baseline respiratory system mechanics and less reactivity to methacholine in the first 3 mo of chronological age (2 mo corrected age), significantly less (P < 0.05) accumulation of smooth muscle around peripheral resistance airways (terminal bronchioles), and significantly better (P < 0.05) alveolarization at the end of 5 mo corrected age compared with continuous IMV for 6 days. We conclude that limiting the duration of IMV following preterm birth of fetal lambs leads to better respiratory system mechanics and structural outcomes later in life.

Multimodal longitudinal respiratory function assessment in very low birth weight 7-year-old children

PURPOSE

Preterm birth is associated with adverse pulmonary outcomes. We aimed to evaluate respiratory morbidities and lung function of very low birth weight (VLBW) Polish children followed up at the age of 7 years old, and to compare with electrical impedance segmentography (EIS) results recorded at 4 years of age.

MATERIALS AND METHODS

VLBW children were compared with term controls using impulse oscillometry and spirometry. Perinatal data and current respiratory morbidities were analyzed and pulmonary function test results were compared with previous EIS results.

RESULTS

We included 40 VLBW children and 30 controls in the analysis. Elevated total airway resistance and forced expiratory volume in the first second below the lower limit of normal were more prevalent in VLBW children compared with term controls (15 vs 0%; 18 vs 0%). A positive bronchodilator response was more common in VLBW children (R_{5 Hz}: 46 vs 13.3%; R_5-20 ​Hz: 65 vs 36.7%). Children with bronchopulmonary dysplasia (BPD) had higher total airway resistance (R_{5 Hz}/R_{5 Hz pred}: 1.35 vs 0.95; p ​< ​0.001), large airway resistance (R_{20 Hz}/R_{20 Hz pred}: 0.89 vs 0.66; p ​= ​0.001), small airway resistance (R_5-20 ​Hz: 0.57 vs 0.34 ​kPa ​L^-1 ​s^-1; p ​= ​0.009), than controls. Strong correlation between BDR in EIS and R_{5 Hz}/R_{5 Hz pred} was observed in children with BPD (r ​= ​0.7).

CONCLUSION

VLBW school-aged children with BPD presented with substantial respiratory morbidity and persistent reduction of lung function, affecting small and large airways and lung parenchyma. EIS may be an alternative tool for lung function assessment in children with BPD.

Right Heart Structure, Geometry and Function Assessed by Echocardiography in 6-Year-Old Children Born Extremely Preterm-A Population-Based Cohort Study

Preterm birth has been associated with altered cardiac phenotype in adults. Our aim was to test the hypothesis that children surviving extremely preterm birth have important structural or functional changes of the right heart or pulmonary circulation. We also examined relations between birth size, gestational age, neonatal diagnoses of bronchopulmonary dysplasia (BPD) and patent ductus arteriosus (PDA) with cardiac outcomes. We assessed a population-based cohort of children born in Sweden before 27 weeks of gestation with echocardiography at 6.5 years of age (n = 176). Each preterm child was matched to a healthy control child born at term. Children born preterm had significantly smaller right atria, right ventricles with smaller widths, higher relative wall thickness and higher estimated pulmonary vascular resistance (PVR) than controls. In preterm children, PVR and right ventricular myocardial performance index (RVmpi’) were significantly higher in those with a PDA as neonates than in those without PDA, but no such associations were found with BPD. In conclusion, children born extremely preterm exhibit higher estimated PVR, altered right heart structure and function compared with children born at term.

Predicting Long-Term Respiratory Outcomes in Premature Infants: Is It Time to Move beyond Bronchopulmonary Dysplasia?

Premature birth has been shown to be associated with adverse respiratory health in children and adults; children diagnosed with bronchopulmonary dysplasia (BPD) in infancy are at particularly high risk. Since its first description by Northway et al. about half a century ago, the definition of BPD has gone through several iterations reflecting the changes in the patient population, advancements in knowledge of lung development and injury, and improvements in perinatal care practices. One of the key benchmarks for optimally defining BPD has been the ability to predict long-term respiratory and health outcomes. This definition is needed by multiple stakeholders for hosts of reasons including: providing parents with some expectations for the future, to guide clinicians for developing longer term follow-up practices, to assist policy makers to allocate resources, and to support researchers involved in developing preventive or therapeutic strategies and designing studies with meaningful outcome measures. Long-term respiratory outcomes in preterm infants with BPD have shown variable results reflecting not only limitations of the current definition of BPD, but also potentially the impact of other prenatal, postnatal and childhood factors on the respiratory health. In this manuscript, we present an overview of the long-term respiratory outcomes in infants with BPD and discuss the role of other modifiable or non-modifiable factors affecting respiratory health in preterm infants. We will also discuss the limitations of using BPD as a predictor of respiratory morbidities and some of the recent advances in delineating the causes and severity of respiratory insufficiency in infants diagnosed with BPD.

Physical Activity in 6.5-Year-Old Children Born Extremely Preterm

Physical activity (PA) can prevent cardiovascular diseases. Because of increased risks of impairments affecting motor activity, PA in children born preterm may differ from that in children born at term. In this prospective cohort study, we compared objectively measured PA in 71 children born extremely preterm (<27 weeks gestational age), to their 87 peers born at term, at 6.5 years of age. PA measured with accelerometer on the non-dominant wrist for 7 consecutive days was compared between index and control children and analyzed for associations to prenatal growth, major neonatal brain injury, bronchopulmonary dysplasia and neonatal septicemia, using ANOVA. Boys born extremely preterm spent on average 22 min less time per day in moderate to vigorous physical activity (MVPA) than control boys (95% CI: -8, -37). There was no difference in girls. Amongst children born extremely preterm, major neonatal brain injury was associated with 56 min less time in MVPA per day (95%CI: -88, -26). Subgroups of children born extremely preterm exhibit lower levels of physical activity which may be a contributory factor in the development of cardiovascular diseases as adults.

Agreement between spirometry and impulse oscillometry for lung function assessment in 6-year-old children born extremely preterm and at term

BACKGROUND

Extremely preterm birth is a risk factor for reduced lung function later in life, and clinical follow-up from early childhood is recommended. Dynamic spirometry is the most widely used method to assess airway obstruction, but impulse oscillometry (IOS) may be an alternative method that is easier to perform in young children. The feasibility and agreement between spirometry and IOS outcome variables has not been investigated in children born extremely preterm.

AIM

To determine the feasibility of and correlation between spirometry and IOS in pre-school children born extremely preterm.

METHODS

Spirometry and IOS were performed in 6-year-old children born extremely preterm (n = 88) and age-matched term controls (n = 84) in Stockholm, Sweden. Correlations between spirometry and IOS outcome variables were analyzed using Pearson's partial correlation, adjusting for height.

RESULTS

Success rate for spirometry (60%) was lower than for IOS (93%) but did not differ significantly between the preterm and term groups (56% and 64% for spirometry, P = .25; and 92% and 94% for IOS, P = .61). Correlations between spirometry and IOS outcomes were at best moderate (Spearman's r = -0.31 to -0.56). Normal IOS identified 69% to 90% of those with normal spirometry. A negative predictive value of 90% was found for R5-R20 versus FEV_0.75 /FVC, suggesting that IOS may be used to exclude obstructive airway disease as measured by spirometry.

CONCLUSION

IOS is a more feasible method than spirometry to assess lung function in young children irrespective of gestational age at birth and could be considered an alternative in children who cannot perform spirometry.

Bronchopulmonary Dysplasia: Then, Now, and Next

Bronchopulmonary dysplasia (BPD) has evolved considerably since its first description over 50 years ago. This review aims to provide a historical framework for conceptualizing BPD and a current understanding of the changing definition, epidemiology, pathophysiology, treatment, and outcomes of BPD. The transdisciplinary approach that led to the initial phenotypic description of BPD continues to hold promise today. Investigators are refining the definition of BPD in light of changes in clinical care and increasing survival rates of very preterm infants. Despite improvements in perinatal care the incidence of BPD continues to increase. There is growing recognition that antenatal risk factors play a key role in the development of BPD. Strategies designed to prevent or limit neonatal lung injury continue to evolve. Defining the phenotype of infants with BPD can meaningfully direct treatment. Infants with BPD benefit from an interdisciplinary approach to longitudinal care with a focus on growth and neurocognitive development. While the ultimate impact of BPD on long-term pulmonary morbidity remains an active area of investigation, current data indicate that most children and adolescents with a history of BPD have a quality of life comparable to that of other preterm infants.

Lung function and pulmonary vascular resistance are not associated in 6-year-old children born extremely preterm

AIM

Children born preterm are at increased risk of reduced lung function. The aim was to test whether lung function was associated with pulmonary vascular resistance.

METHODS

Participants were recruited from a population-based cohort born in 2004-2007. Lung function was assessed with spirometry after administration of a beta2-agonist. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁ ) were determined. Estimations of pulmonary vascular resistance, arterial dimensions, right ventricular wall thickness, sphericity, and systolic (TAPSE) and diastolic functions were performed with echocardiography. Adjusted regression analyses were used to study associations.

RESULTS

Sixty-six children (33 boys) born at 22-26 weeks of gestational age (birthweights 460-1134 g) were assessed at a mean age of 6.7 years. Despite large variations in lung function with FVC z-scores ranging from -4.6 to +2.8, there were no associations between lung function and pulmonary arterial pressure, right ventricular structure or function. Children with higher FVC z-scores (r = .52, β = .55 mm, P = .015) and higher FEV₁ z-scores (r = .58, β = .73 mm, P = .001) exhibited larger pulmonary arteries.

CONCLUSION

In children born extremely preterm, lung function was not associated with pulmonary vascular resistance. Routine echocardiographic evaluation of extremely preterm children may not be indicated at age 6.5 years.

Birth weight and prematurity with lung function at ~17.5 years: "Children of 1997" birth cohort

We aimed to determine if prematurity and lower birth weight are associated with poorer lung function in a non-western developed setting with less marked confounding by socioeconomic position. Using multivariable linear regression in Hong Kong’s “Children of 1997” birth cohort, adjusted associations of prematurity and birth weight with forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and forced expiratory flow at 25–75% of the pulmonary volume (FEF_25–75%) at ~17.5 years were assessed. Associations for birth weight were stronger in boys for FEV₁ (boys: 0.31 L, 95% confidence interval (CI) 0.24 to 0.38, girls: 0.18 L, 95% CI 0.12 to 0.25), FVC (boys: 0.36 L, 95% CI 0.27 to 0.44, girls: 0.22 L, 95% CI 0.15 to 0.28) and FEF_25–75% (boys: 0.35 L, 95% CI 0.21 to 0.49, girls: 0.22 L, 95% CI 0.09 to 0.34) adjusted for age, socioeconomic position and infant and maternal characteristics. Similarly adjusted, preterm birth (compared to full-term birth) was associated with lower FEV₁/FVC and FEF_25–75%. Thus, associations of lower birth weight, especially in boys, and prematurity with poorer lung function at 17.5 years were found. Identifying underlying mechanism might contribute to the improvement of pulmonary health and the prevention of adult respiratory illness.

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.

Bronchopulmonary dysplasia

In the absence of effective interventions to prevent preterm births, improved survival of infants who are born at the biological limits of viability has relied on advances in perinatal care over the past 50 years. Except for extremely preterm infants with suboptimal perinatal care or major antenatal events that cause severe respiratory failure at birth, most extremely preterm infants now survive, but they often develop chronic lung dysfunction termed bronchopulmonary dysplasia (BPD; also known as chronic lung disease). Despite major efforts to minimize injurious but often life-saving postnatal interventions (such as oxygen, mechanical ventilation and corticosteroids), BPD remains the most frequent complication of extreme preterm birth. BPD is now recognized as the result of an aberrant reparative response to both antenatal injury and repetitive postnatal injury to the developing lungs. Consequently, lung development is markedly impaired, which leads to persistent airway and pulmonary vascular disease that can affect adult lung function. Greater insights into the pathobiology of BPD will provide a better understanding of disease mechanisms and lung repair and regeneration, which will enable the discovery of novel therapeutic targets. In parallel, clinical and translational studies that improve the classification of disease phenotypes and enable early identification of at-risk preterm infants should improve trial design and individualized care to enhance outcomes in preterm infants.

Comparison of dermal vs internal light administration in human lungs using the TDLAS-GASMAS technique-Phantom studies

Oxygen and water vapor content, in the lungs of a 3D-printed phantom model based on CT-images of a preterm infant, is evaluated using Tunable Diode Laser Absorption Spectroscopy (TDLAS) in Gas in Scattering Media Absorption Spectroscopy (GASMAS), that is, the TDLAS-GASMAS technique. Oxygen gas is detected through an absorption line near 764 nm and water vapor through an absorption line near 820 nm. A model with a lung containing interior structure is compared to a model with a hollow lung. Compared to the model with the hollow lung, both the mean absorption path length and the transmitted intensity are found to be lower for the model with the structured lung. A new approach, where laser light is delivered internally into the model through an optical fiber, is compared to dermal light administration, that is, illumination onto the skin, for the model with structure inside the lung. The internal light administration generally resulted in larger gas absorption, and higher signal-to-noise ratios, compared to the dermal light administration. The results from the phantom measurements show great promise for the internal illumination approach and a natural next step would be to investigate it further in clinical studies.

2018 year in review: Part 2 of 4: Neonatal lung disease

Pediatric Pulmonology publishes original research, reviews and case reports related to a wide range of children's respiratory disorders. This review (Part 2 of a 4-part series) summarizes the past year's publications in the topic area of neonatal lung diseases, in the context of selected literature from other journals relevant to the discipline.

Neonatal respiratory status predicts longitudinal respiratory health outcomes in preterm infants

OBJECTIVES

To examine the relationship between neonatal respiratory status and longitudinal respiratory health outcomes in preterm infants with very low birth weight (VLBW, birth weight <1500 g).

METHODS

A total of 109 VLBW preterm infants were prospectively assessed for respiratory status using the Toce clinical and radiographic scoring method on a postnatal day 28, and severity of bronchopulmonary dysplasia (BPD) at 36-weeks postmenstrual age (PMA), respiratory morbidity within 1 year of corrected age (CA), pulmonary function test, and six-minute walk test at 4 years of age.

RESULTS

A high Toce clinical score on day 28 was associated with the occurrence of respiratory morbidity within 1 year of CA and poor pulmonary function and functional exercise performance at 4 years of age in VLBW preterm infants (all P < 0.05). BPD at 36-weeks PMA was associated with an increased risk of respiratory morbidity within 1 year of CA and its negative impact on pulmonary function and functional exercise performance at 4 years of age was most pronounced in the severe form (all P < 0.05).

CONCLUSIONS

Early assessments of neonatal respiratory status including Toce clinical score and the severity of BPD are valid to identify VLBW preterm infants who are at risk of adverse longitudinal respiratory health outcomes.

Bronchopulmonary dysplasia: what are its links to COPD?

Emerging evidence suggests that adverse early life events can affect long-term health trajectories throughout life. Preterm birth, in particular, is a significant early life event that affects approximately 10% of live births. Worldwide, prematurity is the number one cause of death in children less than 5 years of age and has been shown to disrupt normal lung development with lasting effects into adult life. Along with impaired lung development, interventions used to support gas exchange and other sequelae of prematurity can lead to the development of bronchopulmonary dysplasia (BPD). BPD is a chronic respiratory disease of infancy characterized by alveolar simplification, small airways disease, and pulmonary vascular changes. Although many survivors of BPD improve with age, survivors of BPD often have chronic lung disease characterized by airflow obstruction and intermittent pulmonary exacerbations. Long-term lung function trajectories as measured by FEV1 can be lower in children and adults with a history BPD. In this review, we discuss the epidemiology and manifestations of BPD and its long-term consequences throughout childhood and into adulthood. Available evidence suggests that disrupted lung development, genetic susceptibility and subsequent environment and infectious events that occur in prenatal and postnatal life likely increase the predisposition of children with BPD to develop early onset chronic obstructive pulmonary disease (COPD). The reviews of this paper are available via the supplemental material section.

Neonatal Pulmonary Magnetic Resonance Imaging of Bronchopulmonary Dysplasia Predicts Short-Term Clinical Outcomes

RATIONALE

Bronchopulmonary dysplasia (BPD) is a serious neonatal pulmonary condition associated with premature birth, but the underlying parenchymal disease and trajectory are poorly characterized. The current National Institute of Child Health and Human Development (NICHD)/NHLBI definition of BPD severity is based on degree of prematurity and extent of oxygen requirement. However, no clear link exists between initial diagnosis and clinical outcomes.

OBJECTIVES

We hypothesized that magnetic resonance imaging (MRI) of structural parenchymal abnormalities will correlate with NICHD-defined BPD disease severity and predict short-term respiratory outcomes.

METHODS

A total of 42 neonates (20 severe BPD, 6 moderate, 7 mild, 9 non-BPD control subjects; 40 ± 3-wk postmenstrual age) underwent quiet-breathing structural pulmonary MRI (ultrashort echo time and gradient echo) in a neonatal ICU-sited, neonatal-sized 1.5 T scanner, without sedation or respiratory support unless already clinically prescribed. Disease severity was scored independently by two radiologists. Mean scores were compared with clinical severity and short-term respiratory outcomes. Outcomes were predicted using univariate and multivariable models, including clinical data and scores.

MEASUREMENTS AND MAIN RESULTS

MRI scores significantly correlated with severities and predicted respiratory support at neonatal ICU discharge (P < 0.0001). In multivariable models, MRI scores were by far the strongest predictor of respiratory support duration over clinical data, including birth weight and gestational age. Notably, NICHD severity level was not predictive of discharge support.

CONCLUSIONS

Quiet-breathing neonatal pulmonary MRI can independently assess structural abnormalities of BPD, describe disease severity, and predict short-term outcomes more accurately than any individual standard clinical measure. Importantly, this nonionizing technique can be implemented to phenotype disease, and has potential to serially assess efficacy of individualized therapies.

Respiratory morbidity through the first decade of life in a national cohort of children born extremely preterm

BACKGROUND

Advances in perinatal care have markedly increased the prospects of survival for infants born extremely preterm (EP). The aim of this study was to investigate hospitalisation rates and respiratory morbidity from five to 11 years of age in a prospective national cohort of EP children born in the surfactant era.

METHODS

This was a national prospective cohort study of all children born in Norway during 1999 and 2000 with gestational age (GA) < 28 weeks or birth weight < 1000 grams, and of individually matched term-born controls recruited for a regional subsample. Data on hospital admissions, respiratory symptoms, and use of asthma medication was obtained by parental questionnaires at 11 years of age.

RESULTS

Questionnaires were returned for 232/372 (62%) EP-born and 57/61 (93%) regional term-born controls. Throughout the study period, 67 (29%) EP-born and seven (13%) term-born controls were admitted to hospital (odds ratio (OR) 2.90, 95% confidence interval (CI): 1.25, 6.72). Admissions were mainly due to surgical procedures, with only 12% due to respiratory causes, and were not influenced by neonatal bronchopulmonary dysplasia (BPD) or low GA(≤ 25 weeks). Respiratory symptoms, asthma and use of asthma medication tended to be more common for EP-born, significantly so for medication use and wheeze on exercise. Neonatal BPD was a risk factor for medication use, but not for current wheeze. In multivariate regression models, home oxygen after discharge (OR 4.84, 95% CI: 1.38, 17.06) and parental asthma (OR 4.38, 95% CI: 1.69, 11.38) predicted current asthma, but neither BPD nor low GA were associated with respiratory symptoms at 11 years of age.

CONCLUSIONS

Hospitalisation rates five to 11 years after EP birth were low, but twice those of term-born controls, and unrelated to neonatal BPD and low GA. Respiratory causes were rare. Respiratory complaints were more common in children born EP, but the burden of symptoms had declined since early childhood.