Respiratory function at age 8-9 after extremely low birthweight or preterm birth in Victoria in 1997

Health-Related Qualities of Life in School-Aged Children with Bronchopulmonary Dysplasia

OBJECTIVE

To determine health-related quality of life (HRQOL) of school-aged children with bronchopulmonary dysplasia (BPD) using the standardized Patient-Reported Outcomes Measurement Information System (PROMIS) assessment tools.

STUDY DESIGN

The Indoor Air Quality and Respiratory Morbidity in Children with BPD Study is an ongoing observational study of school-aged children with BPD. HRQOL is assessed at enrollment by 3 PROMIS questionnaires, Parent Proxy Scale-Global Health 7, Parent Proxy Psychological Stress Experiences-Short Form, and the Parent Proxy Profile-Profile-25. PROMIS data were tested for significant deviation from the standardized T-Score references for normative populations of children.

RESULTS

Eighty-nine subjects enrolled in the AERO-BPD study had complete outcome data for HRQOL. The mean age was 9 (±2) years and 43% were female. Mean days on respiratory support totaled 96 (±40). Across all domains, school-aged children with BPD reported similar or slightly better outcomes than the reference sample. Statistically significant findings of lower depression (P < .0001), fatigue (P < .0001), and pain (P < .0001) scores were found; there was no difference in psychological stress experiences (P = .87), global health (P = .06), anxiety (P = .08), relationships (P = .80), and mobility (P = .59) domains.

CONCLUSIONS

This study demonstrated that children with BPD may have less depression, fatigue, and pain HRQL than the general population. Once validated, these findings may offer reassurance to parents and providers caring for children with BPD.

Expiratory airflow at 7-8 years of age in children born extremely low birthweight from 14 years before to 14 years after the introduction of exogenous surfactant

Background

It is unclear if expiratory airflow in survivors born extremely low birth weight (ELBW; 500-999 g) has improved after the introduction of exogenous surfactant into clinical practice in 1991. The primary aim of this study was to describe the changes in airflow at 7-8 years of age of survivors born ELBW in five discrete cohorts from 14 years before to 14 years after the introduction of exogenous surfactant into clinical practice.

Methods

The cohorts comprised consecutive survivors born ELBW in 1977-82 and 1985-87 at the Royal Women's Hospital, Melbourne, and in 1991-92, 1997 and 2005 in the state of Victoria, Australia. Survival rates to 2-years of age for infants born ELBW in the state of Victoria rose from approximately 1-in-4 to 3-in-4 over the time of this study. Expiratory airflow measurements at 7-8 years included the forced expired volume in 1 s (FEV1), converted to z-scores for age, height, sex, and race.

Findings

There were 596 ELBW participants with expiratory flow data, 280 (47%) of whom had bronchopulmonary dysplasia (BPD). Overall, there was little change in zFEV1 over the 28-year period (mean change per year; 0.003, 95% CI -0.010, 0.015, P = 0.67). There was, however, evidence of an interaction between BPD and year; zFEV1 in those who had BPD fell over time (mean change per year -0.019, 95% CI -0.037, -0.009, P = 0.035), whereas zFEV1 improved in those who did not have BPD (mean change per year 0.021, 95% CI 0.006, 0.037, P = 0.007).

Interpretation

Contrary to recent evidence, expiratory airflow of children born ELBW has not improved with the introduction of surfactant, and may be deteriorating in those who had BPD.

Funding

National Health and Medical Research Council (Australia); Victorian Government's Operational Infrastructure Support Program.

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.

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.

The Consensus Definition of Bronchopulmonary Dysplasia Is an Adequate Predictor of Lung Function at Preschool Age

BACKGROUND

Recent attempts to refine the definition bronchopulmonary dysplasia (BPD) have based its predictive capacity on respiratory outcome in the first 2 years of life, eliminating the pre-existing requirement of 28 days of oxygen therapy prior to 36 weeks postmenstrual age (PMA). The objective of this study was to assess the utility of the 2001 consensus definition in predicting impaired lung function at preschool age.

METHODS

This cohort study included children aged 4-6 years old who were born at gestational age (GA) <32 weeks or bodyweight <1500 g. Univariate and multivariate analyses were performed to assess differences in antenatal and neonatal variables between BPD and non-BPD children. All participants underwent incentive spirometry. Lung function parameters were contrasted with the Global Lung Function Initiative (GLI-2012) reference equations and, together with antenatal and neonatal variables, compared among the different subgroups (no BPD, mild BPD, and moderate-to-severe BPD). A multivariate model was generated to identify independent risk factors for impaired lung function.

RESULTS

GA, hemodynamically significant patent ductus arteriosus, and late sepsis were independent risk factors for the development of BPD. A total of 119 children underwent incentive spirometry. All lung function parameters were significantly altered relative to reference values. Greater impairment of lung function was observed in the mild BPD vs. the no BPD group (forced expiratory volume in the first 0.75 seconds [FEV_0.75]: -1.18 ± 0.80 vs. -0.55 ± 1.13; p = 0.010), but no difference in forced vital capacity (FVC) was observed (-0.32 ± 0.90 vs. -0.18 ± 1; p = 0.534). The moderate-to-severe BPD group exhibited the most severe FEV_0.75 reduction (FEV_0.75: -2.63 ± 1.18 vs. -0.72 ± 1.08; p = 0.000) and was the only condition with FVC impairment (FVC: -1.82 ± 1.12 vs. -0.22 ± 0.87; p = 0.000). The multivariate analysis identified a diagnosis of moderate-to-severe BPD as an independent risk factor for lung function impairment.

CONCLUSION

The 2001 consensus definition of BPD has adequate predictive capacity for lung function measured by spirometry at 4-6 years of age. Moderate-to-severe BPD was the best predictor of respiratory impairment. Children with mild BPD showed greater alteration of FEV_0.75 than those without BPD.

Wheezing in preterm infants and children

Wheezing is a common outcome of preterm birth. This article will review the mechanisms, epidemiology, and treatment of wheezing in preterm children with and without a history of bronchopulmonary dysplasia.

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.

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.

Invasive mechanical ventilation at 36 weeks post-menstrual age, adverse outcomes with a comparison of recent definitions of bronchopulmonary dysplasia

OBJECTIVES

To determine whether the need for invasive mechanical ventilation (iMV) at 36 weeks PMA in patients with severe bronchopulmonary dysplasia (sBPD) identifies those patients at highest risk for tracheostomy or gastrostomy, and to compare sBPD with recent definitions of BPD.

STUDY DESIGN

Observational study from Jan 2015 to Sept 2019 using data from the BPD Collaborative Registry.

RESULTS

Five hundred and sixty-four patients with sBPD of whom 24% were on iMV at 36 weeks PMA. Those on iMV had significantly (p < 0.0001) increased risk for tracheostomy or gastrostomy. The overall mortality rate was 3% and the risk for mortality was substantially greater in those on iMV than in those on noninvasive support at 36 weeks PMA (RR 13.8, 95% CI 4.3-44.5, p < 0.0001). When applying the NICHD definition (2016) 44% had Grade III BPD. When applying the NRN definition, 6% had Grade 1 BPD, 70% had Grade 2 BPD, and 24% had Grade 3 BPD.

CONCLUSIONS

Patients with sBPD who were on iMV at 36 weeks had a significantly greater risk of inhospital mortality and survivors had a significantly greater risk of undergoing tracheostomy and/or gastrostomy. The use of type 2 sBPD or Grade 3 BPD would enhance the ability to target future studies to those infants with sBPD at the highest risk of adverse long-term outcomes.

Asthma prevalence, lung and cardiovascular function in adolescents born preterm

Our main objective was to study respiratory evolution and pulmonary and cardiac function in adolescents born preterm in the post-surfactant era. Observational cross-sectional study, comparing very preterm (< 32 weeks) and moderately-late preterm adolescents (≥ 32 weeks) (74 each group). We recorded respiratory symptoms, spirometry and functional echocardiogram. Very preterm adolescents required more respiratory admissions (45.9% vs. 28.4%) (p = 0.03, OR 2.1, CI95% 1.1–4.2) and had more current asthma (21.6% vs. 9.5%, p = 0.04, OR 2.3, CI95% 1.1–5.2). Preterm subjects with intrauterine growth restriction (IUGR) presented lower FEV₁ (88.7 ± 13.9 vs. 95.9 ± 13.3, p = 0.027) and lower FVC (88.2 ± 13.6 vs. 95.5 ± 13.3, p = 0.025). When assessing right ventricle, very preterm showed a greater E/E’ ratio (p = 0.02) and longer myocardial performance index (MPI) (p = 0.001). Adolescents with IUGR showed less shortening fraction (p = 0.016), worse E/E′ ratio (p = 0.029) and longer MPI (p = 0.06). Regarding left ventricle, very preterm showed less E′ wave velocity (p = 0.03), greater E/E′ ratio (p = 0.005) and longer MPI (p < 0.001). Gestational age < 32 weeks is independently associated with current asthma in adolescence. Children 13–14 years old born very preterm required more respiratory admissions and had poorer diastolic and global function of both ventricles. IUGR is a risk factor for poorer lung function in preterm adolescents, regardless gestational age.

Diaphragm-triggered non-invasive respiratory support in preterm infants

BACKGROUND

Diaphragm-triggered non-invasive respiratory support, commonly referred to as NIV-NAVA (non-invasive neurally adjusted ventilatory assist), uses the electrical activity of the crural diaphragm to trigger the start and end of a breath. It provides variable inspiratory pressure that is proportional to an infant's changing inspiratory effort. NIV-NAVA has the potential to provide effective, non-invasive, synchronised, multilevel support and may reduce the need for invasive ventilation; however, its effects on short- and long-term outcomes, especially in the preterm infant, are unclear.

OBJECTIVES

To assess the effectiveness and safety of diaphragm-triggered non-invasive respiratory support in preterm infants (< 37 weeks' gestation) when compared to other non-invasive modes of respiratory support (nasal intermittent positive pressure ventilation (NIPPV); nasal continuous positive airway pressure (nCPAP); high-flow nasal cannulae (HFNC)), and to assess preterm infants with birth weight less than 1000 grams or less than 28 weeks' corrected gestation at the time of intervention as a sub-group.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2019, Issue 5), MEDLINE via PubMed (1946 to 10 May 2019), Embase (1947 to 10 May 2019), and CINAHL (1982 to 10 May 2019). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-randomised trials.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials that compared diaphragm-triggered non-invasive versus other non-invasive respiratory support in preterm infants.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trial quality and extracted data from included studies. We performed fixed-effect analyses and expressed treatment effects as mean difference (MD), risk ratio (RR), and risk difference (RD) with 95% confidence intervals (CIs). We used the generic inverse variance method to analyse specific outcomes for cross-over trials. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

There were two small randomised controlled trials including a total of 23 infants eligible for inclusion in the review. Only one trial involving 16 infants included in the analysis reported on either of the primary outcomes of the review. This found no difference in failure of modality between NIV-NAVA and NIPPV (RR 0.33, 95% CI 0.02 to 7.14; RD -0.13, 95% CI -0.41 to 0.16; 1 study, 16 infants; heterogeneity not applicable). Both trials reported on secondary outcomes of the review, specific for cross-over trials (total 22 infants; 1 excluded due to failure of initial modality). One study involving seven infants reported a significant reduction in maximum FiO₂ with NIV-NAVA compared to NIPPV (MD -4.29, 95% CI -5.47 to -3.11; heterogeneity not applicable). There was no difference in maximum electric activity of the diaphragm (Edi) signal between modalities (MD -1.75, 95% CI -3.75 to 0.26; I² = 0%) and a significant increase in respiratory rate with NIV-NAVA compared to NIPPV (MD 7.22, 95% CI 0.21 to 14.22; I² = 72%) on a meta-analysis of two studies involving a total of 22 infants. The included studies did not report on other outcomes of interest.

AUTHORS' CONCLUSIONS

Due to limited data and very low certainty evidence, we were unable to determine if diaphragm-triggered non-invasive respiratory support is effective or safe in preventing respiratory failure in preterm infants. Large, adequately powered randomised controlled trials are needed to determine if diaphragm-triggered non-invasive respiratory support in preterm infants is effective or safe.

Association between thoracic musculoskeletal abnormalities and lung function in preterm infants

INTRODUCTION

In view of the difficulties and risks of performing lung function tests in infants and the hypothesis that children with abnormal pulmonary test may exhibit thoracic musculoskeletal alterations.

OBJECTIVES

This study aimed to determine the frequency of abnormal lung function and their relationship.

MATERIALS AND METHODS

This was a cross-sectional study with children from 6 to 12 months of corrected age, born at a gestational age of <37 weeks and with a birthweight ≤1500 g, who were subjected to a lung function test and photogrammetry--an objective and non-invasive procedure. To verify the association between the thoracic musculoskeletal abnormalities and measure changes in lung function, univariate linear regression was used. The level of statistical significance was setted at P < 0.05.

RESULTS

Of the 38 infants, 12 (31.6%) exhibited abnormal lung function, including 9 (23.7%) with obstructive function and 3 (7.9%) with restrictive function. A significant association was noted between forced expiratory volume at 0.5 second <-2 z score and the acromion/xiphoid process/acromion angle (β = 4.935); forced vital capacity <-2 z score and the angle of the manubrium/left acromion/trapezium (β = 0.033) and forced expiratory volume at 0.5 second and forced vital capacity ratio <-2 z score and the inframammillary point/xiphoid process/inframammillary point angle (β = 0.043).

CONCLUSION

Preterm infants with very low birthweight presented a high frequency of abnormal lung function, particularly obstructive type and thoracic musculoskeletal abnormalities were associated with changes in lung function.

Predicting Lung Health Trajectories for Survivors of Preterm Birth

Rates of preterm birth (<37 weeks of gestation) are increasing worldwide. Improved perinatal care has markedly increased survival of very (<32 weeks gestation) and extremely (<28 weeks gestation) preterm infants, however, long term respiratory sequalae are common among survivors. Importantly, individual's lung function trajectories are determined early in life and tend to track over the life course. Preterm infants are impacted by antenatal, postnatal and early life perturbations to normal lung growth and development, potentially resulting in significant shifts from the "normal" lung function trajectory. This review summarizes what is currently known about the long-term lung function trajectories in survivors of preterm birth. Further, this review highlights how antenatal, perinatal and early life factors are likely to contribute to individual lung health trajectories across the life course.

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.

The etiologic origins for chronic obstructive pulmonary disease

COPD, characterized by long-term poorly irreversible airway limitation and persistent respiratory symptoms, has resulted in enormous challenges to human health worldwide, with increasing rates of prevalence, death, and disability. Although its origin was thought to be in the interactions of genetic with environmental factors, the effects of environmental factors on the disease during different life stages remain little known. Without clear mechanisms and radical cure for it, early screening and prevention of COPD seem to be important. In this review, we will discuss the etiologic origins for poor lung function and COPD caused by specific adverse effects during corresponding life stages, as well as try to find new insights and potential prevention strategies for this disease.

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.

Expiratory Flow - Vital Capacity: Airway - Lung Dysanapsis in 7 Year Olds Born Very Preterm?

An index normalizing airway dimension for lung size derived from spirometry was found inversely correlated to lung size in school children born very preterm, indicating larger alveolar volumes draining into comparatively smaller airways. In contrast in children born full term the index was independent of lung size.

How best to capture the respiratory consequences of prematurity?

Chronic respiratory morbidity is a common complication of premature birth, generally defined by the presence of bronchopulmonary dysplasia, both clinically and in trials of respiratory therapies. However, recent data have highlighted that bronchopulmonary dysplasia does not correlate with chronic respiratory morbidity in older children born preterm. Longitudinally evaluating pulmonary morbidity from early life through to childhood provides a more rational method of defining the continuum of chronic respiratory morbidity of prematurity, and offers new insights into the efficacy of neonatal respiratory interventions. The changing nature of preterm lung disease suggests that a multimodal approach using dynamic lung function assessment will be needed to assess the efficacy of a neonatal respiratory therapy and predict the long-term respiratory consequences of premature birth. Our aim is to review the literature regarding the long-term respiratory outcomes of neonatal respiratory strategies, the difficulties of assessing dynamic lung function in infants, and potential new solutions.

Better measures are needed to predict chronic respiratory morbidity in survivors born prematurely http://ow.ly/1L3n30ihq9C

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.

Bronchopulmonary dysplasia: clinical aspects and preventive and therapeutic strategies

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the result of a complex process in which several prenatal and/or postnatal factors interfere with lower respiratory tract development, leading to a severe, lifelong disease. In this review, what is presently known regarding BPD pathogenesis, its impact on long-term pulmonary morbidity and mortality and the available preventive and therapeutic strategies are discussed.

MAIN BODY

Bronchopulmonary dysplasia is associated with persistent lung impairment later in life, significantly impacting health services because subjects with BPD have, in most cases, frequent respiratory diseases and reductions in quality of life and life expectancy. Prematurity per se is associated with an increased risk of long-term lung problems. However, in children with BPD, impairment of pulmonary structures and function is even greater, although the characterization of long-term outcomes of BPD is difficult because the adults presently available to study have received outdated treatment. Prenatal and postnatal preventive measures are extremely important to reduce the risk of BPD.

CONCLUSION

Bronchopulmonary dysplasia is a respiratory condition that presently occurs in preterm neonates and can lead to chronic respiratory problems. Although knowledge about BPD pathogenesis has significantly increased in recent years, not all of the mechanisms that lead to lung damage are completely understood, which explains why therapeutic approaches that are theoretically effective have been only partly satisfactory or useless and, in some cases, potentially negative. However, prevention of prematurity, systematic use of nonaggressive ventilator measures, avoiding supraphysiologic oxygen exposure and administration of surfactant, caffeine and vitamin A can significantly reduce the risk of BPD development. Cell therapy is the most fascinating new measure to address the lung damage due to BPD. It is desirable that ongoing studies yield positive results to definitively solve a major clinical, social and economic problem.

Pulmonary function in former very low birth weight preterm infants in the first year of life

BACKGROUND

Pulmonary function in former preterm infants may be compromised during childhood.

OBJECTIVES

To assess pulmonary function in very-low-birth-weight preterm infants at 6-12 months of corrected age and analyze the factors associated with abnormal pulmonary function.

METHODS

Cross-sectional study with preterm infants at 6-12 months of corrected age with birth weight <1500 g. Children with malformations or affected by neuromuscular and respiratory diseases were excluded. Forced expiratory flows were assessed using the chest compression technique, and volumes were measured by total body plethysmography. Pulmonary function parameters in preterm infants were compared to a control group of same-aged children born at term.

RESULTS

We studied 51 preterm and 37 infants born at term. Preterm infants had: gestational age at birth (30.0 ± 2.5 weeks), birth weight (1179 ± 247 g), 27.5% had bronchopulmonary dysplasia, and 45% received mechanical ventilation. Preterm infants had lower median z-scores in comparison to term infants for the following parameters (p < 0.05): FVC (-0.3 vs. 0.7), FEV_0.5 (-0.5 vs. 0.9), FEV_0.5/FVC (-0.6 vs. -0.5), FEF₅₀ (-0.4 vs. 0.9), FEF₇₅ (-0.3 vs. 0.8), FEF₈₅ (-0.1 vs. 0.6) and FEF_25-75 (-0.5 vs. 1.1). No term child had abnormal lung function, compared to 39.2% of preterm infants (p = 0.001). Factors associated with abnormal pulmonary function were lower gestational age at birth, small for gestational age, need for mechanical ventilation and presence of recurrent wheezing.

CONCLUSIONS

Preterms had a high prevalence of abnormal pulmonary function and lower pulmonary function in comparison to term infants. Prematurity, intrauterine growth restriction, respiratory support and recurrent wheezing were associated with abnormal pulmonary function.

Ventilation in Extremely Preterm Infants and Respiratory Function at 8 Years

BACKGROUND

Assisted ventilation for extremely preterm infants (<28 weeks of gestation) has become less invasive, but it is unclear whether such developments in care are associated with improvements in short-term or long-term lung function. We compared changes over time in the use of assisted ventilation and oxygen therapy during the newborn period and in lung function at 8 years of age in children whose birth was extremely premature.

METHODS

We conducted longitudinal follow-up of all survivors of extremely preterm birth who were born in Victoria, Australia, in three periods - the years 1991 and 1992 (225 infants), 1997 (151 infants), and 2005 (170 infants). Perinatal data were collected prospectively, including data on the duration and type of assisted ventilation provided, the duration of oxygen therapy, and oxygen requirements at 36 weeks of age. Expiratory airflow was measured at 8 years of age, and values were converted to z scores for age, height, ethnic group, and sex.

RESULTS

The duration of assisted ventilation rose substantially over time, with a large increase in the duration of nasal continuous positive airway pressure. Despite the increase in the use of less invasive ventilation over time, the duration of oxygen therapy and the rate of oxygen dependence at 36 weeks rose, and airflows at 8 years of age were worse in 2005 than in earlier periods. For instance, for 2005 versus 1991-1992, the mean difference in the z scores for the ratio of forced expiratory volume in 1 second to forced vital capacity was -0.75 (95% confidence interval [CI], -1.07 to -0.44; P<0.001), and for 2005 versus 1997 the mean difference was -0.53 (95% CI, -0.86 to -0.19; P=0.002).

CONCLUSIONS

Despite substantial increases in the use of less invasive ventilation after birth, there was no significant decline in oxygen dependence at 36 weeks and no significant improvement in lung function in childhood over time. (Funded by the National Health and Medical Research Council of Australia and the Victorian Government's Operational Infrastructure Support Program.).

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.

Mid-childhood lung function in a cohort of children with "new bronchopulmonary dysplasia"

OBJECTIVE

Recent advances in perinatal care and neonatal respiratory therapy have led to a new phenotype of bronchopulmonary dysplasia ("new BPD"). The long-term respiratory outcome of this new form of BPD has yet to be adequately described. Aim of this study was to provide longitudinal data on lung function of an unselected cohort of children born extremely premature (EP) with an extremely low birth weight in the post-surfactant era.

STUDY DESIGN

Respiratory function was assessed twice (at 8 and 12 years) in 48 children born at a gestational age <28 weeks with a birth weight <1,000 g. Twenty-eight of them had BPD (oxygen-dependency at 36 weeks postmenstrual age) (EP-BPD), and 20 not (EP non-BPD). Twenty-seven children born at term served as control group.

RESULTS

The EP-BPD group had significantly lower spirometric values (given as z-scores) than controls, especially in parameters indicating airflow obstruction (8 ys: zFEV1:-1.3 ± 1 vs. 0.5 ± 0.8; 12 ys:-1.6 ± 1 vs. 0.5 ± 0.8, P < 0.001). Despite their better spirometric profile, EP-non-BPD children also had significantly lower parameters than controls (8ys: zFEV1:-0.5 ± 0.8; 12 ys:-0.5 ± 0.9, P < 0.001). During the 4-year follow-up, EP-non-BPD and controls had stable mean z-scores, but EP-BPD had a significant decline in mean zFEV1 (from -1.3 ± 1 to -1.6 ± 1, P = 0.03), zFEV1/FVC (from -0.4 ± 1 to -1.1 ± 1, P = 0.008), and zFEF 25-75% (from -1.2 ± 1 to -1.8 ± 1, P = 0.03).

CONCLUSION

EP children born in the post-surfactant era showed a significant airflow limitation, particularly pronounced in BPD subjects who in addition, presented an abnormal airway growth trajectory with a decline in lung function between the ages of 8 and 12 years. Pediatr Pulmonol. 2016;51:1057-1064. © 2016 Wiley Periodicals, Inc.

Altered breathing mechanics and ventilatory response during exercise in children born extremely preterm

Background

Extreme preterm birth confers risk of long-term impairments in lung function and exercise capacity. There are limited data on the factors contributing to exercise limitation following extreme preterm birth. This study examined respiratory mechanics and ventilatory response during exercise in a large cohort of children born extremely preterm (EP).

Methods

This cohort study included children 8–12 years of age who were born EP (≤28 weeks gestation) between 1997 and 2004 and treated in a large regionalised neonatal intensive care unit in western Canada. EP children were divided into no/mild bronchopulmonary dysplasia (BPD) (ie, supplementary oxygen or ventilation ceased before 36 weeks gestational age; n=53) and moderate/severe BPD (ie, continued supplementary oxygen or ventilation at 36 weeks gestational age; n=50). Age-matched control children (n=65) were born at full term. All children attempted lung function and cardiopulmonary exercise testing measurements.

Results

Compared with control children, EP children had lower airway flows and diffusion capacity but preserved total lung capacity. Children with moderate/severe BPD had evidence of gas trapping relative to other groups. The mean difference in exercise capacity (as measured by oxygen uptake (VO₂)% predicted) in children with moderate/severe BPD was −18±5% and −14±5.0% below children with no/mild BPD and control children, respectively. Children with moderate/severe BPD demonstrated a potentiated ventilatory response and greater prevalence of expiratory flow limitation during exercise compared with other groups. Resting lung function did not correlate with exercise capacity.

Conclusions

Expiratory flow limitation and an exaggerated ventilatory response contribute to respiratory limitation to exercise in children born EP with moderate/severe BPD.

Association between clinical variables related to asthma in schoolchildren born with very low birth weight with and without bronchopulmonary dysplasia

OBJECTIVE

to assess the prevalence, spirometry findings and risk factors for asthma in schoolchildren who were very low birth weight infants with and without bronchopulmonary dysplasia.

METHODS

Observational and cross-sectional study. The parents and/or tutors answered the International Study of Asthma and Allergies in Childhood questionnaire. The schoolchildren were submitted to the skin prick test and spirometry assessment.

RESULTS

54 schoolchildren who were very low birth weight infants were assessed and 43 met the criteria for spirometry. Age at the assessment (bronchopulmonary dysplasia=9.5±0.85; without bronchopulmonary dysplasia=10.1±0.86 years) and birth weight (bronchopulmonary dysplasia=916.7±251.2; without bronchopulmonary dysplasia=1,171.3±190.5g) were lower in the group with bronchopulmonary dysplasia (p<0.05). The prevalence of asthma among very low birth weight infants was 17/54 (31.5%), being 6/18 (33.3%) in the group with bronchopulmonary dysplasia. There was an association between wool blanket use in the first year of life (p=0.026) with the presence of asthma at school age. The skin prick test was positive in 13/17 (76.5%) and 23/37 (62.2%) of patients with and without asthma, respectively. The schoolchildren with asthma had lower z-score values of forced expiratory flow between 25% and 75% of forced vital capacity (n=16; -1.04±1.19) when compared to the group of patients without asthma (n=27; -0.38±0.93) (p=0.049). There was no difference between the spirometry variables in the groups regarding the presence or absence of bronchopulmonary dysplasia.

CONCLUSIONS

Very low birth weight infants with and without bronchopulmonary dysplasia showed a high prevalence of asthma (33.3% and 30.6%, respectively). Pulmonary flow in the small airways was lower in children with asthma.

Children Born Preterm at the Turn of the Millennium Had Better Lung Function Than Children Born Similarly Preterm in the Early 1990s

Objective

Compare respiratory health in children born extremely preterm (EP) or with extremely low birthweight (ELBW) nearly one decade apart, hypothesizing that better perinatal management has led to better outcome.

Design

Fifty-seven (93%) of 61 eligible 11-year old children born in Western Norway in 1999–2000 with gestational age (GA) <28 weeks or birthweight <1000 gram (EP_1999–2000) and matched term-controls were assessed with comprehensive lung function tests and standardized questionnaires. Outcome was compared with data obtained at 10 years of age from all (n = 35) subjects born at GA <29 weeks or birthweight <1001 gram within a part of the same region in 1991–92 (EP_1991–1992) and their matched term-controls.

Results

EP_1999–2000 had significantly reduced forced expiratory flow in 1 second (FEV₁), FEV₁ to forced vital capacity (FEV₁/FVC) and forced expiratory flow between 25–75% of FVC (FEF_25–75), with z-scores respectively -0.34, -0.50 and -0.61 below those of the term-control group, and more bronchial hyperresponsiveness to methacholine (dose-response-slope 13.2 vs. 3.5; p<0.001), whereas other outcomes did not differ. Low birthweight z-scores, but not neonatal bronchopulmonary dysplasia (BPD) or low GA, predicted poor outcome. For children with neonatal BPD, important lung-function variables were better in EP_1999–2000 compared to EP_1991–1992. In regression models, improvements were related to more use of antenatal corticosteroids and surfactant treatment in the EP_1999–2000.

Conclusions

Small airway obstruction and bronchial hyperresponsiveness were still present in children born preterm in 1999–2000, but outcome was better than for children born similarly preterm in 1991–92, particularly after neonatal BPD. The findings suggest that better neonatal management not only improves survival, but also long-term pulmonary outcome.

Adult respiratory outcomes of extreme preterm birth. A regional cohort study

RATIONALE

Lifetime respiratory function after extremely preterm birth (gestational age≤28 wk or birth weight≤1,000 g) is unknown.

OBJECTIVES

To compare changes from 18-25 years of age in respiratory health, lung function, and airway responsiveness in young adults born extremely prematurely to that of term-born control subjects.

METHODS

Comprehensive lung function investigations and interviews were conducted in a population-based sample of 25-year-old subjects born extremely prematurely in western Norway in 1982-1985, and in matched term-born control subjects. Comparison was made to similar data collected at 18 years of age.

MEASUREMENTS AND MAIN RESULTS

At 25 years of age, 46/51 (90%) eligible subjects born extremely prematurely and 39/46 (85%) control subjects participated. z-Scores for FEV1, forced expiratory flow at 25-75% of vital capacity, and FEV1/FVC were significantly reduced in subjects born extremely prematurely by 1.02, 1.26, and 0.88, respectively, and airway resistance (kPa/L/s) was increased (0.23 versus 0.18). Residual volume to total lung capacity increased with severity of neonatal bronchopulmonary dysplasia. Responsiveness to methacholine (dose-response slope; 3.16 versus 0.85) and bronchial lability index (7.5 versus 4.8%) were increased in subjects born extremely prematurely. Lung function changes from 18 to 25 years and respiratory symptoms were similar in the prematurely born and term-born groups.

CONCLUSIONS

Lung function in early adult life was in the normal range in the majority of subjects born extremely prematurely, but methacholine responsiveness was more pronounced than in term-born young adults, suggesting a need for ongoing pulmonary monitoring in this population.

New BPD predicts lung function at school age: Follow-up study and meta-analysis

New treatment practices have improved survival of preterm infants and decreased airway pathology in bronchopulmonary dysplasia (BPD). Our aim was to investigate whether preterm birth, BPD, and the severity of BPD predict lung function in school children that are born in surfactant era. We studied pulmonary function of 88 school-aged children born very preterm (gestational age <32 weeks) and paired them with 88 age- and sex-matched controls born at term. Spirometry and diffusion capacity were recorded. We also performed a meta-analysis covering the era of antenatal corticosteroid and surfactant treatment. BPD was defined as oxygen dependence for ≥ 28 days and it was severity-graded by oxygen requirement at 36 weeks postmenstrual age (mild, none; moderate, FiO2 = 0.22-0.29; severe, FiO2 ≥ 0.30). Preterm children had lower forced expiratory volume in 1 sec (FEV1 ) 86.4 ± 11.8 versus 94.9 ± 10.1 (mean % predicted ± SD; P < 0.001), and lower diffusion capacity (DLCO) 87.6 ± 13.9 versus 93.7 ± 12.0 (P = 0.005) compared with term controls. BPD group differed in both FEV1 (P = 0.037) and DLCO (P = 0.018) from those without BPD. For meta-analysis, search identified 210 articles. Together with present results, six articles met the inclusion criteria. FEV1 of no BPD, all BPD, and moderate to severe BPD groups differed from that in term controls by -7.4, -10.5, and -17.8%, respectively. According to meta-analysis and follow-up study, the adverse effects of prematurity on pulmonary function are still detectable in school-age. BPD was associated with reductions in both diffusion capacity and spirometry. New interventions are required to document a further decrease in the life-long consequences of prematurity.

Functional evidence for continued alveolarisation in former preterms at school age?

Prematurity is the most common disruptor of lung development. The aim of our study was to examine the function of the more vulnerable peripheral airways in former preterm children by multiple-breath washout (MBW) measurements.86 school-aged children, born between 24 and 35 weeks of gestation and 49 term-born children performed nitrogen MBW. Lung clearance index (LCI), and slope III-derived Scond and Sacin were assessed as markers for global, convection-dependent and diffusion-convection-dependent ventilation inhomogeneity, respectively.We analysed the data of 77 former preterm (mean (range) age 9.5 (7.2-12.8) years) and 46 term-born children (mean age 9.9 (6.0-15.9) years). LCI and Sacin did not differ between preterm and term-born children. Scond was significantly elevated in preterm compared to term-born participants (mean difference z-score 1.74, 95% CI 1.17-2.30; p<0.001), with 54% of former preterm children showing elevated Scond. In multivariable regression analysis Scond was significantly related only to gestational age (R(2)=0.37).Normal Sacin provides evidence for a functionally normal alveolar compartment, while elevated Scond indicates impaired function of more proximal conducting airways. Together, our findings support the concept of continued alveolarisation, albeit with "dysanaptic" lung growth in former preterm children.

Understanding the Short- and Long-Term Respiratory Outcomes of Prematurity and Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease associated with premature birth that primarily affects infants born at less than 28 weeks' gestational age. BPD is the most common serious complication experienced by premature infants, with more than 8,000 newly diagnosed infants annually in the United States alone. In light of the increasing numbers of preterm survivors with BPD, improving the current state of knowledge of long-term respiratory morbidity for infants with BPD is a priority. We undertook a comprehensive review of the published literature to analyze and consolidate current knowledge of the effects of BPD that are recognized at specific stages of life, including infancy, childhood, and adulthood. In this review, we discuss both the short-term and long-term respiratory outcomes of individuals diagnosed as infants with the disease and highlight the gaps in knowledge needed to improve early and lifelong management of these patients.

Risk of respiratory syncytial virus infection in preterm infants: reviewing the need for prevention

Premature infants are at substantial risk for a spectrum of morbidities that are gestational age dependent. Respiratory syncytial virus (RSV) infection is most common in the first two years of life with the highest burden in children aged <6 months. Preterm infants ≤35 weeks' gestation are handicapped by incomplete immunological and pulmonary maturation and immature premorbid lung function with the added risk of bronchopulmonary dysplasia. Superimposed RSV infection incites marked neutrophilic airway inflammation and innate immunological responses that further compromise normal airway modeling. This review addresses the epidemiology and burden of RSV disease, focusing on the preterm population. Risk factors that determine RSV-disease severity and hospitalization and the impact on healthcare resource utilization and potential long-term respiratory sequelae are discussed. The importance of disease prevention and the evidence-based rationale for prophylaxis with palivizumab is explored, while awaiting the development of a universal vaccine.

Lung function in adult survivors of very low birth weight, with and without bronchopulmonary dysplasia

INTRODUCTION

The lung function outcome of cohorts of very low birth weight (VLBW; birth weight <1501 g) survivors born in the late 1970s or early 1980s into adulthood at an age when lung growth would be expected to have ceased is not well described. The aim of this study was to report lung function data in adulthood of VLBW survivors compared with normal birth weight controls (>2499 g), and in those who had bronchopulmonary dysplasia (BPD) compared with those without BPD.

MATERIALS AND METHODS

Spirometry and lung volumes were measured according to standard guidelines when subjects were in their mid-20s; there were 47 survivors of birth weight <1000 g, 40 of birth weight 1000-1500 g, and 20 controls of birth weight >2499 g. Results were converted to z-scores.

RESULTS

Both subgroups with birth weight <1501 g had significant reductions in airflow compared with controls, but not compared with each other. There were no significant differences between groups in variables reflecting air trapping. Within the VLBW cohort, those with BPD (n = 24) had reductions in airflow, including the z-score for the forced expired volume in 1 sec (FEV1 ), compared with those without BPD (n = 63). Within the VLBW cohort, there were positive relationships between FEV1 measurements earlier in childhood with those obtained at 25 years of age; these relationships were stronger in those who had BPD in the newborn period, and increased over time.

CONCLUSIONS

VLBW survivors continue to have airways obstruction in their mid-20s compared with controls, particularly those who had BPD in the newborn period.

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

OBJECTIVE

To assess lung function at 8 years old in extremely low birthweight (ELBW) survivors and to identify perinatal determinants associated with impaired lung function.

DESIGN

Retrospective cohort study.

SETTING

Level III neonatal intensive care unit.

PATIENTS

ELBW survivors born in 1990-2004 with available spirometry at 8 years old were studied. Children were excluded if they had a Wechsler Intelligence Scale for Children Third Edition full IQ <70.

MAIN OUTCOME MEASURES

Multivariate logistic regression analysis was used to identify perinatal determinants associated with airway obstruction (forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <80%) at school age and the predictive power of potential determinants. Potential risk factors and predictors assessed in this study were gestational age, birth weight, small for gestational age, sex, chorioamnionitis, premature rupture of membranes, antenatal steroids, surfactant administration, respiratory distress syndrome, postnatal steroids, severe bronchopulmonary dysplasia and bubbly/cystic appearances of the lungs by X-ray during the neonatal period.

RESULTS

Of 656 ELBW survivors, 301 (45.9%) had attended a school-age follow-up at 8 years old. A total of 201 eligible children completed the lung function test. Bubbly/cystic appearance of the lungs (OR 4.84, 95% CI 1.26 to 18.70) was associated with a low FEV1/FVC ratio. Children with bubbly/cystic appearance had characteristics of immaturity and intrauterine inflammation.

CONCLUSIONS

Within a cohort of ELBW infants, a bubbly/cystic appearance of the lungs in the neonatal period was the strongest determinant of a low FEV1/FVC ratio at school age.

How "healthy" should children be when selecting reference samples for spirometry?

How "healthy" do children need to be when selecting reference samples for spirometry? Anthropometry and spirometry were measured in an unselected, multi-ethnic population of school children aged 5-11 years in London, UK, with follow-up assessments 12 months later. Parents provided information on children's birth data and health status. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were adjusted for sex, age, height and ethnicity using the 2012 Global Lungs Initiative equations, and the effects of potential exclusion criteria on the z-score distributions were examined. After exclusions for current and chronic lung disease, acceptable data were available for 1901 children on 2767 occasions. Healthy children were defined as those without prior asthma or hospitalisation for respiratory problems, who were born at full-term with a birthweight ≥2.5 kg and who were asymptomatic at testing. Mean±sd z-scores for FEV1 and FVC approximated 0±1, indicating the 2012 Global Lungs Initiative equations were appropriate for this healthy population. However, if children born preterm or with low birthweight, children with prior asthma or children mildly symptomatic at testing were included in the reference, overall results were similar to those for healthy children, while increasing the sample size by 25%. With the exception of clear-cut factors, such as current and chronic respiratory disease, paediatric reference samples for spirometry can be relatively inclusive and hence more generalisable to the target population.

Early-life origins of chronic respiratory diseases: understanding and promoting healthy ageing

Chronic obstructive respiratory disorders such as asthma and chronic obstructive pulmonary disease often originate early in life. In addition to a genetic predisposition, prenatal and early-life environmental exposures have a persistent impact on respiratory health. Acting during a critical phase of lung development, these factors may change lung structure and metabolism, and may induce maladaptive responses to harmful agents, which will affect the whole lifespan. Some environmental factors, such as exposure to cigarette smoke, type of childbirth and diet, may be modifiable, but it is more difficult to influence other factors, such as preterm birth and early exposure to viruses or allergens. Here, we bring together recent literature to analyse the critical aspects involved in the early stages of lung development, going back to prenatal and perinatal events, and we discuss the mechanisms by which noxious factors encountered early on may have a lifelong impact on respiratory health. We briefly comment on the need for early disease biomarkers and on the possible role of "-omic" technologies in identifying risk profiles predictive of chronic respiratory conditions. Such profiles could guide the ideation of effective preventive strategies and/or targeted early lifestyle or therapeutic interventions.

Persisting hypoxaemia is an insufficient measure of adverse lung function in very immature infants

BACKGROUND

Bronchopulmonary dysplasia (BPD), defined as protracted neonatal hypoxaemia, is considered a risk factor for respiratory disease in adulthood. The relationship between this diagnosis and the actual lung injury appearing in very immature infants is, however, unknown.

OBJECTIVES

To compare lung function at term in very immature infants and full-term infants, and to determine how degree and duration of neonatal hypoxaemia are related to other aspects of lung function.

DESIGN AND METHODS

All surviving, consecutive infants with gestational age below 28 weeks from a geographically defined area were eligible. The alveolar-arterial oxygen pressure difference was assessed as a measure of oxygenation failure. At term, functional residual capacity and gas-mixing efficiency were measured by multiple-breath nitrogen washout, and compliance and conductance of the respiratory system by the occlusion method. The results were compared to those in 50 full-term controls.

MAIN RESULTS

Thirty-seven of 46 eligible infants were included. The preterm infants differed markedly from the full-term infants in all lung functions tested. Infants diagnosed as having BPD had more compromised lung function than those without, but the latter group differed markedly from the full-term group in functional residual capacity, compliance and gas-mixing efficiency. Only the mechanical variables were correlated to hypoxaemia at 36 weeks postmenstrual age (PMA).

CONCLUSIONS

Infants with gestational age below 28 weeks at birth have remarkably impaired lung function at term, regardless of whether they carry the diagnosis BPD or not. All very immature infants may be at risk of future respiratory disease and should be monitored appropriately.

How to avoid misinterpreting lung function tests in children: a few practical tips

Assessments of pulmonary function play an integral part in the clinical management of school age children as well as providing objective outcome measures in clinical and epidemiological research studies. Pulmonary function tests (PFTs) can also be undertaken in sleeping infants and in awake young children from 3 years of age. However, the clinical utility of such assessments, which are generally confined to specialist centres, has yet to be established. Whether requesting or undertaking paediatric PFTs, or simply reading about how these tests have been applied in research studies, it is essential to question whether results have been interpreted in a meaningful way. This review summarises some of the issues that need to be considered, including: why the tests are being performed; which tests are most likely to detect the suspected pathophysiology; how often such tests should be repeated; whether results are likely to be reliable (in terms of data quality, repeatability and the availability of suitable reference equations with which to distinguish the effects of disease from those of growth and development), and whether the selected tests are likely to be feasible in the individual child or study group under investigation.

Respiratory outcomes for the tiniest or most immature infants

Extremely low birth weight (<1000 g birth weight) or extremely preterm (<28 weeks of gestation) infants are surviving in greater numbers as neonatal care advances. Many of these survivors, especially those who develop bronchopulmonary dysplasia, have more respiratory ill health in the first years after discharge home, reduced respiratory function and impaired exercise capacity throughout childhood and into adulthood compared with term-born controls. It is important to establish the long-term respiratory outcomes for the tiniest or most immature survivors as they grow older, since they may contribute disproportionately to rates of chronic obstructive pulmonary disease and respiratory ill-health in adulthood.

Epidemiology of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is among the most common and serious sequelae of preterm birth. BPD affects at least one-quarter of infants born with birth weights less than 1500 g. The incidence of BPD increases with decreasing gestational age and birth weight. Additional important risk factors include intrauterine growth restriction, sepsis, and prolonged exposure to mechanical ventilation and supplemental oxygen. The diagnosis of BPD predicts multiple adverse outcomes including chronic respiratory impairment and neurodevelopmental delay. This review summarizes the diagnostic criteria, incidence, risk factors, and long-term outcomes of BPD.

Bronchopulmonary dysplasia: the earliest and perhaps the longest lasting obstructive lung disease in humans

Bronchopulmonary dysplasia (BPD) is one of the most important sequelae of premature birth and the most common form of chronic lung disease of infancy. From a clinical standpoint BPD subjects are characterized by recurrent respiratory symptoms, which are very frequent during the first years of life and, although becoming less severe as children grow up, they remain more common than in term-born controls throughout childhood, adolescence and into adulthood. From a functional point of view BPD subjects show a significant airflow limitation that persists during adolescence and adulthood and they may experience an earlier and steeper decline in lung function during adulthood. Interestingly, patients born prematurely but not developing BPD usually fare better, but they too have airflow limitations during childhood and later on, suggesting that also prematurity per se has life-long detrimental effects on pulmonary function. For the time being, little is known about the presence and nature of pathological mechanisms underlying the clinical and functional picture presented by BPD survivors. Nonetheless, recent data suggest the presence of persistent neutrophilic airway inflammation and oxidative stress and it has been suggested that BPD may be sustained in the long term by inflammatory pathogenic mechanisms similar to those underlying COPD. This hypothesis is intriguing but more pathological data are needed. A better understanding of these pathogenetic mechanisms, in fact, may be able to orient the development of novel targeted therapies or prevention strategies to improve the overall respiratory health of BPD patients.