Cardiopulmonary exercise performance in prematurely born children

Cardiopulmonary Exercise Performance of Children Born Non-Extremely Preterm

Data on exercise tolerance of children born non-extremely preterm are sparse. We aimed to explore the cardiopulmonary exercise testing (CPET) characteristics in this population. We studied 63 children (age 7-12 years) born at 290/7-366/7 weeks of gestation (34 were late preterm, 29 were preterm) and 63 age-matched, term-born controls. All performed spirometry and CPET (cycle ergometry). There were no differences in activity levels and spirometric parameters between the group of preterm-born children and controls. A peak oxygen uptake (VO2peak) of <80% was noted in 25.4% of the term-born and 49.2% of preterm-born children (p = 0.001). Term-born participants presented similar VO2peak to late-preterm children but higher than those born at <340/7 weeks of gestation (p = 0.002). Ventilatory limitation was noted in 4.8% of term and 7.9% of preterm participants, while only one preterm child presented cardiovascular limitation. Children born before 34 weeks of gestation had higher respiratory rates and smaller tidal volumes at maximum exercise, as well as lower oxygen uptake for the level of generated work. We conclude that school-age children born at 29-34 weeks of gestation may present decreased exercise performance attributed to an altered ventilatory response to exercise and impaired O2 utilization by their skeletal muscles rather than other cardiopulmonary limiting factors.

Preterm birth and exercise capacity: what do we currently know?

Objectives

The long-term cardiopulmonary outcomes following preterm birth during the surfactant era remain unclear. Respiratory symptoms, particularly exertional symptoms, are common in preterm children. Therefore, cardiopulmonary exercise testing may provide insights into the pathophysiology driving exertional respiratory symptoms in those born preterm. This review aims to outline the current knowledge of cardiopulmonary exercise testing in the assessment of children born preterm in the surfactant era.

Design

This study is a narrative literature review.

Methods

Published manuscripts concerning the assessment of pulmonary outcomes using cardiopulmonary exercise testing in preterm children (aged <18 years) were reviewed. Search terms related to preterm birth, bronchopulmonary dysplasia, and exercise were entered into electronic databases, including Medline, PubMed, and Google Scholar. Reference lists from included studies were scanned for additional manuscripts.

Results

Preterm children have disrupted lung development with significant structural and functional lung disease and increased respiratory symptoms. The association between these (resting) assessments of respiratory health and exercise capacity is unclear; however, expiratory flow limitation and an altered ventilatory response (rapid, shallow breathing) are seen during exercise. Due to the heterogeneity of participants, treatments, and exercise protocols, the effect of the aforementioned limitations on exercise capacity in children born preterm is conflicting and poorly understood.

Conclusion

Risk factors for reduced exercise capacity in those born preterm remain poorly understood; however, utilizing cardiopulmonary exercise testing to its full potential, the pathophysiology of exercise limitation in survivors of preterm birth will enhance our understanding of the role exercise may play. The role of exercise interventions in mitigating the risk of chronic disease and premature death following preterm birth has yet to be fully realized and should be a focus of future robust randomized controlled trials.

Aerobic Exercise Training Response in Preterm-Born Young Adults with Elevated Blood Pressure and Stage 1 Hypertension: A Randomized Clinical Trial

Rationale: Premature birth is an independent predictor of long-term cardiovascular risk. Individuals affected are reported to have a lower rate of [Formula: see text]o2 at peak exercise intensity ([Formula: see text]o2PEAK) and at the ventilatory anaerobic threshold ([Formula: see text]o2VAT), but little is known about their response to exercise training. Objectives: The primary objective was to determine whether the [Formula: see text]o2PEAK response to exercise training differed between preterm-born and term-born individuals; the secondary objective was to quantify group differences in [Formula: see text]o2VAT response. Methods: Fifty-two preterm-born and 151 term-born participants were randomly assigned (1:1) to 16 weeks of aerobic exercise training (n = 102) or a control group (n = 101). Cardiopulmonary exercise tests were conducted before and after the intervention to measure [Formula: see text]o2PEAK and the [Formula: see text]o2VAT. A prespecified subgroup analysis was conducted by fitting an interaction term for preterm and term birth histories and exercise group allocation. Measurements and Main Results: For term-born participants, [Formula: see text]o2PEAK increased by 3.1 ml/kg/min (95% confidence interval [CI], 1.7 to 4.4), and the [Formula: see text]o2VAT increased by 2.3 ml/kg/min (95% CI, 0.7 to 3.8) in the intervention group versus controls. For preterm-born participants, [Formula: see text]o2PEAK increased by 1.8 ml/kg/min (95% CI, -0.4 to 3.9), and the [Formula: see text]o2VAT increased by 4.6 ml/kg/min (95% CI, 2.1 to 7.0) in the intervention group versus controls. No significant interaction was observed with birth history for [Formula: see text]o2PEAK (P = 0.32) or the [Formula: see text]o2VAT (P = 0.12). Conclusions: The training intervention led to significant improvements in [Formula: see text]o2PEAK and [Formula: see text]o2VAT, with no evidence of a statistically different response based on birth history. Clinical trial registered with www.clinicaltrials.gov (NCT02723552).

Growth, lung function, and physical activity in schoolchildren who were very-low-birth-weight preterm infants

Objective:

To compare somatic growth, lung function, and level of physical activity in schoolchildren who had been very-low-birth-weight preterm infants (VLBWPIs) or normal-birth-weight full-term infants.

Methods:

We recruited two groups of schoolchildren between 8 and 11 years of age residing in the study catchment area: those who had been VLBWPIs (birth weight < 1,500 g); and those who had been normal-birth-weight full-term infants (controls, birth weight ≥ 2,500 g). Anthropometric and spirometric data were collected from the schoolchildren, who also completed a questionnaire regarding their physical activity. In addition, data regarding the perinatal and neonatal period were collected from the medical records of the VLBWPIs.

Results:

Of the 93 schoolchildren screened, 48 and 45 were in the VLBWPI and control groups, respectively. No significant differences were found between the groups regarding anthropometric characteristics, nutritional status, or pulmonary function. No associations were found between perinatal/neonatal variables and lung function parameters in the VLBWPI group. Although the difference was not significant, the level of physical activity was slightly higher in the VLBWPI group than in the control group.

Conclusions:

Among the schoolchildren evaluated here, neither growth nor lung function appear to have been affected by prematurity birth weight, or level of physical activity.

[Respiratory outcome of bronchopulmonary dysplasia in school-age children]

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease of infancy. The influence of its initial severity on long-term respiratory outcome remains uncertain.

OBJECTIVES

The purpose of this study was to examine the impact of "new BPD" on respiratory morbidity as well as respiratory function at rest and during exercise in school-age children.

METHODS

The 93 preterm newborns (<33 weeks gestation) presenting with BPD between 1997 and 2004 at the Rennes University Hospital had been proposed for a specific follow-up program. The children included in this cohort and presenting without severe handicap or motor deficit were eligible for this observational retrospective study. Their standardized clinical evaluation and the results of the pulmonary function tests and cardiopulmonary exercise tests performed between the ages of 7 and 14 years were studied. BPD was considered to be moderate when respiratory or oxygen support continued at 36 weeks gestation with an FiO2 less than 30% and severe when FiO2 was greater than 30%.

RESULTS

Among the 36 children assessed, the initial severity of the BPD was mild in 12 cases, moderate in 12 cases, and severe in 12 cases. The mean age at the time of the pulmonary function test (PFT) was 9.9 (±1.9) years, 19 children (53%) had respiratory symptoms during the year before the test, and six (17%) underwent long-term treatment. The PFT was abnormal for 32 children (89%): 23 showed airway obstruction, 16 hyperinflation, three increases in bronchial reactivity, and two restrictions. The residual volume/total lung capacity ratio was the only parameter related to the severity of BPD (P<0.05). The cardiopulmonary exercise test was given to 35 children: 15 of them had normal exercise ability but with a limited ventilatory reserve.

CONCLUSIONS

Half of the children included in this "new-BPD" follow-up cohort had clinical respiratory morbidity and most of the children followed presented with persistent alterations in pulmonary function tests at school age, which were not associated with significant alterations in the maximum aerobic performance.

Effect of preterm birth on exercise capacity: A systematic review and meta-analysis

BACKGROUND

Survivors of preterm-birth have increased prevalence of respiratory, cardiovascular, and neurological diseases in later life however, the overall impact of prematurity on cardiorespiratory exercise capacity is unclear.

OBJECTIVE

We, therefore, systematically reviewed the literature on cardiorespiratory exercise capacity in survivors of preterm birth.

METHODOLOGY

Relevant studies up to March 2013 were searched using eight electronic health databases. Studies reporting exercise capacity in participants born preterm (<37 weeks) were included. The main outcome of interest was oxygen uptake (V˙O2max⁡) at maximal exercise. Data were categorized into four groups: (i) preterm-born subjects including those with or without bronchopulmonary dysplasia (BPD) but excluding study groups biased towards BPD; (ii) preterm-born subjects (BPD excluded); (iii) preterm-born subjects who had BPD28 (defined as oxygen dependency at 28 days of life) in infancy; (iv) preterm born subjects with BPD36 (oxygen dependency at 36 weeks post menstrual age) in infancy.

RESULTS

From 9,341 abstracts, 22 included publications reported V˙O2max⁡ in ml/kg/min from 685 preterm and 680 term-born subjects. Overall 20 studies reported results for preterm-born subjects including BPD; 14 studies for the preterm group excluding BPD; 10 studies for the BPD28 group; and 8 studies for BPD36 group. The mean differences (95% CI) for the four groups were -2.20 (-3.70, -0.70) ml/kg/min; -2.26 (-4.44, -0.07 ml/kg/min; -3.04 (-5.48, -0.61) ml/kg/min, and -3.05 (-5.93, -0.18) ml/kg/min, respectively.

CONCLUSION

Despite marked deficits in spirometry, preterm-born children have a marginally decreased V˙O2max⁡, which is unlikely to be of great clinical significance. Pediatr Pulmonol. 2015; 50:293-301. © 2014 Wiley Periodicals, Inc.

Fitness limitations in non-disabled extremely low birthweight adolescents

AIM

This study aims to compare non-disabled otherwise healthy extremely low birthweight (ELBW) (<1000 g) children and term-born peers in an investigation of relationship between cardiorespiratory endurance and parent report of competence.

METHODS

Forty-eight of 105 eligible ELBW 11- to 13-year-old children (27 male) and 55 term-born school peers (28 male) completed a 20-m shuttle run, anthropometric measures, respiratory function tests and the Motor Assessment Battery for Children. Parents completed the Child Behavior Checklist (CBCL).

RESULTS

The ELBW group had poorer cardiorespiratory endurance (P = 0.002), growth (P = 0.002), respiratory function (P = 0.003) and motor ability (P < 0.001) than term-born peers. Parents reported the ELBW children to be less competent than term-born peers: CBCL total T score mean difference -9, 95% confidence interval -14, -5 (P < 0.001). Cardiorespiratory endurance predicted competence (regression coefficient 0.865; 95% confidence interval 0.352, 1.378; P = 0.001) independent of prematurity, growth, respiratory function, motor score, gender and socio-economic status. Cardiorespiratory endurance had association with social competence for all participating children, but was related to CBCL Activities Competence only for the ELBW children who were the significantly less fit group.

CONCLUSIONS

The poor cardiorespiratory endurance prevalent in non-disabled otherwise healthy ELBW children is associated with general competence independent of prematurity and of the impact of other mild physical deficits, gender or socio-economic status. The relationship demonstrated between cardiorespiratory endurance and competence to engage in general activities of daily living, seen only in the less fit ELBW children, identifies the fitness levels in non-disabled ELBW children as a barrier to participation.

Long-term pulmonary outcomes of patients with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the commonest cause of chronic lung disease in infancy. The incidence of BPD has remained unchanged despite many advances in neonatal care. BPD starts in the neonatal period but its effects can persist long term. Premature infants with BPD have a greater incidence of hospitalization, and continue to have a greater respiratory morbidity and need for respiratory medications, compared to those without BPD. Lung function abnormalites, especially small airway abnormalities, often persist. Even in the absence of clinical symptoms, BPD survivors have persistent radiological abnormalities and presence of emphysema has been reported on chest computed tomography scans. Concern regarding their exercise tolerance remains. Long-term effects of BPD are still unknown, but given reports of a more rapid decline in lung function and their suspectibility to develop chronic obstructive pulmonary disease phenotype with aging, it is imperative that lung function of survivors of BPD be closely monitored.

Exercise-induced bronchoconstriction in school-aged children who had chronic lung disease in infancy

OBJECTIVES

To assess for exercise-induced bronchoconstriction in 8- to 12-year-old children who had chronic lung disease (CLD) in infancy, and to evaluate the response of bronchoconstriction to bronchodilation with albuterol in comparison with preterm and term controls.

STUDY DESIGN

Ninety-two children, including 29 with CLD, 33 born preterm at ≤32 weeks' gestation, and 30 born at term, underwent lung spirometry before and after cycle ergometry testing and after postexercise bronchodilation with albuterol.

RESULTS

Doctor-diagnosed asthma and exercise-induced wheeze were reported more frequently in the CLD group than in the preterm and term groups, but only 10% were receiving a bronchodilator. There were no differences among the groups in peak minute ventilation, oxygen uptake, or carbon dioxide output at maximum exercise. After maximal exercise, predicted forced expiratory volume in 1 second (FEV1) decreased from a mean baseline value of 81.9% (95% CI, 76.6-87.0%) to 70.8% (95% CI, 65.5-76.1%) after exercise in the CLD group, from 92.0% (95% CI, 87.2-96.8%) to 84.3% (95% CI, 79.1-89.4%) in the preterm group, and from 97.5% (95% CI, 92.5-102.6%) to 90.3% (95% CI, 85.1-95.5%) in the term group. After albuterol administration, FEV1 increased to 86.8% (95% CI, 81.7-92.0%) in the CLD group, 92.1% (95% CI, 87.3-96.9%) in the preterm group, and 97.1% (95% CI, 92.0-102.3%) in the term group. The decrease in predicted FEV1 after exercise and increase in predicted FEV1 after bronchodilator use were greatest in the CLD group (-11.0% [95% CI, -18.4 to -3.6%] and 16.0% [95% CI, 8.6-23.4%], respectively; P < .005 for both), with differences of <8% in the 2 control groups.

CONCLUSION

School-age children who had CLD in infancy had significant exercise-induced bronchoconstriction that responded significantly to bronchodilation. Reversible exercise-induced bronchoconstriction is common in children who experienced CLD in infancy and should be actively assessed for and treated.

Encouraging pulmonary outcome for surviving, neurologically intact, extremely premature infants in the postsurfactant era

OBJECTIVE

The aim of this study was to determine the long-term pulmonary outcome of extreme prematurity at a single tertiary-care center from 1997 to 2001 in the postsurfactant era.

METHODS

We assessed symptoms, exhaled nitric oxide, spirometry, methacholine challenge (provocative concentration of methacholine required to decrease FEV₁ by 20% [PC(20)]), lung volumes, diffusion, and cardiopulmonary exercise tolerance.

RESULTS

Of 279 infants born, 192 survived to discharge, and 79 of these developed bronchopulmonary dysplasia (BPD) (65 mild, 12 moderate, two severe). We studied a subgroup of 53 neurologically intact preterm subjects aged 10 ± 1.5 years (28 with BPD [born, 26.2 ± 1.4 weeks; birth weight, 821 ± 164 g] and 25 without BPD [born, 27.2 ± 1 weeks; birth weight, 1,050 ± 181 g]) and compared them with 23 term control subjects. Of the BPD cases, 21 were mild, seven were moderate, and none was severe; 77.4% of subjects received antenatal steroids, and 83% received postnatal surfactant. Sixty percent of the preterm subjects wheezed at age < 2 years compared with 13% of the control subjects (P < .001), but only 13% wheezed in the past year compared with 0% of control subjects (not significant). For preterm and control subjects, respectively (mean ± SD), FEV₁ % predicted was 85% ± 10% and 94% ± 10% (P < .001), with limited reversibility; residual volume/total lung capacity was 29.3% ± 5.5% and 25% ± 8% (P < .05); diffusing capacity/alveolar volume was 89.6% ± 9.2% and 97% ± 10% (P < .005); and PC(20) was 6.5 ± 5.8 mg/mL and 11.7 ± 5.5 mg/mL (P < .001). PC(20) was < 4 mg/mL in 49% of preterm subjects despite normal exhaled nitric oxide. Most measurements were similar in premature subjects with and without BPD. Peak oxygen consumption and breathing reserve were normal, but % predicted maximal load (measured in Watts) was 69% ± 15% for subjects with BPD compared with 88% ± 23% for subjects without and 86% ± 20% for control subjects (P < .01).

CONCLUSIONS

Pulmonary outcome was encouraging at mid-childhood for neurologically intact survivors in the postsurfactant era. Despite mechanical ventilation and oxygen therapy, most had no or mild BPD. Changes found probably reflect the hypoplastic lungs of prematurity.

Hyperventilation during exercise in very low birth weight school-age children may implicate inspiratory muscle weakness

OBJECTIVES

To study the ventilatory response during exercise in 8- to 10-year-old children born in 1998 to 2000 with a birthweight <1500 g (very low birthweight [VLBW]).

STUDY DESIGN

We studied 19 VLBW children and 20 full-term children paired for age and sex. A physical activity questionnaire was administered. Lean body mass, spirometry, and maximal inspiratory pressure were assessed at rest. Gas exchange, breathing pattern, and the tension-time index of the inspiratory muscles, a noninvasive indicator of inspiratory muscle effort, were evaluated during a continuous incremental cycling protocol.

RESULTS

VLBW children had lower weight, height, lean body mass, and maximal inspiratory pressure than control subjects. Their physical activity level was not different. During exercise, they had a higher respiratory rate and minute ventilation for the same metabolic level (VCO(2)/kg) and a higher tension-time index of the inspiratory muscles for the same exercise level (percentage of maximal oxygen consumption).

CONCLUSIONS

The lower inspiratory muscle strength observed in school-age VLBW children resulted in a higher inspiratory effort during incremental exercise. The rapid but not shallow breathing pattern adopted by this population during exercise may have been in response to their lower inspiratory muscle resistance to fatigue. VLBW children complaining of dyspnea should be investigated with exercise testing.

Lower conditioning leisure-time physical activity in young adults born preterm at very low birth weight

Background

Adults born preterm at very low birth weight (VLBW, <1500 g) have elevated levels of risk factors for cardiovascular diseases and type 2 diabetes. Preliminary observations suggest that this could partly be explained by lower rates of physical activity. The aim of this study was to assess physical activity in healthy young adults born preterm at very low birth weight compared with term-born controls.

Methodology/Principal Findings

We studied 94 unimpaired young adults, aged 21–29 years, born at VLBW and 101 age-, sex-, and birth hospital-matched term-born controls from one regional center in Southern Finland. The participants completed a validated 30-item 12-month physical activity questionnaire and the NEO-Personality Inventory based on the Big Five taxonomy, the most commonly used classification of personality traits. Yearly frequency, total time, total volume and energy expenditure of conditioning and non-conditioning leisure-time physical activity (LTPA) and commuting physical activity were compared between VLBW and term-born subjects. A subset of participants underwent dual-energy x-ray absorptiometry for body composition measurement. Data were analyzed by multiple linear regression. Compared with controls, VLBW participants had lower frequency [−38.5% (95% CI; −58.9, −7.7)], total time [−47.4% (95% CI; −71.2, −4.1)], total volume [−44.3% (95% CI; −65.8, −9.2)] and energy expenditure [−55.9% (95% CI; −78.6, −9.4)] of conditioning LTPA when adjusted for age, sex, body mass index, smoking, parental education and personality traits. Adjusting for lean body mass instead of body mass index attenuated the difference. There were no differences in non-conditioning LTPA or commuting physical activity.

Conclusions/Significance

Compared with term-born controls, unimpaired VLBW adults undertake less frequent LTPA with lower total time and volume of exercise resulting in lower energy expenditure. Differences in personality that exist between the VLBW and term-born groups do not seem to explain this association.

Aerobic capacity and exercise performance in young people born extremely preterm

OBJECTIVES

The goal of this study was to compare aerobic capacity and exercise performance of children and adolescents born extremely preterm and at term, and to relate findings to medical history and lifestyle factors. Potential cohort effects were assessed by studying subjects born in different decades.

METHODS

Two area-based cohorts of subjects born with gestational age ≤28 weeks or birth weight ≤1000 g in 1982-1985 and 1991-1992 and matched control subjects born at term were compared by using standardized maximal treadmill exercise and pulmonary function tests. Background data were collected from questionnaires and medical records.

RESULTS

Seventy-five of 86 eligible preterm subjects (87%) and 75 control subjects were assessed at mean ages of 17.6 years (n = 40 + 40) and 10.6 years (n = 35 + 35). At average, measures of aerobic capacity for subjects born preterm and at term were in the same range, whereas average running distance was modestly reduced for those born preterm. Leisure-time physical activity was similarly and positively associated with exercise capacity in preterm and term-born adolescents alike, although participation was lower among those born preterm. Neonatal bronchopulmonary dysplasia and current forced expiratory vol in 1 second was unrelated to exercise capacity. Differences between subjects born preterm and at term had not changed over the 2 decades studied.

CONCLUSION

Despite their high-risk start to life and a series of potential shortcomings, subjects born preterm may achieve normal exercise capacity, and their response to physical training seems comparable to peers born at term.

[Adult respiratory sequelae of premature birth]

INTRODUCTION

Between 5 and 7% of babies are born prematurely. In the paediatric age group, the respiratory morbidity of these patients is well known, particularly in cases of bronchopulmonary dysplasia (BPD). On the other hand, very few data are available concerning their adult respiratory status.

BACKGROUND

There are currently three different groups of ex-premature babies: (1) those with no BPD who are usually not considered as respiratory high-risk adults but have not been well studied; (2) ex-premature babies with BPD who have an increased risk of asthma, respiratory infections, bronchial obstruction aggravated by smoking, and non-atopic bronchial hyperreactivity; this group has been well studied but not beyond 30 years of age; (3) the babies born very prematurely and affected with a new form of BPD due to neonatal intensive care at a very immature stage of pulmonary development, and for whom the future in adult life is unknown but worrying because of reduced lung volumes since birth.

VIEWPOINTS AND CONCLUSIONS

The respiratory physician must be aware of these groups of adults who he may encounter and who may develop, sooner or later, a certain type of chronic obstructive pulmonary disease.

Respostas cardiopulmonares durante o esforço em crianças e adolescentes nascidas prematuras

OBJETIVO: Descrever as respostas cardiopulmonares durante o esforço em crianças e adolescentes nascidos prematuros. FONTES DE DADOS: Busca nas bases científicas em saúde SciELO, Lilacs e PubMed, utilizando-se os descritores: "pressão arterial", "capacidade física", "cardiovascular", "prematuro", "criança", adolescente", "função pulmonar", nos idiomas inglês e português. Foram selecionados artigos publicados nos últimos 20 anos. SÍNTESE DOS DADOS: Crianças e adolescentes com histórico de prematuridade apresentam sinais de obstrução das vias aéreas, menores valores de função pulmonar e de capacidade ao exercício, maior incidência de hipertensão arterial e/ou valores mais elevados da pressão arterial sistólica do que os nascidos a termo. Além disso, há indícios de que as alterações na resistência vascular sistêmica desde os primeiros dias de vida comprometam o desenvolvimento cardiovascular até a idade adulta, predispondo a maiores riscos cardiovasculares. CONCLUSÕES: O esforço físico nos indivíduos nascidos prematuros acarreta respostas cardiopulmonares diferentes dos nascidos a termo, atribuídas a particularidades no desenvolvimento desses sistemas inerentes ao prematuro.

Post-natal corticosteroids are associated with reduced expiratory flows in children born very preterm

AIM

Infants born very prematurely often received corticosteroids to minimise the risk of developing bronchopulmonary dysplasia (BPD) but their long term impact on lung function at school age is unclear.

METHODS

A cross-sectional study of 105 children [mean gestation of 27 weeks] was undertaken. Lung function assessments were conducted at a mean age of 10 years according to standard criteria. Corticosteroid dose was obtained from the medical record.

RESULTS

Spirometry in the BPD group was not significantly different to the non-BPD group, mean per-cent predicted (95% confidence interval) forced expiratory volume in 1 s (FEV1) 83% (79, 87) versus 86% (83, 90), FEF25%-75% 67% (60, 73) versus 75% (69, 81). Antenatal steroid treatment alone did not adversely affect airflow FEV1, 88% (84.92) versus 90% (82.97), and forced expiratory flow (FEF)25%-75%, 75% (69.81) versus 87% (70.104). Children who received post-natal corticosteroids had significantly lower flows than those who did not (FEV1 82% (78.85) vs. 88% (85.92), P = 0.006; FEF25%-75% 65% (59.71) vs. 78% (72.84), P = 0.003). Regression analysis revealed days on oxygen and days ventilated were statistically significant but weak predictors of airflow at 10 years of age.

CONCLUSIONS

A diagnosis of BPD did not predict reduced spirometry in middle childhood. Children who received post-natal corticosteroids as preterm infants had reduced expiratory flows compared with those who did not. While post-natal corticosteroids may be a marker of severity of lung disease, the potential of post-natal corticosteroids to influence lung development requires further investigation.

Preterm birth and respiratory disease in later life

Chronic respiratory diseases are a common complication of preterm birth, particularly among very immature infants or those suffering from bronchopulmonary dysplasia. Major progress in the treatment of preterm newborns has changed the pattern of late respiratory complications. The major respiratory problem in infancy and early childhood is respiratory exacerbations caused by infections (particularly viral ones), which need hospitalization. The symptoms become mild in school-age children; however, a group of children still present with chronic airway obstruction defined by recurrent episodes of wheezing and decreased lung function tests (decreased forced expiratory volume). For some preterm infants, particularly those with bronchopulmonary dysplasia, obstructive lung disease persists into adulthood. They are very likely to develop chronic obstructive pulmonary disease or similar disease later in life. In these patients, a program of lung function monitoring and pulmonary prophylaxis by means of elimination of specific risk factors in adulthood is advisable.

Aerobic fitness and physical activity levels of children born prematurely following randomization to postnatal dexamethasone

OBJECTIVE

To investigate the effects of postnatal dexamethasone treatment on aerobic fitness and physical activity levels in school-aged children born with very low birth weight (VLBW).

STUDY DESIGN

This was a follow-up study of 65 VLBW infants who participated in a randomized controlled trial of dexamethasone (DEX) to reduce ventilator dependency. Aerobic fitness was determined from peak oxygen uptake (VO(2peak)) with a cycle ergometer. Habitual physical activity was assessed by questionnaire.

RESULTS

A trend for a treatment with an interaction between treatment and of diagnosis of chronic lung disease (CLD) was found, with the children in the placebo group with CLD having the lowest VO(2peak) (P = .09). Reduced fitness was seen in 53% of the group treated with DEX and 48% of the group given placebo. No between-group differences in physical activity were seen. Parental reports suggested that nearly two-thirds of the children participated in < 1 hour per week of vigorous physical activity, which was explained in part by decreased large airway function (r = 0.30; P = .03).

CONCLUSIONS

We found no adverse effect of postnatal DEX on aerobic fitness or habitual physical activity at school age. However, the reduced fitness and physical activity levels emphasize the need for closer follow-up and early interventions promoting physical activity to reduce the risk of chronic disease in this at-risk population.

Review Series: What goes around, comes around: childhood influences on later lung health?: Long-term follow-up of infants with lung disease of prematurity

The incidence of live preterm birth is increasing and concomitantly the survival of preterm babies has increased over the last 30 years due to advances in neonatal care. Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease that develops as a consequence of perinatal and/or neonatal lung injury following preterm birth and the pathology has also changed with changes in neonatal care. There are data suggesting that there is increased respiratory morbidity of ex-preterm subjects in childhood. It is only now that large populations of preterm subjects are reaching adulthood and may be at risk of persistent respiratory morbidity. This review will summarize the current knowledge in adulthood of respiratory sequelae following preterm birth; specifically it will review respiratory symptoms, pulmonary function, exercise capacity and structural lung disease as determined by high resolution computed tomography scans in ex-preterm survivors with and without BPD. Whether prematurity-related lung disease is associated with chronic obstructive airways disease will be discussed.

Adults born at very low birth weight exercise less than their peers born at term

OBJECTIVE

To study the effects of very low birth weight (VLBW, <1500 g) birth on physical activity, an important protective and modifiable factor.

STUDY DESIGN

VLBW participants (n=163) with no major disability and 188 individuals born at term (mean age, 22.3 years; range, 18.5-27.1) completed a standardized questionnaire of physical activity.

RESULTS

VLBW participants reported less leisure-time conditioning physical activity. They were 1.61-fold more likely to "not exercise much," 1.61-fold more likely to exercise infrequently (once a week or less), 2.75-fold more likely to exercise with low intensity (walking), and 3.11-fold more likely to have short exercise sessions (<30 minutes). The differences were present even in subjects with no history of bronchopulmonary dysplasia or asthma and were only slightly attenuated when adjusted for height, parental education, lean body mass, and percent body fat.

CONCLUSIONS

Unimpaired adults who were VLBW exercise less during their leisure time than adults born at term. Promoting physical activity may be particularly important in the VLBW population to counteract the risks of chronic disease in adult life.

Exercise testing in children with lung diseases

Exercise is an important aspect of health and development in children. By placing the pulmonary system under stress, exercise testing may reveal subtle dynamic abnormalities that are not apparent on conventional static pulmonary function tests. Furthermore, exercise testing assesses the functional impact of respiratory disease on children. Exercise testing has been used in children with a variety of respiratory diseases such as exercise induced bronchoconstriction, asthma, cystic fibrosis and bronchopulmonary dysplasia to assess the severity of disease as well as response to various interventions. Furthermore, there is good evidence that exercise testing is a useful tool to help determine prognosis in patients with cystic fibrosis. In addition to the clinical utility, exercise testing is also becoming an increasingly important outcome measure in research studies.

Early oxygen uptake recovery following exercise testing in children with chronic chest diseases

The value of exercise testing as an objective measure of disease severity in patients with chronic chest diseases (CCD) is becoming increasingly recognized. The aim of this study was to investigate changes in oxygen uptake (VO2) during early recovery following maximal cardiopulmonary exercise testing (CPXT) in relation to functional capacity and markers of disease severity. Twenty-seven children with CCD (age 12.7 +/- 3.1 years; 17 female) [19 children with Cystic fibrosis (CF) (age 13.4 +/- 3.1 years; 10 female) and 8 with other stable non-CF chest diseases (NON-CF) (age 11.1 +/- 2.2 years; 7 female)] and 27 healthy controls (age 13.2 +/- 3.3 years; 17 female) underwent CPXT on a cycle ergometer. On-line respiratory gas analysis measured VO2 before and during CPXT to peak VO2) (VO2(peak)), and during the first 10 min of recovery. Early VO2 recovery was quantified by the time (sec) to reach 50% of the VO2 (peak) value. Early VO2 recovery was correlated against spirometry [forced expiratory volume in 1 sec (FEV(1)) and forced expiratory flow between 25% and 75% of the forced vital capacity (FEF(25-75))] and aerobic fitness (VO2)(peak)) as a measure of functional capacity. Disease severity was graded in the CF patients by the Shwachman score (SS). Compared to controls, children with CCD demonstrated a significantly reduced VO2(peak) (P = 0.011), FEV(1) (P < 0.001), FEF(25-75) (P < 0.001), and a significantly prolonged early (VO2) recovery (P = 0.024). In the CF patients the SS was significantly correlated with early VO2 recovery (r = -0.63, P = 0.004), FEV(1) (r = 0.72, P = 0.001), and FEF(25-75) (r = 0.57, P = 0.011). In the children with CCD, FEV(1), FEF(25-75), and BMI were not significantly correlated with VO2(peak) or early VO2 recovery. Lung function does not necessarily reflect aerobic fitness and the ability to recover from exercise in these patients. A significant relationship was found between VO2(peak) and early VO2 recovery (r = -0.39, P = 0.044) in the children with CCD, showing that a greater aerobic fitness corresponded with a faster recovery.

Effects of preterm birth and fetal growth retardation on cardiovascular risk factors in young adulthood

BACKGROUND

The association between low birth weight (LBW) and increased risk of obesity, hypertension and cardiovascular disease later in life is well documented in epidemiological studies. However, clinical follow-up studies of LBW populations have only partly supported this.

AIMS

Evaluate associations between LBW and body fat, blood pressure (BP), lung and endothelial function, and maximal oxygen uptake (VO(2max)) in 18 year old young adults.

SUBJECTS

Thirty-seven subjects born prematurely with birth weight <1501 g (VLBW group), 47 born at term with low weight (<10th centile) for gestational age (SGA group) and 63 controls with normal birth weight participated in the study.

OUTCOME MEASURES

Anthropometric measurements, BP, endothelial function, lung function and VO(2max) were recorded.

RESULTS

Both LBW groups were shorter, lighter, had smaller head circumference and higher subscapular-to-triceps skinfold-ratio than controls. Systolic and mean arterial BP was higher in the VLBW compared with the control group, whereas there were no differences between the groups in endothelial function. The VLBW group had reduced dynamic lung volumes lower carbon monoxide transfer factor and lower VO(2max) compared with controls. In particular young adults born VLBW who were also growth retarded in utero had higher indices of central body fat, higher BP and lower VO(2max).

CONCLUSION

We found that very preterm birth, but not growth retardation at term, was associated with higher BP and a less favourable fat distribution. In particular, the young adults born VLBW who were also growth retarded in utero had less favourable outcomes.

[Exercise alveolar hypoventilation in long-term survivors of bronchopulmonary dysplasia]

BACKGROUND

We aimed to confirm that children who have survived bronchopulmonary dysplasia (BPD) display lower ventilation during exercise than healthy children, and to determine whether alveolar hypoventilation associated with exercise-induced hypoxemia occurred in these children.

METHODS

Twenty children with BPD (birth weight 1441+/-523 g [mean +/- SD], gestational age 31+2.3 weeks), aged 7 to 14 years, and 18 matched healthy children, born at term, performed resting pulmonary function and cardiopulmonary incremental exercise tests. Arterialized capillary blood gases were measured at rest and at maximal exercise in the BPD group.

RESULTS

The BPD group showed moderate expiratory airflow limitation and hyperinflation. Maximal oxygen uptake and ventilatory threshold were similar in the two groups. The BPD group displayed ventilatory limitation on exercise, with greater use of the ventilatory reserve (p<0.01), lower maximal ventilation (p<0.01), tidal volume (p=0.01). Changes in ventilation (p<0.0001) and tidal volume (p=0.003) during exercise were significantly smaller in the BPD group than in controls, at similar submaximal workloads. At peak exercise, we observed hypoxemia in 12 BPD children (60%). In the subgroup with hypoxemia, a significant increase in PaCO2 (p=0.01) was measured at peak exercise, showing alveolar hypoventilation sustained by the lower tidal volume.

CONCLUSIONS

Despite normal maximal aerobic performance, BPD children showed ventilatory limitation on exercise, frequently with hypoxemia and alveolar hypoventilation. Despite an improvement in their pulmonary condition, continued follow-up by cardiopulmonary exercise testing, is strongly recommended.

Exercise testing and chronic lung diseases in children

Exercise activity is an important part of daily life for both healthy children and children with respiratory diseases. Overall fitness level and responses to exercise can be assessed through cardiopulmonary exercise tests (using a treadmill or a cycloergometer). In asthmatic children exercise tests are useful to diagnose exercise-induced bronchoconstriction, which may affect up to 80% of asthmatic subjects. In cystic fibrosis patient, as the disease progresses, lung function deteriorates and exercise tolerance likewise diminishes. This reduced tolerance may not be predicted on the base of a standard spirometry while an exercise test can offer useful information. Eventually, exercise testing is useful in children with bronchopulmonary dysplasia to determine any presence and extent of gas exchange and ventilation dysfunction during exercise. Exercise challenges are a valuable tool to assess exercise tolerance that may be not adequately reflected by resting lung function tests.

Pulmonary outcomes in bronchopulmonary dysplasia

The incidence of bronchopulmonary dysplasia (BPD), defined as oxygen need at 36 weeks of postmenstrual age, is about 30% for infants with birth weights <1000 g. BPD is associated with persistent structural changes in the lung that result in significant effects on lung mechanics, gas exchange, and pulmonary vasculature. Up to 50% of infants with BPD require readmission to the hospital for lower respiratory tract illness in the first year of life. Long-term measurements of lung function in BPD include normalization of pulmonary mechanics and some lung volumes over time as somatic and lung growth occur, whereas abnormality of small airway function persists. The majority of data reveals no long-term decrease in exercise capacity. Mild to moderate radiological abnormalities persist. BPD is a result of dynamic processes involving inflammation, injury, repair, and maturation. Infants with BPD have significant pulmonary sequelae during childhood and adolescence, and continued surveillance of young adults with BPD is critical.

Airway function measurements and the long-term follow-up of survivors of preterm birth with and without chronic lung disease

This seventh paper in a review series on different aspects of chronic lung disease following preterm birth focuses on the current knowledge of respiratory symptoms, airway function, airway hyperresponsiveness, and exercise capacity from childhood to adulthood. This paper further considers the long-term implications of these studies for both future research and clinical practice.

Long-term pulmonary sequelae in children who were treated with extracorporeal membrane oxygenation for neonatal respiratory failure

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for neonates with intractable respiratory failure, but the long-term pulmonary outcome is unknown. Our aim was to investigate the long-term pulmonary sequelae of these children.

STUDY DESIGN

We studied 50 children at 11.1 +/- 1.1 years (mean +/- SD) who had been treated with neonatal ECMO for meconium aspiration syndrome (38%), sepsis (18%), sepsis with pneumonia (12%), congenital diaphragmatic hernia (12%), congenital heart disease (8%), persistent pulmonary hypertension of the newborn (6%), and respiratory distress syndrome (4%) and 27 healthy controls (10.8 +/- 1.6 years). All subjects completed a respiratory questionnaire and performed pulmonary function and graded cardiopulmonary exercise testing.

RESULTS

Neonatal ECMO survivors had hyperinflation (median residual volume: 131%), airway obstruction (median forced expired volume in 1 second: 79%), lower oxygen saturation with exercise, and lower peak oxygen consumption than controls. The ECMO group achieved similar exercise minute ventilation to controls, with more rapid and shallow breathing. ECMO survivors had an increased frequency of exercise-induced bronchospasm. Those who required higher inspired oxygen tension and ventilator pressures after weaning from ECMO had lower forced expired volume in 1 second and oxygen saturation values.

CONCLUSION

Neonatal ECMO survivors experience lung injury lasting into later childhood. Lung dysfunction correlates with the extent and duration of barotrauma and oxygen exposure as neonates.

Cardiopulmonary outcome of neonatal extracorporeal membrane oxygenation at ages 10–15 years

OBJECTIVE

The purpose of this study was to evaluate the long-term cardiopulmonary outcome at ages 10-15 yrs following neonatal extracorporeal membrane oxygenation (ECMO). The specific aims of the study were to assess baseline aerobic capacity, cardiac function, and pulmonary function in neonatal ECMO survivors using graded exercise testing, echocardiography, and pulmonary function tests.

DESIGN

Cohort study.

SETTING

Exercise and pulmonary function laboratories of a large children's hospital.

PATIENTS

Seventeen 10- to 15-yr-old children treated with ECMO as neonates for meconium aspiration syndrome and 17 age-matched healthy controls.

INTERVENTIONS

Children were evaluated by use of physical exam, electrocardiogram, echocardiogram, treadmill stress test, and pulmonary function tests.

MEASUREMENTS AND MAIN RESULTS

Average weight, height, and age were similar between the groups. Both pre- and postexercise pulmonary function tests revealed air trapping and mild lower airway obstruction in the ECMO group, compared with mean pulmonary functions in the normal range for the control group. The mean forced expiratory volume in 1 sec, the forced expiratory flow between 25% and 75% of vital capacity, and the ratio between residual volume and total lung capacity were significantly different between the ECMO group and the control group. Although the ECMO group exhibited baseline and postexercise lung function abnormalities, there were no differences in maximal oxygen consumption between the two groups and all subjects reached anaerobic threshold. By regression analysis, the gestational age, duration of oxygen, and exercise score were significantly correlated with baseline lung function, using forced expiratory flow between 25% and 75% of vital capacity as the dependent variable.

CONCLUSIONS

Despite abnormalities in baseline and postexercise pulmonary functions, ECMO graduates have similar aerobic capacity to age-matched healthy controls. The most significant factor in predicting long-term pulmonary outcome in ECMO graduates is the duration of oxygen use following decannulation.

Head size and motor performance in children born prematurely

PURPOSE

The objective of this study was to determine the relationship between head circumference (HC) and motor performance in 6- to 12-yr-old children born prematurely (PRE: birthweight < or = 1500 g, gestational age < or = 32 wk) and in children born at term (CON).

METHODS

Thirty-three PRE and 21 CON without an apparent neurological deficit participated in this study. HC was measured on the day of testing and was rated as small HC (SHC, HC more than 1 SD below the 50th percentile of reference data) or as normal HC (NHC). Subjects were examined by an experienced neuropediatrician, and whole-body coordination was assessed by the Körper-Koordinationstest für Kinder (KTK). Peak exercise performance was determined by a Wingate test and an incremental cycling test to volitional fatigue. Net oxygen cost of cycling was measured during four different tasks lasting 5-7 min each. Subjects pedaled at an intensity corresponding to 30% and 60% of peak oxygen uptake ([OV0312]O(2peak)) at a cadence of 36 and 76 rpm, respectively.

RESULTS

Prematures with SHC showed no statistically significant difference in their neurological examination and whole-body coordination compared with prematures with NHC. Wingate test performance and [OV0312]O(2peak) relative to body mass were similar among SHC, NHC, and CON. In SHC, but not in NHC and CON, net oxygen cost of cycling increased significantly (P < 0.05) when cadence was increased from 36 to 76 rpm.

CONCLUSION

At the age of 6-12 yr, SHC have a higher oxygen cost of cycling in exercise tasks requiring high velocity, which might be explained-at least in part-by an impaired neural control of intra- and intermuscular coordination.

Discharge and aftercare in chronic lung disease of the newborn

This article deals with the discharge planning and continuing care of babies with chronic lung disease of the newborn (CLD), especially those with a continuing oxygen requirement, with some reference to longer term outcome. The pattern of CLD has changed since early descriptions, and the most useful definition for persisting morbidity in a baby with lung disease is a continuing oxygen requirement beyond 36 weeks post-menstrual age. Long-term oxygen therapy to maintain oxygen saturation at a mean of 95% or more and prevent levels below 90% is the cornerstone of management, and with adequate oxygen therapy the excess mortality previously reported in CLD can largely be avoided. Care must be given to the method of assessing oxygen saturation: overnight monitoring using appropriate recording devices is recommended. Exposure to respiratory viruses should be minimized where possible. Metabolic requirements are increased, but if efforts are made to maintain adequate energy input the long-term outlook for catch-up growth in height is good. Respiratory morbidity is increased in early life, but this improves in later childhood, along with lung function and exercise tolerance. Although respiratory symptoms should be treated as they arise, there is no evidence for long-term benefit from any pharmacological intervention in CLD.

Health-related fitness of seven- to 10-year-old children with histories of preterm birth

PURPOSE

The purpose of this study was to investigate health-related fitness and physical activity levels of seven-to 10-year-old children with histories of preterm birth.

METHODS

Twenty-two children, aged seven to 10 years, that were born five to 10 weeks preterm were recruited into the study and matched based on age, gender, race, and body mass index to control group subjects who were born full term. Components of health-related fitness, body composition, flexibility, muscular strength and endurance, cardiorespiratory endurance, and physical activity levels were examined.

RESULTS

No differences were found between the groups in total skinfold measures, flexibility, peak O2 consumption, or level of reported physical activity. There were significant differences in all subtests of the Bruininks-Oseretsky Test of Motor Proficiency (p < 0.001).

CONCLUSIONS

Although significant differences in motor proficiency were found by school age the children born preterm did not demonstrate activity limitations or participation restrictions. Physical therapists can advise parents of children born five to 10 weeks preterm that in all probability their school-age child will not be limited in sport team or physical activity involvement and can achieve expected levels of cardiovascular fitness.

Exercise and the child born prematurely

With the increase in survival rates of children born prematurely, issues related to their active pursuits and responses to exercise have been gaining increasing attention. In some preterm children with an extremely low birthweight, bronchopulmonary dysplasia or cerebral palsy exercise capacity may be limited, especially in tasks requiring good neuromotor coordination. Deficiencies in aerobic and anaerobic performance, strength and coordination may even occur in children without overt manifestations of a neuromuscular or pulmonary disease. However, as a rule, children born prematurely may engage in physical activities and competitive sports without limitations. Exercise is safe in almost all such children as long as precautions are taken to avoid exercise-induced bronchoconstriction. However, to date there are no studies that have determined the efficacy of training. A wide variety of activities should be encouraged in all children born prematurely at an early age, to support the development of skills and to compensate for the possible effects of their premature birth on coordination.