Bronchopulmonary dysplasia in the 1990s: a review for the pediatrician

Inhaled bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants and is associated with respiratory morbidity. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increased compliance and tidal volume, and decreased airway resistance, have been documented with the use of bronchodilators in infants with CLD. Therefore, bronchodilators are widely considered to have a role in the prevention and treatment of CLD, but there remains uncertainty as to whether they improve clinical outcomes. This is an update of the 2016 Cochrane review.

OBJECTIVES

To determine the effect of inhaled bronchodilators given as prophylaxis or as treatment for chronic lung disease (CLD) on mortality and other complications of preterm birth in infants at risk for or identified as having CLD.

SEARCH METHODS

An Information Specialist searched CENTRAL, MEDLINE, Embase, CINAHL and three trials registers from 2016 to May 2023. In addition, the review authors undertook reference checking, citation searching and contact with trial authors to identify additional studies.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials involving preterm infants less than 32 weeks old that compared bronchodilators to no intervention or placebo. CLD was defined as oxygen dependency at 28 days of life or at 36 weeks' postmenstrual age. Initiation of bronchodilator therapy for the prevention of CLD had to occur within two weeks of birth. Treatment of infants with CLD had to be initiated before discharge from the neonatal unit. The intervention had to include administration of a bronchodilator by nebulisation or metered dose inhaler. The comparator was no intervention or placebo.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Critical outcomes included: mortality within the trial period; CLD (defined as oxygen dependency at 28 days of life or at 36 weeks' postmenstrual age); adverse effects of bronchodilators, including hypokalaemia (low potassium levels in the blood), tachycardia, cardiac arrhythmia, tremor, hypertension and hyperglycaemia (high blood sugar); and pneumothorax. We used the GRADE approach to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included two randomised controlled trials in this review update. Only one trial provided useable outcome data. This trial was conducted in six neonatal intensive care units in France and Portugal, and involved 173 participants with a gestational age of less than 31 weeks. The infants in the intervention group received salbutamol for the prevention of CLD. The evidence suggests that salbutamol may result in little to no difference in mortality (risk ratio (RR) 1.08, 95% confidence interval (CI) 0.50 to 2.31; risk difference (RD) 0.01, 95% CI -0.09 to 0.11; low-certainty evidence) or CLD at 28 days (RR 1.03, 95% CI 0.78 to 1.37; RD 0.02, 95% CI -0.13 to 0.17; low-certainty evidence), when compared to placebo. The evidence is very uncertain about the effect of salbutamol on pneumothorax. The one trial with usable data reported that there were no relevant differences between groups, without providing the number of events (very low-certainty evidence). Investigators in this study did not report if side effects occurred. We found no eligible trials that evaluated the use of bronchodilator therapy for the treatment of infants with CLD. We identified no ongoing studies.

AUTHORS' CONCLUSIONS

Low-certainty evidence from one trial showed that inhaled bronchodilator prophylaxis may result in little or no difference in the incidence of mortality or CLD in preterm infants, when compared to placebo. The evidence is very uncertain about the effect of salbutamol on pneumothorax, and neither included study reported on the incidence of serious adverse effects. We identified no trials that studied the use of bronchodilator therapy for the treatment of CLD. Additional clinical trials are necessary to assess the role of bronchodilator agents in the prophylaxis or treatment of CLD. Researchers studying the effects of inhaled bronchodilators in preterm infants should include relevant clinical outcomes in addition to pulmonary mechanical outcomes.

Bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increased compliance and tidal volume and decreased pulmonary resistance have been documented with the use of bronchodilators in infants with CLD. Therefore, bronchodilators might have a role in the prevention and treatment of CLD.

OBJECTIVES

To determine the effect of bronchodilators given as prophylaxis or as treatment for CLD on mortality and other complications of preterm birth in infants at risk for or identified as having CLD.

SEARCH METHODS

On 2016 March 7, we used the standard strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (from 1966), Embase (from 1980) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; from 1982). We searched clinical trials databases, conference proceedings and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. We applied no language restrictions.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials involving preterm infants were eligible for inclusion. Initiation of bronchodilator therapy for prevention of CLD had to occur within two weeks of birth. Treatment of patients with CLD had to be initiated before discharge from the neonatal unit. The intervention had to include administration of a bronchodilator by nebulisation, by metered dose inhaler (with or without a spacer device) or by intravenous or oral administration versus placebo or no intervention. Eligible studies had to include at least one of the following predefined clinical outcomes: mortality, CLD, number of days on oxygen, number of days on ventilator, patent ductus arteriosus (PDA), pulmonary interstitial emphysema (PIE), pneumothorax, intraventricular haemorrhage (IVH) of any grade, necrotising enterocolitis (NEC), sepsis and adverse effects of bronchodilators.

DATA COLLECTION AND ANALYSIS

We used the standard method described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Two review authors extracted and assessed all data provided by each study. We reported risk ratio (RR), risk difference (RD) and number needed to treat for an additional beneficial outcome (NNTB) with 95% confidence interval (CI) for dichotomous outcomes and mean difference (MD) for continuous data. We assessed the quality of the evidence by using the GRADE approach.

MAIN RESULTS

For this update, we identified one new randomised controlled trial investigating effects of bronchodilators in preterm infants. This study, which enrolled 73 infants but reported on 52 infants, examined prevention of CLD with the use of aminophylline. According to GRADE, the quality of the evidence was very low. One previously included study enrolled 173 infants to look at prevention of CLD with the use of salbutamol. According to GRADE, the quality of the evidence was moderate. We found no eligible trial that studied the use of bronchodilator therapy for treatment of individuals with CLD. Prophylaxis with salbutamol led to no statistically significant differences in mortality (RR 1.08, 95% CI 0.50 to 2.31; RD 0.01, 95% CI -0.09 to 0.11) nor in CLD (RR 1.03, 95% CI 0.78 to 1.37; RD 0.02, 95% CI -0.13 to 0.17). Results showed no statistically significant differences in other complications associated with CLD nor in preterm birth. Investigators in this study did not comment on side effects due to salbutamol. Prophylaxis with aminophylline led to a significant reduction in CLD at 28 days of life (RR 0.18, 95% CI 0.04 to 0.74; RD -0.35, 95% CI -0.56 to -0.13; NNTB 3, 95% CI 2 to 8) and no significant difference in mortality (RR 3.0, 95% CI 0.33 to 26.99; RD 0.08, 95% CI -0.07 to 0.22), along with a significantly shorter dependency on supplementary oxygen in the aminophylline group compared with the no treatment group (MD -17.75 days, 95% CI -27.56 to -7.94). Tests for heterogeneity were not applicable for any of the analyses, as each meta-analysis included only one study.

AUTHORS' CONCLUSIONS

Data are insufficient for reliable assessment of the use of salbutamol for prevention of CLD. One trial of poor quality reported a reduction in the incidence of CLD and shorter duration of supplementary oxygen with prophylactic aminophylline, but these results must be interpreted with caution. Additional clinical trials are necessary to assess the role of bronchodilator agents in prophylaxis or treatment of CLD. Researchers studying the effects of bronchodilators in preterm infants should include relevant clinical outcomes in addition to pulmonary mechanical outcomes. We identified no trials that studied the use of bronchodilator therapy for treatment of CLD.

Lung Injury and Bronchopulmonary Dysplasia in Newborn Infants

Bronchopulmonary dysplasia is the most common morbidity among surviving premature infants. Injury to the developing lung is the result of the interaction between a susceptible host and a number of contributing factors such as mechanical ventilation and infection. The resulting persistent impairment of pulmonary function and need for ongoing therapy are the underlying characteristics of bronchopulmonary dysplasia. Important insights into the pathogenesis of bronchopulmonary dysplasia have led to numerous therapies and preventive approaches. Although significant progress has been made, in order to further affect the incidence and severity of the disease, we need to further study (a) the genetically determined predisposing factors, (b) the relative contribution of the various pathogenetic pathways, and, most important, (c) how to best translate the knowledge gained from these studies into effective clinical approaches.

Bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increase in compliance and tidal volume and decrease in pulmonary resistance have been documented with use of bronchodilators in studies of pulmonary mechanics in infants with CLD. Therefore, it is possible that bronchodilators might have a role in the prevention and treatment of CLD.

OBJECTIVES

To determine the effect of bronchodilators given either prophylactically or as treatment for CLD on mortality and other complications of prematurity in preterm infants at risk for or having CLD.

SEARCH METHODS

For this update of the review, searches of The Cochrane Library, Issue 3, 2012; MEDLINE 1966; EMBASE; CINAHL; personal files and reference lists of identified trials were performed in March 2012. In addition Web of Science and abstracts from the Annual meetings of the Pediatric Academic Societies were searched electronically from 2000 to 2012 on PAS Abstracts2view(TM.) No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials involving preterm infants were eligible for inclusion. Initiation of bronchodilator therapy had to occur within two weeks of birth for prevention of CLD. For treatment of CLD, treatment had to be initiated before discharge from the neonatal unit. The intervention had to include the administration of a bronchodilator either by nebulisation, metered dose inhaler (with or without a spacer device), intravenously or orally versus placebo or no intervention. Eligible studies had to include at least one of the predefined clinical outcomes (mortality, CLD, number of days on oxygen, number of days on ventilator, patent ductus arteriosus (PDA), pulmonary interstitial emphysema (PIE), pneumothorax, any grade of intraventricular haemorrhage (IVH), necrotising enterocolitis (NEC), sepsis and adverse effects of bronchodilators. Adverse effects of bronchodilators included hypokalaemia, tachycardia, cardiac arrhythmias, tremor, hypertension and hyperglycaemia).

DATA COLLECTION AND ANALYSIS

We used the standard method described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Two investigators extracted and assessed all data for each study. We reported risk ratio (RR) and risk difference (RD) with 95% confidence intervals (CI) for dichotomous outcomes and weighted mean difference (WMD) for continuous data.

MAIN RESULTS

In this update we identified four randomised controlled trials investigating the effects of bronchodilators in preterm infants. None of these studies fulfilled our inclusion criterion that clinical outcomes should be reported. One eligible study was previously found dealing with prevention of CLD; this study used salbutamol and enrolled 173 infants. No eligible studies were found dealing with treatment of CLD. Prophylaxis with salbutamol did not show a statistically significant difference in mortality (RR 1.08; 95% CI 0.50 to 2.31; RD 0.01; 95% CI -0.09 to 0.11) or CLD (RR 1.03; 95% CI 0.78 to 1.37; RD 0.02; 95% CI -0.13 to 0.17). No statistically significant differences were seen in other complications associated with CLD or preterm birth. No side effects due to salbutamol were commented on in this study.

AUTHORS' CONCLUSIONS

There are insufficient data to reliably assess the use of salbutamol for the prevention of CLD. Further clinical trials are necessary to assess the role of salbutamol or other bronchodilator agents in prophylaxis or treatment of CLD. Researchers studying the effects of bronchodilators in preterm infants should include relevant clinical outcomes in addition to pulmonary mechanical outcomes.

Resting energy expenditure in children with neonatal chronic lung disease and obstruction of the airways

Children with history of broncho-pulmonary dysplasia (BPD) often suffer from growth failure and lung sequelae. The main objective of this study was to test the role of pulmonary obstruction on resting energy expenditure (REE) and nutritional status in BPD. Seventy-one children with BPD (34 boys and 37 girls) and 30 controls (20 boys and 10 girls) aged 4-8 years were enrolled. Body composition was assessed by bio-impedancemetry measurements; REE was measured by indirect calorimetry. Predicted REE was calculated using the Schofield equation. The population of children with BPD was divided into three groups: children without obstruction of the airways, children with moderate obstruction of the airways, and children with severe obstruction. Children with BPD were significantly smaller and leaner than controls. Altered body composition (reduction of fat mass) was observed in BPD children that suffered from airway obstruction. REE was significantly lower in children with BPD compared to controls, but when adjusted for weight and fat-free mass no significant difference was observed irrespective of pulmonary status. Airway obstruction in children with BPD does not appear to be associated with an increased REE. Moreover altered REE could not explain the altered nutritional status that is still observed in BPD in later childhood. This supports the hypothesis that body composition and pulmonary function in BPD in later childhood are fixed sequelae originating from the neonatal period.

Pathogenesis of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), initially described 40 years ago, is a dynamic clinical entity that continues to affect tens of thousands of premature infants each year. BPD was first characterized as a fibrotic pulmonary endpoint following severe Respiratory Distress Syndrome (RDS). It was the result of pulmonary healing after RDS, high oxygen exposure, positive pressure ventilation, and poor bronchial drainage secondary to endotracheal intubation in premature infants. With improved treatment for RDS, including surfactant replacement, oxygen saturation monitoring, improved modes of mechanical ventilation, antibiotic therapies, nutritional support, and infants surviving at younger gestations, the clinical picture of BPD has changed. In the following pages, we will summarize the multifaceted pathophysiologic factors leading to the pulmonary changes in "new" BPD, which is primarily characterized by disordered or delayed development. The contribution of hyperoxia and hypoxia, mechanical forces, vascular maldevelopment, inflammation, fluid management, patent ductus arteriosus (PDA), nutrition, and genetics will be discussed.

From the archives of the AFIP: Lung disease in premature neonates: radiologic-pathologic correlation

Pulmonary disease is the most important cause of morbidity in preterm neonates, whose lungs are often physiologically and morphologically immature. Surfactant deficiency in immature lungs triggers a cascade of alveolar instability and collapse, capillary leak edema, and hyaline membrane formation. The term respiratory distress syndrome (RDS) has come to represent the clinical expression of surfactant deficiency and its nonspecific histologic counterpart, hyaline membrane disease. Historically, chest radiographs of infants with RDS predictably demonstrated decreased pulmonary expansion, symmetric generalized reticulogranular lung opacities, and air bronchograms. Refinements in perinatal medicine, including antenatal glucocorticoid administration, surfactant replacement therapy, and increasingly sophisticated ventilatory strategies have decreased the prevalence of RDS and air leak, altered familiar radiographic features, and lowered the threshold of potential viability to a gestational age of approximately 23 weeks. Alveolar paucity and pulmonary interstitial thickness in these profoundly premature neonates impair normal gas exchange and may necessitate prolonged mechanical ventilation, increasing the risk of lung injury. Bronchopulmonary dysplasia (BPD), alternatively termed chronic lung disease of infancy, is a disorder of lung injury and repair originally ascribed to positive-pressure mechanical ventilation and oxygen toxicity. Before the advent of surfactant replacement therapy, chest radiographs of infants with classic BPD demonstrated coarse reticular lung opacities, cystic lucencies, and markedly disordered lung aeration that reflected alternating regions of alveolar septal fibrosis and hyperinflated normal lung parenchyma. In the current era of surfactant replacement, BPD is increasingly a disorder of very low-birth-weight neonates with arrested alveolar and pulmonary vascular development, minimal alveolar septal fibrosis and inflammation, and more subtle radiographic abnormalities.

Preterm infants with congenital heart disease and bronchopulmonary dysplasia: postoperative course and outcome after cardiac surgery

OBJECTIVE

Success in treatment of premature infants has resulted in increased numbers of neonates who have bronchopulmonary dysplasia (BPD) and require surgical palliation or repair of congenital heart disease (CHD). We sought to investigate the impact of BPD on children with CHD after heart surgery.

METHODS

This was a retrospective, multicenter study of patients who had BPD, defined as being oxygen dependent at 28 days of age with radiographic changes, and CHD and had cardiac surgery (excluding arterial duct ligation) between January 1991 and January 2002. Forty-three infants underwent a total of 52 cardiac operations. The median gestational age at birth was 28 weeks (range: 23-35 weeks), birth weight was 1460 g (range: 431-2500 g), and age at surgery was 2.7 months (range: 1.0-11.6 months). Diagnoses included left-to-right shunts (n = 15), conotruncal abnormalities (n = 13), arch obstruction (n = 6), univentricular hearts (n = 4), semilunar valve obstruction (n = 3), Shone syndrome (n = 1), and cor triatriatum (n = 1).

RESULTS

Thirty-day survival was 84% with 6 early and 6 late postoperative deaths. Survival to hospital discharge was 68%. There was 50% mortality for patients with univentricular hearts and severe BPD. The median duration of preoperative ventilation was 76 days (range: 2-244 days) and of postoperative ventilation was 15 days (range: 1-141 days). The median duration of cardiac ICU stay was 7.5 days (range: 1-30 days) and of hospital stay was 115 days (range: 35-475 days). Current pulmonary status includes on room air (n = 14), O2 at home (n = 4), and ventilated at home (n = 4) or in hospital (n = 4), and 5 patients were lost to follow-up.

CONCLUSIONS

BPD has significant implications for children who have CHD and undergo cardiac surgery, leading to prolonged ICU and hospital stays, although most survivors are not O2 dependent. Postoperative mortality was highest among patients with univentricular hearts and severe BPD. Optimal timing of surgery and strategies to improve outcome remains to be delineated.

Inhaled corticosteroids for abnormal pulmonary function in children with a history of chronic lung disease of infancy: study protocol [ISRCTN55153521]

Background

There is considerable evidence from the literature that children with chronic lung disease of infancy (CLD) have abnormal pulmonary function in childhood and this could have an impact on their life quality and overall health. There are similarities between CLD and asthma, and corticosteroids are the mainstay treatment for asthma. Many physicians use inhaled corticosteroids in children with CLD with no evidence. Therefore we wish to conduct a randomized double-blinded placebo controlled trial to test for the role of inhaled corticosteroids in children aged from3 to 9 years with a history of CLD. Our primary hypothesis will be that inhaled corticosteroids are beneficial in children with CLD.

Methods

Our primary hypothesis is that using inhaled steroids; Beclomethasone Dipropionate (QVAR) 100 mcg 2 puffs 2 times a day for 6 weeks will improve the respiratory system resistance and the quality of life in children with CLD.

Discussion

We propose that Beclomethasone Dipropionate (QVAR) will affect the pulmonary function after 6 weeks of treatment. In summary we think that our study will highlight knowledge on whether the use of inhaled steroids is clinically effective for CLD.

Bronchopulmonary dysplasia in preterm infants: pathophysiology and management strategies

Bronchopulmonary dysplasia (BPD) has classically been described as including inflammation, architectural disruption, fibrosis, and disordered/delayed development of the infant lung. As infants born at progressively earlier gestations have begun to survive the neonatal period, a 'new' BPD, consisting primarily of disordered/delayed development, has emerged. BPD causes not only significant complications in the newborn period, but is associated with continuing mortality, cardiopulmonary dysfunction, re-hospitalization, growth failure, and poor neurodevelopmental outcome after hospital discharge. Four major risk factors for BPD include premature birth, respiratory failure, oxygen supplementation, and mechanical ventilation, although it is unclear whether any of these factors is absolutely necessary for development of the condition. Genetic susceptibility, infection, and patent ductus arteriosus have also been implicated in the pathogenesis of the disease. The strategies with the strongest evidence for effectiveness in preventing or lessening the severity of BPD include prevention of prematurity and closure of a clinically significant patent ductus arteriosus. Some evidence of effectiveness also exists for single-course therapy with antenatal glucocorticoids in women at risk for delivering premature infants, surfactant replacement therapy in intubated infants with respiratory distress syndrome, retinol (vitamin A) therapy, and modes of respiratory support designed to minimize 'volutrauma' and oxygen toxicity. The most effective treatments for ameliorating symptoms or preventing exacerbation in established BPD include oxygen therapy, inhaled glucocorticoid therapy, and vaccination against respiratory pathogens.Many other strategies for the prevention or treatment of BPD have been proposed, but have weaker or conflicting evidence of effectiveness. In addition, many therapies have significant side effects, including the possibility of worsening the disease despite symptom improvement. For instance, supraphysiologic systemic doses of glucocorticoids lessen the incidence of BPD in infants at risk for the disease, and promote weaning of oxygen and mechanical ventilation in infants with established BPD. However, the side effects of systemic glucocorticoid therapy, most notably the recently recognized adverse effects on neurodevelopment, preclude their routine use for the prevention or treatment of BPD. Future research in BPD will most probably focus on continued incremental improvements in outcome, which are likely to be achieved through the combined effects of many therapeutic modalities.

Nutrition et dysplasie bronchopulmonaire

Bronchopulmonary dysplasia remains a frequent complication of extreme prematurity. In preterm neonates catch-up and pulmonary alveolar growth occur during the first two years of life. However 10 to 25% of preterm infants with bronchopulmonary dysplasia are under-nourished after two years of age, and 30 to 60% of them also suffer from persistent airway obstruction, hyperinflation and bronchial hyperreactivity. Recommendations on nutritional requirements in this population are not yet clearly defined, but an adequate nutritional status in prenatal and early postnatal period can have long-term consequences on brain and lung development. There are a few randomised trial of nutrition for preterm infants with bronchopulmonary dysplasia after discharge. Caloric and protein requirements in this population are probably higher than in full-term infants. Moreover there are potential benefits in using specific nutrients: supplementation with long chain polyunsaturated fatty acids could decrease lung inflammation injuries, glutamine is the main source of energy of pneumocyte, vitamin A is essential for lung development, inositol is necessary for surfactant synthesis, vitamin E and selenium have anti-oxidant effects. Controlled nutritional trial are needed with a long term follow-up in late childhood in order to test their effects on growth and pulmonary status.

Cognitive and academic consequences of bronchopulmonary dysplasia and very low birth weight: 8-year-old outcomes

OBJECTIVE

To examine the effects of bronchopulmonary dysplasia (BPD) and very low birth weight (VLBW) on the cognitive and academic achievement of a large sample of 8-year-old children.

METHODS

Infants who were VLBW and had BPD (n = 98) or did not have BPD (n = 75) and term infants (n = 99) were followed prospectively to age 8. Groups were compared on measures assessing 4 broad areas of functioning: intelligence, achievement, gross motor, and attentional skills. Measures included the Wechsler Intelligence Scale for Children III, the Woodcock Johnson Test of Achievement-Revised, the Bruininks-Oseretsky Test of Motor Proficiency, the Tactual Performance Test (spatial memory), and the Continuous Performance Test (attention). School outcomes were assessed by parent and teacher report, as well as from school records. Groups were comparable on socioeconomic status, sex, and race. The total sample of BPD, VLBW, and term children was compared on all outcome measures. In addition, neurologic risk was assessed in the present sample and included the following: intraventricular hemorrhage, echodense lesions, porencephaly, hydrocephalus, ventriculoperitoneal shunt, meningitis, and periventricular leukomalacia. Individual difference analyses were conducted for neurologically intact children in all 3 groups. Finally, treatment effects were examined by comparing BPD children who had received steroids as part of their treatment with BPD children who had not.

RESULTS

The BPD group demonstrated deficits compared with VLBW and term children in intelligence; reading, mathematics, and gross motor skills; and special education services. VLBW children differed from term children in all of the above areas, except reading recognition, comprehension, and occupational therapy. Attentional differences were obtained between BPD and term children only. The BPD group (54%) was more likely to be enrolled in special education classes than VLBW (37%) or term children (25%). In addition, more BPD children (20%) achieved full-scale IQ scores <70, in the mental retardation range, compared with either VLBW (11%) or term (3%) children, with all VLBW children significantly more likely than term children to achieve IQs in the subaverage category. After controlling for birth weight and neurologic problems, BPD and/or duration on oxygen predicted lower performance IQ, perceptual organization, full-scale IQ, motor and attentional skills, and special education placement. The qualitative classification of BPD (present or absent) was a significant predictor for lower scores on measures of applied problems; motor skills; and incidence of speech-language, occupational, and physical therapies. Individual difference analyses were performed to ascertain whether differences between the risk groups were primarily attributable to neurologic complications. Even with the neurologically intact sample of BPD and VLBW children, differences between the term comparison group and both the BPD and VLBW groups were found for many outcome measures. When birth weight and neurologic complications were controlled, BPD and severity of BPD were associated with lower performance and full-scale IQ, poorer perceptual organization, attention, and motor skills, as well as lower school achievement and greater participation in special education, including occupational, physical, and speech-language therapies. Treatment protocol may in part be responsible for differences observed in our BPD sample. Steroid and nonsteroid groups of BPD children differed significantly in performance IQ (72.8 vs 84.8) and full-scale IQ (77.0 vs 85.2); perceptual organization (74.0 vs 85.2); Bruininks-Oseretsky Test of Motor Proficiency score (36.6 vs 44.7); and participation in special education (78% vs 48%), occupational therapy (71% vs 44%), and physical therapy (71% vs 41%). In every instance, BPD children who received steroids fared more poorly than BPD children who did not receive steroids.

CONCLUSIONS

BPD and duration on oxygen have long-term adverse effects on cognitive and academic achievement above and be beyond the effects of VLBW. The problems that have been identified at 8 years of age highlight the need for continued monitoring of the learning, behavior, and development of BPD children to intervene with children who are at risk for school problems.

Infant and caregiving factors affecting weight-for-age and motor development of full-term and premature infants at 1 year post-term

Guided by a theoretical process model, we examined direct and indirect effects of infants' biologic condition and experience, the caregiving environment, and caloric intake variables on two outcomes, weight-for-age and motor development, for 52 full-term and 47 premature infants at 12 months post-term age. For full-term infants, birth weight and infant expression of positive affect and behavior during feeding had predicted positive direct effects on weight-for-age. Infant regulation of negative affect and behavior had an unexpected negative effect on this outcome. For premature infants, severity of acute illness, mother's regulation of negative affect and feeding behavior, and caloric intake affected weight-for-age in unpredicted directions. Caregiving variables had indirect effects, through caloric intake, on both outcomes only for premature infants. The findings suggest the theoretical process model differs for premature infants and full-term infants, both in the contributing variables and in the processes of effects.

Rehospitalization of extremely-low-birth-weight infants in first 2 years of life

AIMS

To determine whether (1) chronic lung disease (CLD) is the prime reason for extremely-low-birth-weight (ELBW) infant readmission during the first 2 years of life, (2) surfactant and other advanced therapies have reduced ELBW infant readmissions, (3) home oxygen therapy (HOT) is efficacious for this group.

STUDY DESIGN

The hospital records of these ELBW infants were reviewed retrospectively. Data on age, diagnosis, treatment, and duration of each hospitalization were compiled and analyzed for their association to CLD and to readmission for CLD and other reasons.

SUBJECTS

All 60 surviving infants with a birth body weight of less than 1001 g (ELBW) born from January 1993 to February 1998 were followed up to 2 years (mean 20.4 +/- 7.4 months) to evaluate their respiratory outcome.

RESULTS

Forty-two percent of these infants developed CLD. Upon discharge from the hospital, 28% (7/25) of the patients were given HOT for a median period of 60 days. Of the 47 ELBW infants who were studied the entire 2-year period, 72% were readmitted. Infants with CLD were readmitted more frequently (p=0.045) and had longer hospital stays during the first 2 years of life (p=0.034) than those without CLD. Respiratory illness was the main reason for readmission (55%) of these ELBW infants. The incidence of readmission due to respiratory tract infection was not significantly different in infants with CLD (61%) and infants without respiratory complications (44%) (p=0.159).

CONCLUSIONS

Infants with CLD (whether receiving HOT or not) showed no higher readmission rate due to respiratory infection, but the HOT group did have higher morbidity. The premature lung itself rather than the presence of CLD, as we would expect, makes ELBW infants more prone to readmission for respiratory illness.

Inhaled glucocorticoid therapy in infants at risk for neonatal chronic lung disease

The primary impetus for the study of inhaled glucocorticoid therapy in the treatment and prevention of neonatal chronic lung disease (CLD) was to achieve effective anti-inflammatory therapy with few adverse effects. Initial reports of inhaled glucocorticoid therapy in infants with established CLD suggest modest improvement in neonatal respiratory outcomes. Recent randomized trials also indicate that inhaled glucocorticoid therapy may provide some benefit, but have not demonstrated a reduction in CLD. Some studies suggest that the pulmonary response to systemic glucocorticoid may be greater and faster than response to inhaled glucocorticoid therapy. Few adverse effects have been noted with inhaled glucocorticoid therapy. One limitation of studies of inhaled glucocorticoid therapy is the uncertainty of the dose delivered and deposited in peripheral airways and regions of the lungs. Experience with and systematic study of inhaled glucocorticoid therapy is still in its early stages. The role of inhaled glucocorticoid therapy in the treatment and prevention of CLD is evolving. Advances in delivery devices and new developments of drug formulations should improve aerosol delivery and deposition in infants. Given the clinical dilemma of systemic glucocorticoid therapy and potential benefits demonstrated by recent trials of inhaled glucocorticoid therapy, further study of inhaled glucocorticoid therapy for CLD is warranted.

Superoxide dismutase for preventing chronic lung disease in mechanically ventilated preterm infants

BACKGROUND

Free oxygen radicals have been implicated in the pathogenesis of chronic lung disease in preterm infants. Superoxide dismutase is a naturally occurring enzyme which provides a defence against such oxidant injury. Exogenously administered superoxide dismutase has been tested in clinical trials to prevent chronic lung disease in preterm infants.

OBJECTIVES

To determine if exogenously administered superoxide dismutase is efficacious in the prevention of chronic lung disease in preterm infants who are mechanically ventilated, and efficacious in decreasing the following outcomes: bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, retinopathy of prematurity, necrotizing enterocolitis, patent ductus arteriosus and mortality. To determine the frequency and nature of adverse effects of superoxide dismutase.

SEARCH STRATEGY

We searched Medline (1966 - 2000) and the Cochrane Controlled Trials Register (CCTR) using the following keywords: [bronchopulmonary dysplasia OR chronic lung disease] AND superoxide dismutase, limited to human studies in newborn infants (infant, newborn). We hand searched the reference lists of articles located and the abstracts of the Society for Pediatric Research (USA) (published in Pediatric Research) from 1980 - 2000.

SELECTION CRITERIA

Randomized controlled trials where subjects were preterm infants who had developed or were at risk of developing respiratory distress syndrome requiring assisted ventilation and who were randomly allocated to receive either superoxide dismutase (in any form, by any route) or placebo or no treatment. We included studies which reported any of the following outcomes: chronic lung disease, bronchopulmonary dysplasia, any intraventricular hemorrhage, intraventricular hemorrhage grades III/IV, patent ductus arteriosus, periventricular leukomalacia, retinopathy of prematurity, necrotizing enterocolitis, neonatal mortality, death prior to discharge and neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

We extracted and assessed separately all data for each study and entered final data into RevMan. We did not perform subgroup analyses (which were originally planned) because only two studies were eligible for inclusion. We assessed the methodological quality of the studies by assessing the risk for bias. We pooled the outcomes of infants who had developed bronchopulmonary dysplasia at 28 days with those who had died at 28 days to derive the combined outcome of bronchopulmonary dysplasia or death at 28 days. Similarly we pooled the outcomes of infants who had respiratory problems after discharge with those who had died prior to discharge to derive the combined outcome of respiratory problems after discharge or death. We used the standard method of the Cochrane Neonatal Review Group for statistical analysis, using a fixed effect model.

MAIN RESULTS

Two randomized controlled trials were included for analysis. No differences were found in either study or in the pooled data in death prior to discharge, oxygen dependency at 36 weeks corrected age, oxygen dependency at 28 days of life or in other outcomes. In one study (Rosenfeld 1984), survivors who had been treated with superoxide dismutase had a shorter duration of continuous positive airway pressure (4.9 vs 9.7 days), a lower frequency of respiratory problems after discharge (relative risk 0.33, 95% confidence limits 0.11, 0.96) and a lower frequency of chest radiograph abnormalities (relative risk 0.30, 95% confidence limits 0.11, 0.87) compared to survivors who received placebo. A third study was available only in abstract form and will be evaluated for inclusion after publication.

REVIEWER'S CONCLUSIONS

Based on currently available published trials, there is insufficient evidence to draw firm conclusions about the efficacy of superoxide dismutase in preventing chronic lung disease of prematurity. Data from a small number of treated infants suggest that it is well tolerated and has no serious adverse effects.

Bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants (< 37 weeks gestational age) and has a multifactorial etiology. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increase in compliance and tidal volume and decrease in pulmonary resistance have been documented with use of bronchodilators in short term studies of pulmonary mechanics in infants with CLD. Therefore it is possible that bronchodilators might have a role in the prevention and treatment of CLD.

OBJECTIVES

To evaluate the effect of bronchodilators, given prophylactically or as treatment for chronic lung disease, on mortality and other complications of preterm births.

SEARCH STRATEGY

The search strategy used to identify studies was according to the guidelines of the Cochrane Neonatal Review Group. Searches were made of MEDLINE 1966 to December 2000, EMBASE 1980 to January 2001, CINAHL 1982 to December 2000, the Cochrane Library Issue 1, 2001, personal files and reference lists of identified trials. The following terms were used: bronchopulmonary dysplasia, chronic lung disease, bronchodilator agents, adrenergic agents, anticholinergic agents, albuterol, aminophylline, atropine, caffeine, clenbuterol, cromakalim, ephedrine, epinephrine, fenoterol, hexoprenaline, ipratropium, isoetharine, isoproterenol, orciprenaline, procaterol, terbutaline, theophylline, tretoquinol.

LIMITS

newborn, infant; human, clinical trial or controlled clinical trial, meta analysis, multicenter study or randomised controlled trial. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled clinical trials involving preterm infants. Initiation of bronchodilator therapy had to occur within two weeks of birth for prevention of CLD. For treatment of CLD treatment should have been initiated before discharge from the neonatal unit. The intervention had to include the randomised administration of a bronchodilator either by nebulisation, metered dose inhaler with or without a spacer device, intravenously or orally, versus placebo or no intervention. Eligible studies had to include at least one of the following outcomes: mortality, CLD at 28 days or at 36 weeks corrected GA, number of days on oxygen, number of days on ventilator, patent ductus arteriosus (PDA), pulmonary interstitial emphysema (PIE), pneumothorax, any grade of intraventricular haemorrhage, necrotizing enterocolitis (NEC), sepsis and adverse effects of bronchodilators.

DATA COLLECTION AND ANALYSIS

We used the standard method for the Cochrane Collaboration as described in the Cochrane Collaboration handbook. Two investigators (GN, AO) extracted and assessed all data for each study. Any disagreement was resolved by discussion. Relative risk (RR) and risk difference (RD) with 95% confidence intervals (CI) are reported for dichotomous outcomes and mean difference (WMD) for continuous data.

MAIN RESULTS

One eligible study was found dealing with prevention of CLD; this study used salbutamol and enrolled 173 infants. No eligible studies were found dealing with treatment of CLD. Prophylaxis with salbutamol did not show a statistically significant difference in mortality [RR 1.08 (95% CI 0.50, 2.31); RD 0.01 (95% CI -0.09, 0.11)], CLD (mild, moderate or severe) [RR 1.03 (95% CI 0.78, 1.37); RD 0.02 (95% CI -0.13, 0.17)], need for iv dexamethasone [RR 0.77 (95% CI 0.49, 1.19); RD -0.08 (95% CI -0.22, 0.05)], respiratory infections [RR 0.61 (95% CI 0.27, 1.39); RD -0.06 (95% CI -0.16, 0.04)] or positive blood culture [RR 1.06 (95% CI 0.54, 2.06); RD 0.01 (95% CI -0.10, 0.12)]. There was no statistically significant difference in duration of ventilatory support [MD -1.63 days (95% CI -5.63, 2.37)], duration of oxygen supply [MD -2.82 days (95% CI -11.91, 6.27)] or age of weaning from respiratory support (defined as assisted ventilation or oxygen supplementation) [MD -2.87 days (95% CI -11.28, 5.54)]. No side effects due to salbutamol were commented on in this study.

REVIEWER'S CONCLUSIONS

There are insufficient data to reliably assess the use of salbutamol for the prevention of CLD. Further clinical trials are necessary to assess the role of salbutamol or other bronchodilator agents in prophylaxis or treatment of CLD.

Strategies for prevention of neonatal chronic lung disease

Chronic lung disease (CLD) of prematurity remains a substantial problem despite modern perinatal and neonatal care. CLD remains related to gestational age and lung immaturity, although it has become clear that severe initial lung disease is not a prerequisite for CLD to develop. Attempts to prevent CLD to date have not adequately addressed the multifactorial nature of the complex pathophysiology that leads to CLD. Thus, results have been modest at best. Prevention of CLD will require a multifaceted approach with specific interventions and care practices focused on different aspects of the pathway that leads to CLD. This review considers new information related to causation of CLD and the magnitude of the effect of prevention strategies tested to date. This article also advances the hypothesis that CLD is preventable with a global strategy of minimizing inciting events, optimizing management, and specific therapies aimed at intrinsic vulnerabilities.

A role for hyaluronan in macrophage accumulation and collagen deposition after bleomycin-induced lung injury

Elevated concentrations of hyaluronan (HA) are associated with the accumulation of macrophages in the lung after injury. We have investigated the role of HA in the inflammatory and fibrotic responses to lung injury using the intratracheal instillation of bleomycin in rats as a model. After bleomycin-induced lung injury, both HA content in bronchoalveolar lavage (BAL) and staining for HA in macrophages accumulating in injured areas of the lung were maximal at 4 d. Increased HA in BAL correlated with increased locomotion of isolated alveolar macrophages. HA-binding peptide was able to specifically block macrophage motility in vitro. Importantly, systemic administration of HA-binding peptide to rats before injury not only decreased alveolar macrophage motility and accumulation in the lung, but also reduced lung collagen alpha (I) messenger RNA and hydroxyproline contents. We propose a model in which HA plays a critical role in the inflammatory response and fibrotic consequences of acute lung injury.

Postnatal glucocorticosteroid therapy for treatment and prevention of neonatal chronic lung disease

Neonatal chronic lung disease (CLD) is a persistent complication, primarily of premature infants. Postnatal glucocorticoid therapy is widely used in the treatment and prevention of CLD. Most studies reveal acute improvement in the pulmonary status of infants treated with postnatal glucocorticoid therapy. Recent studies of 'earlier' intervention (< 14 days of age) demonstrated a reduction in mortality and in the occurrence of CLD between 28 days of age and 36 weeks postmenstrual age. Great concern remains, however, regarding the potential adverse outcomes, including growth inhibition, infection, catastrophic GI complications and CNS injury. Therefore, the use of postnatal glucocorticoid therapy remains controversial with respect to the clinical indications for initiating therapy, the dose, duration, onset and route of administration, as well as potential benefits and risks. Inhaled glucocorticoid therapy is increasingly used to treat and prevent CLD in order to avoid adverse effects of high dose systemic glucocorticoid therapy. Recent studies with inhaled glucocorticoid therapy show promise. Further work, however, for improving aerosol delivery and deposition, will be needed to refine their role in the prevention and treatment of CLD. Future studies enabling early, accurate identification of infants at greatest risk for CLD, coupled with a more comprehensive understanding of the different pathogeneses, will provide information regarding appropriate timing of onset, dosing, route of therapy and duration of intervention.

Understanding airway disease in infants

Large airway diseases manifest in ways distinct from those of small airway diseases. Noisy breathing that begins early in life suggests a congenital lesion of the large airways. The findings of elevated respiratory rate, in conjunction with subcostal retractions, hyperinflation to percussion, and musical wheezes, are diagnostic of small airway obstruction. Differentiating large from small airway disease is crucial, because each disease has a distinct diagnosis, and treatment of the 2 disease types can be quite different. When these principles are applied to a patient with wheezing or other signs of airway compromise, it becomes fairly easy to differentiate large from small airway disease. The treatment of patients with large airway disease can be substantially different from that of patients with small airway disease. Being able to differentiate the two is critically important. With the use of the history, physical examination, and radiographic evaluations described earlier, nearly every patient can be given an accurate diagnosis and treated appropriately.