Recurrent wheezing in very preterm infants

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

Early-Life Nutrition in Preterm Infants and Risk of Respiratory Infections and Wheezing: A Scoping Review

INTRODUCTION

Preterm birth is a common early-life event that can lead to long-term consequences. The incidence of wheezing, asthma, and respiratory tract infections is higher in children born prematurely than in the general population. The purpose of this review was to synthesize the existing literature on the role of early-life nutrition in the later risk of respiratory morbidities.

METHODS

A scoping review of the literature was performed by searching three online databases. Inclusion criteria were: infants born <37 GWk, comparing human milk versus any other type of milk feeding formulation. Our primary outcomes were wheezing or asthma or respiratory tract infections after discharge. Two authors independently screened the results and extracted study characteristics using a predefined charting form.

RESULTS

Nine articles were included (eight cohort studies and one randomized trial). Four studies supported the protective effect of breastfeeding on wheezing or respiratory infections or both. Four studies did not confirm this association. One study confirmed the protective role of breastfeeding only on the subgroup of girls. There was a high heterogeneity among the included studies, in the type of milk feeding, outcomes, and age at follow-up.

CONCLUSIONS

The current evidence is conflicting. The high heterogeneity and methodological flaws could have influenced the results of the studies. Carefully designed studies are required to define the role of early-life nutrition among preterm infants on their long-term respiratory outcomes.

Prematurity-associated wheeze: current knowledge and opportunities for further investigation

Prematurity-associated wheeze is a common complication of preterm birth, with significant impact on the health and healthcare utilization of former preterm infants. This wheezing phenotype remains poorly understood and difficult to predict. This review will discuss the current state of the literature on prematurity-associated wheeze. We will discuss etiology and pathophysiology, and offer two conceptual models for the pathogenesis of this complex condition. This review will also identify current methods of ascertainment, and discuss the strengths and limitations of each. We will explore research-backed approaches to prevention and management, and finally suggest both pre-clinical and clinical avenues for investigation. An in-depth understanding of prematurity-associated wheeze will aid clinicians in its diagnosis and management, and inspire scientists to pursue much-needed further study into causes and prevention of this common and impactful condition. IMPACT: There is no recent, concise review on the current state of research on prematurity-associated wheeze, which is a rapidly evolving area of study. This article highlights causal models of wheeze, methods of ascertainment, management strategies for the clinician, and opportunities for further research for the physician scientist.

Risk factors for bronchiolitis, recurrent wheezing, and related hospitalization in preterm infants during the first year of life

BACKGROUND

Airway diseases are highly prevalent in infants and cause significant morbidity. We aimed to determine the incidence and risk factors for respiratory morbidity in a Spanish cohort of moderate-to-late preterm (MLP) infants prospectively followed during their first year of life.

METHODS

SAREPREM is a multicenter, prospective, longitudinal study. Preterm infants born at 32-35 weeks of gestation with no comorbidities were enrolled within 2 weeks of life and followed at 2-4 weeks, 6, and 12 months of age. Multivariate mixed-models were performed to identify independent risk factors associated with (i) development of bronchiolitis, (ii) recurrent wheezing, or (iii) related hospital admissions.

RESULTS

Overall, 977 preterm infants were included, and 766 (78.4%) completed follow-up. Of those, 365 (47.7%) developed bronchiolitis during the first year, 144 (18.8%) recurrent wheezing, and 48 (6.3%) were hospitalized. While low birthweight, day care attendance (DCA) and school-age siblings were significantly and independently associated with both the development of bronchiolitis and recurrent wheezing, lower maternal age increased the risk for bronchiolitis and respiratory-related hospitalizations. Lastly, mechanical ventilation was associated with a higher risk of bronchiolitis and history of asthma in any parent increased the likelihood of developing recurrent wheezing.

CONCLUSIONS

In this study, several non-modifiable parameters (family history of asthma, low birthweight, need for mechanical ventilation) and modifiable parameters (young maternal age, DCA, or exposure to school-age siblings) were identified as significant risk factors for the development of bronchiolitis and recurrent wheezing during the first year of life in MLP infants.

Respiratory illness contributed significantly to morbidity in children born extremely premature or with extremely low birthweights in 1999-2000

AIM

This study investigated respiratory morbidity and risk factors during the first five years of life after extremely preterm birth.

METHODS

Paediatric assessments and parental questionnaires were obtained at two and five years of age in this national prospective cohort of 372 Norwegian children born during 1999-2000 at a gestational age of <28 weeks or birthweight <1,000 grams.

RESULTS

Paediatric assessments were obtained for 100% and 82% of the children at two and five years of age and completed questionnaires for 71% and 76%, respectively. Total readmission rates decreased from 49 to 14% at one to five years, and readmissions for respiratory causes fell from 31 to 3%. Bronchopulmonary dysplasia (BPD) or gestational age was not associated with readmissions for respiratory causes in multiple logistic regression models. However, both BPD and gestational age ≤ 25 weeks was associated with wheezing during the first year and the use of asthma medication during the first two years. BPD was associated with asthma medication between three and five years but not significantly at five years.

CONCLUSION

Respiratory morbidity decreased during the first five years of life but was still more common than expected. It was unrelated to BPD and gestational age at five years of age.

Hair nicotine levels in children with bronchopulmonary dysplasia

BACKGROUND

Tobacco smoke exposure (TSE) may increase respiratory morbidities in young children with bronchopulmonary dysplasia (BPD). Rapid respiratory rates, close proximity to a smoking caregiver, and increased dermal absorption of tobacco smoke components can contribute to systemic exposure. In this study, hair nicotine levels were used as a biomarker of chronic TSE in young children with BPD to determine if hair nicotine levels correlate with caregiver self-report of TSE and respiratory morbidities.

METHODS

From 2012 to 2014, hair nicotine levels were measured from consecutive children seen in a BPD outpatient clinic and compared with caregiver questionnaires on household smoking. The relationship between respiratory morbidities and self-reported TSE or hair nicotine level was assessed.

RESULTS

The mean hair nicotine level from 117 children was 3.1 ± 13.2 ng/mg. Hair nicotine levels were significantly higher in children from smoking households by caregiver self-report compared with caregivers who reported no smoking (8.2 ± 19.7 ng/mg vs 1.8 ± 10.7; P < .001). In households that reported smoking, hair nicotine levels were higher in children with a primary caregiver who smoked compared with a primary caregiver who did not smoke. Among children with BPD who required respiratory support (n = 50), a significant association was found between higher log hair nicotine levels and increased hospitalizations and limitation of activity.

CONCLUSIONS

Chronic TSE is common in children with BPD, with hair nicotine levels being more likely to detect TSE than caregiver self-report. Hair nicotine levels were also a better predictor of hospitalization and activity limitation in children with BPD who required respiratory support at outpatient presentation.

Secondhand smoke exposure in preterm infants with bronchopulmonary dysplasia

OBJECTIVES

Preterm infants and children with bronchopulmonary dysplasia (BPD) often experience significant respiratory morbidities during the first two years of life. Second hand smoke (SHS) has been demonstrated to lead to respiratory morbidities in the general population. The objectives of this study were to assess the prevalence/impact of SHS on preterm infants and children with BPD.

METHODS

Subjects (n = 352) were recruited from the Johns Hopkins BPD outpatient clinic between January 2008 and August 2012. Second hand smoke exposure and respiratory morbidities were assessed through questionnaires and chart review.

RESULTS

Twenty-eight percent of preterm infants with BPD were exposed to SHS in the home setting, despite having significant lung disease. SHS was associated with multiple measures of socio-economic status, including lower household income (P < 0.001), lower caregiver education level (P = 0.013), and having public versus private insurance (P = 0.002). We found no difference in acute care use or chronic symptoms with SHS exposure. We observed trends that preterm infants who were exposed to SHS were more likely to be prescribed inhaled corticosteroids (P = 0.054) and were weaned off of supplemental oxygen over 2 months later (P = 0.13) than infants not exposed to SHS.

CONCLUSION

SHS exposure in preterm infants with BPD is common, even in those receiving supplemental oxygen and respiratory medications. Although there were no associations between respiratory outcomes and self-reported SHS exposure, trends toward increased use of inhaled steroids and a longer duration of supplemental oxygen use were noted. Further work is needed to determine more accurate means of assessing SHS risk in this vulnerable population.

The relationship between the first episode of wheezing and matrix metalloproteinases-9 and MMP-2 and tissue inhibitors of MMP-1 levels in preterm infants

AIMS

Matrix metalloproteinases (MMP) have been associated with neonatal lung morbidity and MMP dysregulation contributes to the pathology of chronic and acute lung disorders. Most of the previous studies were performed in the 1(st) weeks of life of the preterm newborns. There are no data on the serum levels of MMP-2, MMP-9 or tissue inhibitors of matrix metalloproteinases (TIMP-1) from preterm infants recovering from lung morbidities. We aimed to compare MMP-2, MMP-9 and TIMP-1 levels in preterm and term infants hospitalized with their first episode of wheezing.

METHODS

We prospectively evaluated 18 preterm infants with a history of chronic lung disease, respiratory distress syndrome or oxygen therapy and 14 age- and sex-matched term infants who were admitted for a first episode of wheezing. We quantified total serum concentrations of MMP-2, MMP-9 and TIMP-1 to assess whether these serum markers levels were associated with the first episode of wheezing in infants with a history of oxygen therapy during the neonatal period.

RESULTS

Upon hospitalization, MMP-2 and TIMP-1 levels were higher in preterm infants than in term infants. In contrast, there was no significant relationship between MMP-9 levels or the MMP-9/TIMP-1 ratio between preterm and term infants. The area under the receiver operating characteristic curve for MMP-2 was 0.70 (95% confidence interval [CI] 0.51-0.89). The area under the curve for TIMP-1 was 0.78 (95% CI 0.61-0.94). MMP-9, MMP-2 and TIMP-1 levels did not correlate with gestational age, gender or severity of wheezing.

CONCLUSION

The negative proportion of MMP-9 to TIMP-1 that we detected in term infants was not present in preterm infants. The balance of MMP-9 to TIMP-1 may have been disrupted by lung damage in the premature infants. Overproduction of MMP-2 and TIMP-1 in the serum may be associated with the pathogenesis of wheezing in preterm infants.

Performance of commonly used respiratory questionnaire items in a cohort of infants born preterm

Background

Items from respiratory questionnaires validated in older children are often used in research studies of preterm infants, although they have not been validated in this population. We aimed to assess both test-retest reliability and convergent validity of a group of commonly used respiratory questionnaire items in a cohort of preterm infants.

Methods

The health status of 300 preterm infants was assessed by telephone questionnaire as part of a prospective cohort study. The questionnaire items analyzed in this study included six commonly used respiratory questions. The questionnaire responses used in this analysis were from the telephone follow-up in this cohort at six months of age adjusted for prematurity. A repeat interview one to two weeks after this interview was performed in a subset of subjects to assess test-retest reliability. The convergent validity of the respiratory items was also assessed by calculating the associations among the responses to the respiratory questions.

Results

A total of 43 infants were singletons that met the criteria for test-retest reliability analysis. All of the respiratory questions demonstrated fair to strong test-retest reliability. Among 206 respondents, respiratory questionnaire items also demonstrated strong convergent validity, in that caretakers reporting wheezing or whistling in the chest were significantly more likely to also report other respiratory events.

Conclusions

This selection of standard respiratory questionnaire items performed well for research purposes in this population.

Factors associated with rehospitalizations of very low birthweight infants: impact of a transition home support and education program

OBJECTIVE

To determine the effects of a transition-home education and support program, BPD, and health insurance type on VLBW infant rehospitalizations at 3 and 7 months corrected age. It was hypothesized that the transition-home program would be associated with decreased rehospitalizations between Phase 1 and 2, and public health insurance and BPD would be associated with increased rehospitalizations.

METHODS

274 infants with birth weight <1500 g were enrolled in two successive years of a transition-home program (Phase 1-start-up) and (Phase 2-full implementation) and followed to 7 months CA.

RESULTS

The Phase 2 rehospitalization rates were lower but not statistically significant at both 3 months (20% and 15%; p=0.246), and 7 months (24% and 17%; p=0.171). Infants with public insurance had twice as many rehospitalizations by 3 months (28% versus 11%; p=0.018) in Phase 1. In regression analyses the intervention effects did not achieve significance for the cohort at 3 months (OR=0.63; CI=0.33 to 1.20) or 7 months (OR=0.61; CI=0.33 to 1.13). BPD and public insurance did not reach significance in the models whereas siblings were significantly associated with increased odds of rehospitalization. In subgroup analyses for infants on pubic health insurance the intervention significantly decreased the odds of rehospitalization between Phase 1 and 2(OR=0.43; CI=0.19 to 0.96) at 3 months.

CONCLUSIONS

Our findings suggest that a transition-home program may be beneficial to reduce the rehospitalization rate for VLBW infants, and infants on public insurance may derive greater benefit.

Maternal smoking during pregnancy, prematurity and recurrent wheezing in early childhood

BACKGROUND

Prenatal maternal smoking and prematurity independently affect wheezing and asthma in childhood.

OBJECTIVE

We sought to evaluate the interactive effects of maternal smoking and prematurity upon the development of early childhood wheezing.

METHODS

We evaluated 1,448 children with smoke exposure data from a prospective urban birth cohort in Boston. Maternal antenatal and postnatal exposure was determined from standardized questionnaires. Gestational age was assessed by the first day of the last menstrual period and early prenatal ultrasound (preterm < 37 weeks gestation). Wheezing episodes were determined from medical record extraction of well and ill/unscheduled visits. The primary outcome was recurrent wheezing, defined as ≥ 4 episodes of physician documented wheezing. Logistic regression models and zero inflated negative binomial regression (for number of episodes of wheeze) assessed the independent and joint association of prematurity and maternal antenatal smoking on recurrent wheeze, controlling for relevant covariates.

RESULTS

In the cohort, 90 (6%) children had recurrent wheezing, 147 (10%) were exposed to in utero maternal smoke and 419 (29%) were premature. Prematurity (odds ratio [OR] 2.0; 95% confidence interval [CI], 1.3-3.1) was associated with an increased risk of recurrent wheezing, but in utero maternal smoking was not (OR 1.1, 95% CI 0.5-2.4). Jointly, maternal smoke exposure and prematurity caused an increased risk of recurrent wheezing (OR 3.8, 95% CI 1.8-8.0). There was an interaction between prematurity and maternal smoking upon episodes of wheezing (P = 0.049).

CONCLUSIONS

We demonstrated an interaction between maternal smoking during pregnancy and prematurity on childhood wheezing in this urban, multiethnic birth cohort.

Virus respiratorio sincitial, metapneumovirus y virus parainfluenza humanos: cuadro clínico y fisiopatología

El VRSh causa la mayor parte de las bronquiolitis del lactante, infecciones respiratorias bajas que provocan trastornos respiratorios obstructivos y sibilancias. Los factores relacionados con las características del paciente (prematuridad, enfermedades asociadas, predisposición genética), con el virus (VRShA, genotipo, etc.) o el ambiente (contaminación, tabaquismo, etc.) son determinantes en la génesis de las bronquiolitis y determinan su gravedad. La mortalidad de la bronquiolitis es del 0,005-0,2% dependiendo de las características del paciente. No se conoce la fisiopatología de la bronquiolitis por VRSh. El papel directo del virus sobre el epitelio, la inmadurez del pulmón del lactante y, como se ha demostrado recientemente, el papel de la reacción inflamatoria, son factores destacados. También es probable que haya mecanismos inmunopatológicos (anticuerpos IgE, respuesta CD4+ Th2, etc.) que intervengan en ciertas bronquiolitis. La inmunidad anti-VRSh nunca llega a ser completa y las reinfecciones son frecuentes en los niños pequeños y las personas de edad avanzada, en quienes la infección por el VRSh representa aproximadamente el 5% de las afecciones respiratorias bajas. Con frecuencia se presentan con un cuadro de neumopatía infecciosa atípica con signos de bronquiolitis. Las infecciones debidas al VPIh3 suelen manifestarse por bronquiolitis, y las infecciones secundarias al VPIh1 y al 2 por laringotraqueítis. No se conoce bien la expresión clínica de las infecciones por VPIh4. El MPVh causa bronquiolitis comparables en todos sus aspectos a las que origina el VRSh.

Allergic diseases among very preterm infants according to nutrition after hospital discharge

To determine whether a cow's milk-based human milk fortifier (HMF) added to mother's milk while breastfeeding or a cow's milk-based preterm formula compared to exclusively mother's milk after hospital discharge, increases the incidence of developing allergic diseases among very preterm infants (VPI) during the first year of life. Of a cohort of 324 VPI (gestational age 24-32 wk), the exclusively breastfed VPI were shortly before discharge randomized to breastfeeding without fortification or supplementing with a fortifier. Those not breastfed were fed a preterm formula. The intervention period was from discharge until 4 months corrected age (CA). Follow-up was performed at 4 and 12 months CA including specific IgE to a panel of allergens at 4 months CA. The incidence during and prevalence at 12 months CA of recurrent wheezing (RW) was 39.2% and 32.7%, while atopic dermatitis (AD) was 18.0% and 12.1%, respectively. Predisposition to allergic disease increased the risk of developing AD (p=0.04) [OR 2.6 (95% CI 1.0-6.4)] and the risk of developing RW (p=0.02) [OR 2.7 (95% CI 1.2-6.3)]. Boys had an increased risk of developing RW (p=0.003) [OR 3.1 (95% CI 1.5-6.5)]. No difference was found between nutrition groups. None developed food allergy. Compared to exclusively breastfed, VPI supplemented with HMF or fed exclusively a preterm formula for 4 months did not have an increased risk of developing allergic diseases during the first year of life.

Exploring modifiable risk factors for wheezing in African American premature infants

OBJECTIVE

To examine the degree to which obesity during infancy, consistent exposure to secondhand smoke, and parenting (positive attention, maternal involvement, and negative control) were related to early development of wheezing in a cohort of African American premature infants at 2, 6, 12, 18, and 24 months corrected age.

DESIGN

Secondary analysis of a subset of variables from a larger nursing support intervention study.

SETTING

Two regional perinatal centers in the southeastern United States.

PARTICIPANTS

One hundred and sixty-eight African American premature infants (70 boys, 98 girls) who weighed less than 1,750 g or required mechanical ventilation and their mothers.

METHODS

The presence of wheezing was obtained from maternal report at 2, 6, 12, 18, and 24 months. Infants were considered to have medically significant wheezing if they were using bronchodilators or pulmonary anti-inflammatory medications.

RESULTS

The percentage of infants who had medically significant wheezing increased from 12% at 2 months to 24% at 24 months corrected age. Infants who received more positive attention from their mothers had a slightly higher increase in the probability of developing wheezing over time. Infants of mothers who received public assistance had an increased probability of wheezing. Consistent exposure to secondhand smoke, obesity during infancy, maternal negative control, and maternal involvement were not related to the development of wheezing.

CONCLUSION

These findings suggest that the likelihood of developing wheezing in African American premature infants is associated with receiving more positive attention from their mothers and having mothers who receive public assistance. Because modifiable risk factors were not highly related to wheezing, intervention efforts need to focus on early identification and treatment of wheezing and asthma-related symptoms.

Environmental Modifiers of Chronic Lung Disease of Prematurity During Infancy

Chronic lung disease is a common complication of prematurity with substantial mortality and morbidity. Although the variation seen in bronchopulmonary dysplasia has a strong genetic component, the limited environmental variation in neonatal intensive care units may lead to underestimates of the contribution of environmental factors to lung disease variation. Once discharged from the hospital, preterm infants are exposed to a variety of environmental factors that likely worsen their disease. Recognition of these factors may lead to improved outcomes in this vulnerable population through more effective guidelines and counseling. This review examines the role of selected outpatient environmental factors on respiratory outcomes during infancy in preterm infants with lung disease.

Parental and household smoking and the increased risk of bronchitis, bronchiolitis and other lower respiratory infections in infancy: systematic review and meta-analysis

BACKGROUND

Passive smoke exposure increases the risk of lower respiratory infection (LRI) in infants, but the extensive literature on this association has not been systematically reviewed for nearly ten years. The aim of this paper is to provide an updated systematic review and meta-analysis of studies of the association between passive smoking and LRI, and with diagnostic subcategories including bronchiolitis, in infants aged two years and under.

METHODS

We searched MEDLINE and EMBASE (to November 2010), reference lists from publications and abstracts from major conference proceedings to identify all relevant publications. Random effect pooled odds ratios (OR) with 95% confidence intervals (CI) were estimated.

RESULTS

We identified 60 studies suitable for inclusion in the meta-analysis. Smoking by either parent or other household members significantly increased the risk of LRI; odds ratios (OR) were 1.22 (95% CI 1.10 to 1.35) for paternal smoking, 1.62 (95% CI 1.38 to 1.89) if both parents smoked, and 1.54 (95% CI 1.40 to 1.69) for any household member smoking. Pre-natal maternal smoking (OR 1.24, 95% CI 1.11 to 1.38) had a weaker effect than post-natal smoking (OR 1.58, 95% CI 1.45 to 1.73). The strongest effect was on bronchiolitis, where the risk of any household smoking was increased by an OR of 2.51 (95% CI 1.96 to 3.21).

CONCLUSIONS

Passive smoking in the family home is a major influence on the risk of LRI in infants, and especially on bronchiolitis. Risk is particularly strong in relation to post-natal maternal smoking. Strategies to prevent passive smoke exposure in young children are an urgent public and child health priority.

[Effectiveness of therapeutic education and respiratory rehabilitation programs for the patient with asthma]

Asthma is a chronic complex and heterogeneous disease, with great variability and has a huge impact, not only on patients who suffer the disease but also their families and society in general. The education of the asthmatic patient and their families is essential for therapeutic intervention. Through continuous, dynamic and adaptive education, changes in attitudes and behaviours of the patient and family can be achieved, and will undoubtedly lead to an improvement in their quality of life. Among other non-pharmacological interventions, respiratory rehabilitation is an alternative treatment, and is primarily aimed at patients with moderate to severe asthma. Although the latest clinical practice guidelines published in the scientific literature recommend two strategies for treatment, the results of relevant publications are diverse. The objective of this study was to describe the effectiveness of therapeutic and educational programs in respiratory rehabilitation of the asthmatic patient.

Is there a link between wheezing in early childhood and adverse birth outcomes? A systematic review

We aimed to provide a summary of the existing published knowledge on the association between adverse birth outcomes and the development of wheezing during the first two years of life. We carried out a systematic review of epidemiological studies within the MEDLINE database. Epidemiological studies on human subjects, published in English, were included in the review. A comprehensive literature search yielded 72 studies for further consideration. Following the application of the eligibility criteria we identified nine studies. A positive association and an excess risk of wheezing during the first two years of life were revealed for adverse birth outcomes.

Fatores associados à morbidade respiratória entre 12 e 36 meses de vida de crianças nascidas de muito baixo peso oriundas de uma UTI neonatal pública

O objetivo do estudo foi estimar a morbidade respiratória entre 12 e 36 meses em crianças prematuras e identificar os fatores associados. A população compreendeu 84 crianças de uma coorte de prematuros de muito baixo peso. O desfecho foi a taxa de incidência de morbidade respiratória. A associação entre as variáveis independentes e morbidade respiratória foi verificada por modelo linear generalizado. Entre 12 e 24 meses, 56,3% das crianças apresentaram morbidade respiratória. Entre 24 e 36 meses, 38,1% das crianças foram acometidas. As variáveis associadas à morbidade respiratória foram: displasia broncopulmonar (RT = 1,9; IC95%: 1,2-2,9), complacência pulmonar alterada (RT = 1,6; IC95%: 1,1-2,2), pneumonia neonatal (RT = 2,8; IC95%: 2,0-4,0), persistência do canal arterial (RT = 1,6; IC95%: 1,1-2,4) e morbidade respiratória no primeiro ano de vida (RT = 1,8; IC95%: 1,3-2,6). A incidência de morbidade respiratória entre 12 e 36 meses se manteve elevada neste grupo de crianças de alto risco, o que reforça a necessidade de acompanhamento e de intervenções efetivas na prevenção do adoecimento e na melhora da qualidade de vida destas crianças e suas famílias.

Environmental exposures and respiratory morbidity among very low birth weight infants at 1 year of life

INTRODUCTION

Preterm infants have a substantially increased risk of developing respiratory illnesses. The goal of this study was to consider the impact of modifiable postnatal exposures on respiratory morbidity among a cohort of very low birth weight (VLBW) infants.

OBJECTIVES

(1) Assess the rates of respiratory morbidity and exposure to indoor respiratory triggers in a population of VLBW infants at 1 year; (2) determine the association between exposures and respiratory morbidity.

METHODS

We enrolled 124 VLBW infants into a prospective cohort study. Parents were called at 1 year to assess respiratory outcomes and environmental exposures. We used bivariate and multivariate analyses to assess the relationship between environmental exposures and acute care for respiratory illnesses.

RESULTS

At 1 year, 9% of infants had physician-diagnosed asthma, 47% required >or=1 acute visit and 11% required hospitalisation for respiratory illness. The majority of infants (82%) were exposed to at least one indoor respiratory trigger. Infants living with a smoker (61% vs 40%) and infants exposed to pests (62% vs 39%) were more likely than unexposed infants to require acute care for respiratory problems. In a multivariate regression controlling for demographics, birth weight, bronchopulmonary dysplasia, and family history of asthma or allergies, both living with a smoker (OR 2.62; CI 1.09 to 6.29) and exposure to pests (OR 4.41; CI 1.22 to 15.94) were independently associated with the need for acute care for respiratory illnesses.

CONCLUSIONS

In this sample, respiratory morbidity and exposure to triggers were common. VLBW infants may benefit from interventions that decrease exposure to respiratory triggers.

One-year respiratory outcomes of preterm infants enrolled in the Nitric Oxide (to prevent) Chronic Lung Disease trial

OBJECTIVE

To identify whether inhaled nitric oxide treatment decreased indicators of long-term pulmonary morbidities after discharge from the neonatal intensive care unit.

STUDY DESIGN

The Nitric Oxide (to Prevent) Chronic Lung Disease trial enrolled preterm infants (<1250 g) between 7 to 21 days of age who were ventilated and at high risk for bronchopulmonary dysplasia. Follow-up occurred at 12 +/- 3 months of age adjusted for prematurity; long-term pulmonary morbidity and other outcomes were reported by parents during structured blinded interviews.

RESULTS

A total of 456 infants (85%) were seen at 1 year. Compared with control infants, infants randomized to inhaled nitric oxide received significantly less bronchodilators (odds ratio [OR] 0.53 [95% confidence interval 0.36-0.78]), inhaled steroids (OR 0.50 [0.32-0.77]), systemic steroids (OR 0.56 [0.32-0.97]), diuretics (OR 0.54 [0.34-0.85]), and supplemental oxygen (OR 0.65 [0.44-0.95]) after discharge from the neonatal intensive care unit. There were no significant differences between parental report of rehospitalizations (OR 0.83 [0.57-1.21]) or wheezing or whistling in the chest (OR 0.70 [0.48-1.03]).

CONCLUSIONS

Infants treated with inhaled nitric oxide received fewer outpatient respiratory medications than the control group. However, any decision to institute routine use of this dosing regimen should also take into account the results of the 24-month neurodevelopmental assessment.

Late respiratory outcomes after preterm birth

Chronic respiratory morbidity is common following premature birth, particularly if complicated by bronchopulmonary dysplasia (BPD) development. Affected patients can remain oxygen dependent for many months, but unusually beyond two years. Those requiring supplementary oxygen at home have increased healthcare utilisation, even during the preschool years when no longer oxygen dependent. More than 50% of "BPD" patients require readmission in the first two years, particularly for respiratory infections. Prematurely born children, especially those who had BPD, are more likely to suffer frequent troublesome symptoms at school age and in adolescence than term born controls. This is associated with evidence of airways obstruction. Although lung function improves as the clinical condition improves, abnormalities can be detected even in young adults who had severe BPD. Nowadays, severe BPD is uncommon, but those with "new" BPD may have abnormal antenatal lung growth, whether they achieve appropriate catch up lung growth needs careful investigation.

Cord blood cytokines and acute lower respiratory illnesses in the first year of life

OBJECTIVES

Little is known about the relation between cytokine profile at birth and acute lower respiratory illnesses in the first year of life. The purpose of this work was to examine the relation between cytokine secretions by cord blood mononuclear cells and acute lower respiratory illness in a birth cohort of 297 children.

METHODS

Cord blood mononuclear cells were isolated, and secretion of interferon-gamma, interleukin-13, interleukin-10, and tumor necrosis factor-alpha at baseline and in response to allergens (Blatella germanica 2 and Dermatophagoides farinae 1) and mitogen (phytohemagglutinin) were quantified using enzyme-linked immunosorbent assay. Acute lower respiratory illness was defined as a parental report of a diagnosis of bronchiolitis, pneumonia, bronchitis, and/or croup by a health care professional in the first year of life. Differences in the levels of cord blood cytokines between children with and without acute lower respiratory illness were examined using 2-sample Wilcoxon tests. Logistic regression models were used to examine the relation between various categories of cord blood cytokines and acute lower respiratory illness.

RESULTS

Median levels of interferon-gamma secreted by cord blood mononuclear cells in response to Blatella germanica 2 and Dermatophagoides farinae 1 were higher among children without acute lower respiratory illness as compared with children with acute lower respiratory illness. After adjustment for other covariates, the odds of acute lower respiratory illness was reduced among children in the top category (at or more than the median of detectable values) of interferon-gamma level, significantly so in response to Blatella germanica 2.

CONCLUSIONS

In a cohort of children from the general population, we found that upregulated interferon-gamma secretion at birth is associated with reduced risk of acute lower respiratory illness in the first year of life.

Altered airway responsiveness in adult sheep born prematurely: effects of allergen exposure

The aim of this study was to determine the effects of preterm birth per se on airway function in adult sheep. Preterm birth was induced at approximately 0.89 of term. At approximately 1 year of age the authors measured pulmonary resistance (RL) and airway responsiveness before and after house dust mite (HDM) challenge. Mature preterm sheep tended to have greater baseline RL than controls (P = .12): the smaller preterm sheep showed significantly greater RL than controls following bronchoconstrictor challenge. Preterm animals tended to have greater baseline total blood leukocyte count (P = .06). It was concluded that preterm sheep, especially with low postnatal growth, have greater airway responsiveness to bronchoconstrictor and higher baseline RL.

Neonatal risk factors for respiratory morbidity during the first year of life among premature infants

CONTEXT AND OBJECTIVE

There have been dramatic increases in very low birth weight infant survival. However, respiratory morbidity remains problematic. The aim here was to verify associations between pulmonary mechanics, pulmonary structural abnormalities and respiratory morbidity during the first year of life.

DESIGN AND SETTING

Prospective cohort study at Instituto Fernandes Figueira, Fundação Oswaldo Cruz, Rio de Janeiro.

METHODS

Premature infants with birth weight < 1500 g were studied. Lung function tests and high-resolution chest tomography were performed before discharge. During the first year, infants were assessed for respiratory morbidity (obstructive airways, pneumonia or hospitalization). Neonatal lung tests and chest tomography and covariables potentially associated with respiratory morbidity were independently assessed using relative risk (RR). RR was subsequently adjusted via logistic regression.

RESULTS

Ninety-seven newborn infants (mean birth weight: 1113 g; mean gestational age: 28 weeks) were assessed. Lung compliance and lung resistance were abnormal in 40% and 59%. Tomography abnormalities were found in 72%; respiratory morbidity in 53%. Bivariate analysis showed respiratory morbidity associated with: mechanical ventilation, prolonged oxygen use (beyond 28 days), oxygen use at 36 weeks, respiratory distress syndrome, neonatal pneumonia and patent ductus arteriosus. Multivariate analysis gave RR 2.7 (confidence interval: 0.7-10.0) for simultaneous lung compliance and chest tomography abnormalities. Adjusted RR for neonatal pneumonia and mechanical ventilation were greater.

CONCLUSIONS

Upon discharge, there were high rates of lung mechanism and tomography abnormalities. More than 50% presented respiratory morbidity during the first year. Neonatal pneumonia and mechanical ventilation use were statistically significant risk factors.

Wheezing illness and re-hospitalization in the first two years of life after neonatal respiratory distress syndrome

OBJECTIVES

To determine the impact of respiratory distress syndrome (RDS) on wheezing illnesses and re-hospitalizations in children as old as 2 years of age.

STUDY DESIGN

We observed 2 geographically defined cohorts of children with RDS born after 26 weeks of gestation during 1990 to 1995 and 1996 to 1999 and gestationally paired control subjects. Recurrent wheezing illness and the re-hospitalizations caused by a respiratory condition were recorded.

RESULTS

In the first year of life, 47 of 224 infants with RDS and 18 of 224 control subjects born in 1990 to 1995 had recurrent wheezing illness (P <.005) compared with 21 of 109 infants with RDS and 14 of 109 control subjects in the latter cohort (P=.27). A higher number of infants with RDS were readmitted to the hospital (25% versus 13%, P=.002) in the former period, and they spent more days in hospital during both periods. The frequencies of wheezing remained constant in the second year of life, but hospital admissions decreased. Siblings at home, male sex, and bronchopulmonary dysplasia were additional risk factors of wheezing illnesses.

CONCLUSION

RDS increases the incidence of wheezing illnesses during the first 2 years of life. Changes in the management of RDS during the 1990s was associated with a decreased incidence of subsequent RDS-associated respiratory morbidity.

Hypoallergenic formulas--when, to whom and how long: after more than 15 years we know the right indication!

Hypoallergenic formulas are processed by enzymatic hydrolysis of different protein sources such as bovine casein/whey and soy followed by further processing such as heat treatment and/or ultrafiltration, or they are based on amino acid mixtures. The products have been classified according to the degree of protein hydrolysis as 'extensively' or 'partially' hydrolysed protein products. Product properties may be characterized by biochemical techniques, and reduction of allergenicity may be assessed in vitro with various immunological methods, and in vivo with skin prick tests, patch tests and challenge tests. In vitro tests do not predict the allergenic effects in humans, and at present there is no evidence of a specific threshold of immunogenic protein. Only pure amino acid mixtures are considered to be nonallergenic. Other 'hypoallergenic' products contain residual allergenicity. At present, the potential of a product for treatment and prevention of food allergy can only be determined by clinical trials using scientifically appropriate standards. It has been recommended that dietary products for treatment of cow's milk protein allergy in infants should be tolerated by at least 90% (with 95% confidence) of infants with documented cow's milk protein allergy. Some extensively hydrolysed products and amino-acid-based products have met these criteria. Formulas intended for prevention should have a very low, if any, allergenic activity until otherwise proven. So far there are no firm criteria available for the design of hypoallergenic foods for prevention. Newborns included in prevention studies should be from high-risk families; they should be randomized at birth and fed the formula when supplements are needed for at least the first 4-6 months of life. Follow-up should be at least 18 months, and children should be investigated when symptoms appear. Validated clinical criteria, including controlled food challenges, should be used for diagnosis. Infants fed formulas that claim to prevent or delay allergy should have a statistically significant lower prevalence of allergy when compared with infants fed a standard cow's milk formula. Feeding high-risk infants a documented hypoallergenic formula combined with avoidance of solid foods during the first 4-6 months reduces the cumulative incidence of cow's milk protein allergy and atopic dermatitis as compared with a standard cow's-milk-based formula. Partially hydrolysed formulas may have an effect, though it seems to be less than that of extensively hydrolysed formulas at present. Thus, if exclusive breast-feeding for 4-6 months is not possible in high-risk infants, a documented hypoallergenic formula and avoidance of solid foods are recommended for the first 4 months of life.

Dietary prevention of allergic diseases in infants and small children. Part III: Critical review of published peer-reviewed observational and interventional studies and final recommendations

The role of primary prevention of allergic diseases has been a matter of debate for the last 40 years. In order to shed some light on this issue, a group of experts of the Section of Pediatrics EAACI reviewed critically the existing literature on the subject. An analysis of published peer-reviewed observational and interventional studies was performed following the statements of evidence as defined by WHO. The results of the analysis indicate that breastfeeding is highly recommended for all infants irrespective of atopic heredity. A dietary regimen is unequivocally effective in the prevention of allergic diseases in high-risk children. In these patients breastfeeding combined with avoidance of solid food and cow's milk for at least 4-6 months is the most effective preventive regimen. In the absence of breast milk, formulas with documented reduced allergenicity for at least 4-6 months should be used.

Pulmonary Function at Follow-up of Very Preterm Infants from the United Kingdom Oscillation Study

Prematurely born infants supported by conventional ventilation (CV) frequently have abnormal pulmonary function when assessed in childhood. The aim of this study was to test the hypothesis that infants who were randomly assigned to high-frequency oscillatory ventilation would have superior pulmonary function at follow-up compared with those who received CV (UK Oscillation Study). Infants from 12 trial centers were recruited for pulmonary function testing at a single center. Seventy-six infants, of a mean gestational age 26.4 weeks, were studied after sedation with chloral hydrate at between 11 and 14 months of age, corrected for prematurity. Infants assigned to CV had similar pulmonary function compared with those assigned to high-frequency oscillatory ventilation, with mean (SD) results as follows: functional residual capacity measured by whole-body plethysmography, 26.9 (6.3) versus 26.5 (6.4) ml/kg; functional residual capacity measured by helium dilution, 24.1 (5.4) versus 23.5 (5.7) ml/kg; inspiratory airway resistance, 3.3 (1.3) versus 3.4 (1.6) kPa. second. L; expiratory airway resistance, 4.4 (2.8) versus 4.1 (2.5) kPa. second. L; respiratory rate, 31.2 (6.0) versus 33.9 (8.0) breaths/minute. We conclude that early use of high-frequency oscillatory ventilation in very preterm infants appears to offer no advantage over CV in terms of pulmonary function at follow-up.

Helper T-lymphocyte-related chemokines in healthy newborns

Atopic disease is characterized by an imbalance in cytokines secreted from Th1 and Th2 lymphocytes. The association between atopy and serum levels of atopy-related chemokines in umbilical cord blood (UCB) has not been evaluated. This study formulates the reference ranges of thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), eotaxin (EOX), monocyte chemotactic protein 1 (MCP-1), and interferon-gamma-inducible protein 10 (IP-10) in UCB of term neonates and investigates the relation between these chemokines and the development of atopy during infancy. The concentrations of total IgE and chemokines in UCB serum were measured by microparticle immunoassay and sandwich enzyme immunoassay, respectively. A total of 124 singleton healthy newborns were investigated. Fifty-three (43%) infants had family history of allergic diseases, and 26 (21%) had increased serum total IgE concentrations. The median (interquartile range) serum TARC, MDC, EOX, MCP-1, and IP-10 concentrations, in pg/mL, were 425 (300-639), 786 (561-1050), 36 (28-45), 156 (116-205), and 38 (29-49), respectively. Multiparity was associated with increased serum MDC (p = 0.017). Serum chemokine concentrations were not associated with total IgE levels or family history of allergies. The median (interquartile range) serum MDC concentrations in newborns who developed wheezing during infancy and those without wheezing were 1259 pg/mL (945-1523) and 782 pg/mL (551-992), respectively (p = 0.010). This study provides reference ranges of Th-specific chemokines in UCB serum of singleton term neonates. Increased serum MDC concentrations at birth are associated with the occurrence of wheezing during infancy.

Respiratory symptoms and lung function in relation to atopy in children born preterm

Respiratory morbidity is a major health problem among children. The aim of this study was to compare the background of respiratory problems of children born preterm with that of children born full-term, with special reference to atopy. The study comprised two cohorts of 10-year-old children: a group of 72 children born preterm with birth weights of less than 1,501 g, and a group of 65 children born full-term with birth weights of over 2,500 g. Histories of respiratory and atopic symptoms, and of risk factors for atopy, were collected with a questionnaire. Predisposition to atopy was verified by skin-prick testing and by measuring serum total and antigen-specific IgEs. Lung function was evaluated by spirometry testing. Children born preterm had significantly more wheezing. In them, the lifetime prevalence of wheezing was 43%, vs. 17% in children born full-term (P = 0.001; odds ratio, 3.71; 95% confidence interval, 1.67-8.25). In the full-term group, wheezing was associated with atopy: 64% of wheezers were atopic; in the preterm group, 23% of wheezers were atopic (difference between groups, P = 0.024). Children born preterm expired significantly lower spirometry values of forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), FEV1/FVC ratio, forced expiratory flow after 50% of vital capacity has been exhaled (FEF50), and forced expiratory flow during middle half of FVC (FEF25-75). In the preterm group, wheezing, asthma, and low gestational age, but not atopy, were significantly associated with lower lung function values. Wheezers of the preterm group who still wheezed at age 10 were significantly more often atopic than those who no longer wheezed (62% vs. 9%, P = 0.006). In conclusion, we demonstrated a significant difference between groups in the association of atopy with respiratory problems. However, although atopy was not associated with a lifetime prevalence of respiratory symptoms in prematurely born children, an atopic predisposition in them was found to associate with persistence of wheezing.

Pulmonary function and exercise capacity for ELBW survivors in preadolescence: effect of neonatal chronic lung disease

OBJECTIVE

To assess pulmonary function and exercise capacity of apparently asymptomatic children who were born extremely preterm.

STUDY DESIGN

Pulmonary function and treadmill testing were performed on 50 children 9 to 15 years old who had birth weight <801 g (extremely low birth weight [ELBW]) and without apparent neurodevelopmental or pulmonary disabilities, compared with 25 children born at term with normal birth weight (NBW). Medical history and physical activity levels were assessed by parent questionnaire. Group differences were determined by two-sample t test. Secondary analysis was performed to assess significant influence of neonatal chronic lung disease (CLD) on outcome measures.

RESULTS

Twenty percent of ELBW subjects but no subjects with NBW had clinically abnormal pulmonary function (>2 SD from norms, P=.026). All significant pulmonary function differences except peak expiratory flow rate percentages were accounted for by ELBW subjects who had CLD. Oxygen consumption measurements were significantly lower for subjects with ELBW (30.3+/-6.9 and 38.5+/-5.2 mL/kg/min, P=.000), independent of CLD status.

CONCLUSION

Pulmonary function abnormalities consistent with obstructive lung disease were more frequently detected in ELBW children who had neonatal CLD. Low oxygen consumption measurements suggest a lower level of fitness for ELBW children compared with children with NBW.

Breastfeeding and allergic disease: a multidisciplinary review of the literature (1966-2001) on the mode of early feeding in infancy and its impact on later atopic manifestations

BACKGROUND

Strategies to prevent children from developing allergy have been elaborated on the basis of state-of-the-art reviews of the scientific literature regarding pets and allergies, building dampness and health, and building ventilation and health. A similar multidisciplinary review of infant feeding mode in relation to allergy has not been published previously. Here, the objective is to review the scientific literature regarding the impact of early feeding (breast milk and/or cow's milk and/or formula) on development of atopic disease. The work was performed by a multidisciplinary group of Scandinavian researchers.

METHODS

The search in the literature identified 4323 articles that contained at least one of the exposure and health effect terms. A total of 4191 articles were excluded mainly because they did not contain information on both exposure and health effects. Consequently, 132 studies have been scrutinized by this review group.

RESULTS

Of the 132 studies selected, 56 were regarded as conclusive. Several factors contributed to the exclusions. The studies considered conclusive by the review group were categorized according to population and study design.

CONCLUSIONS

The review group concluded that breastfeeding seems to protect from the development of atopic disease. The effect appears even stronger in children with atopic heredity. If breast milk is unavailable or insufficient, extensively hydrolysed formulas are preferable to unhydrolysed or partially hydrolysed formulas in terms of the risk of some atopic manifestations.

Evaluation of the wheezy infant

BACKGROUND

The infant with persistent or recurrent wheezing during the first 2 years of life poses a diagnostic dilemma, which can be a source of anxiety to both physicians and parents. A suggested diagnostic approach to the causes of infantile wheezing is outlined.

OBJECTIVES

1. To review the physiologic considerations of the infant's airways that predispose to wheezing. 2. To discuss the key physical findings, family history, and risk factors associated with wheezing in infants. 3. To develop a rational approach to the differential diagnosis and management of infantile wheezing.

DATA SOURCES

The MEDLINE database as well as our clinical experience pertaining to infantile wheezing.

CONCLUSIONS

This review discusses the diagnostic evaluation and treatment of the wheezing infant. We suggest that infant pulmonary function testing may be used as one diagnostic aid in the workup of the wheezing infant.

Postpartum smoking behaviors and immune response in mothers of term and preterm infants

Infants exposed to secondhand smoke, especially preterm infants with a very low birth weight (VLBW), have an increased risk for developing health problems. Smoking has been associated with numerous health problems in mothers and may reduce immune functioning as well. The purposes of this study were to examine smoking in postpartum mothers of term and preterm infants and to examine the relationship between smoking and immune status. Peripheral blood was drawn on 142 women at four data-collection points and tested for cotinine, immune cell phenotypes, and immune functioning. Overall, 39% of the participants smoked in the postpartum period, but 49% of mothers who delivered preterm infants smoked compared to only 28% of mothers who delivered term infants. There was no difference in cotinine levels between the smokers in both groups of postpartum mothers, nor was smoking related to immune phenotypes or immune function. Given the documented health risks to the mother and infant and the significant number of women who continue to smoke in the postpartum period, it is imperative that health care providers continue to assess smoking status and provide smoking-cessation counseling at every encounter.

Very low birthweight and asthma by age seven years in a national cohort

Several studies have suggested that very low birthweight (VLBW < 1500 g) is associated with increased rates of respiratory problems in childhood and that the presence of chronic lung disease further increases the risk. We aimed to assess rates of asthma at 7-8 years of age in a national cohort of VLBW infants born in 1986 and for whom perinatal data were available. Two hundred ninety-nine former VLBW children (96% of surviving children living in New Zealand) were assessed at a home visit. Parents were asked a comprehensive questionnaire, including three questions aimed at assessing morbidity from asthma: 1) was the child diagnosed as having asthma before age 7 years; 2) was the child still experiencing asthma at the age of 7 years; and 3) was the child prescribed daily medication for asthma at the age of 7 years. Overall, 50% of the cohort had been diagnosed with asthma before age 7, compared with 27% of a sample of New Zealand children assessed contemporaneously in an international study; 32% had asthma at age 7, and 11% were taking daily medication. All three categories of asthma were associated with a family history of asthma, but there was no association with any perinatal factors. A diagnosis of asthma before age 7 was more likely when the mother smoked in pregnancy (P < 0.005) and currently smoked (P < 0.01), and trended so when parents lacked high school qualifications and in Maori or Pacific Island families (P < 0.10). In contrast, daily medication was more frequent when parents had educational qualifications and in non-Maori or Pacific Island families (P < 0.05). On multiple logistic regression, a family history of asthma was a significant predictor for any and current asthma (P < 0.001) and daily medication (P < 0.05); maternal smoking in pregnancy was a significant predictor for any asthma (P < 0.05); and non-Maori or Pacific Island ethnicity was a significant predictor for asthma treatment (P < 0.05). We conclude that rates of childhood asthma are high in this VLBW cohort, but the high prevalence appears to be unrelated to perinatal factors, including respiratory morbidity. There are suggestions that social factors contribute to both asthma risk and treatment.

Pediatric origins of adult lung disease. 1. The contribution of airway development to paediatric and adult lung disease

In summary, factors that affect airway growth early in development appear to cause physiological effects that can be persistent. Reduced airway function early in life does not necessarily result in persistent symptoms, but the long term effects and impact on the development of chronic airflow limitation in adults are yet to be determined. Generally, long term sequelae seem to be related to the severity of the initial insult, but the development of persistent increased bronchial responsiveness is an independent risk factor for symptoms and abnormal lung function in later life. In addition, there appear to be separate genetic factors that influence atopy, airway development, and bronchial responsiveness.

Measuring respiratory outcome

Chronic respiratory morbidity is a common outcome of very premature birth. Infants who are chronically oxygen dependent with an abnormal chest radiograph are described as suffering from chronic lung disease (CLD), and those with the worst abnormalities diagnosed as having bronchopulmonary dysplasia. CLD infants are very likely to be readmitted to hospital during infancy, particularly during a respiratory syncytial virus (RSV) epidemic. Very low birthweight, prematurity and CLD are associated with recurrent respiratory symptoms and lung function abnormalities during the preschool years. These problems are detected even in adolescents who were chronically oxygen dependent after premature birth. Further research to identify effective preventative strategies is urgently required.

A risk-benefit assessment of drugs used for neonatal chronic lung disease

Improvements in neonatal intensive care have resulted in more extremely low birthweight babies surviving who are at risk of developing chronic lung disease. The preterm lung is vulnerable as it is both structurally immature and deficient in surfactant and antioxidant defences. Mechanical ventilation and high inspired oxygen concentrations are often necessary for preterm babies to survive but they can cause pulmonary inflammation which leads to lung damage. Abnormal healing in the presence of ongoing inflammation leads to airways remodelling which can result in protracted respiratory problems in these babies. A commonly used definition for chronic lung disease is the requirement for supplemental oxygen beyond 36 weeks' postconception. Many drugs that are commonly used for chronic lung disease have not been subjected to proper randomised controlled trials but are widely used on the basis of small studies showing short term benefits. They can be broadly divided into 2 groups. First, there are preventative drugs that are administered early to reduce oxygen toxicity and pulmonary inflammation. Secondly, there are those administered in established chronic lung disease, designed to reduce respiratory morbidity. Pulmonary inflammation in the neonate is reduced by systemic corticosteroids. Corticosteroid therapy within the first 2 weeks of life enables earlier extubation of preterm babies with subsequent reduced chronic lung disease and improved neonatal survival when given between 7 and 14 days. However, there is an increased risk of gastrointestinal haemorrhage, metabolic derangement, ventricular hypertrophy and potential effects on long term growth and brain development. Diuretics and inhaled bronchodilators improve pulmonary compliance and reduce oxygen requirements in established chronic lung disease but probably have little effect in reducing the incidence. In babies with established chronic lung disease, home oxygen therapy enables earlier discharge and prophylaxis against respiratory syncytial virus can reduce morbidity from bronchiolitis. All of the above therapies have adverse effects that need to be considered before initiating treatment. Recently, new drugs have become available which may be beneficial. These include inhaled nitric oxide for reduction of ventilation-perfusion mismatching, recombinant human superoxide dismutase for protection against oxidative stress and alpha-1 proteinase inhibitor which may reduce airways remodelling. At present these therapies are undergoing clinical trials. Exogenous surfactant is beneficial in respiratory distress syndrome and may reduce the risk of chronic lung disease but there have been no randomised controlled trials of its use in established chronic lung disease. Drugs which have been tried unsuccessfully include erythromycin, ambroxol and mast cell stabilisers.

Hospital admissions in the first year of life in very preterm infants

OBJECTIVE

To analyse hospital readmissions to 1 year in infants < 33 weeks' gestation.

STUDY DESIGN

Cohort of very preterm infants born in Western Australia.

METHODS

Parental social class, history of asthma, race, gestational age, birthweight, sex, severity of respiratory disease and oxygen requirement at 28 days chronic lung disease (CLD), 36 weeks and term, maternal smoking, cohabitation with siblings, breast-feeding duration and hospital readmissions were recorded prospectively.

RESULTS

Data were available for 538 of 560 (96%) infants discharged. Eight died in the first year. Two hundred and twenty-five infants (42%) had 443 readmissions, of which 370 were medical and 73 surgical. Risk factors for medical readmission were Aboriginal race, male sex and CLD. Breast-feeding was protective. Risk factors for surgical admission were male sex, lower gestation, severe hyaline membrane disease, severe CLD and birthweight < 10th centile.

CONCLUSIONS

Readmission is common after very preterm birth. Risk factors for medical and surgical admission differ with CLD being the only perinatal factor associated with both medical and surgical admission.

Health effects of passive smoking. 1. Parental smoking and lower respiratory illness in infancy and early childhood

BACKGROUND

A systematic quantitative review was conducted of evidence relating parental smoking to acute lower respiratory illness in the first three years of life.

METHODS

Fifty relevant publications were identified after consideration of 692 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search, completed in April 1997, identified 24 studies ascertaining illnesses in a community setting, including five surveys of schoolchildren with retrospective ascertainment of early chest illness, and 17 studies of admissions to hospital for lower respiratory illness in early life. Thirty eight studies were included in a quantitative overview using random effects modelling to derive pooled odds ratios.

RESULTS

The results of community and hospital studies are broadly consistent, with only one publication reporting a reduced risk among children of smokers. The pooled odds ratios were 1.57 (95% CI 1.42 to 1.74) for smoking by either parent and 1.72 (95% CI 1.55 to 1.91) for maternal smoking. There is a significantly increased risk of early chest illness associated with smoking by other household members in families where the mother does not smoke (1.29, 95% CI 1.16 to 1.44). The associations with parental smoking are robust to adjustment for confounding factors, and show evidence of a dose-response relationship in most studies in which this has been investigated.

CONCLUSIONS

The relationship between parental smoking and acute lower respiratory illness in infancy is very likely to be causal. Although it is impossible to distinguish the independent contributions of prenatal and postnatal maternal smoking, the increased risk associated with smoking by other household members suggests that exposure to environmental tobacco smoke after birth is a cause of acute chest illness in young children.