Parental smoking and airway reactivity in healthy infants

Tobacco Exposure During Pregnancy and Infections in Infants up to 1 Year of Age: The Japan Environment and Children's Study

BACKGROUND

Tobacco exposure during pregnancy is associated with several adverse outcomes in infants. We investigated the association between tobacco exposure during pregnancy (both active and second-hand) and various infections in infants up to 1 year.

METHODS

This prospective cohort study used a fixed dataset (jecs-an-20180131) from the Japan Environment and Children's Study of registered births in Japan during 2011-2014 that included 104,065 fetal records from enrolled pregnant women. Based on the participants' responses to the questionnaire on smoking status, mothers were first divided into "never smoked," "quit smoking," and "current smoker" groups and then into "no second-hand smoking (SHS)" and "SHS" groups. Infectious diseases included central nervous system infection, otitis media (OM), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), gastroenteritis (GI), and urinary tract infection. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated using logistic regression analysis and adjusted for maternal, socioeconomic, and postnatal confounding factors.

RESULTS

Among the 73,205 newborns enrolled, multivariable analysis revealed that the aOR of LRTI and GI was 1.20 (95% CI, 1.07-1.33) and 1.18 (95% CI, 1.04-1.35), respectively, for the "current smoker with/without SHS" group compared with the "never smoked without SHS" group. "Quit smoking without SHS" was not associated with the risk of LRTI. SHS was associated with an increased risk of OM, URTI, LRTI, and GI, especially with LRTI and GI.

CONCLUSION

Exposure to tobacco smoke during pregnancy was associated with an increased risk of OM, URTI, LRTI, and GI in infants during their first year of life.

Respiratory Compliance in Late Preterm Infants (340/7-346/7 Weeks) after Antenatal Steroid Therapy

OBJECTIVE

To compare respiratory compliance in late preterm infants (34^0/7-34^6/7 weeks) who received antenatal steroids vs matched late preterm infants who did not receive antenatal steroids.

STUDY DESIGN

This was a single-center prospective cohort study. Patients were matched for birth weight, gestational age, race, and sex. Respiratory compliance was the primary outcome measured with the single breath occlusion technique.

RESULTS

We studied 25 late preterm infants treated with antenatal steroids and 25 matched infants who did not receive antenatal steroids. The treated infants had a significantly increased respiratory compliance/kg (adjusted 95% CI 0.05, 0.49; P = .016) and fewer required continuous positive airway pressure (P = .007) or >24 hours of supplemental oxygen (P = .046). There was no difference in surfactant therapy.

CONCLUSIONS

Respiratory compliance was significantly increased in this cohort of late preterm infants born at 34^0/7-34^6/7 weeks who received antenatal steroids compared with matched infants who did not receive antenatal steroids. Although not randomized, these data provide physiologic support for the possible beneficial effects of antenatal steroids in late preterm infants.

The Relationship Between Tobacco Smoke Exposure and Airflow Obstruction in US Children: Analysis of the National Health and Nutrition Examination Survey (2007-2012)

BACKGROUND

It has been difficult to determine the individual impact of prenatal and postnatal tobacco smoke exposure (TSE) on childhood lung function, as children are often exposed to both.

OBJECTIVE

The goal of this study was to determine the association between current TSE and airflow obstruction while adjusting for self-reported prenatal TSE.

METHODS

Children aged 6 to 11 years who participated in the National Health and Nutrition Examination Survey (2007-2012) who had serum cotinine levels measured and spirometry performed were included. Logistic regression was used to determine the association between log-transformed serum cotinine level and airflow obstruction while adjusting for confounders; the analysis was then stratified according to asthma status. The final model included both log-transformed serum cotinine level and prenatal exposure as covariates.

RESULTS

The sample consisted of 2,070 children; 9.6% had airflow obstruction. The association between cotinine levels and airflow obstruction was significant in an unadjusted analysis (OR, 1.12 [95% CI, 1.02-1.23]). In the multivariate analysis with both exposures included as covariates, serum cotinine level was not significantly associated with airflow obstruction (OR_adj, 1.07 [95% CI, 0.94-1.21]), and no association was seen in children with asthma and nonasthmatic children. Prenatal smoking was associated with airflow obstruction in children with asthma (OR_adj, 2.51 [95% CI, 1.08-5.79]) but not in nonasthmatic children (OR_adj, 1.08 [95% CI, 0.53-2.18]).

CONCLUSIONS

Current TSE was not independently associated with airflow obstruction in school-aged children. Prenatal TSE was associated with airflow obstruction in children with asthma. Repeated studies into potential mediators and confounders of this relationship are needed.

Impulse oscillometry, spirometry, and passive smoking in healthy children and adolescents

OBJECTIVE

To identify changes in the forced and quiet breathing parameters of lung function in healthy children and adolescents exposed to passive smoking (PS).

METHOD

Comparative cross-sectional study. Healthy schoolchildren aged 6 to 14 years. We collected anthropometric data, lung function parameters using spirometry (forced breathing), and quiet breathing parameters using impulse oscillometry. The sample was divided into two groups according to exposure to PS: passive smoking group (PSG) and non-passive smoking group (NPSG). For the statistical analysis, the Shapiro-Wilk test was used to verify data normality and the T-test or Mann-Whitney test to compare spirometric and oscillometric parameters between groups (p≤0.05).

MAIN FINDINGS

The study included 78 children and adolescents, with 14 boys and 25 girls in each group. There were differences in the mean values for peak expiratory flow (p=0.01). There were no significant differences between the groups in values for z-score and lower limit of normal. The PSG had higher mean absolute values for reactance area (X5=0.05) and significant percentage of predicted values for the following impulse oscillometry parameters: central airway resistance (R20%, p=0.03) and for the indicators of presence of airway obstruction (Fres%, p=0.01; X5%=0.01% and AX%, p=0.01).

CONCLUSION

Children and adolescents exposed to PS had lower values for the spirometric variables and higher values for the oscillometric variables, indicating changes in forced and quiet parameters of lung function compared to the NPSG.

Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP): Rationale, design, and methods of a randomized, controlled trial of vitamin C supplementation in pregnancy for the primary prevention of effects of in utero tobacco smoke exposure on infant lung function and respiratory health

Despite strong anti-smoking efforts, at least 12% of American women cannot quit smoking when pregnant resulting in >450,000 smoke-exposed infants born yearly. Smoking during pregnancy is the largest preventable cause of childhood respiratory illness including wheezing and asthma. Recent studies have shown a protective effect of vitamin C supplementation on the lung function of offspring exposed to in utero smoke in a non-human primate model and an initial human trial. Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP) is a randomized, double-blind, placebo-controlled trial to evaluate pulmonary function at 3months of age in infants delivered to pregnant smokers randomized to 500mg/day of vitamin C versus placebo during pregnancy. Secondary aims evaluate the incidence of wheezing through 12months and pulmonary function testing at 12months of age. Women are randomized between 13 and 23weeks gestation from clinical sites in Portland, Oregon at Oregon Health & Science University and PeaceHealth Southwest Medical Center and in Indianapolis, Indiana at Indiana University and Wishard Hospital. Vitamin C supplementation occurs from randomization to delivery. Monthly contact with participants and monitoring of medical records is performed to document medication adherence, changes in smoking and medical history, and adverse events. Pulmonary function testing of offspring occurs at 3 and 12months of age and incidence of wheezing and respiratory illness through 12months is captured via at least quarterly questionnaires. Ancillary studies are investigating the impact of vitamin C on placental blood flow and DNA methylation.

Early Childhood Risk Factors for Decreased FEV1 at Age Six to Seven Years in Young Children with Cystic Fibrosis

RATIONALE

There are limited objective measures of the severity of lung disease before children are able to routinely perform spirometry, generally at age 6 years. Identifying risk factors for reduced lung function at age 6 provides opportunities to intervene and slow the progression of cystic fibrosis (CF) lung disease.

OBJECTIVES

To evaluate early childhood predictors of lung function at age 6-7 in a large U.S. CF cohort in the current era of widespread early eradication therapy for Pseudomonas aeruginosa (P. aeruginosa).

METHODS

Participants were children with CF enrolled before age 4 in the Early Pseudomonas Infection Control (EPIC) Observational Study, a multicenter, longitudinal study that enrolled P. aeruginosa-negative children not exceeding 12 years of age. Linear regression was used to estimate the association between potential early childhood risk factors and the best FEV1% predicted at age 6-7 years.

MEASUREMENTS AND MAIN RESULTS

Four hundred and eighty-four children (of 1,797 enrolled in the EPIC Observational Study) met the eligibility criteria for this analysis. Mean (SD) age at enrollment was 2.0 (1.3) years. In a multivariable model adjusted for age at enrollment, the following risk factors were significantly associated with lower mean (95% confidence interval) FEV1% predicted at age 6-7: weight percentile less than 10% during the year of enrollment (-5.3 [-9.1, -1.5]), P. aeruginosa positive during the year of enrollment (-2.8 [-5.7, 0.0]), crackles or wheeze during the year of enrollment (-5.7 [-9.4, -1.9]), mother's education of high school or less (-4.2 [-7.3, -1.2]), and mother smoked during pregnancy (-4.4 [-8.8, 0.1]).

CONCLUSIONS

In this large U.S. cohort, we identified several early childhood risk factors for lower FEV1 at age 6-7 years, most of which are modifiable. Clinical trial registered with www.clinicaltrials.gov (NCT00097773).

Pulmonary function in infants with swallowing dysfunction

BACKGROUND

Swallowing dysfunction can lead to recurring aspiration and is frequently associated with chronic symptoms such as cough and wheezing in infants. Our objective was to describe the characteristics of infants with swallowing dysfunction, determine if pulmonary function abnormalities are detectable, and if they improve after therapy.

METHODS

We studied 38 infants with a history of coughing and wheezing who had pulmonary function tests performed within two weeks of their diagnosis of swallowing dysfunction. The raised lung volume rapid thoracoabdominal compression technique was used. After 6 months of therapy, 17 of the infants repeated the tests.

RESULTS

Initially, 25 had abnormal spirometry, 18 had abnormal plethysmography, and 15 demonstrated bronchodilator responsiveness. Six months later test were repeated for seventeen patients. Ten patients had continued abnormal spirometry, two patients remained normal, three patients' abnormal spirometry had normalized, and two patients' previously normal studies became abnormal. Eight of the 17 patients had continued abnormal plethysmography, six had continued normal plethysmography, and three patients' normal plethysmography became abnormal. After 6 months of treatment, eight patients demonstrated bronchodilator responsiveness, of which five continued to demonstrate bronchodilator responsiveness and three developed responsiveness. The remainder either continued to be non- bronchodilator responsive (two) or lost responsiveness (three.) The findings of the abnormal tests in most infants tested is complicated by frequent occurrence of other co-morbidities in this population, including gastroesophageal reflux in 23 and passive smoke exposure in 13 of the infants.

CONCLUSIONS

The interpretation of lung function changes is complicated by the frequent association of swallowing dysfunction with gastroesophageal reflux and passive smoke exposure in this population. Six months of medical therapy for swallowing dysfunction/gastroesophageal reflux did not significantly improve pulmonary function in these infants. Long-term studies will be necessary to determine which of these changes persists into adulthood.

Atopy, cytokine production, and airway reactivity as predictors of pre-school asthma and airway responsiveness

BACKGROUND

Childhood asthma is often characterized by recurrent wheezing, airway hyper-reactivity, atopy, and altered immune characteristics; however, our understanding of the development of these relationships from early in life remains unclear. The aim of our study was to evaluate whether atopy, cytokine production by peripheral blood mononuclear cells (PBMCs), and airway responsiveness, assessed in infants and toddlers, are associated with asthma and airway responsiveness at 4-years of age.

METHODS

Infants with eczema (N = 116), enrolled prior to wheezing, were assessed at entry (mean age of 10.7 months), at 1-year follow-up (N = 112), and at 4-years of age (N = 94). Total serum IgE, specific IgE to allergens, and cytokines produced by stimulated PBMCs, were assessed at entry and 1-year follow-up. Spirometry was obtained at all 3-visits, while airway reactivity to methacholine was assessed at entry and 1-year follow-up, and bronchodilator (BD) responsiveness, as well as current asthma was assessed at 4-years of age.

RESULTS

We found that pre-school children with asthma had lower spirometry and a greater BD-response. Serum IgE, particularly to egg and/or milk, and altered cytokine production by PBMCs at entry to the study were associated with asthma, lower spirometry, and greater airway responsiveness at 4-years of age. In addition, we found that airway responsiveness, as well as spirometry, tracked from infancy to 4-years of age.

CONCLUSIONS

While spirometry and airway responsiveness track longitudinally from early in life, atopy and cytokine production by PBMCs are associated not only with an increased risk of pre-school asthma, but also lower spirometry and increased airway responsiveness.

Respiratory function in healthy late preterm infants delivered at 33-36 weeks of gestation

OBJECTIVE

To compare pulmonary function testing including respiratory compliance (Crs) and time to peak tidal expiratory flow to expiratory time (TPTEF:TE) at term corrected age in healthy infants born at 33-36 weeks of gestation versus healthy infants delivered at term.

STUDY DESIGN

We performed a prospective cohort study of late preterm infants born at 33-36 weeks without clinical respiratory disease (<12 hours of >0.21 fraction of inspired oxygen) and studied at term corrected age. The comparison group was term infants matched for race and sex to the preterm infants and studied within 72 hours of delivery. Crs was measured with the single breath occlusion technique. A minimum of 50 flow-volume loops were collected to estimate TPTEF:TE.

RESULTS

Late preterm infants (n = 31; mean gestational age 34.1 weeks, birth weight 2150 g) and 31 term infants were studied at term corrected age. The late preterm infants had decreased Crs (1.14 vs 1.32 mL/cm H(2)O/kg; P < .02) and decreased TPTEF:TE (0.308 vs 0.423; P < .01) when compared with the term infants. Late preterm infants also had an increased respiratory resistance (0.064 vs 0.043 cm H(2)O/mL/s; P < .01).

CONCLUSIONS

Healthy late preterm infants (33-36 weeks of gestation) studied at term corrected age have altered pulmonary function when compared with healthy term infants.

Maternal smoking and the retinoid pathway in the developing lung

BACKGROUND

Maternal smoking is a risk factor for pediatric lung disease, including asthma. Animal models suggest that maternal smoking causes defective alveolarization in the offspring. Retinoic acid signaling modulates both lung development and postnatal immune function. Thus, abnormalities in this pathway could mediate maternal smoking effects. We tested whether maternal smoking disrupts retinoic acid pathway expression and functioning in a murine model.

METHODS

Female C57Bl/6 mice with/without mainstream cigarette smoke exposure (3 research cigarettes a day, 5 days a week) were mated to nonsmoking males. Cigarette smoke exposure continued throughout the pregnancy and after parturition. Lung tissue from the offspring was examined by mean linear intercept analysis and by quantitative PCR. Cell culture experiments using the type II cell-like cell line, A549, tested whether lipid-soluble cigarette smoke components affected binding and activation of retinoic acid response elements in vitro.

RESULTS

Compared to tobacco-naïve mice, juvenile mice with tobacco toxin exposure had significantly (P < 0.05) increased mean linear intercepts, consistent with an alveolarization defect. Tobacco toxin exposure significantly (P < 0.05) decreased mRNA and protein expression of retinoic acid signaling pathway elements, including retinoic acid receptor alpha and retinoic acid receptor beta, with the greatest number of changes observed between postnatal days 3-5. Lipid-soluble cigarette smoke components significantly (P < 0.05) decreased retinoic acid-induced binding and activation of the retinoic acid receptor response element in A549 cells.

CONCLUSIONS

A murine model of maternal cigarette smoking causes abnormal alveolarization in association with altered retinoic acid pathway element expression in the offspring. An in vitro cell culture model shows that lipid-soluble components of cigarette smoke decrease retinoic acid response element activation. It is feasible that disruption of retinoic acid signaling contributes to the pediatric lung dysfunction caused by maternal smoking.

Maternal smoking and fetal lung signals--an in utero MRI investigation

OBJECTIVE

To investigate whether fetal lung signals and fetal lung signal progression over gestation observed on magnetic resonance imaging are different in mothers who reported smoking during pregnancy compared with nonsmoking controls.

METHOD

Cross-sectional retrospective study of 100 consecutive singleton pregnancies that underwent magnetic resonance imaging. Fetal lung-liver signal intensity ratios of 18 fetuses of mothers who reported smoking during pregnancy were compared with 82 fetuses of nonsmoking controls.

RESULTS

Average gestational age at magnetic resonance imaging was 26.4 ± 5.2 weeks (Range 18.4-38.2 weeks). Cases reported smoking between 2 and 15 cigarettes per day. The mean number of cigarettes per day for cases was 9.2 ± 3.4. Mean fetal lung-liver signal intensity ratios did not differ significantly between the two groups (p = 0.8). They showed a linear increase with gestational age (r(2) = 0.3). Multiple regression analysis of lung-liver signal intensity ratios using gestational age and smoking status as predictors revealed a significant influence of gestational age (p < 0.0001) but not maternal smoking status (p = 0.8) on fetal lung-liver signal intensity ratios.

CONCLUSIONS

Fetuses of mothers who reported smoking during pregnancy show similar lung signals and lung signal progression over gestation on magnetic resonance imaging as nonsmoking controls.

Formaldehyde exposure and lower respiratory infections in infants: findings from the PARIS cohort study

BACKGROUND

Certain chemical pollutants can exacerbate lower respiratory tract infections (LRIs), a common childhood ailment. Although formaldehyde (FA) is one of the most common air pollutants found in indoor environments, its impact on infant health is uncertain.

OBJECTIVE

Our aim was to determine the impact of FA exposure on the LRI incidence during the first year of life of infants from the Pollution and Asthma Risk: an Infant Study (PARIS) birth cohort.

METHODS

FA was measured in a random sample of 196 infants' dwellings, and exposure to this pollutant was estimated for 2,940 infants using predictive models based on measurements and data about potential determinants of FA levels. Health data were collected from parents by regular self-administered questionnaires. We used multivariate logistic regressions to estimate associations between FA exposure and the occurrence of LRI and wheezy LRI (wLRI), adjusting for potential confounders/risk factors.

RESULTS

During the first year of life, 45.8% of infants had at least one LRI, and LRI occurred simultaneously with wheezing in 48.7% of cases. The FA predictive models correctly classified 70% of dwellings as having high or low exposure, and we estimated that 43.3% of infants were exposed throughout the first year to levels of FA > 19.5 µg/m3. FA exposure was significantly associated with LRI and wLRI before and after adjustment for known LRI risk factors/confounders. For an interquartile increase in FA levels (12.4 μg/m3), we estimated a 32% [95% confidence interval (CI): 11, 55] and 41% (95% CI: 14, 74) increase in the incidence of LRI and wLRI, respectively.

CONCLUSION

The findings of this study suggest that infants exposed to FA at an early age have an increased incidence of LRI.

Maternal smoking and fetal lung volume-an in utero MRI investigation

OBJECTIVE

To investigate whether fetal lung volume and fetal lung volume growth over gestation are different in mothers who reported smoking during pregnancy compared to non-smoking controls.

METHOD

Cross-sectional retrospective study of the data of 200 consecutive singleton pregnancies that underwent magnetic resonance imaging (MRI). Fetal lung volumes of 32 fetuses of mothers who reported smoking during pregnancy were compared to 168 fetuses of non-smoking controls.

RESULTS

Cases reported smoking between 2 and 30 cigarettes per day. The mean number of cigarettes per day for cases was 10.2 ± 6.1. After logarithmic transformation, lung volumes showed a linear increase with gestational age (r(2) = 0.7). Multiple regression analysis revealed a significant influence of gestational age (p < 0.0001) but not maternal smoking status (p = 1.0) on fetal lung volumes. Comparison of the relative difference between observed and predicted lung volumes for both groups by means of unpaired t-test revealed no significant influence of maternal smoking status on this variable (p = 0.9).

CONCLUSIONS

Fetuses of mothers who reported smoking during pregnancy show similar lung volumes and lung volume growth in MRI compared to non-smoking controls. Our data suggest that a reduced lung volume is not responsible for the increase in respiratory symptoms associated with prenatal smoking.

Evaluation of airway reactivity and immune characteristics as risk factors for wheezing early in life

BACKGROUND

Childhood asthma is most often characterized by recurrent wheezing, airway hyperreactivity, and atopy; however, our understanding of these relationships from early in life remains unclear. Respiratory tract illnesses and atopic sensitization early in life might produce an interaction between innate and acquired immune responses, leading to airway inflammation and heightened airway reactivity.

OBJECTIVE

We hypothesized that premorbid airway reactivity and immunologic characteristics of infants without prior episodes of wheezing would be associated with subsequent wheezing during a 1-year follow-up.

METHODS

One hundred sixteen infants with chronic dermatitis were enrolled before episodes of wheezing. Airway reactivity, allergen-specific IgE levels, cytokine production by stimulated PBMCs, and percentages of dendritic cells were measured on entry, and airway reactivity was reassessed at the 1-year follow-up. Linear regression models were used to evaluate a predictor's effect on continuous outcomes.

RESULTS

Milk sensitization, egg sensitization, or both were associated with heightened airway reactivity before wheezing and after the onset of wheezing; however, these factors were not associated with an increased risk of wheezing. There was an interaction between initial airway reactivity and wheezing as a determinant of airway reactivity at follow-up. In addition, cytokine production by stimulated PBMCs was a risk factor for wheezing, whereas increased percentages of conventional dendritic cells were protective against wheezing.

CONCLUSION

Our data in a selected cohort of infants support a model with multiple risk factors for subsequent wheezing that are independent of initial airway reactivity; however, the causative factors that produce wheezing very early in life might contribute to heightened airway reactivity.

Potential misinterpretation of infant lung function unless prospective healthy controls are studied

SUMMARY RATIONALE: Reliable interpretation of pulmonary function tests relies on appropriate reference data, which remain very limited for infants.

OBJECTIVES

This study aimed to assess the validity of published reference equations for forced expiratory flow-volume (FEFV) data in infants when using current, commercially available equipment, and how this could impact on interpretation of results from infants with lung disease.

METHODS

The Jaeger Masterscreen BabyBody (v4.67) equipment was used to perform partial and raised volume FEFV maneuvers in healthy infants and those with cystic fibrosis (CF). Results were initially expressed as Z-scores using published reference equations. Multilevel modeling was used to calculate differences, if any, from predicted scores in healthy infants.

RESULTS

Data were available from 66 healthy full term infants on 89 test occasions; [median (range) postnatal age 49.4 (12-101) weeks. All FEFV outcomes were significantly lower than predicted, with mean (SD) Z-score differences of -0.4 (1.1) for FVC; -0.6 (1.0) for FEV(0.5); -1.0 (1.0) for FEF(25-75) and -1.4 (1.1) for V'(maxFRC). After adjustments using multilevel modeling, mean Z-scores were within 0.1 (SD approximately 1.0) predicted for all outcomes in healthy infants. Among 50 infants with CF, studied on 85 test occasions, results were "abnormal" (<-1.96 Z-scores) on 35 (41%) and 37 (45%) test occasions for FEV(0.5) and FEF(25-75), respectively, when using published equations. This fell to 24 (28%) and 20 (24%), respectively, after adjustment.

CONCLUSIONS

Dependence on published equations for interpreting FEFV data in infants may lead to misinterpretation of lung function status, which could impact adversely both in the research setting and on clinical management. Use of a contemporary control group or establishment of equipment-specific reference data is essential for meaningful interpretation of infant lung function data.

Common cold decreases lung function in infants with recurrent wheezing

Background

Common acute viral respiratory infections (colds) are the most frequent cause of exacerbations in infants with recurrent wheezing (RW). However, there is no quantitative information about the effect of colds on the lung function of infants with RW. This study was undertaken to determine the effect of common cold on forced expiratory parameters measured from raised lung volume in infants with RW.

Methods

Spirometric lung function (expiratory flows from raised lung volume) was randomly assessed in 28 infants with RW while they had a common cold and when asymptomatic.

Results

It was found that during colds there was a significant decrease in all forced expiratory parameters and this was much more evident for flows (FEF_50%, FEF_75% and FEF_25–75%) which were definitively abnormal (less than −1.65 z-score) in the majority of infants. There was not association between family asthma, tobacco exposure, and other factors, with the extent of lung function decrease during colds. Tobacco during pregnancy but not a history of family asthma was significantly associated to lower expiratory flows; however, the association was significant only when infants were asymptomatic.

Conclusion

This study shows that common colds cause a marked reduction of lung function in infants with RW.

Association of passive exposure of pregnant women to environmental tobacco smoke with asthma symptoms in children

Environmental tobacco smoke (ETS) is a significant risk factor for the presence and increased severity of asthma- and allergy-related symptoms in children. Smoking during pregnancy has detrimental effects on asthma-associated outcomes in childhood. Whether passive exposure of pregnant women to ETS may also lead to asthma in their offspring, is not known. The aim of this study was to investigate the association of passive exposure of pregnant women to ETS and asthma- and/or allergy-related symptoms in Preschool children. Cross-sectional data were collected with questionnaires from 2374 Preschool children, recruited from public and private nurseries and day-care centers. Parental smoking was significantly associated with wheezing symptoms in their children. Mother's active smoking during pregnancy significantly increased the risk for occurrence of asthma symptoms and/or medically diagnosed asthma in Preschool children in a dose-dependent manner. Passive exposure to ETS, mainly during the third trimester of pregnancy, was significantly associated with asthma- and allergy-related symptoms after adjusting for several confounders in a multivariate analysis (current wheeze: OR = 1.42, 95% CI = 1.06-1.91, pruritic rash ever: OR= 1.45, 95% CI = 1.01-2.08). Passive exposure of pregnant women to ETS during the third trimester is positively associated with asthma- and allergy-related symptoms in their Preschool age children. Public health policies should be oriented not only towards smoking cessation, but also reinforce elimination of ETS exposure of pregnant women.

Tobacco smoke exposure in hospitalised Aboriginal children in Central Australia

AIM

Child exposure to tobacco smoke is detrimental to health. Australian Aboriginal people have a higher rate of cigarette smoking compared with the national average. Thus, we aim to measure the proportion of children admitted to Alice Springs Hospital who are exposed to tobacco smoke at home, to correlate this with prevalence of regular cough and gauge smokers' interest in quitting.

METHOD

A questionnaire was administered verbally to carers of children admitted to Alice Springs Hospital, November 2006 to January 2007. Main outcome measures were presence of a smoker at home and presence of a regular cough. We measured the interest of carers and speculated interest of other smokers in quitting. Eighty-two questionnaires were completed (60% of children admitted during the study period). Eighty-nine per cent of children were Aboriginal.

RESULTS

As so few non-Aboriginal children were included in the study, their results were not included in analysis. Sixty-four per cent of children lived with at least one smoker. Seventy per cent of children exposed to smoke at home lived with more than one smoker. Point prevalence of reported regular cough was 33%. Forty-three per cent of children who lived with at least one smoker had regular cough compared with 13% in those who did not (P= 0.035). The rate ratio for regular cough when living with a smoker versus when not living with a smoker was 2.77 (95% confidence interval: 1.06-7.23). Forty-two per cent of the smokers expressed interest in quitting.

CONCLUSION

It is concerning that the majority of hospitalised children were exposed to tobacco smoke at home, while fewer than half of smokers were interested in quitting.

Prenatal determinants of neonatal lung function in high-risk newborns

BACKGROUND

Neonatal lung function is suspected to be associated with wheezy disorders, but little is known about risk factors for the early lung function.

OBJECTIVES

To study prenatal determinants of neonatal lung function.

METHODS

This is a clinical, prospective birth cohort study of 411 newborns, the Copenhagen Prospective Study on Asthma in Childhood, in a single-center research clinic dedicated solely to this longitudinal birth cohort study. Lung function was determined at 1 month of age by infant spirometry (the raised volume rapid thoraco-abdominal compression technique) and bronchial responsiveness to methacholine by transcutaneous oxygen measurements. Risk factor analyses included anthropometrics; demographics; socioeconomic factors; parental atopic history; previous deliveries; exposures during the third trimester to the mother's smoking, alcohol, and medicines; third trimester pregnancy complications including mother's asthma status; and mode of delivery.

RESULTS

Lung function was determined in 404 neonates, age 6 weeks. Neonates with body mass index in the upper quartile had 14% lower baseline forced expiratory volume at 0.5 second, and neonates of mothers smoking during the third trimester had 7% lower baseline forced expiratory volume at 0.5 second. Sex or parental atopic disease did not affect the neonatal lung function and bronchial responsiveness. Maternal intake of paracetamol during the third trimester was associated with doubling of the bronchial responsiveness in the neonates, but the statistical significance may have been driven by outliers. Bronchial responsiveness exhibited a parabola development with tripling of bronchial responsiveness reaching the nadir at 3 months of age, but this needs replication in a study with repetitive measurements within individuals.

CONCLUSION

High body mass index in newborns and mothers smoking is associated with reduced neonatal lung function. This suggests that the association between body proportion and wheezing disorders may be a result of shared genes or prenatal nutrition.

Expired nitric oxide and airway reactivity in infants at risk for asthma

BACKGROUND

Family histories of atopy, as well as histories of atopic dermatitis and food allergy, are important risk factors for an infant to have asthma. Although atopic sensitization appears to contribute to the development of asthma, it is unclear when the airways become involved with the atopic process and whether airway function relates to the atopic characteristics of the infant.

OBJECTIVE

We sought to evaluate whether atopic infants without prior episodes of wheezing have increased expired nitric oxide (eNO) levels and heightened airway reactivity.

METHODS

Infants with eczema were recruited, and atopic status was defined by specific IgE levels to foods or aeroallergens and total IgE levels. eNO, forced expiratory flow at 75% exhaled volume (FEF(75)), and airway reactivity to inhaled methacholine were measured in sedated infants. Airway reactivity was quantified by using the provocative concentration to decrease FEF(75) by 30%.

RESULTS

Median age for the 114 infants evaluated was 10.7 months (range, 2.6-19.1 months). Infants sensitized to egg or milk compared with infants sensitized to neither egg nor milk had lower flows (FEF(75): 336 vs 285 mL/s, P < .003) and lower lnPC(30) (mg/mL) provocative concentrations to decrease FEF(75) by 30% (-0.6 vs -1.2, P < .02) but no difference in eNO levels. Infants with total serum IgE levels of greater than 20 IU/mL had higher eNO levels compared with infants with IgE levels of 20 IU/mL or less (14.6 vs 11.2 ppb, P < .023) but no difference in forced flows or airway reactivity.

CONCLUSIONS

Our findings suggest that atopic characteristics of the infant might be important determinants of the airway physiology of forced expiratory flows, airway reactivity, and eNO.

Air pollution and pulmonary function in asthmatic children: effects of prenatal and lifetime exposures

BACKGROUND

Prenatal and early life periods represent critical windows for oxidant pollutant-induced lung remodeling. The objective of this study was to examine the association of prenatal and lifetime exposures to air pollutants with pulmonary function in a cohort of children with asthma.

METHODS

Prenatal and lifetime exposure to several air pollutants was reconstructed for 232 children with asthma from the San Joaquin Valley of California, USA. Prenatal and lifetime residences were geocoded. We obtained data on monthly average ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), and particulate matter with a median aerodynamic diameter <10 microm (PM10) concentrations. Metrics were created for key developmental periods. Predictive models were developed for 8 pulmonary function measures. A newly-developed stepwise model selection procedure-the Deletion/Substitution/Addition algorithm-was implemented and results were compared with those obtained using traditional stepwise methods.

RESULTS

Second-trimester exposure to NO2 negatively affected forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1), and first trimester exposure to PM10 negatively affected peak expiratory flow (PEF) rate. Exposure to CO in early years of life also had a negative effect on FEV1/FVC and forced expiratory flow between 25% and 75% of FVC (FEF25-75)/FVC. Second trimester exposure to PM10 and exposure to CO in the first 6 years of life had negative effects on forced expiratory flow at 25% of FVC. Prenatal, but not trimester-specific, exposure to CO was negatively associated with FEF25-75. Effects were limited to subgroups, such as children who were African American, those diagnosed with asthma before the age of 2 years, and those exposed to maternal smoking during pregnancy.

CONCLUSION

Prenatal and early-life exposures to CO, PM10, and NO2 have a negative effect on pulmonary function in subgroups of asthmatic children.

Lung structure and function of infants with recurrent wheeze when asymptomatic

Infants with recurrent wheeze have repeated episodes of airways obstruction; however, relatively little is known about the structure and function of their lungs when not symptomatic. The current authors evaluated whether infants with recurrent wheeze have smaller airway lumens or thickened airway walls, as well as decreased airway function. High-resolution computed tomography images 1 mm thick were obtained at three anatomic locations at an elevated lung volume and at functional residual capacity. Forced expiratory flows were also measured in subjects with recurrent wheeze. Airway lumen, wall areas and lung tissue density were not significantly different for recurrent wheeze (n = 17) and control (n = 14) subjects; however, subjects with recurrent wheeze had lower forced expiratory flows than predicted. Similar findings were obtained when subjects were grouped by exposure to tobacco smoke. These findings indicate that infants with recurrent wheeze, as well as exposure to tobacco smoke, have lower airway function when not symptomatic. The lower forced expiratory flows may result from a degree of airway narrowing that could not be resolved with the methodology employed or from other mechanisms, such as more collapsible airways or decreased pulmonary elastic recoil.

Effects of early cigarette smoke exposure on early immune development and respiratory disease

Exposure to tobacco constituents during early development remains a common but avoidable toxic exposure, which has been clearly linked with decreased lung growth and subsequent wheezing illness. There is also now emerging evidence that tobacco smoke can influence early immune function. This includes alterations in cytokine production by the fetoplacental unit, as detected ex vivo in cord blood, as well as in patterns of fetal mononuclear cell responses in vitro. Recent studies also suggest that the newborns of smoking mothers have altered signalling through Toll-like receptors (TLRs) that are essential for innate microbial responses. This may be implicated in the increased predisposition to infection in exposed infants. TLR-mediated innate response pathways are also believed to be important in promoting regulatory pathways that inhibit allergic immune responses. However, although a number of studies have documented associations between early cigarette smoke exposure and subsequent allergic disease, this remains controversial. This review explores the consequences of smoking on these important aspects of early development, including potential mechanisms, interactions with predisposing asthma genes and a potential role in epigenetic regulation. Although parental smoking may not be the primary factor in the changing prevalence of asthma and respiratory disease, we propose that it is an important contributor, with significant potential to interact with other genetic factors and environmental risk factors to influence disease propensity.

How can we measure the impact of pollutants on respiratory function in very young children? Methodological aspects

There is increasing evidence that air pollution particularly affects infants and small preschool children. However, detecting air pollution effects on lung function in small children is technically difficult and requires non-invasive methods that can assess lung function and inflammatory markers in larger cohorts. This review discusses the principles, usefulness and shortcomings of various lung function techniques used to detect pollution effects in small children. The majority of these techniques have been used to detect effects of the dominant indoor pollutant, tobacco exposure. However there is increasing evidence that non-invasive lung function techniques can also detect the effects of outdoor air pollution.

The effects of antenatal smoking on lung function and respiratory symptoms in infants and children

We highlight evidence demonstrating antenatal smoking exposure is an important risk factor for increased respiratory symptoms and lung function abnormalities in infants and children. Epidemiological studies have demonstrated an excess both of wheezing in the first two years after birth and asthma and persistent wheezing in older children. Lung function testing in children exposed to antenatal smoking has demonstrated a reduction in airway function. Antenatal exposure of nicotine to animal models results in pulmonary hypoplasia, fewer but larger alveoli and altered airway morphology. Pulmonary function testing, however, has not demonstrated that infant lung volume is affected by antenatal smoking exposure, other than due to the expected effect of smoking on somatic growth, but there is an adverse effect on airway development. There is no evidence that antenatal smoking exposure increases bronchial hyperreactivity, rather it may be associated with a diminished response to both bronchoconstrictors and bronchodilators in infants.

Maternal positive skin prick test results and asthma prediction after early childhood wheezing

BACKGROUND

Previous studies have used parental history of asthma or allergy but not positive skin prick test results to predict the evolution of asthma in wheezing infants.

OBJECTIVE

To determine whether positive parental skin prick test results serve as a predictive factor for the subsequent development of asthma in a child with a history of wheezing before the age of 3 years.

METHODS

In a retrospective cohort study we investigated 91 individuals from 71 families. Enrollment criteria were age 6 to 40 years, history of wheezing before the age of 3 years, and no chronic lung disease other than asthma. Each participant was asked about current asthma-related symptoms, underwent pulmonary function testing, and underwent skin prick testing. Participants' parents underwent skin prick testing and measurement of total serum IgE levels.

RESULTS

Asthma was diagnosed in 56 participants (61%). Although maternal positive skin prick test results conferred a 3.4-fold risk of asthma (P = .02), neither the mother's nor the father's self-reported allergy or asthma was predictive of later development of asthma.

CONCLUSION

The presence of parental, and especially maternal, positive skin prick test results is a significant predictive factor for the subsequent development of asthma in early childhood wheezing.

[Advances in the study of infant lung function: forced expiratory maneuvers from an increased lung volume]

Forced expiratory maneuvers from an increased lung volume in infants date from 1989 and consist of raising the inspiratory volume by applying a specific inflation pressure until a level close to the total lung capacity is reached. The chest and abdomen are then compressed by means of an inflatable jacket in order to obtain a forced expiratory flow-volume curve similar to that obtained for an adult. Forced expiration from an increased lung volume in infants is useful, just as the maneuver is in older patients, for studying airway function, diagnosing obstructive diseases early, and assessing response to treatment. The objective of this review is to provide information on the physiological bases and technical aspects of a lung function test that has proven highly useful for the study of the airways of healthy infants as well as those with respiratory diseases.

Relationship of pulmonary function among women and children to indoor air pollution from biomass use in rural Ecuador

Approximately half the world uses biomass fuel for domestic energy, resulting in widespread exposure to indoor air pollution (IAP) from biomass smoke. IAP has been associated with many respiratory diseases, though it is not clear what relationship exists between biomass use and pulmonary function. Four groups containing 20 households each were selected in Santa Ana, Ecuador based on the relative amount of liquid petroleum gas and biomass fuel that they used for cooking. Pulmonary function tests were conducted on each available member of the households 7 years of age. The pulmonary functions of both children (7-15 years) and women (16 years) were then compared between cooking fuel categories using multivariate linear regression, controlling for the effects of age, gender, height, and exposure to tobacco smoke. Among the 80 households, 77 children and 91 women performed acceptable and reproducible spirometry. In multivariate analysis, children living in homes that use biomass fuel and children exposed to environmental tobacco smoke had lower forced vital capacity and lower forced expiratory volume in 1s (P<0.05). However, no significant difference in pulmonary function was observed among women in different cooking categories. Results of this study demonstrate the harmful effects of IAP from biomass smoke on the lung function of children and emphasize the need for public health efforts to decrease exposure to biomass smoke.

Environmental tobacco smoke suppresses nuclear factor-kappaB signaling to increase apoptosis in infant monkey lungs

RATIONALE

Exposure to environmental tobacco smoke in early life has adverse effects on lung development. Apoptosis plays an essential role in development; however, the molecular mechanisms of pulmonary apoptosis induced by environmental tobacco smoke is unknown.

OBJECTIVES

To investigate the mechanistic role of nuclear factor (NF)-kappaB, a critical cell survival pathway, in the developing lungs exposed to environmental tobacco smoke.

METHODS

Timed-pregnant rhesus monkeys and their offspring were exposed to filtered air or to aged and diluted sidestream cigarette smoke as a surrogate to environmental tobacco smoke (a total suspended particulate concentration of 0.99 mg/m(3) for 6 h/d, 5 d/wk) from 45-50 d gestational age to 72-77 d postnatal age (n = 4/group).

MEASUREMENTS AND MAIN RESULTS

NF-kappaB-DNA binding activity, regulated anti-apoptotic genes, and apoptosis were measured in lung tissues. Exposure to environmental tobacco smoke significantly suppressed NF-kappaB activation pathway and activity. Environmental tobacco smoke further down-regulated NF-kappaB-dependent anti-apoptotic genes and induced activation of caspases, cleavage of cellular death substrates (poly(ADP)-ribose polymerase and caspase-activated DNase) and an increase in the rate of apoptosis in the lung parenchyma. No significant alterations were observed for activator protein 1, p53 or Akt activity.

CONCLUSIONS

Our results indicate that exposure to low levels of environmental tobacco smoke during a critical window of maturation in the neonatal nonhuman primate may compromise lung development with potential implications for future lung growth and function. These findings support our hypothesis that NF-kappaB plays a key role in the regulation of the apoptotic process.

Asthma and panic in young adults: a 20-year prospective community study

RATIONALE

Psychologic factors are increasingly recognized to influence the onset and course of asthma. Previous cross-sectional community-based studies have provided evidence for a relatively specific association between asthma and panic.

OBJECTIVES

To examine concurrent and longitudinal associations between asthma and panic in young adults.

MEASUREMENTS AND MAIN RESULTS

Prospective community-based cohort study of young adults (n = 591) followed between ages 19 and 40. Information was derived from six subsequent semistructured diagnostic interviews conducted by professionals. Cross-sectionally (over the whole study period), asthma was more strongly associated with panic disorder (odds ratio [OR] = 4.0; 95% confidence interval [CI], 1.7, 9.3) than with any panic, which included panic disorder and panic attacks (OR = 2.1; 95% CI, 1.1, 4.5). Longitudinally, after adjusting for potentially confounding variables, active asthma predicted subsequent panic disorder (OR = 4.5; 95% CI, 1.1, 20.1), and the presence of panic disorder predicted subsequent asthma activity (OR = 6.3; 95% CI, 2.8, 14.0). Asthma predicted any panic (OR = 2.7; 95% CI, 1.1, 7.1), whereas any panic did not predict subsequent asthma activity. Associations were stronger in smokers than in nonsmokers, and stronger in women than in men. Smoking, early-childhood anxiety, and a family history of allergy were important confounders of the asthma-panic association.

CONCLUSIONS

This is the first long-term follow-up study on asthma and panic. It showed dose-response-type relationships between panic and asthma, and bidirectional longitudinal associations between the two conditions. It provided evidence for familial factors and smoking as possible shared etiologic explanations.