Children with smoking parents have a higher airway resistance measured by the interruption technique

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.

Airway resistance in children measured using the interrupter technique: reference values

OBJECTIVE

The interrupter technique is used for determining interrupter resistance (Rint) during quiet breathing. This noninvasive method requires minimal cooperation and can therefore be useful in evaluating airway obstruction in uncooperative children. To date, no reference values have been determined for Rint in a Brazilian population. The objective of this study was to define a prediction equation for airway resistance using the interrupter technique for healthy children aged 3-13 years.

METHODS

This was a prospective, cross-sectional study involving preschool and school children in Porto Alegre, Brazil, in whom Rint was measured during peak expiratory flow.

RESULTS

One-hundred and ninety-three children were evaluated. Univariate analysis using linear regression showed that height, weight and age correlated significantly and independently with Rint. Multiple regression with height, weight, age and gender as variables resulted in a model in which only height and weight were significant, independent predictors of Rint. Collinearity was identified among height, weight and age.

CONCLUSIONS

Reference values and an equation for calculating Rint in healthy children were obtained and are adjusted for height.

Cigarette smoke, inflammation, and lung injury: a mechanistic perspective

Inflammation is a common feature in the pathogenesis of cigarette smoke-associated diseases. The recruitment of inflammatory cells into the lung following cigarette smoke exposure presents a risk of tissue damage through the release of toxic mediators, including proteolytic enzymes and reactive oxygen species. This review represents a toxicological approach to investigation of cigarette smoke-induced lung injury, with a focus on laboratory studies and an emphasis on inflammatory mechanisms. The studies discussed in this review analyze the role of inflammation and inflammatory mediators in the development of injury. In cases where information relating to cigarette smoke is limited, examples are taken from other models of lung injury applicable to cigarette smoke. The primary aim of the review is to summarize published work so as to permit (1) an evaluation of chronic lung injury and inflammatory responses in animal models, (2) a discussion of inflammatory mediators in the development of chronic injury, and (3) identification of immunological mechanisms of injury. These studies discuss the currently understood roles of cytokines, cell adhesion molecules, and oxidative stress in inflammatory reactions and lung injury. A role for lipocortin 1 (annexin 1), a naturally occurring defense factor against inflammation, is discussed because of the possibility that impaired synthesis and degradation of lipocortin 1 will influence immune responses in animals exposed to cigarette smoke either by augmenting T helper cell Th1 response or by shifting Th1 to Th2 response. While Th1 augmentation will increase the risk for development of emphysema, Th1 to Th2 shift will favor development of asthma.

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.

Inhaled corticosteroids for recurrent respiratory symptoms in preschool children in general practice: randomized controlled trial

BACKGROUND

Therapy with inhaled corticosteroids (ICS) is beneficial in patients with asthma. However, in preschool children with symptoms like cough, wheeze, or shortness of breath diagnosing asthma is difficult. Therefore, the role of ICS in the management of preschool children with recurrent respiratory symptoms is unclear. We assessed the effectiveness of ICS in preschool children with recurrent respiratory symptoms in general practice.

METHODS

In this multicenter, randomized, double blind, placebo controlled trial, 96 children aged 1-5 years consulting their general practitioners for recurrent respiratory symptoms and in whom treatment with ICS was considered by the general practitioner were randomly allocated to receive ICS (fluticasone propionate 200 mcg/day by metered dose inhaler/spacer combination) or placebo for 6 months. Outcome assessments were carried out 1, 3, and 6 months after randomization. The primary outcome measure was the symptom score (cough, shortness of breath and wheeze during day and night) as measured by a symptom diary card. Secondary endpoints were symptom-free days, use of rescue medication, adverse events, and lung function variables as measured by the interrupter technique and forced oscillation technique.

RESULTS

During the 6 months treatment period, symptoms improved in both groups, with no differences between ICS and placebo. In addition, none of the secondary outcome parameters showed differences between both treatment groups.

CONCLUSION

ICS treatment has no beneficial effect in preschool children with recurrent respiratory symptoms in general practice. We therefore recommend a watchful waiting policy with only symptomatic treatment in these children. General practitioners and pediatricians should be aware of the high probability of overtreatment when prescribing ICS in these children.

Biomarkers to assess the utility of potential reduced exposure tobacco products

To date, we have no valid biomarkers that serve as proxies for tobacco-related disease to test potential reduced exposure products. This paper represents the deliberations of four workgroups that focused on four tobacco-related heath outcomes: Cancer, nonmalignant pulmonary disease, cardiovascular disease, and fetal toxicity. The goal of these workgroups was to identify biomarkers that offer some promise as measures of exposure or toxicity and ultimately may serve as indicators for future disease risk. Recommendations were based on the relationship of the biomarker to what is known about mechanisms of tobacco-related pathogenesis, the extent to which the biomarker differs among smokers and nonsmokers, and the sensitivity of the biomarker to changes in smoking status. Other promising biomarkers were discussed. No existing biomarkers have been demonstrated to be predictive of tobacco-related disease, which highlights the importance and urgency of conducting research in this area.

Biomarkers to assess the utility of potential reduced exposure tobacco products

To date, we have no valid biomarkers that serve as proxies for tobacco-related disease to test potential reduced exposure products. This paper represents the deliberations of four workgroups that focused on four tobacco-related heath outcomes: Cancer, nonmalignant pulmonary disease, cardiovascular disease, and fetal toxicity. The goal of these workgroups was to identify biomarkers that offer some promise as measures of exposure or toxicity and ultimately may serve as indicators for future disease risk. Recommendations were based on the relationship of the biomarker to what is known about mechanisms of tobacco-related pathogenesis, the extent to which the biomarker differs among smokers and nonsmokers, and the sensitivity of the biomarker to changes in smoking status. Other promising biomarkers were discussed. No existing biomarkers have been demonstrated to be predictive of tobacco-related disease, which highlights the importance and urgency of conducting research in this area.

Airway resistance measurements in pre-school children with asthmatic symptoms: the interrupter technique

Measuring airway resistance in pre-school children with the interrupter technique has proven to be feasible and reliable in daily clinical practice and research settings. Whether it contributes to diagnosing asthma in pre-school children still remains uncertain. From the results of previous studies a need for standardisation of the technique has emerged. In this overview we will elaborate on research concerning the position of the interrupter technique in the difficult process of diagnosing asthma in pre-school children.

Parental smoking and lung function in children: an international study

RATIONALE

Both prenatal and postnatal passive smoking have been linked with respiratory symptoms and asthma in childhood. Their differential contributions to lung function growth in the general children's population are less clear.

OBJECTIVE

To study the relative impact of pre- and postnatal exposure on respiratory functions of primary school children in a wide range of geographic settings, we analyzed flow and volume data of more than 20,000 children (aged 6-12 yr) from nine countries in Europe and North America.

METHODS

Exposure information had been obtained by comparable questionnaires, and spirometry followed a protocol of the American Thoracic Society/European Respiratory Society. Linear and logistic regressions were used, controlling for individual risk factors and study area. Heterogeneity between study-specific results and mean effects were estimated using meta-analytic tools.

MAIN RESULTS

Smoking during pregnancy was associated with decreases in lung function parameters between -1% (FEV1) and -6% maximal expiratory flow at 25% of vital capacity left (MEF25). A 4% lower maximal midexpiratory flow (MMEF) corresponded to a 40% increase in the risk of poor lung function (MMEF < 75% of expected). Associations with current passive smoking were weaker though still measurable, with effects ranging from -0.5% (FEV1) to -2% maximal expiratory flow (MEF50).

CONCLUSIONS

Considering the high number of children exposed to maternal smoking in utero and the even higher number exposed to passive smoking after birth, this risk factor for reduced lung function growth remains a serious pediatric and public health issue.