Relationship between FEV1/FVC and age in children with asthma.

INTRODUCTION: Forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) normally decreases through childhood, increases briefly during early adolescence, and then declines throughout life. The physiology behind this temporary increase during early adolescence is not well understood. The objective of this study was to determine if this pattern occurs in children with asthma. DESIGN: Single-center, cross-sectional, retrospective analysis of pulmonary function tests obtained over a 5-year period in children 5-18 years of age with persistent asthma. RESULTS: A total of 1793 patients satisfied all inclusion and exclusion criteria. The mean age (±SD) was 10.4 ± 3.8 years. Forty-eight percent were female. Mean FEV1/FVC was 0.83 ± 0.09. FEV1/FVC was lower at 5 years of age than in healthy children, declined from age 5 to 11 by 5.7% compared to 7.3% in healthy girls, and 5.8% compared to 9.4% in healthy boys. FEV1/FVC increased in early adolescence, but at age 16, was 5.6% lower in male children compared to healthy children, and 5.4% lower in females. The ratio was lower in obese children at all ages but demonstrated the same curvilinear shape as healthy children. In absolute terms, FEV1 grew proportionately more than FVC during early adolescence, so the ratio of FEV1/FVC increased during that period. The curvilinear shape of the curve remained in postbronchodilator testing, though significantly blunted. CONCLUSIONS: FEV1/FVC is lower in children with persistent asthma than healthy children, but the "Shepherd's Hook" pattern is preserved. This was true in obese patients with asthma, although their FEV1/FVC ratios were lower throughout all stages of childhood and adolescence.

Changes in Body Mass Index in Children and Adolescents with Asthma during the COVID-19 Pandemic.

Background: Increased weight gain in children during the COVID-19 pandemic has been reported. Changes in weight in children with asthma during this period have not been well described. Methods: Retrospective review of children with asthma, 6-18 years of age, seen in 2019 and 2020. Mean monthly rates of change in body mass index (BMI) were compared between years. Demographic and asthma-related factors were examined. Results: Two hundred sixty-seven patients were enrolled. BMI increased by 0.128 ± 0.283 kg/m2/month during the pandemic year as compared with 0.084 ± 0.160 kg/m2/month during the previous year (P = 0.03). Patients with baseline overweight or obesity trended toward higher rates of BMI increase than those starting with normal weight, with the greatest BMI increase occurring in the severely obese. Conclusions: In this single-site study of children with asthma, there was a greater monthly rate of BMI gain during the early pandemic as compared with that observed in the previous year.

The relationship between weight and pulmonary outcomes in overweight and obese people with cystic fibrosis: A retrospective observational study.

Background: A major focus in cystic fibrosis (CF) care aims to increase weight gain. Rates of overweight and obese people with CF have gradually increased over the past decade. Obesity could be a risk for restriction of lung volumes and airway obstruction as well as increase rates of pulmonary exacerbations in people with CF. Aim: To assess the relationship between weight categories and pulmonary outcomes in children and adults with CF. Methods: Patients 6 years of age and older were categorized into weight categories based on the Centers for Disease Control and Prevention (CDC) definitions. A retrospective chart review was conducted to obtain lung function testing and other outcomes. Results: One hundred five patients with a median age of 20.6 years were included in this analysis. 8.4%, 64%, 18%, and 10% of patients were underweight, normal/healthy weight, overweight, and obese, respectively. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) (% predicted) did not differ between patients with weights in the normal range versus patients in the overweight/obese categories. Linear regression analysis showed a direct correlation between body mass index (BMI) and FEV1 that continued as BMI entered overweight and obese categories in both pediatric and adult patients. Overweight/obese patients did not have increased rates of pulmonary exacerbations compared to those in the normal/healthy weight category. Conclusion: As CF therapies continue to improve, an increasing number of people with CF are exceeding the CDC's normal-weight range. Gaining weight past the normal range does not appear to negatively impact pulmonary health of people with CF. If this trend of increased weight gain continues, it remains to be seen if it will eventually negatively affect lung health.

Counseling Tobacco Smoke Exposure Reduction Measures in Pediatrics: A Quality Improvement Project.

With over 40% of children in the USA exposed to tobacco smoke, the AAP recommends tobacco smoke exposure (TSE) assessment during clinic visits. We aimed to increase the rates of TSE screening and provider counseling regarding TSE reduction using an evidence-based approach. Methods: We conducted the project at a large pediatric pulmonology practice. Baseline caregiver surveys and medical record review of TSE documentation took place in July/August, 2019. From September 2019 to July 2021, PDSA cycles were conducted to increase TSE screening and reduce counseling. Results: Before starting the project, 18% of smoking caregivers acknowledged smoking in the home and 41% in the car. While caregivers strongly desired to decrease TSE (median 9.4/10 on Likert scale), physician counseling of TSE reduction was offered only to 44%. PDSA cycles led to refining our patient passport, a document used during patient intake, which increased screening of TSE from 46% to 85%. Creating an educational handout in our electronic record addressing TSE increased TSE reduction counseling from 44% to 80% of children with smokers in the home. Conclusions: Incorporating TSE screening into established nursing documentation of vital signs led to the sustained screening of TSE among children in a pediatric pulmonology practice. Embedding educational material in our electronic record and changes in clinic processes increased TSE reduction counseling. Similar changes could improve rates of counseling caregivers of other guidelines aimed to improve the children's health.

Airway closing index in school-age children during exercise bronchoprovocation.

OBJECTIVE: Airway Closing Index (ACI), the ratio of % change in FVC to % change in FEV1 with bronchoprovocation, may represent changes in airflow due to airway closure, as opposed to airway narrowing. The objective of this study was to evaluate ACI during exercise bronchoprovocation (EB) in children. METHODS: Children, 6 to 18 years of age, who underwent EB using a stationary bicycle ergometer over a 6-year period were reviewed. Pulmonary function, including ACI, in patients with a positive exercise challenge, defined as ≥10% decrease in FEV1 following exercise, were compared to patients with a negative challenge. RESULTS: A total of 1030 children with a median age of 13 (IQR 11-15) underwent EB, of which 376 (37%) had a positive exercise challenge. There was wide variability in ACI, with a median of 0.75 (0.28-1.21). Median ACI in those with a positive test was 0.68 (IQR 0.41-0.93) compared to 0.84 (IQR 0.09-1.06) for those with a negative test, p = 0.017. Median ACI was higher in older children (p < 0.001) and females (p < 0.0001). Median percent change in FEV1 following bronchodilator for children in the highest quintile for ACI was 4.5 (IQR 1.3-8.1) compared to 5.5 (IQR 2-9.2) for children in the lowest quintile, p = 0.04. CONCLUSIONS: There is wide variability in the ACI in children undergoing EB. ACI was lower in children with a positive challenge, the significance is unknown. Children with higher ACI may have increased airway closure with bronchoprovocation, and less response to bronchodilators.

Stable to improved cardiac and pulmonary function in children with high-risk sickle cell disease following haploidentical stem cell transplantation.

Children with sickle cell disease (SCD) are at high-risk of progressive, chronic pulmonary and cardiac dysfunction. In this prospective multicenter Phase II trial of myeloimmunoablative conditioning followed by haploidentical stem cell transplantation in children with high-risk SCD, 19 patients, 2.0-21.0 years of age, were enrolled with one or more of the following: history of (1) overt stroke; (2) silent stroke; (3) elevated transcranial Doppler velocity; (4) multiple vaso-occlusive crises; and/or (5) two or more acute chest syndromes and received haploidentical transplants from 18 parental donors. Cardiac and pulmonary centralized cores were established. Pulmonary function results were expressed as percent of the median of healthy reference cohorts, matched for age, sex, height and race. At 2 years, pulmonary functions including forced expiratory volume (FEV), FEV1/ forced vital capacity (FVC), total lung capacity (TLC), diffusing capacity of lung for carbon monoxide (DLCO) were stable to improved compared to baseline values. Importantly, specific airway conductance was significantly improved at 2 years (p < 0.004). Left ventricular systolic function (fractional shortening) and tricuspid regurgitant velocity were stable at 2 years. These results demonstrate that haploidentical stem cell transplantation can stabilize or improve cardiopulmonary function in patients with SCD.

Safety and efficacy of lenabasum in a phase 2 randomized, placebo-controlled trial in adults with cystic fibrosis.

BACKGROUND: Few therapies specifically address the chronic airway inflammation in cystic fibrosis (CF) that contributes to progressive destruction of lung tissue and loss of lung function. Lenabasum is a cannabinoid type 2 receptor (CB2) agonist that resolves inflammation in a number of in vitro and in vivo models. METHODS: A Phase 2 double-blind, randomized, placebo-controlled study assessed the safety and tolerability of lenabasum in adults with CF. Subjects with FEV1% (ppFEV1) ≥40% predicted were randomized to lenabasum 1 or 5 mg or placebo once daily (QD) (Weeks 1-4), then 20 mg QD, 20 mg twice daily (BID) or placebo (Weeks 5-12), with follow-up at Week 16. Pulmonary exacerbations (PEx) were recorded and biomarkers of blood and lung inflammation were measured. RESULTS: Of 89 subjects randomized, 51 lenabasum and 23 placebo-only subjects completed the study. No deaths or serious or severe adverse events (AE) were considered related to lenabasum. Most AEs were mild/moderate, and the most common were PEx, hemoptysis, dry mouth, and upper respiratory infection. Three lenabasum and one placebo-only subjects discontinued the study for a treatment related AE. New PEx were treated with intravenous antibiotics in 4.0% of lenabasum-treated vs. 11.4% of placebo-treated subjects, during Weeks 1-4 and 5.2% compared to 13.0% during Weeks 5-12 (p<0.2). No significant differences in ppFEV1 were observed between treatment groups. Sputum neutrophils, eosinophils, and neutrophil elastase were numerically reduced, and significant (p<0.05) reductions in IL-8 and immunoglobulin G levels occurred with lenabasum. CONCLUSIONS: The safety findings of lenabasum, coupled with biomarker data, support further testing in a larger study with a longer duration.

Incidence and prevalence of common respiratory pathogens before and after implementation of the Cystic Fibrosis Foundation Infection Prevention and Control Guideline.

BACKGROUND: The 2013 Cystic Fibrosis Foundation's Infection Prevention and Control Guideline (CFF IP&C) was developed to reduce the risk of acquisition and transmission of respiratory pathogens in patients with cystic fibrosis (CF). OBJECTIVE: We hypothesised that the incidence of common CF respiratory pathogens would decrease at our centre after implementation of the guideline. METHODS: All patients with CF seen at our centre from August 2012 through August 2017 who had respiratory cultures were included. Patients were excluded from incidence analysis if they did not have at least one culture per year. Quarterly data were collected for one year before and three years after implementation of the guidelines to determine the incidence and prevalence of seven organisms commonly found in respiratory cultures of patients with CF. RESULTS: Quarterly and annual incidence and prevalence rates of common organisms did not change during the study period. DISCUSSION: There were no significant differences in the incidence or prevalence of common respiratory organisms in the first three years after implementation of the CF IP&C guideline. Long-term follow-up is needed to determine if changes occur over time.

Perceptions of safety monitoring in CF clinical studies and potential impact on future study participation.

BACKGROUND: Individuals with CF and their parents cite safety concerns as barriers to participating in clinical studies. We assessed whether a brochure/infographic describing patient safety monitoring processes could reduce knowledge and attitude barriers regarding safety monitoring. We also identified factors associated with likely participation in future CF studies. METHODS: Respondents from three CF centers in the U.S. were randomly assigned to receive the safety monitoring brochure/infographic or an unrelated brochure. Fifty parents of children with CF <16, 50 adolescents with CF 16-21, and 50 adults with CF ≥22 years old were recruited to complete the study survey. Factors associated with survey responses and with reported likelihood of participating in future studies were assessed. RESULTS: Overall the safety monitoring brochure/infographic was associated with increased likelihood of future participation in non-drug studies (aOR 2.30, CI95 1.01-5.28), but not in drug studies. Non-Hispanic respondents reported greater likelihood of participating in a future drug study than Hispanic respondents (aOR 3.18, CI95 1.30-7.74). Adults with CF (aOR 2.62, CI95 1.05-6.51) and parents (aOR 4.49, CI95 1.66-12.15) were more likely than adolescents to report they would ask their care team about clinical trials. Confidence in safety monitoring was associated with reported likelihood of future participation in drug studies. CONCLUSIONS: Potential future participation in CF drug and/or non-drug studies was associated with respondent age and ethnicity, receiving the safety monitoring brochure/infographic, and confidence in safety monitoring. Our findings underscore the need for education about safety monitoring, with targeted approaches for the Hispanic CF population and adolescents.

Bronchodilators, Antibiotics, and Oral Corticosteroids Use in Primary Care for Children With Cough.

Real-world management decisions for acute cough in children in primary care practice are not well understood. This study is an analysis of 560 encounters for children with cough, 19 days to 18 years of age, seen in a predominantly suburban academic pediatric practice, over 1 year. Past history, cough duration, and cough characteristics significantly affected treatment decisions. Children with cough frequently had a history of preterm birth, allergies, asthma, and neurological conditions. Most common therapies were bronchodilators, antibiotics, and oral corticosteroids. Children prescribed antibiotics were older, more likely to have a wet or productive cough, history of sinusitis, pneumonia or dysphagia, and longer cough duration. Children prescribed oral corticosteroids were younger, less likely to be wet or productive and more likely to have history of asthma or dysphagia. Children prescribed bronchodilators were more likely to have fever, nasal congestion, and wheezing and history of previous asthma, pneumonia, or dysphagia.

Clinical characterization of children with resistant airflow obstruction, a multicenter study.

OBJECTIVE: To characterize a cohort of children with airflow limitation resistant to bronchodilator (BD) therapy. METHODS: Pulmonary function tests performed in children 6-17 years of age at 15 centers in a clinical research consortium were screened for resistant airflow limitation, defined as a post-BD FEV1 and/or an FEV1/FVC less than the lower limits of normal. Demographic and clinical data were analyzed for associations with pulmonary function. RESULTS: 582 children were identified. Median age was 13 years (IQR: 11, 16), 60% were males; 62% were Caucasian, 28% were African-American; 19% were obese; 32% were born prematurely and 21% exposed to second hand smoke. Pulmonary diagnoses included asthma (93%), prior significant pneumonia (28%), and bronchiectasis (5%). 65% reported allergic rhinitis, and 11% chronic sinusitis. Subjects without a history of asthma had significantly lower post-BD FEV1% predicted (p = 0.008). Subjects without allergic rhinitis had lower post-BD FEV1% predicted (p = 0.003). Children with allergic rhinitis, male sex, obesity and Black race had better pulmonary function post-BD. There was lower pulmonary function in children after age 11 years without a history of allergic rhinitis, as compared to those with a history of allergic rhinitis. CONCLUSIONS: The most prevalent diagnosis in children with BD-resistant airflow limitation is asthma. Allergic rhinitis and premature birth are common co-morbidities. Children without a history of asthma, as well as those with asthma but no allergic rhinitis, had lower pulmonary function. Children with BD-resistant airflow limitation may represent a sub-group of children with persistent obstruction and high risk for life-long airway disease.

Building New York State Centers of Excellence in Children's Environmental Health: A Replicable Model in a Time of Uncertainty.

Public health programs may be seriously affected in periods of federal retrenchment. During these times, state-based strategies provide an alternate pathway for advancing public health.A 12-year campaign to secure state support for a network of Centers of Excellence in Children's Environmental Health (CEH) promoting health of children across New York State is described. It was driven by rising rates of asthma, birth defects, developmental disorders, and other noncommunicable diseases in children; growing evidence associating hazardous environmental exposures with these conditions; and recognition that federal resources in CEH are insufficient.Critical campaign elements were (1) formation of a statewide coalition of academic health centers, health care providers, public health officials, community advocates, and other stakeholders; (2) bipartisan collaborations with legislative champions and government leaders; (3) assessment of the burden of developmental disorders and noncommunicable diseases associated with environmental exposures among children; (4) maps documenting the presence of environmental hazards in every county statewide; (5) iterative charting of a changing political landscape; and (6) persistence. The 2017 award of a 5-year, $10 million contract to establish Centers of Excellence in CEH demonstrates the value of this statewide strategy.

Comparison of the Severity of Respiratory Disease in Children Testing Positive for Enterovirus D68 and Human Rhinovirus.

OBJECTIVE: To compare the characteristics and severity of respiratory disease in children testing positive for enterovirus D68 (EV-D68) and for human rhinovirus (RhV). STUDY DESIGN: A retrospective single center study of children presenting with acute respiratory symptoms and positive polymerase chain reaction for RhV/EV from September 1, 2014 through October 31, 2014 was performed. Specimens were subsequently tested specifically for EV-D68 and specimens identified as RhV were subtyped when possible into RhV-A, RhV-B, and RhV-C species. Clinical manifestations in patients with EV-D68 were compared with those with non-EV-D68, RhV, and RhV-C. RESULTS: Of the 173 patients included in the analysis, 72 tested positive for EV-D68, 61 for RhV, and 30 for RhV-C. There were significantly fewer infants in the EV-D68 group. Patients with EV-D68 were more likely than those without EV-D68, and specifically with RhV-C, to have fever and wheezing. Patients with EV-D68 received more magnesium sulfate for respiratory distress not responding adequately to repeated doses of inhaled albuterol. Hospitalized patients with EV-D68 received more bronchodilator therapy than patients with RhV. Patients with EV-D68 were more likely to be admitted to the intensive care unit and were older than patients without EV-D68. There was no difference in length of overall hospitalization or time in the pediatric intensive care unit. CONCLUSIONS: Children with EV-D68 appeared to have more severe respiratory disease on admission than children with RhV as evidenced by higher rates of fever, wheezing, bronchodilator use and pediatric intensive care unit admission. Despite the initial difference in severity, no significant difference in length of stay was found suggesting that patients with EV-D68 recovered as quickly as other groups.

Clinical Sensitivity of Cystic Fibrosis Mutation Panels in a Diverse Population.

Infants are screened for cystic fibrosis (CF) in New York State (NYS) using an IRT-DNA algorithm. The purpose of this study was to validate and assess clinical validity of the US FDA-cleared Illumina MiSeqDx CF 139-Variant Assay (139-VA) in the diverse NYS CF population. The study included 439 infants with CF identified via newborn screening (NBS) from 2002 to 2012. All had been screened using the Abbott Molecular CF Genotyping Assay or the Hologic InPlex CF Molecular Test. All with CF and zero or one mutation were tested using the 139-VA. DNA extracted from dried blood spots was reliably and accurately genotyped using the 139-VA. Sixty-three additional mutations were identified. Clinical sensitivity of three panels ranged from 76.2% (23 mutations recommended for screening by ACMG/ACOG) to 79.7% (current NYS 39-mutation InPlex panel), up to 86.0% for the 139-VA. For all, sensitivity was highest in Whites and lowest in the Black population. Although the sample size was small, there was a nearly 20% increase in sensitivity for the Black CF population using the 139-VA (68.2%) over the ACMG/ACOG and InPlex panels (both 50.0%). Overall, the 139-VA is more sensitive than other commercially available panels, and could be considered for NBS, clinical, or research laboratories conducting CF screening.

Effect of a soy isoflavone supplement on lung function and clinical outcomes in patients with poorly controlled asthma: a randomized clinical trial.

IMPORTANCE: Soy isoflavone supplements are used to treat several chronic diseases, although the data supporting their use are limited. Some data suggest that supplementation with soy isoflavone may be an effective treatment for patients with poor asthma control. OBJECTIVE: To determine whether a soy isoflavone supplement improves asthma control in adolescent and adult patients with poorly controlled disease. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, randomized, double-blind, placebo-controlled trial conducted between May 2010 and August 2012 at 19 adult and pediatric pulmonary and allergy centers in the American Lung Association Asthma Clinical Research Centers network. Three hundred eighty-six adults and children aged 12 years or older with symptomatic asthma while taking a controller medicine and low dietary soy intake were randomized, and 345 (89%) completed spirometry at week 24. INTERVENTIONS: Participants were randomly assigned to receive soy isoflavone supplement containing 100 mg of total isoflavones (n=193) or matching placebo (n=193) in 2 divided doses administered daily for 24 weeks. MAIN OUTCOMES AND MEASURES: The primary outcome measure was change in forced expiratory volume in the first second (FEV1) at 24 weeks. Secondary outcome measures were symptoms, episodes of poor asthma control, Asthma Control Test score (range, 5-25; higher scores indicate better control), and systemic and airway biomarkers of inflammation. RESULTS: Mean changes in prebronchodilator FEV1 over 24 weeks were 0.03 L (95% CI, -0.01 to 0.08 L) in the placebo group and 0.01 L (95% CI, -0.07 to 0.07 L) in the soy isoflavone group, which were not significantly different (P = .36). Mean changes in symptom scores on the Asthma Control Test (placebo, 1.98 [95% CI, 1.42-2.54] vs soy isoflavones, 2.20 [95% CI, 1.53-2.87]; positive values indicate a reduction in symptoms), number of episodes of poor asthma control (placebo, 3.3 [95% CI, 2.7-4.1] vs soy isoflavones, 3.0 [95% CI, 2.4-3.7]), and changes in exhaled nitric oxide (placebo, -3.48 ppb [95% CI, -5.99 to -0.97 ppb] vs soy isoflavones, 1.39 ppb [95% CI, -1.73 to 4.51 ppb]) did not significantly improve more with the soy isoflavone supplement than with placebo. Mean plasma genistein level increased from 4.87 ng/mL to 37.67 ng/mL (P < .001) in participants receiving the supplement. CONCLUSIONS AND RELEVANCE: Among adults and children aged 12 years or older with poorly controlled asthma while taking a controller medication, use of a soy isoflavone supplement, compared with placebo, did not result in improved lung function or clinical outcomes. These findings suggest that this supplement should not be used for patients with poorly controlled asthma. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01052116.

Differences in perspective on prognosis and treatment of children with trisomy 18.

Differences in perspective between physicians caring for children with trisomy 18 may be confusing and stressful for parents. The hypothesis of this study was that neonatologists and pediatric pulmonologists differ in their opinions regarding long-term prognosis and recommended interventions. Neonatologists and pediatric pulmonologists in New York State were surveyed. Respondents were asked to report their personal experience caring for affected children, opinions on prognosis, major influences on their opinions, and their likelihood of recommending specific medical or surgical interventions for two clinical vignettes. A total of 393 surveys were mailed, 327 to neonatologists and 66 to pediatric pulmonologists. Sixty-six (20%) neonatologists and 21 (32%) pediatric pulmonologists completed the survey. Neonatologists had cared for more patients with trisomy 18. Twenty-nine percent of pediatric pulmonologists had never cared for a patient with trisomy 18 compared to 2% of neonatologists, P < 0.001. Pediatric pulmonologists were more likely to recommend almost all interventions including antibiotics for pneumonia, mechanical ventilation, cardiac and orthopedic surgery, and "full code resuscitation." Neonatologists were more likely to recommend comfort care only or palliative care. Fifty-four percent of neonatologists and 5% of pediatric pulmonologists thought patients with trisomy 18 without significant congenital heart disease would die before age one despite aggressive medical care, P < 0.001. The major influences impacting these recommendations also varied. Pediatric pulmonologists are more optimistic about the prognosis for children than neonatologists and more likely to recommend medical and surgical interventions. Experience with the condition and perception of survivability may contribute to these differences in approach.

The effects of low-level environmental tobacco smoke exposure on pulmonary function tests in preschool children with asthma.

OBJECTIVES: Though parents of children with asthma smoke, they often avoid smoking in their homes or near their children, thus limiting exposure. It is not known if such low-level environmental tobacco smoke (ETS) results in measurable exposure or affects lung function. The objectives of this study were to measure urinary cotinine in preschool children with asthma, and to examine the relationship between low-level ETS exposure and pulmonary function tests (PFTs). METHODS: Preschool children with asthma were enrolled. Parents completed questionnaires on ETS exposure and asthma control, urinary cotinine concentrations were measured and PFTs were compared between subjects with and without recent ETS exposure. RESULTS: Forty one subjects were enrolled. All parents denied smoking in their home within the last 2 weeks, but 14 (34%) parents admitted to smoking outside their homes or away from their children. Fifteen (37%; 95%CI: 23-53) of the children had urinary cotinine levels ≥1 ng/ml, of which seven (17%; 95%CI: 8-32) had levels ≥5 ng/ml. FEV1 and FEV0.5 were lower in subjects with a urinary cotinine level ≥5 ng/ml as compared to those with levels <1 ng/ml or between 1 and 5 ng/ml; both at baseline and after inhalation of albuterol. Five of seven subjects with urinary cotinine levels ≥5 ng/ml had FEV0.5 less than 65% of predicted values. There were no significant differences in IOS measures. CONCLUSIONS: Despite parental denial of smoking near their children, preschool children may be exposed to ETS. Such low-level ETS exposure may affect lung function, possibly in a dose-dependent manner.

Relationship between sweat chloride, sodium, and age in clinically obtained samples.

BACKGROUND: The relationship between sweat electrolytes and age is uncertain, as is the value of measuring sodium or the chloride:sodium ratio. METHODS: 13,785 sweat tests performed over 23 years at one center through the Macroduct collection in clinically obtained samples were analyzed. RESULTS: Sweat chloride tended to decrease over the first year of life, slowly increase until the fourth decade, then either level off or slightly decrease. In children, sweat sodium overlapped between those with positive and negative sweat tests, but not in adults. If the sweat test was positive, there was a higher likelihood of having a chloride:sodium ratio >1, but most subjects with a ratio >1 did not have CF. CONCLUSIONS: Sweat chloride and sodium vary with age. Measurement of sweat sodium did not add discriminatory value. The proportion of subjects with a chloride:sodium ratio >1, with or without CF, varied greatly between age ranges.