Decrease In Peak Expiratory Flow Research Articles

Change in peak expiratory flow over time among workers exposed to polyvinyl chloride dust.

To evaluate the variation of peak expiratory flow (PEF) over a working week among non-smoking workers without previous asthma who have been exposed to polyvinyl chloride (PVC) dust. We conducted a cross-sectional study among 42 operators with exposure to PVC dust (filling hoppers to feed extrusion machines) and 23 employees without exposure to PVC dust in a plant producing PVC pipes in West Africa. A pre-tested questionnaire was administered and PEF was measured using a portable peak flow meter after a day off (day 1), on day 3 and at the end of the week (day 6). The two groups did not differ by age or body mass index. Dyspnoea was more prevalent in exposed workers than controls (52% vs. 13%, P = 0.002). PEF decreased more significantly in exposed workers than controls (-8% vs. -3% on day 3 and -10% vs. -5% on day 6, both P = 0.004). The duration of exposure did not affect PEF variability in the exposed groups. The decrease of PEF over the working week in workers exposed to PVC dust is consistent with occupational asthma, although standard measures to diagnose occupational asthma were not used. This result reinforces the need to prevent excessive exposure to PVC dust.

Impact of close-proximity air pollution on lung function in schoolchildren in the French West Indies

BackgroundHigh levels of asthma prevalence and severity of respiratory symptoms have been found in the Caribbean but little is known about the impact of air pollution in these regions.This study aimed to describe air pollution and measure the associations with child lung function in Guadeloupe (French West Indies).MethodsData from 30 randomly chosen elementary schools (8–13 years old) were obtained using a standardized protocol adapted from the ISAAC2 study. We considered two health outcomes: peak expiratory flow (PEF) before running and the variation in peak expiratory flow (ΔPEF) after running. The associations between pollutants and outcomes were investigated using several air pollution exposure models: i) medium-term exposure to close-proximity pollution both indoor and outdoor for ozone (O3) and nitrogen dioxide (NO2) and ii) short- and medium-term exposure to background pollution for O3, NO2, sulphur dioxide (SO2) and small particulate matter (PM10).ResultsOf 1,463 children, 277 (16%) were found to have asthma. A 1-μg/m3 increase in medium-term exposure to outdoor close-proximity pollution by O3 was associated with a PEF decrease (β = −0.32; 95% CI: −0.61;-0.03). No association was found with NO2 regarding close-proximity pollution. The association between medium-term exposure to background pollution and PEF decrease was stronger in asthmatic children than in non-asthmatic children for O3. No reduction in PEF or ΔPEF was shown with NO2, SO2 and PM10 pollutants but a significant association was found between PM10 and PEF increase.ConclusionsOur results suggest that O3 could have an acute effect on child lung function in the Caribbean even at a low concentration (below the WHO guidelines). Further research in the Caribbean is needed to confirm these findings.

The association between ambient temperature and children's lung function in Baotou, China.

The objective of this study is to examine the association between ambient temperature and children's lung function in Baotou, China. We recruited 315 children (8-12 years) from Baotou, China in the spring of 2004, 2005, and 2006. They performed three successive forced expiratory measurements three times daily (morning, noon, and evening) for about 5 weeks. The highest peak expiratory flow (PEF) was recorded for each session. Daily data on ambient temperature, relative humidity, and air pollution were monitored during the same period. Mixed models with a distributed lag structure were used to examine the effects of temperature on lung function while adjusting for individual characteristics and environmental factors. Low temperatures were significantly associated with decreases in PEF. The effects lasted for lag 0-2 days. For all participants, the cumulative effect estimates (lag 0-2 days) were -1.44 (-1.93, -0.94) L/min, -1.39 (-1.92, -0.86) L/min, -1.40 (-1.97, -0.82) L/min, and -1.28 (-1.69, -0.88) L/min for morning, noon, evening, and daily mean PEF, respectively, associated with 1 °C decrease in daily mean temperature. Generally, the effects of temperature were slightly stronger in boys than in girls for noon, evening, and daily mean PEF, while the effects were stronger in girls for morning PEF. PM2.5 had joint effects with temperature on children's PEF. Higher PM2.5 increased the impacts of low temperature. Low ambient temperatures are associated with lower lung function in children in Baotou, China. Preventive health policies will be required for protecting children from the cold weather.

Increased H1N1 Infection Rate in Children With Asthma

In 2009, H1N1 influenza resulted in 87 000 hospitalizations among children. The most common comorbidity for patients hospitalized as a result of H1N1 infection was asthma. Were children with asthma more likely to be infected with H1N1 influenza?A total of 161 children aged 4 to 12 years, 95 with asthma and 66 without asthma, were recruited from within a study of 193 children being studied for the effects of rhinovirus infection on asthma.The children provided 8 weekly nasal mucus samples that were analyzed for respiratory viruses by polymerase chain reaction. Upper respiratory infection and asthma symptoms, morning peak expiratory flow rates, and albuterol use were recorded on daily diary cards. Loss of asthma control was defined as at least moderate asthma symptoms and either a decrease in peak expiratory flow of ≥20% or use of albuterol for ≥2 days per week.Three hundred forty-six infections were detected: rhinoviruses (62%), enterovirus (12%), H1N1 (10%), adenovirus (2%), and multiple viruses (13%). When multiple viruses were detected in a single sample, rhinovirus (80%) and H1N1 (51%) were the most common. Thirty-four percent of children were infected with H1N1; rates were higher in children with asthma (41%) than in children without asthma (24%) (odds ratio: 2.2; 95% confidence interval: 1.1–4.4; P = .03). Asthma did not affect rates of infection with rhinovirus (90% in each group), enterovirus (30% vs 24%), adenovirus (11% vs 12%), or other viruses (6% vs 5%). Rates of loss of asthma control per infection were as follows: H1N1, 38% (9 of 24); rhinovirus, 21% (27 of 127); and the combination of rhinovirus and H1N1, 44% (4 of 9).Given the increased susceptibility of children with asthma to infection, these findings reinforce the need for yearly influenza vaccination to prevent infection and raise new questions about the mechanism for enhanced susceptibility to influenza infection in asthma.Influenza infection is more likely to cause chest symptoms in a child with underlying asthma, but in addition, this study suggests that children with asthma also become infected at a higher rate. This increased susceptibility to infection appeared to be unique to influenza virus as opposed to rhinovirus and other viruses. Whereas the mechanism of this increased susceptibility to infection with a particular virus needs to be explored, infection with the particular virus involved (influenza) can often be prevented by vaccination.

Assessment of the biological effects of welding fumes emitted from metal inert gas welding processes of aluminium and zinc-plated materials in humans

The aim of this study was to investigate biological effects and potential health risks due to two different metal-inert-gas (MIG) welding fumes (MIG welding of aluminium and MIG soldering of zinc coated steel) in healthy humans. In a threefold cross-over design study 12 male subjects were exposed to three different exposure scenarios. Exposures were performed under controlled conditions in the Aachener Workplace Simulation Laboratory (AWSL). On three different days the subjects were either exposed to filtered ambient air, to welding fumes from MIG welding of aluminium, or to fumes from MIG soldering of zinc coated materials. Exposure was performed for 6 h and the average fume concentration was 2.5 mg m(-3). Before, directly after, 1 day after, and 7 days after exposure spirometric and impulse oscillometric measurements were performed, exhaled breath condensate (EBC) was collected and blood samples were taken and analyzed for inflammatory markers. During MIG welding of aluminium high ozone concentrations (up to 250 μg m(-3)) were observed, whereas ozone was negligible for MIG soldering. For MIG soldering, concentrations of high-sensitivity CRP (hsCRP) and factor VIII were significantly increased but remained mostly within the normal range. The concentration of neutrophils increased in tendency. For MIG welding of aluminium, the lung function showed significant decreases in Peak Expiratory Flow (PEF) and Mean Expiratory Flow at 75% vital capacity (MEF 75) 7 days after exposure. The concentration of ristocetin cofactor was increased. The observed increase of hsCRP during MIG-soldering can be understood as an indicator for asymptomatic systemic inflammation probably due to zinc (zinc concentration 1.5 mg m(-3)). The change in lung function observed after MIG welding of aluminium may be attributed to ozone inhalation, although the late response (7 days after exposure) is surprising.

Detection of exacerbations in asthma based on electronic diary data: results from the 1-year prospective BIOAIR study

BackgroundObjective measures are required that may be used as a proxy for exacerbations in asthma. The aim was to determine the sensitivity and specificity of electronic diary data to detect...

Small-airways dysfunction associates with respiratory symptoms and clinical features of asthma: A systematic review

Traditionally, asthma has been considered a disease that predominantly involves the large airways. Today, this concept is being challenged, and increasing evidence has become available showing that abnormalities in the small airways also contribute to the clinical expression of asthma. The small airways can be affected by inflammation, remodeling, and changes in the surrounding tissue, all contributing to small-airways dysfunction. In this article we have performed a systematic review of the literature on the association between small-airways dysfunction and clinical signs and symptoms of asthma. This review shows that small-airways dysfunction associates with worse control of asthma, higher numbers of exacerbations, the presence of nocturnal asthma, more severe bronchial hyperresponsiveness, exercise-induced asthma, and the late-phase allergic response. Importantly, small-airways dysfunction can already be present in patients with mild asthma. Our review provides suggestive evidence that a better response of the small airways to inhaled steroids or montelukast associates with better asthma control. For this reason, an early recognition of small-airways dysfunction is important because it enables the physician to start timely treatment to target the small airways. It is important to develop simpler and more reliable tools (eg, questionnaires or bronchial provocation tests with small-particle stimuli) to assess the presence and extent of small-airways dysfunction in daily clinical practice.

Recurrent apnea episodes as an onset of a primary pulmonary hypertension, a case report

A 15-year-old teenager boy presented to emergency room, because of dyspnoea and prolonged dry cough, worsening at night time. He gained 15kg in the last 6mo, when began complaining of physical load intolerance. He was suspected having asthma in case the positive family history and allergy to house dust mites was confirmed. No specific treatment was given, no other investigations were done. He became worse in the last 3mo: night sweats and wheezing increased, face, eyes swelling episodes in the morning appeared. He was healthy by then. Findings: weight 89 kg (97‰), height 179 cm (90‰). His face seemed as if swollen, flushed, dilated capillaries on the chest were observed. No other pathological findings on clinical evaluation. Blood, urine tests and CRP were normal. Spirometry: severely decreased peak expiratory flow (PEF), no other changes. Increased mediastinal size on chest X-ray was suspected. The patient was hospitalised for further investigations. Not enough data supporting allergic asthma, atypical infections, TB, GERD, cardiac pathology were found. Due to weight gain in a short time he was consulted by endocrinologist and further tests recommended. But increased ESR (24mm/h), b2 microglobulin (1.83mg/l), constantly decreased PEF-metry results (max volume of 270ml) and primary changes on X-ray resembled more severe condition. Repeated chest X-ray showed persistent mediastinal enlargement, and the limited homogenic mass on lateral view. Chest CT demonstrated anterior mediastinal enlargement due to non homogenic masses; lymphoid-like masses surrounding the aortic arch, spreading to all the superior mediastinum and tracheal bifurcation, circularly surrounding all the aortic branches, pressing superior v. cava, distal postclavicular venous part, merging with postclavicular lymph node conglomerates; infiltrating pericardium. Mediastinal tumor was suspected and biopsy was planned. The procedure and ventilation were complicated due to tracheal obstruction and significant bleeding. Afterwards the patient was treated at the PICU where he was on continues ventilation without possibility for extubation due to expressed pressure to trachea. The swelling of upper part of the body was significant as well. Methylprednisolone till the answer of the biopsy was started, but without any success. Biopsy results revealed sarcoma of the primitive formed elements of the blood. The patient was transferred to leukemia center. Conclusion: Not every child with asthmatic complaints could have asthma. If complaints persist or progress, the more extent evaluation, especially chest X-ray should be done. Every child with mediastinal enlargement on chest X-ray should undergo screening for oncological conditions.

An Asthma Patient with Steroid-resistant Decrease in Peak Expiratory Flow after the Great East Japan Earthquake Showing Spontaneous Recovery after 1 Month

People living in Japan were affected in various ways after the Great East Japan earthquake of March 11, 2011. A 52-year-old female asthma patient not directly affected by the disaster experienced a decrease in peak expiratory flow (PEF) immediately after the earthquake. Despite increasing the inhaled and oral corticosteroid doses, her PEF did not recover. One month later, her PEF level abruptly returned to normal with minimal medications, which were previously ineffective, and the asthma-related symptoms vanished. The stabilization of her state of mind and actual social state seemed to be a part of the reason for the patient's recovery.

A Case Report of Food-Dependent Exercise-Induced Anaphylaxis in a Patient who was Sensitive to Pork

Food-dependent exercise-induced anaphylaxis (FDEIA) is a specific variant of exercise-induced anaphylaxis that requires both vigorous physical activity and the ingestion of specific foods. In particular, it is rare occurrence for FDEIA to be associated with meat in Korea. A 15-year-old female had generalized urticaria, dyspnea, severe cough, headache, dizziness, and vomiting after singing and dancing for 1 hour and after ingesting grilled pork. Skin prick tests showed a strong positive reaction to pork, whereas the results of an oral food challenge and exercise provocation tests were negative. However, the exercise provocation test after pork ingestion showed a positive reaction manifested by generalized urticaria, cough, mild dyspnea, and a 23% decreased peak expiratory flow rate. Three allergens to pork (67 kDa, 90 kDa, and 15 kDa) reacted with the patient’s serum on immunoglobulin E immunoblotting. We report a case of pork-dependent exercise-induced anaphylaxis in a patient who was sensitive to pork. [Pediatr Allergy Respir Dis(Korea) 2012;22: 116-121]

Abstract withdrawn

Methods A 2–3-week run-in period with twice daily (BID) MF100μg, MF-200μg, or MF-400μg was performed before subject (≥12y) randomization to BID: MF/F-100/10μg, MF100μg, F-10μg, or placebo for 26weeks (n=746); MF/F-200/ 10mg, MF-200μg, F-10μg, or placebo for 26weeks (n=781); MF/F-200/10μg, MF/F-400/10μg, or MF-400μg for 12weeks (n=728 ). Assessment of asthma deterioration (ie, 20% decrease in forced expiratory volume in 1s [FEV1]; 30% decrease in peak expiratory flow [PEF] on ≥2 consecutive days; or clinically judged deterioration [ie, emergency treatment, hospitalization, or treatment with excluded medications]) was a co-primary endpoint for studies, and a secondary endpoint for study. Post hoc pair-wise comparisons of pooled MF/F vs MF, F, and placebo treatment groups were performed.

Impact of race on asthma treatment failures in the asthma clinical research network.

Recent studies suggest that people with asthma of different racial backgrounds may respond differently to various therapies. To use data from well-characterized participants in prior Asthma Clinical Research Network (ACRN) trials to determine whether racial differences affected asthma treatment failures. We analyzed baseline phenotypes and treatment failure rates (worsening asthma resulting in systemic corticosteroid use, hospitalization, emergency department visit, prolonged decrease in peak expiratory flow, increase in albuterol use, or safety concerns) in subjects participating in 10 ACRN trials (1993-2003). Self-declared race was reported in each trial and treatment failure rates were stratified by race. A total of 1,200 unique subjects (whites = 795 [66%]; African Americans = 233 [19%]; others = 172 [14%]; mean age = 32) were included in the analyses. At baseline, African Americans had fewer asthma symptoms (P < 0.001) and less average daily rescue inhaler use (P = 0.007) than whites. There were no differences in baseline FEV(1) (% predicted); asthma quality of life; bronchial hyperreactivity; or exhaled nitric oxide concentrations. A total of 147 treatment failures were observed; a significantly higher proportion of African Americans (19.7%; n = 46) experienced a treatment failure compared with whites (12.7%; n = 101) (odds ratio = 1.7; 95% confidence interval, 1.2-2.5; P = 0.007). When stratified by treatment, African Americans receiving long-acting β-agonists were twice as likely as whites to experience a treatment failure (odds ratio = 2.1; 95% confidence interval, 1.3-3.6; P = 0.004), even when used with other controller therapies. Despite having fewer asthma symptoms and less rescue β-agonist use, African-Americans with asthma have more treatment failures compared with whites, especially when taking long-acting β-agonists.

Decreased peak expiratory flow in pediatric passive smokers

Background Indonesia ranks fifth among countries with the highest aggregate levels of tobacco consumption in the world. Infants and children exposed to environmental tobacco smoke have increased rates of asthma, respiratory and ear infections, as well as reduced lung function. The effects of tobacco smoke exposure on lung function in children have been reported to be dependent on the source of smoke and the length and dose of exposure. Lung function may also be affected by a child’s gender and asthma status.Objective To compare peak expiratory flow (PEF) in pediatric passive smokers to that of children not exposed to second hand smoke, and to define factors that may affect PEF in passive smokers.Methods In August 2009 we conducted a cross-sectional study at an elementary school in the Langkat district. Subjects were aged 6 to 12 years, and divided into two groups: passive smokers and those not exposed to secondhand smoke. Subjects’ PEFs were measured with a Mini-Wright peak flow meter. Measurements were performed in triplicate with the highest value recorded as the PEF. Demographic data including age, sex, weight, height, family income, parental education levels and occupations were obtained through questionnaires.Results Of the 170 participants, 100 were passive smokers and 70 were not exposed to secondhand smoke. Age distribution, weight and height were similar in both groups. We observed a significant difference in PEFs between the group of passive smokers and the group not exposed to secondhand smoke, 211.3 L/minute (SD 61.08) and 242.7 L/minute (SD 77.09), respectively (P &lt; 0.005). The number of years of exposure to smoke (P = 0.079) and the number of cigarettes smoked daily in the household (P = 0.098) did not significantly influence PEF.Conclusion The PEF in pediatric passive smokers was significantly lower than that of children not exposed to secondhand smoke. PEF in passive smokers was not influenced by the number of years of smoke exposure or the number of cigarettes smoked daily in the household.

Toxicological Evaluation of Realistic Emission Source Aerosols (TERESA)—Power plant studies: assessment of breathing pattern

Our approach to study multi-pollutant aerosols isolates a single emissions source, evaluates the toxicity of primary and secondary particles derived from this source, and simulates chemical reactions that occur in the atmosphere after emission. Three U.S. coal-fired power plants utilizing different coals and with different emission controls were evaluated. Secondary organic aerosol (SOA) derived from α-pinene and/or ammonia was added in some experiments. Male Sprague-Dawley rats were exposed for 6 h to filtered air or different atmospheric mixtures. Scenarios studied at each plant included the following: primary particles (P); secondary (oxidized) particles (PO); oxidized particles + SOA (POS); and oxidized and neutralized particles + SOA (PONS); additional control scenarios were also studied. Continuous respiratory data were obtained during exposures using whole body plethysmography chambers. Of the 12 respiratory outcomes assessed, each had statistically significant changes at some plant and with some of the 4 scenarios. The most robust outcomes were found with exposure to the PO scenario (increased respiratory frequency with decreases in inspiratory and expiratory time); and the PONS scenario (decreased peak expiratory flow and expiratory flow at 50%). PONS findings were most strongly associated with ammonium, neutralized sulfate, and elemental carbon (EC) in univariate analyses, but only with EC in multivariate analyses. Control scenario O (oxidized without primary particles) had similar changes to PO. Adjusted R2 analyses showed that scenario was a better predictor of respiratory responses than individual components, suggesting that the complex atmospheric mixture was responsible for respiratory effects.

Predicting asthma exacerbations: Peak expiratory flow revisited

The ability to predict and prevent future exacerbations has been a consistent focus of asthma research. Although some progress has been made on identifying factors associated with an increased risk of exacerbation at the population and individual levels, no measure or instrument is available for widespread use in the asthma community. In this issue of the Journal, Thamrin et al present a statistical method used to calculate the future exacerbation risk for a patient (as defined by deterioration in percent predicted peak expiratory flow [PEF]) based on the history of fluctuations in lung function (percent predicted PEF). The authors challenge us to reframe our analytic approach to asthma. Frey et al have suggested that a patient with asthma should be thought of as a complex, nonlinear dynamic systems network; such a network exhibits fluctuations over time in physiologic and clinical variables. However, such a system also exhibits memory effects, and although changes can occur over time, the recent past will include most of the pertinent information needed to predict the short-term future risk. Viewingasthma through this framework, it follows that the single best individual parameter to predict the risk of an exacerbation over the next year is the history of an exacerbation in the prior year. The natural history of asthma in any given patient is a summation of personal characteristics (eg, demographics, inflammatory profile, and lungmechanics), genetics, both the physical (exposure to environment [environmental tobacco smoke, pollution, and allergens]) and psychosocial (access to care) environment, and therapy (including adherence). The complex interaction of these factors results in the overall clinical phenotype expressed by a patient, and this helps explain why the recent past is a strong predictor of future events. Modeling asthma as a complex, nonlinear dynamic system also fits with our increasing recognition of the heterogeneity of asthma. Patients with asthma present differently in regard to symptoms, physiologic measures, inflammatory indices, and perception of obstruction; measuring a single parameter at a single point might not

Nature and frequency of respiratory involvement in chronic progressive external ophthalmoplegia

Chronic progressive external ophthalmoplegia (CPEO) is a relatively common mitochondrial disorder. Weakness of the extra-ocular, limb girdle and laryngeal muscles are established clinical features. Respiratory muscle involvement however has never been studied systematically, even though respiratory complications are one of the main causes of death. We therefore determined the prevalence and nature of respiratory muscle involvement in 23 patients with genetically confirmed CPEO. The main finding was decreased respiratory muscle strength, both expiratory (76.8% of predicted, p = 0.002) and inspiratory (79.5% of predicted, p = 0.004). Although the inspiratory vital capacity (92.5% of predicted, p = 0.021) and the forced expiratory volume in 1 s (89.3% of predicted, p = 0.002) were below predicted values, both were still within the normal range in the majority of patients. Expiratory weakness was associated with a decreased vital capacity (ρ = 0.502, p = 0.015) and decreased peak expiratory flow (ρ = 0.422, p = 0.045). Moreover, expiratory muscle strength was lower in patients with limb girdle weakness (62.6 ± 26.1% of predicted vs. 98.9 ± 22.5% in patients with normal limb girdle strength, p = 0.003), but was not associated with other clinical features, subjective respiratory complaints, disease severity or disease duration. Since respiratory involvement in CPEO is associated with severe morbidity and mortality, the present data justify periodic assessment of respiratory functions in all CPEO patients.

Effect of hourly concentration of particulate matter on peak expiratory flow in hospitalized children: A panel study

BackgroundLittle information is available on the possible association between hourly short-term air pollution and peak expiratory flow (PEF) in asthmatic children.MethodsPEF was measured twice daily, from October through December, 2000, in 17 children aged 8 to 15 years hospitalized with severe asthma. A total of 1198 PEF measurements were made at 7 a.m. and 1175 at 7 p.m. Measurements were conducted immediately prior to medication under the guidance of trained nurses. PEF changes were estimated in 10-μg/m3 increments of particulate matter with a 50% cut-off aerodynamic diameter of ≤2.5 μm (PM2.5), with adjustment for sex, age, height, and temperature. Lagged-hour exposures of up to 24 hours were examined.ResultsIncreased 24-hour mean concentration of PM2.5 was associated with a decrease in both morning and evening PEF (-3.0 l/minute; 95%CI: -4.6, -1.4 and -4.4 l/minute; 95%CI: -7.1, -1.7, respectively). In addition, hourly concentrations of PM2.5 and PEF showed a significant association between some lags of PM2.5 and PEF. Effect size was almost -3 l/minute in both morning and evening PEF for an hourly PM2.5 concentration of 10 μg/m3 in several lags. Even after adjustment for other air pollutants, some of the significant associations with PEF remained.ConclusionAmong hospitalized children with severe asthma, increased hourly concentration of PM2.5 was associated with a decrease in PEF.

Respiratory Effects of Commuters' Exposure to Air Pollution in Traffic

Much time is spent in traffic, especially during rush hours, when air pollution concentrations on roads are relatively high. Controlled exposure studies have shown acute respiratory effects of short, high exposures to air pollution from motor vehicles. Acute health effects of lower real-life exposures in traffic are unclear. Exposures of 34 healthy, nonsmoking adult volunteers were repeatedly measured while commuting for 2 hours by bus, car, or bicycle. Particle number (PN), particulate matter (PM2.5 and PM10), and soot exposures were measured. Lung function and airway resistance were measured directly before, directly following, and 6 hours after exposure. Exhaled nitric oxide (NO) was measured directly before and 6 hours after exposure. Inhaled doses were estimated based on monitored heart rates. Mixed models were used to analyze effects of exposure on changes in health parameters after exposure compared with before. PN, PM10, and soot were associated with decreased peak expiratory flow directly following but not 6 hours after exposure. PN doses were associated with decreases in maximum midexpiratory flow and forced expiratory flow (FEV1) 6 hours after exposure, whereas PN and soot exposures were associated with increased maximum midexpiratory flow and FEV1 directly after exposure. PN and soot were associated with increased exhaled NO after car and bus but not bicycle trips. PN was also associated with an increase in airway resistance directly following exposure but not 6 hours later. We found modest effects of 2-hour in-traffic exposure to air pollutants on peak flow, exhaled NO, and airway resistance.

Predicting future risk of asthma exacerbations using individual conditional probabilities

Determination of future risk of exacerbations is a key issue in the management of asthma. We previously developed a method to calculate conditional probabilities (π) of future decreases in lung function by using the daily fluctuations in peak expiratory flow (PEF). We aimed to extend calculation of π values to individual patients, validated by using electronically recorded data from 2 past clinical trials. Twice-daily PEF data were analyzed from 78 patients with severe (study A) and 61 patients with poorly controlled (study B) asthma. For each patient, the π value was calculated from 5000 PEF data points simulated based on the correlation and distribution properties of observed PEF. Given an initial PEF, the π value was defined as the probability of a decrease in PEF to less than 80% of predicted value on 2 consecutive days within a month. These probabilities were then compared with actual occurrences of such events and clinically defined exacerbations within the following month. π Values were related to actual occurrences of decreases in PEF (adjusted R(2) > 0.800 for both studies). Every increase of 10% in π value was associated with an odds ratio of having a future exacerbation of 1.24 (95% CI, 1.07-1.43) for study Aand 1.13 (95% CI, 1.02-1.26) for study B, with better sensitivity and specificity than clinic-measured FEV(1). These results from 2 independent datasets with differing asthmatic populations and differing exacerbation criteria provide support that clinically relevant quantification of individual future risk of exacerbations is possible.

Reduction in Asthma Deteriorations in Subjects With Persistent Asthma Uncontrolled on Low-, Medium-, or High-Dose Inhaled Corticosteroids: A Pooled Analysis From Three Clinical Trials Using Combined Mometasone Furoate/Formoterol

Methods A 2–3-week run-in period with twice daily (BID) MF100μg, MF-200μg, or MF-400μg was performed before subject (≥12y) randomization to BID: MF/F-100/10μg, MF100μg, F-10μg, or placebo for 26weeks (n=746); MF/F-200/ 10mg, MF-200μg, F-10μg, or placebo for 26weeks (n=781); MF/F-200/10μg, MF/F-400/10μg, or MF-400μg for 12weeks (n=728 ). Assessment of asthma deterioration (ie, 20% decrease in forced expiratory volume in 1s [FEV1]; 30% decrease in peak expiratory flow [PEF] on ≥2 consecutive days; or clinically judged deterioration [ie, emergency treatment, hospitalization, or treatment with excluded medications]) was a co-primary endpoint for studies, and a secondary endpoint for study. Post hoc pair-wise comparisons of pooled MF/F vs MF, F, and placebo treatment groups were performed.