Respiratory effects of exposure to diesel traffic in persons with asthma

BACKGROUND

Air pollution from road traffic is a serious health hazard, and people with preexisting respiratory disease may be at increased risk. We investigated the effects of short-term exposure to diesel traffic in people with asthma in an urban, roadside environment.

METHODS

We recruited 60 adults with either mild or moderate asthma to participate in a randomized, crossover study. Each participant walked for 2 hours along a London street (Oxford Street) and, on a separate occasion, through a nearby park (Hyde Park). We performed detailed real-time exposure, physiological, and immunologic measurements.

RESULTS

Participants had significantly higher exposures to fine particles (<2.5 microm in aerodynamic diameter), ultrafine particles, elemental carbon, and nitrogen dioxide on Oxford Street than in Hyde Park. Walking for 2 hours on Oxford Street induced asymptomatic but consistent reductions in the forced expiratory volume in 1 second (FEV1) (up to 6.1%) and forced vital capacity (FVC) (up to 5.4%) that were significantly larger than the reductions in FEV1 and FVC after exposure in Hyde Park (P=0.04 and P=0.01, respectively, for the overall effect of exposure, and P<0.005 at some time points). The effects were greater in subjects with moderate asthma than in those with mild asthma. These changes were accompanied by increases in biomarkers of neutrophilic inflammation (sputum myeloperoxidase, 4.24 ng per milliliter after exposure in Hyde Park vs. 24.5 ng per milliliter after exposure on Oxford Street; P=0.05) and airway acidification (maximum decrease in pH, 0.04% after exposure in Hyde Park and 1.9% after exposure on Oxford Street; P=0.003). The changes were associated most consistently with exposures to ultrafine particles and elemental carbon.

CONCLUSIONS

Our observations serve as a demonstration and explanation of the epidemiologic evidence that associates the degree of traffic exposure with lung function in asthma.

Effect of exposure to traffic on lung development from 10 to 18 years of age: a cohort study

BACKGROUND

Whether local exposure to major roadways adversely affects lung-function growth during the period of rapid lung development that takes place between 10 and 18 years of age is unknown. This study investigated the association between residential exposure to traffic and 8-year lung-function growth.

METHODS

In this prospective study, 3677 children (mean age 10 years [SD 0.44]) participated from 12 southern California communities that represent a wide range in regional air quality. Children were followed up for 8 years, with yearly lung-function measurements recorded. For each child, we identified several indicators of residential exposure to traffic from large roads. Regression analysis was used to establish whether 8-year growth in lung function was associated with local traffic exposure, and whether local traffic effects were independent of regional air quality.

FINDINGS

Children who lived within 500 m of a freeway (motorway) had substantial deficits in 8-year growth of forced expiratory volume in 1 s (FEV(1), -81 mL, p=0.01 [95% CI -143 to -18]) and maximum midexpiratory flow rate (MMEF, -127 mL/s, p=0.03 [-243 to -11), compared with children who lived at least 1500 m from a freeway. Joint models showed that both local exposure to freeways and regional air pollution had detrimental, and independent, effects on lung-function growth. Pronounced deficits in attained lung function at age 18 years were recorded for those living within 500 m of a freeway, with mean percent-predicted 97.0% for FEV1 (p=0.013, relative to >1500 m [95% CI 94.6-99.4]) and 93.4% for MMEF (p=0.006 [95% CI 89.1-97.7]).

INTERPRETATION

Local exposure to traffic on a freeway has adverse effects on children's lung development, which are independent of regional air quality, and which could result in important deficits in attained lung function in later life.

Changes in the normal maximal expiratory flow-volume curve with growth and aging

On the basis of their answers to a self-administered questionnaire, 697 nonsmoking healthy subjects were chosen from a randomly selected sample representative of the white non-Mexican-American population of Tucson, Arizona, enrolled in a longitudinal study of respiratory health. For each subject, the first satisfactory set of flow-volume data obtained during the first 3 consecutive surveys was selected for analysis. For forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), the single best value for each subject was selected. Other flow-volume measurements were derived from the single test with the best sum FEV, plus FVC. These data were used to derive improved prediction equations for each sex by age group for 5 spirometric and flow-volume variables. The resulting predicted values demonstrate the effects of development, maturation, and senescence on ventilatory function. "Normal" limits are proposed that take into consideration the between-subject variability and non-Gaussian distribution of the various measurements.

Roflumilast--an oral anti-inflammatory treatment for chronic obstructive pulmonary disease: a randomised controlled trial

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterised by progressive airflow limitation associated with chronic inflammation. There are few treatment options for the disease. This study assessed the efficacy and safety of roflumilast, a phosphodiesterase-4 inhibitor, in patients with moderate to severe COPD.

METHODS

This phase III, multicentre, double-blind, randomised, placebo-controlled study was undertaken in an outpatient setting. 1411 patients with COPD were randomly assigned roflumilast 250 microg (n=576), roflumilast 500 microg (n=555), or placebo (n=280) given orally once daily for 24 weeks. Primary outcomes were postbronchodilator FEV1 and health-related quality of life. Secondary outcomes included other lung function parameters and COPD exacerbations. Analyses were by intention to treat.

FINDINGS

1157 (82%) patients completed the study; 32 (11%) withdrew from the placebo group, 100 (17%) from the roflumilast 250 microg group, and 124 (22%) from the roflumilast 500 microg group. Postbronchodilator FEV1 at the end of treatment significantly improved with roflumilast 250 microg (by 74 mL [SD 18]) and roflumilast 500 microg (by 97 mL [18]) compared with placebo (p<0.0001). Improvement in health-related quality of life was greater with roflumilast 250 microg (-3.4 units [0.6]) and roflumilast 500 microg (-3.5 units [0.6]) than with placebo (-1.8 units [0.8]), although the differences between treatment groups were not significant. The mean numbers of exacerbations per patient were 1.13 (2.37), 1.03 (2.33), and 0.75 (1.89) with placebo, roflumilast 250 microg, and roflumilast 500 microg, respectively. Most adverse events were mild to moderate in intensity and resolved during the study.

INTERPRETATION

Roflumilast is a promising candidate for anti-inflammatory COPD treatment because it improved lung function and reduced exacerbations compared with placebo. Long-term studies are needed to fully assess the effect on health-related quality of life.

Interleukin-4 receptor in moderate atopic asthma. A phase I/II randomized, placebo-controlled trial

Interleukin-4 mediates important proinflammatory functions in asthma, including induction of the IgE isotype switch, expression of VCAM-1 on endothelium, mucin production, 15-lipoxygenase activity, and Th2 lymphocyte stimulation leading to the secondary synthesis of IL-4, IL-5, and IL-13. Soluble recombinant human IL-4 receptor (IL-4R; Nuvance; altrakincept) inactivates naturally occurring IL-4 without mediating cellular activation. Nebulized IL-4R has a serum half-life of approximately 1 wk. In this double-blind, placebo-controlled trial, 25 patients with moderate asthma requiring inhaled corticosteroids were randomly assigned to receive a single nebulized dose of IL-4R 1,500 microg, IL-4R 500 microg, or placebo after stopping inhaled corticosteroids. No drug-related toxicity was observed. Treatment with IL-4R produced significant improvement in FEV(1) on Day 4 (1,500 microg versus placebo; p < 0.05) and in FEF(25-75) on Days 2 and 4 (1,500 microg versus placebo; p < 0.05). Asthma symptom scores stabilized among patients treated with IL-4R 1, 500 microg, despite abrupt withdrawal of corticosteroids, but not in the IL-4R 500 microg group or the placebo group (p < 0.05). Patients in the IL-4R 1,500 microg group also required significantly less beta(2)-agonist rescue use (p < 0.05). Anti-inflammatory effects were further demonstrated by significantly reduced exhaled nitric oxide (p < 0.05).

CONCLUSIONS

A single dose of IL-4R appears safe and effective in moderate asthma. The 1,500 microg dose appears as safe but significantly more effective than the 500 microg dose.

Asthma and gastroesophageal reflux: acid suppressive therapy improves asthma outcome

PURPOSE

To determine (1) the appropriate omeprazole (Prilosec) dose required for adequate acid suppression in asthmatics with gastroesophageal reflux, (2) whether aggressive acid suppressive therapy of gastroesophageal reflux improves asthma outcome in asthmatics with gastroesophageal reflux, (3) the time course of asthma improvement, and (4) demographic, esophageal, or pulmonary predictors of a positive asthma response to antireflux therapy.

PATIENTS AND METHODS

Thirty nonsmoking adult asthmatics with gastroesophageal reflux (asthma defined by American Thoracic Society criteria and reflux defined by symptoms and abnormal 24-hour esophageal pH testing) were recruited from the outpatient clinics of a 900-bed university hospital. Patients underwent baseline studies including a demographic questionnaire, esophageal manometry, dual-probe 24-hour esophageal pH test, barium esophogram, and pulmonary spirometry. During the 4-week pretherapy phase, patients recorded reflux and asthma symptom scores and peak expiratory flow rates (PEFs) upon awakening, 1 hour after dinner, and at bedtime. Patients began 20 mg/d omeprazole, and the dose was titrated until acid suppression was documented by 24-hour pH test. Patients remained on this acid suppressive dose for 3 months. Responders were identified by a priori definitions: asthma symptom reduction by >20% and/or PEF increase by >20%. Asthma symptom scores, PEF's baseline and posttherapy pulmonary spirometry were analyzed.

RESULTS

Twenty-two (73%) patients were asthma symptom and /or PEF responders: 20 (67%) were asthma symptom responders, and 6 (20%) were PEF responders. Responders reduced their asthma symptoms by 57% (P<0.001), improved their morning and night PEFs by 8% and 9% (both P <0.005), and had improvement in forced expiratory volume at 1 second (P <0.02), mean forced expiratory flow during the middle half (25% to 75%) of the forced vital capacity (P <0.04), and peak expiratory flow (P <0.01) with acid suppressive therapy. Mean acid suppressive dose of omeprazole was 27 mg/d (+/-2.2) with 27% (8) patients requiring more than 20 mg/d. The presence of regurgitation or excessive proximal esophageal reflux predicted asthma response with 100% sensitivity, 100% negative predictive value, specificity of 44% and a positive predictive value of 79%.

CONCLUSIONS

Acid suppressive therapy with omeprazole improves asthma symptoms and/or PEFs by >20% and improves pulmonary function in 73% of asthmatics with gastroesophageal reflux after 3 months of acid suppressive therapy. Many asthmatics (27%) required >20 mg/d of omeprazole to suppress acid. The presence of regurgitation and/or excessive proximal esophageal reflux predicts a positive asthma outcome.

Reduced exposure to PM10 and attenuated age-related decline in lung function

BACKGROUND

Air pollution has been associated with impaired health, including reduced lung function in adults. Moving to cleaner areas has been shown to attenuate adverse effects of air pollution on lung function in children but not in adults.

METHODS

We conducted a prospective study of 9651 adults (18 to 60 years of age) randomly selected from population registries in 1990 and assessed in 1991, with 8047 participants reassessed in 2002. There was complete information on lung volumes and flows (e.g., forced vital capacity [FVC], forced expiratory volume in 1 second [FEV1], FEV1 as a percentage of FVC, and forced expiratory flow between 25 and 75% of the FVC [FEF25-75]), smoking habits, and spatially resolved concentrations of particulate matter that was less than 10 microm in aerodynamic diameter (PM10) from a validated dispersion model assigned to residential addresses for 4742 participants at both the 1991 and the 2002 assessments and in the intervening years.

RESULTS

Overall exposure to individual home outdoor PM10 declined over the 11-year follow-up period (median, -5.3 mug per cubic meter; interquartile range, -7.5 to -4.2). In mixed-model regression analyses, with adjustment for confounders, PM10 concentrations at baseline, and clustering within areas, there were significant negative associations between the decrease in PM10 and the rate of decline in FEV1 (P=0.045), FEV1 as a percentage of FVC (P=0.02), and FEF25-75 (P=0.001). The net effect of a decline of 10 microg of PM10 per cubic meter over an 11-year period was to reduce the annual rate of decline in FEV1 by 9% and of FEF25-75 by 16%. Cumulative exposure in the interval between the two examinations showed similar associations.

CONCLUSIONS

Decreasing exposure to airborne particulates appears to attenuate the decline in lung function related to exposure to PM10. The effects are greater in tests reflecting small-airway function.

NO in exhaled air of asthmatic children is reduced by the leukotriene receptor antagonist montelukast

Nitric oxide in exhaled air (FENO) is increased in asthmatic children, probably reflecting aspects of airway inflammation. We have studied the effect of the leukotriene receptor antagonist (LTRA) montelukast on FENO with a view to elucidate potential anti-inflammatory properties of LTRAs. Twenty-six asthmatic children 6 to 15 yr of age completed a double-blind crossover trial of 2 wk of treatment with 5 mg montelukast once daily versus placebo. FENO was measured during single-breath exhalation at a constant flow rate of 0.1 to 0.13 L/s against a resistance of 10 kPa/L/s. Eleven children were receiving maintenance treatment with inhaled steroids during the study (mean daily dose, 273 microgram), whereas the other 15 used only inhaled beta(2)-agonists as required. The within-subject coefficient of variation of FENO over a 2-wk interval for the 26 children was 38%. FENO was significantly reduced by 20% after the 2-wk treatment with montelukast as compared with placebo as well as compared with baseline. This effect occurred rapidly with a 15% fall in FENO within 2 d. The effect of montelukast on FENO was independent of concurrent steroid treatment. The effect on FENO is probably not caused by bronchodilatation since FENO increased significantly after inhalation of terbutaline. In conclusion, FENO in asthmatic children was significantly decreased from montelukast, which corroborates anti- inflammatory properties of LTRA.

Effects of obesity and fat distribution on ventilatory function: the normative aging study

OBJECTIVE

Although the influence of obesity on ventilatory function has long been recognized, the nature of the relationship and the mechanisms are not yet clear. The purpose of this report was to examine the effects of overall obesity and fat distribution on ventilatory function.

METHODS

Multiple measurements over > 30 years from 507 subjects with lifelong tobacco consumption of < or = 1 pack-year were analyzed separately in five age decades from 30 to 79 years. FVC, FEV1, ratio of FEV1 to FVC, and maximal midexpiratory flow rate (MMEF) were each adjusted for age and stature. Relative adiposity (or obesity) was assessed using the body mass index (BMI). Subscapular skinfold thickness, abdominal girth, and the ratio of abdominal girth to hip breadth (AG/HB) were used as measures of body fat distribution. Multiple linear regression was used to explore the effects of overall adiposity and body fat distribution on ventilatory function.

RESULTS

BMI was positively associated with the ratio of FEV1 to FVC at all ages (p < 0.01), and negatively with FVC and MMEF between 40 and 69 years (p < 0.01). After adjustment for BMI, subscapular skinfold thickness was negatively associated with both FVC and FEV1 (p < or = 0.02) among men aged 30 to 59 years, whereas AG/HB was negatively associated with FVC and FEV1 in men aged 50 to 59 years only (p < or = 0.0004).

CONCLUSIONS

Body fat distribution has independent effects on ventilatory function after adjustment for overall obesity in men. The finding that age modifies this association has implications for future research.

Medical and surgical treatment of nonallergic asthma associated with gastroesophageal reflux

Patients presenting to a chest clinic because of adult-onset wheezing with no history of allergy had a 90 percent prevalence of gastroesophageal reflux, even though reflux symptoms were mild or absent. Ninety patients were randomly assigned to receive cimetidine or an identical placebo or to undergo antireflux surgery. During a six-month period, all groups improved clinically; the cimetidine and surgical groups improved more than the placebo group. The intake of pulmonary medication decreased significantly in both cimetidine and surgical groups. Pulmonary function test results improved in the cimetidine- and surgically treated patients; improvement was not statistically significant. At long-term follow-up, the surgical group maintained clinical improvement and decreased pulmonary medication intake, whereas the placebo group worsened. We conclude that gastroesophageal reflux can play a significant role in some patients with nonallergic pulmonary disease and that its treatment can improve pulmonary symptoms and objective measurements of pulmonary function.

Bronchoscopic volume reduction with valve implants in patients with severe emphysema

Eight patients with severe emphysema entered a pilot study of unilateral volume reduction by endobronchial valve insertion. Five patients had emphysema judged too severe for volume reduction surgery and three refused the operation. After valve insertions, the median forced expiratory volume in 1 s (FEV1) increased from 0.79 L (range 0.61-1.07) to 1.06 L (0.75-1.22) (difference 34%, p=0.028) and the median diffusing capacity (TL(CO)) increased from 3.05 mL/min/mm Hg (2.35-4.71) to 3.92 mL/min/mm Hg (2.89-5.40) (difference 29%, p=0.017). CT scans showed a substantial reduction in regional volume in four of the eight patients. Two patients developed a transient pneumothorax (one requiring drainage) but we recorded no other important adverse effects during follow-up. Lung-volume reduction can be achieved with unilateral bronchoscopically placed valve implants in patients with severe emphysema with acceptable short-term safety and worthwhile functional benefits.

Association of respiratory viral infections with pulmonary deterioration in patients with cystic fibrosis

In a two-year prospective study, we examined the effect of respiratory viral infections on pulmonary function in 49 patients with cystic fibrosis (mean age, 13.7 years). Nineteen normal siblings (mean age, 14) served as controls. Subjects were assessed quarterly and at the time of any respiratory illness. Each assessment included nasal washes for viral isolation and blood drawing for respiratory viral serologic studies. Pulmonary-function tests were performed at least twice yearly. Respiratory illnesses were reported significantly more often in the patients (3.7 per year) than in the normal siblings (1.7 per year), although the frequency of proved viral infections (1.67 per year) was identical. In the patients with cystic fibrosis significant correlations (P less than 0.0001) were found between the annual incidence of viral infections and every measure of disease progression in the two-year period, including the rate of decline of the Shwachman score (r = 0.71), the percentage of ideal weight for height (r = 0.80), the forced vital capacity (r = 0.85), the forced expiratory volume in the first second (r = 0.84), the forced midexpiratory flow rate (r = 0.68), and the frequency (r = 0.53) and duration (r = 0.84) of hospitalizations for respiratory exacerbations. We conclude that frequency of viral respiratory infections is closely associated with pulmonary deterioration in patients with cystic fibrosis.

The maximal expiratory flow-volume curve. Normal standards, variability, and effects of age

From a randomly selected population representative of the white population of Tucson, Ariz., satisfactory flow-volume data were obtained for 3,115 persons. Data from the 746 subjects who were totally free of symptoms or history of cardiorespiratory disease and who had never smoked were used in determining "normal" prediction equations for spirometric parameters and maximal expiratory flows. The maximal expiratory flow-volume curve showed considerable intersubject variability, but little change in shape of the mean maximal expiratory flow-volume curve was seen with advancing age when the effects of disease, insult, or injury were excluded.

Airway inflammation in young marijuana and tobacco smokers

Forty healthy young subjects, ages 20 to 49 yr, underwent videobronchoscopy, mucosal biopsy, and bronchial lavage to evaluate the airway inflammation produced by habitual smoking of marijuana and/or tobacco. Videotapes were graded in a blinded manner for central airway erythema, edema, and airway secretions using a modified visual bronchitis index. The bronchitis index scores were significantly higher in marijuana smokers (MS), tobacco smokers (TS), and in combined marijuana/tobacco smokers (MTS), than in nonsmokers (NS). As a pathologic correlate, mucosal biopsies were evaluated for the presence of vascular hyperplasia, submucosal edema, inflammatory cell infiltrates, and goblet cell hyperplasia. Biopsies were positive for two of these criteria in 97% of all smokers and for three criteria in 72%. By contrast, none of the biopsies from NS exhibited greater than one positive finding. Finally, as a measure of distal airway inflammation, neutrophil counts and interleukin-8 (IL-8) concentrations were determined in bronchial lavage fluid. The percentage of neutrophils correlated with IL-8 levels and exceeded 20% in 0 of 10 NS, 1 of 9 MS, 2 of 9 TS, and 5 of 10 MTS. We conclude that regular smoking of marijuana by young adults is associated with significant airway inflammation that is similar in frequency, type, and magnitude to that observed in the lungs of tobacco smokers.

Families of lines: random effects in linear regression analysis

Laboratory experiments often involve two groups of subjects, with a linear phenomenon observed in each subject. Simple linear regression as propounded in standard textbooks is inadequate to treat this experimental design, particularly when it comes to dealing with random variation of slopes and intercepts among subjects. The author describes several techniques that can be used to compare two independent families of lines and illustrates their use with laboratory data. The methods are described tutorially, compared, and discussed in the context of more sophisticated and more naive approaches to this common data-analytic problem. Technical details are supplied in APPENDIX A.

Effect of parental cigarette smoking on the pulmonary function of children

The authors have investigated the effects of parental smoking patterns on the pulmonary function of children in East Boston, Massachusetts. A crude inverse dose-response relationship was observed between the level of FEF25--75% predicted of children who never smoked and the number of smoking parents in the household. Compared to children with two non-smoking parents, the level of FEF25--75% predicted was 0.156 and 0.355 standard deviation units lower for children with one and two currently smoking parents, respectively. An additional decline in level of FEF25--75% predicted was observed for children who themselves had smoked. Smoking children with two smoking parents had an average FEF25--75% predicted level which was 0.355 standard deviation units lower than non-smoking children with two smoking parents. These data not only confirm that cigarette smoking by young children and teenagers has direct measurable effects on their pulmonary function, but also show that cigarette smoking by parents has a measurable effect on the pulmonary function of their children which is independent of any direct use of cigarettes by the children.

Regional distribution of emphysema: correlation of high-resolution CT with pulmonary function tests in unselected smokers

High-resolution computed tomography (CT) was correlated with pulmonary function tests in the evaluation of regional emphysema in 59 smokers. The lung was divided into upper (above the carina tracheae) and lower (below the carina tracheae) zones, and the degree of emphysema was graded with a subjective and an objective measurement. Functional emphysema was defined as a diffusion capacity less than 75% of predicted and forced expiratory volume in 1 second less than 80% of predicted. Three of 15 (20%) subjects with functional emphysema had no subjective evidence of emphysema at high-resolution CT, and 10 of 25 (40%) with emphysema at high-resolution CT had no functional abnormalities consistent with emphysema. Even though the upper lung zones were more severely affected by emphysema, the degree of emphysema in the lower zones had a stronger correlation with pulmonary function abnormalities. The upper lung zones are a relatively silent region where extensive destruction may occur before functional abnormalities become known.

Pulmonary fibrosis associated with tracheobronchial aspiration. A study of the frequency of hiatal hernia and gastroesophageal reflux in interstitial pulmonary fibrosis of obscure etiology

Tracheobronchial aspiration of gastric secretions has been suggested in published reports as a possible cause for idiopathic pulmonary fibrosis. Forty-eight of 131 patients with roentgenographic evidence of pulmonary fibrosis had no established etiologic diagnosis after individualized evaluations. They were prospectively studied by upper gastrointestinal series to determine the incidence of gastroesophageal reflux. The incidence of both hiatal hernia and reflux were statistically higher in the study group than in a group of 270 age-matched controls who had upper gastrointestinal series for the usual indications; (2) a subgroup of 15 patients who had pulmonary fibrosis and serologic evidence which suggested immune-mediated diseases; and (3) a subgroup of 23 patients with pulmonary fibrosis of established etiology. The patients in the study group could be further characterized by clinical and roentgenographic presentations, low maximum-mid-expiratory flow rates, and lung biopsies compatible with interstitial fibrosis. These observations and other cited evidence are supportive of the concept that repeated, small tracheobronchial aspirations of gastric acid secretions over a long period of time may cause interstitial pulmonary fibrosis.

Effects of ambient ozone on respiratory function in active, normal children

Respiratory functions were measured on a daily basis by spirometry over a period of 4 wk at a summer camp at Fairview Lake in northwestern New Jersey. Fifty-three boys and 38 girls 8 to 15 yr of age participated in the study on at least 7 days; 37 children were in residence for 4 wk, 34 for the first 2 wk only; and 20 for the last 2 wk. There were 72 whites, 15 blacks, 3 Asians, and 1 Hispanic in the study group. Multiple regression analyses indicated that the O3 concentration in the previous hour, the cumulative daily O3 exposure during the hours between 9 A.M. and the function measurement, ambient temperature, and humidity were the most explanatory environmental variables for daily variations in function, with the 1 - h O3 concentration having the strongest influence. Linear regressions were performed for each child between O3 concentration and function, and all average slopes were significantly negative (p less than 0.05) for FVC, FEV1, PEFR, and FEF25-75 for all children, and for boys and girls separately. Comparable results were obtained in data subsets (i.e., children studied during the first or second 2 wk only, and for data sets truncated at O3 less than 80 and O3 less than 60 ppb). The average regression slopes (+/- SE) for FVC and FEV1, respectively, were -1.03 +/- 0.24 and -1.42 +/- 0.17 ml/ppb, whereas for PEFR and FEF25-75 they were -6.78 +/- 0.73 and -2.48 +/- 0.26 ml/s/ppb.(ABSTRACT TRUNCATED AT 250 WORDS)

The quality of well-being in cystic fibrosis

Traditional outcome measures in CF include PFTs, exercise tests, and several scoring systems that depend on pulmonary status and are largely subjective. The Quality of Well-being scale (QWB) is a widely used tool for measuring quality of life by three subscales: mobility, physical activity, and social activity, with points assigned within each subscale. The QWB has been shown to be valid in patients with COPD. We administered the QWB scale to 44 patients with CF, aged 7 to 36 years, and examined the relationship between QWB and PFTs, and in 15 patients the QWB vs exercise performance (peak VO2) on a progressive cycle ergometer test. QWB was significantly correlated with each variable examined: QWB vs FEV1, r = 0.5518 (p less than .0001); QWB vs FEF25-75%, r = 0.4793 (p less than .001); QWB vs PEFR, r = 0.4018 (p less than .01); QWB vs peak VO2, r = 0.5778 (p less than .01). The QWB scale is an objective measure that is significantly correlated with measures of performance and pulmonary function in CF. The relationship is not one of identity; further, the QWB is broad based and takes into account general well-being, not just pulmonary health, adding an important dimension to the care of patients with CF.

Heat and water loss from the airways and exercise-induced asthma

Exercise-induced asthma was studied in 8 asthmatics using various conditions of inspired air during exercise. The exercise consisted of walking on a treadmill for 10 min, with a speed and grade elevation adjusted to achieve the target heart rate of approximately 90% of predicted maximum. Pulmonary function tests were performed pre- and post-exercise to determine exercise-induced asthma. With inspired air at 23 degrees C and 15% relative humidity (RH), the post-exercise forced expiratory volume in a sec (FEV1), maximal mid-expiratory flow rate (MMEF), and specific airway conductance (SGaw) decreased to an average of 69, 59 and 38% of the pre-exercise baseline, respectively. In contrast, the exercise-induced asthma was clearly prevented in all subjects by using inspired air at 37 degrees C and 100% RH, when the post-exercise FEV1, MMEF, and SGaw were 99, 100 and 91% of the baseline, respectively. Inspiration of warm, dry air or humid, room air reduced but did not prevent exercise-induced asthma. The results indicate that the primary stimulus for exercise-induced asthma may be heat loss and/or water loss from the airways during exercise.

Low exhaled nitric oxide in school-age children with bronchopulmonary dysplasia and airflow limitation

Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, may be associated with long-term airflow limitation. Survivors of BPD may develop asthma-like symptoms in childhood, with a variable response to beta(2)-agonists. However, the pathologic pathways underlying these respiratory manifestations are still unknown. The aim of this study was to measure exhaled nitric oxide (FE(NO)) and lung function in a group of 31 school-age survivors of BPD. They showed variable degrees of airflow obstruction (mean FEV(1) 77.8 +/- 2.3% predicted) unresponsive to beta(2)-agonists in 72% of the subjects. Their FE(NO) values (geometric mean [95% confidence interval]: 7.7 [+/- 1.1] ppb) were significantly lower than in a group of healthy matched control subjects born at term (10.7 [+/- 1.1] ppb, p < 0.05) and a group of preterm children without BPD (9.9 [+/- 1.1] ppb, p < 0.05). The children with BPD were also compared with a group of 31 patients with asthma with a comparable airflow limitation (FEV(1) 80.2 +/- 2.1% predicted) and showed FE(NO) values four times lower than in those with asthma (24.9 [+/- 1.2] ppb, p < 0.001). In conclusion, unlike children with asthma, school-age survivors of BPD have airflow limitation associated with low FE(NO) values and lack of reversibility to beta(2)-agonists, probably as a result of mechanisms related to early life structural changes in the airways.

Bronchiolitis obliterans after lung transplantation: detection using expiratory HRCT

OBJECTIVE

The objective of this study was to determine if air trapping, as detected on expiratory high-resolution CT (HRCT), is useful as an indicator of bronchiolitis obliterans (BO) in lung transplant recipients.

MATERIALS AND METHODS

Corresponding inspiratory and expiratory HRCT images at five different levels and spirometry were obtained in 21 lung transplant recipients. Eleven patients had BO proved by transbronchial biopsy specimens; the remaining 10 patients had no pathologic or functional evidence of airways disease. Two "blinded" observers assessed the inspiratory images for the presence of bronchiectasis and mosaic pattern of lung attenuation, and the expiratory images for presence and extent of air trapping. Statistical comparison of the frequency of HRCT findings between patients with and without BO was performed using Fisher's Exact Test.

RESULTS

On inspiratory images, bronchiectasis and mosaic pattern of lung attenuation were present in 4 (36%) and 7 (64%) of 11 patients with BO, and 2 (20%) and 1 (10%) of 10 patients without BO (p>0.05 and p<0.05), respectively. The sensitivity, specificity, and accuracy of bronchiectasis and mosaic pattern for BO were 36%, 80%, and 57%, and 64%, 90%, and 70%, respectively. On expiratory images, air trapping was found in 10 of 11 (91%) patients with BO compared to 2 of 10 (20%) patients without BO (p<0.002). Air trapping was found to have a sensitivity of 91%, specificity of 80%, and accuracy of 86% for BO. Air trapping was identified in one patient with BO who had normal results of baseline spirometric function tests.

CONCLUSION

Air trapping, as detected on expiratory HRCT, was the most sensitive and accurate radiologic indicator of BO in the lung transplant population.

Body fat distribution, body composition, and respiratory function in elderly men

BACKGROUND

Most population studies have reported weak or nonsignificant associations between body mass index (BMI; in kg/m2) and lung function.

OBJECTIVE

This study focused on the distinct effects of fat distribution and body composition on lung function and examined these relations in elderly men.

DESIGN

The study was a cross-sectional evaluation of 2744 men aged 60-79 y who were free of cardiovascular disease and cancer and were drawn from general practices in 24 British towns. Anthropometric and body-composition [including fat mass (FM), fat-free mass (FFM), and percentage body fat (%BF) evaluated with bioelectric impedance] measurements were made, and lung function was examined by using spirometry.

RESULTS

Height-standardized forced expiratory volume in 1 s (FEV1) was diminished only in lean (BMI < 22.5) and obese (BMI > or = 30) men, but forced vital capacity (FVC) tended to decrease with increasing BMI (P < 0.01). All other measures of adiposity [ie, waist circumference (WC), waist-hip ratio (WHR), FM, and %BF] were significantly and inversely related to FEV1 and FVC after adjustment for confounders, including age and cigarette smoking (all: P < 0.05). This was seen both in nonobese (BMI < 30) and obese men. FFM was positively associated with FEV1 (P = 0.03) and to a lesser extent with FVC. Higher BMI and FFM were both associated with reduced odds of a low FEV1-FVC ratio (ie, <70%).

CONCLUSION

Total body fat and central adiposity are inversely associated with lung function, but increased FFM reflecting increases in muscle mass is associated with increased lung function and lower odds of low FEV1:FVC in the elderly.

The response to exercise in normal and asthmatic children

Twenty-five normal and 105 asthmatic children were exercised on a treadmill. Pulmonary function was assessed before and after exercise. The maximum fall from the resting value in normal subjects depended on the test used: PEFR 12.5%; FEV1 10%; MMEF 26%; V50 30%; V25 33%. Using these criteria, PEFR and FEV1 detected 99% of those asthmatic children who had a positive exercise response. The largest fall from the resting value was seen with the MMEF, but this test detected only 70% of the positive responders. The pre-exercise function did not affect the severity of the response but did have an effect on the incidence of exercise-induced bronchospasm.