Ambulatory patient-activated arrhythmia monitoring: comparison of a new wrist-applied monitor with a conventional precordial device

Sensitivity of forced expiratory flow between 25% and 75% of the vital capacity (FEF25-75) in detecting airway obstruction was investigated in 14 children with mild-moderate asthma, allergic to house dust mites, while at high altitude (1756 m). Forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), FEF25-75, and peak expiratory flow (PEF) were measured every 2 weeks for 12 weeks (total, 84 measurements). The presence or absence of wheezing at the chest auscultation was ascertained before each test. During the study period, a significant improvement of both mean (SD) FEF25-75 [61 (12)% vs. 68 (11)% of the predicted value, p = 0.005] and PEF [95 (16)% vs. 103 (13)%, p = 0.002] was observed. FEV1 changed only marginally [82 (7)% vs. 86 (6)%, p = 0.05]. Wheezing was present on 12/84 occasions. Wheezing was associated with abnormal FEF25-75 values on most occasions but not with abnormal FEV1 or PEF. FEF25-75 was decreased on 51% of days in which wheezing was absent. FEV1 and PEF were, respectively, normal in 69% (p < 0.0001) and 92% (p < 0.0001) of measurements in which FEF25-75 was abnormal. These results suggest that FEF25-75 may be considered a good indicator of airflow obstruction and a sensitive marker of respiratory improvement in asthmatic children during reduced antigen exposure.     

Relationship between pulmonary test variables and asthma and wheezing: a validation of self-report of asthma

We investigated the relationship between the pulmonary test variable measurements and self-reported asthma and wheezing from a cross-sectional study conducted in Saskatchewan. Based on the responses to the questionnaire, the subjects were classified into asthmatic, wheezing, and asymptomatic groups. For both male and female subjects the mean values of forced expiratory volume in 1 s (FEV1), forced expiratory flow during the middle half of the forced vital capacity (FEF25-75), and FEV1/FVC ratio were lowest in asthmatics, followed by wheezing and asymptomatic groups, respectively. This trend was also observed in forced vital capacity (FVC) for men but not for women. After adjusting for current smoking status, the trend in the means across the three groups was statistically significant in men for FEV1 (p = 0.03), FEF25-75 (p = 0.002), and FEV1/FVC ratio (p = 0.002) and in women for FEF25-75 (p < 0.001) and FEV1/FVC ratio (p < 0.001). The differences in the adjusted means of FVC, FEV1, FEF25-75, and FEV1/FVC ratio between asymptomatic subjects and the other two groups were significant in both male and female subjects. Significant differences were also observed between asthmatics and wheezing groups in the adjusted means of FEF25-75 and FEV1/FVC ratio in male and female subjects. We conclude that the self-report of asthma has a high level of validity against the criterion of concurrently measured pulmonary test variables.     

Airway response of children with primary ciliary dyskinesia to exercise and beta2-agonist challenge

In primary ciliary dyskinesia (PCD), chest physiotherapy for airway clearance is essential. Exercise and inhaled beta2-agonists can produce bronchodilation thereby augmenting physiotherapy. However, both can also cause bronchoconstriction, and the effects of these stimuli in PCD are not known. In a preliminary study, the mean coefficients of variation for forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) in children with PCD were determined. They were 5.4%, 4.4% and 8.4%, respectively. Twelve children with PCD and 12 normal children performed pulmonary functions under resting conditions; during and after a validated treadmill exercise test; and before and 15 min after 200 microg of inhaled salbutamol. At baseline, FEV1, FVC, forced mid-expiratory flow (FEF25-75%) and PEFR were significantly reduced in the PCD group compared with the control group. Exercise produced a significant increase in PEFR in the PCD group. There was no significant difference between the groups in response to salbutamol. Within the PCD group, exercise produced a significantly greater increase in PEFR than beta2-agonist therapy. In conclusion, in children with primary ciliary dyskinesia there is evidence of obstructive pulmonary disease. In these children, exercise is a more potent stimulus for bronchodilation than by inhaled beta2-agonists. Enhancement of airway clearance may best be achieved by encouraging patients to exercise before physiotherapy rather than by inhaling beta2-agonists, but the effects of each should be assessed for each individual before instigating treatment.     

Intrasubject variability of maximal expiratory flow volume curve

Analysis of airflow in the terminal portion of the maximal expiratory flow volume curve has been suggested as a useful test for the early diagnosis of chronic airways obstruction. Whether such an analysis can identify early disease, and whether any subsequent action can prevent the progress of chronic airways obstruction, is unknown and will require prospective studies. As a precursor of such a study we have tried to establish the intrasubject variability of those tests of forced expiration which may be used for screening. We therefore measured expiratory flow volume curves of five healthy males and five healthy females aged 20-30 years as this is an age-group in which early detection of airways obstruction may be of value. Flow volume curves were obtained on the same day of the week for six weeks, and on three separate days during this period we carried out three flow volume curves every hour from 9 am to 6 pm. The data were subjected to analysis of variance to determine the variability of each measurement. Data were collected from forced expired volume in one second (FEV1) forced vital capacity (FVC), maximum expiratory flow rates at 50% and 75% of expired vital capacity, and forced expiratory time (FET). The results showed no consistent pattern of diurnal variation over the working day. The variation in any subject for FEV1 and FVC over the study period was considerably less than variations detected in the maximal expiratory flow rates at 50% and 75% of the expired vital capacity and FET. Our results suggest that the intrasubject variation found in flow rates of the terminal portion of the maximal expiratory flow volume curve and forced expiratory time may limit the usefulness of these tests in detecting early airways obstruction. FEV1 and FVC are more reproducible tests and are therefore particularly suited for cross-sectional screening. The more sensitive maximal expiratory flow volume curve may, however, be more useful for long-term studies in individuals when the onset of disease is sought, or for short-term challenge studies requiring the most sensitive index of change in airway characteristics.     

Bronchial obstruction and exhaled nitric oxide response during exercise in cold air

This study examines whether exhausting exercise in cold air induces bronchial obstruction and changes in exhaled [NO] and in exhaled NO output (V'NO). Thus, eight well-trained males performed two incremental exercise tests until exhaustion, followed by 5 min of recovery in temperate (22 degrees C) and cold (-10 degrees C) environments, at random. At -10 degrees C, they were dressed in warm clothes. Ventilation (V'E), oxygen consumption (V'O2), carbon dioxide production, cardiac frequency (fC), and [NO] and V'NO were measured continuously. Before and after each test, the subjects' maximal expiratory flow-volume curves and peak expiratory flow, forced expiratory volume in one second (FEV1) and forced expiratory flow at 25 (FEF25), 50 (FEF50) and 75% (FEF75) of forced vital capacity were determined. At -10 degrees C, significant decreases in FEV1 and FEF75 were observed after exercise. At rest and at the same submaximal intensity, V'O2, V'E and fC did not differ significantly. At rest and up to approximately 50% peak V'O2, [NO] and V'NO values were lower at -10 degrees C than at 22 degrees C. Thereafter, and during recovery, the V'NO response became similar at both -10 and 22 degrees C. This study confirms that considerable hyperpnoea in cold air causes a detectable airway obstruction. This airway cooling also induces an initial decrease in the exhaled NO response. Since endogenous NO-production is involved in bronchial dilation, it cannot be excluded that this lack of production may favour the appearance of airway obstruction.     

Should sperm donors be paid? A survey of the attitudes of the general public

Human immunodeficiency virus (HIV) infection has been associated with a wide spectrum of pulmonary disease. We report three HIV-seropositive patients with rapidly worsening airway obstruction associated with bronchiectasis. All subjects (age range 33-39 yrs) were cigarette smokers. Two had previously used intravenous drugs. The CD4 lymphocyte count ranged 40-250 cells x mm(-3). All individuals had complained of increasing dyspnoea for 3-6 months. Within 1 yr, they all developed severe airway obstruction with a decrease in both forced expiratory volume in one second (FEV1) and ratio of FEV1 to forced vital capacity (FEV1/FVC) to less than 60% of predicted value, and a decrease in mean forced expiratory flow at 25-75% of the forced vital capacity (FEF25-75) to less than 35% of predicted value. Computed tomography of the chest disclosed bilateral dilated and thickened bronchi. No classical causes of genetic or acquired bronchiectasis were identified in our patients. Recurrent bacterial bronchitis occurred in the follow-up period of the three patients. In conclusion, unusually rapid airway obstruction associated with bronchiectasis should be added to the wide spectrum of respiratory complications of human immunodeficiency virus infection.     

Twin imitation for antisocial behavior: Implications for genetic and family environment research.

When twin pairs influence each other's behavior, observed variance is greater for monozygotic (MZ) twins than for dizygotic (DZ) twins under at least 1 of 2 conditions: (1) The trait has some heritability, and (2) MZ twins influence each other more than do DZ twins. Applied to a trait that has an underlying continuous distribution but is measured as a dichotomy, the presence of reciprocal twin influence predicts that if the base rate for the trait is not exactly 50%, then the prevalence of the trait should differ in MZ and DZ twin pairs. This prediction held for registered criminality in a large twin cohort. Methods of analysis that permit reciprocal twin interaction not only provide better statistical fits to the data but also yield estimates of heritability that agree with adoption data. Results suggest that the genetic influence on registered criminality may be more modest than previously thought. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of nasal continuous positive airway pressure on reversible or fixed upper and lower airway obstruction

Our study was to assess whether there were differential effects of nasal continuous positive airway pressure (nCPAP) on different kinds of obstruction in either upper or lower airways in patients with chronic obstructive pulmonary disease (COPD). nCPAP (6 cmH2O for ten minutes) was applied to 7 patients with reversible extrathoracic upper airway obstruction (RUAO) and 3 patients with fixed extrathoracic upper airway obstruction (FUAO). Eighteen stable asthmatics, receiving methacholine challenge to induce a more than 20% reduction in FEV1, were randomly investigated for the effect of nCPAP or sham pressure on reversible lower airway obstruction. Nine stable COPD patients were enrolled to study the effect on irreversible lower airway obstruction. Maximal expiratory and inspiratory flow volume curves and dyspnoea scores were obtained before and after immediate withdrawal of nCPAP. In the RUAO group, nCPAP significantly improved stridor and dyspnoea scores, decreased the ratio of FEF50/FIF50 from 2.05 +/- 0.25 to 1.42 +/- 0.16, and increased peak inspiratory flow (PIF) as well as forced inspiratory vital capacity by 26 +/- 8% and 9 +/- 4%, respectively. In expiratory phase, there was no significant change in pulmonary functions. In asthmatics, nCPAP significantly reversed methacholine-induced bronchoconstriction increasing forced vital capacity by 10 +/- 3%, FEV1 by 15 +/- 4% and PIF by 32 +/- 11%. nCPAP significantly increased the response to bronchodilators. The improvement in airflow rate persisted for at least 5 min after nCPAP withdrawal and was highly correlated with the response to bronchodilators. There was no significant effect of nCPAP on airflow rate in COPD patients. Subjective dyspnoea score changes paralleled the pulmonary function improvement. We conclude that there are differential effects of nCPAP on airflow rates in patients with different nature of airway obstruction. Patients with airway obstruction caused by structural changes may not benefit from the use of nCPAP in improving airflow rates.     

Reduced asthma symptoms with n-3 fatty acid ingestion are related to 5-series leukotriene production

Asthma may respond to dietary modification, thereby reducing the need for pharmacologic agents. This study determined the effectiveness of n-3 polyunsaturated fatty acid (PUFA) ingestion in ameliorating methacholine-induced respiratory distress in an asthmatic population. The ability of urinary leukotriene excretion to predict efficacy of n-3 PUFA ingestion was assessed. After n-3 PUFAs in ratios to n-6 PUFAs of 0.1:1 and 0.5:1 were ingested sequentially for 1 mo each; patient respiratory indexes were assessed after each treatment. Forced vital capacity (FVC), forced expiratory volume for 1 s (FEV1), peak expiratory flow (PEF), and forced expiratory flow 25-75% (FEF 25-75) were measured along with weekly 24-h urinary leukotriene concentrations. With low n-3 PUFA ingestion, methacholine-induced respiratory distress increased. With high n-3 PUFA ingestion, alterations in urinary 5-series leukotriene excretion predicted treatment efficacy. Elevated n-3 PUFA ingestion resulted in a positive methacholine bronchoprovocation dose change in > 40% of the test subjects (responders). The provocative dose to cause a 20% reduction (PD20) in FEV1, FVC, PEF, and FEF25-75 values could not be calculated because of a lack of significant respiratory reduction. Conversely, elevated n-3 PUFA ingestion caused some of the patients (nonresponders) to further lose respiratory capacity. Five-series leukotriene excretion with high n-3 PUFA ingestion was significantly greater for responders than for nonresponders. A urinary ratio of 4-series to 5-series leukotrienes < 1, induced by n-3 PUFA ingestion, may predict respiratory benefit.     

Fetal alcohol syndrome in twins of alcoholic mothers: concordance of diagnosis and IQ

The effects of teratogens can be modified by genetic differences in fetal susceptibility and resistance. Twins of alcoholic mothers provide a unique opportunity to study this phenomenon with respect to alcohol teratogenesis. Sixteen pairs of twins, 5 MZ and 11 DZ, all heavily exposed to alcohol prenatally, were evaluated. They represented all available twins of alcohol-abusing mothers who were on the patient rolls of the authors. The rate of concordance for diagnosis was 5/5 for MZ and 7/11 for DZ twins. In two DZ pairs, one twin had fetal alcohol syndrome (FAS), while the other had fetal alcohol effects (FAE). In 2 other DZ pairs, one twin had no diagnosis while one had FAE. IQ scores were most similar within pairs of MZ twins and least similar within pairs of DZ twins discordant for diagnosis. Despite equivalent alcohol exposure within twin pairs, alcohol teratogenesis appears to be more uniformly expressed in MZ than in DZ twins. These data are interpreted as reflecting the modulating influence of genes in the expression of the teratogenic effects of alcohol.     

Bounds on null functions of linear digital imaging systems

OBJECTIVE: The purpose of this investigation was to quantitatively assess abnormally low attenuation of the lung by use of three-dimensional volumetric reconstructions from routine helical CT and to assess their correlation with pulmonary function tests. MATERIALS AND METHODS: Helical CT was performed in 100 patients in full inspiration. Examination was also performed in full expiration in 53 of these patients. Three-dimensional volumetric reconstructions were performed for total lung volumes at inspiration and at expiration, with a threshold of -896 H on inspiratory CT and -790 H on expiratory CT, to quantify emphysematous change. Correlation was made with pulmonary function tests in 79 patients. RESULTS: CT volumetric assessments of abnormally low attenuation of the lung at inspiration and expiration had a high correlation (r2 = .84, p < or = .0001). In comparison with pulmonary function tests, both inspiratory low attenuation of the lung and expiratory low attenuation of the lung correlated well with the logarithm of the ratio of the forced expiratory volume in 1 sec (FEV1) to the forced vital capacity (r2 = .74, p < or = .0001 and r2 = .74, p < or = .0001, respectively) and with the percentage of predicted ratio of the FEV1 to the forced vital capacity (r2 = .69, p < or = .0001 and r2 = .69, p < or = .0001, respectively). Linear correlations were also seen with FEV1, residual volume, and forced residual capacity. CONCLUSION: Three-dimensional volumetric reconstructions of hypoattenuating lung correlate well with pulmonary function tests. In addition, inspiratory and expiratory data are also correlative, suggesting that a dedicated expiratory examination is not needed. This easily obtainable information will prove useful for patients with obstructive lung disease from emphysema, providing a measure of pulmonary function status in this population.     

Landscape ecology and epidemiology of vector-borne diseases: tools for spatial analysis

We studied twins to examine the genetics of epilepsy syndromes. We ascertained 358 twin pairs in whom one or both reported seizures. After evaluation, 253 of 358 (71%) had seizure disorders and 105 pairs were false positives. Among the monozygous (MZ) pairs, more were concordant for seizures (48 of 108; casewise concordance = 0.62 +/- 0.05) than among the dizygous (DZ) pairs (14 of 145; casewise concordance = 0.18 +/- 0.04). In 94% of concordant MZ pairs, and 71% of concordant DZ pairs, both twins had the same major epilepsy syndrome. When analyzed according to major epilepsy syndrome, the casewise concordances for generalized epilepsies (MZ = 0.82; DZ = 0.26), both idiopathic (MZ = 0.76; DZ = 0.33) and symptomatic (MZ = 0.83; DZ = 0), were greater than those for partial epilepsies (MZ = 0.36; DZ = 0.05), with intermediate values seen for febrile seizures (MZ = 0.58; DZ = 0.14) and unclassified epilepsies (MZ = 0.53; DZ = 0.18). We conclude that genetic factors are particularly important in the generalized epilepsies but also play a role in the partial epilepsies. The high frequency of concordant MZ pairs with the same major syndrome strongly suggests there are syndrome-specific genetic determinants rather than a broad genetic predisposition to seizures.     

Determinants of plasma levels of plasminogen activator inhibitor-1 : A study of normotensive twins

We investigated whether plasma levels of the plasminogen activator inhibitor type 1 antigen (PAI-1:Ag) are genetically determined in monozygotic (MZ) and dizygotic (DZ) twins. Twenty-five pairs of healthy twins underwent measurements of PAI-1:Ag and other variables, including body mass index, mean blood pressure, plasma renin activity, insulin, and glucose. To ascertain the zygosity of twins, highly discriminating micro- and minisatellite systems with variable numbers of tandem repeats were analyzed by PCR amplification followed by polyacrylamide gel electrophoresis. Subjects were also genotyped for the 4G/5G polymorphism by PCR. Estimates of genetic variance and heritability were obtained for PAI-1:Ag, and for body mass index, mean blood pressure, plasma renin activity, glucose, and insulin by jointly examining data in a path analysis with TWINAN90. Results showed that 12 pairs of twins were MZ and 13 were DZ. All tests of genetic variance [within pair (WP): F=6.24, P=0.002; among component (AC): F=2.62, P=0.04; average absolute difference t test=3. 00, P=0.004] showed significant genetic variance of PAI-1:Ag, but not of the other variables. Three tests of heritability (WP=0.837, P=0.002; AC=1.791, P<0.05; intraclass correlation: 1.180, P=0.001) consistently showed significant PAI-1:Ag heritability. Additive genetic influences (A), dominance genetic effect (D), and random environmental influences (E) accounted for 0.714, 0.154, and 0.132 of PAI-1:Ag variance, respectively. No effect of different 4G/5G genotypes was found. Thus, these results show significant genetic variance and heritability of PAI-1:Ag and suggest that A is more important than both D and E in determining PAI-1:Ag variance.     

Methods development for epidemiologic investigations of the health effects of prolonged ozone exposure. Part I: Variability of pulmonary function measures

The acute and subacute effects of ambient concentrations of ozone on lung function have been studied extensively in a variety of settings. Such studies generally have focused on measures of function that reflect either lung volumes or flows that are influenced by the physiology of large and small airways (e.g., forced expiratory volume in one second [FEV1). Data from animal studies suggest that the effects of prolonged exposure to elevated ambient concentrations of ozone result in abnormalities in the centriacinar region of the lung; and dosimetry models for humans predict that long-term exposure to ozone could impact the same areas of the human lung. However, alterations in structure at this level of the lung are not well reflected by measuring FEV1 until substantial structural changes have occurred. Measures of the lung function that reflect the functional mechanics of airways smaller than 2 mm in diameter are considered to be more relevant. At least one epidemiologic study has provided evidence that small-airway functions may be relevant to effects of prolonged exposure to environments with high concentrations of oxidants. A considerable body of physiologic data has established that flow rates measured during the terminal portion of a maximum expiratory flow-volume (MEFV) curve are largely governed by airways smaller than 2 mm in diameter A similar interpretation has been given to changes in the slope of phase III (delta N2) of the single-breath nitrogen washout (SBNW) curve. Despite the attractiveness of these measures in relation to airway physiology, some data suggest that measurements of flow via the terminal portions of MEFV and SBNW curves have much greater within-subject variability than forced vital capacity (FVC and FEV1. The present study was undertaken as part of a larger feasibility study to develop methods to study the effects of prolonged exposure to elevated ambient ozone levels on lung function in adolescents. A convenience sample of 239 freshmen (ages 16-20 years) entering the University of California, Berkeley were recruited to participate in this protocol. All were lifelong residents of the San Francisco Bay Area or the Los Angeles Basin. Subjects were studied on two occasions five to seven days apart. At each test session, subjects performed up to eight forced expiratory maneuvers to produce three acceptable and reproducible MEFV curves by modified American Thoracic Society criteria. Tests of SBNW were then performed on the basis of detailed criteria for validity and reproducibility. Eight attempts to generate three curves were allowed. The delta N2 was obtained by a least-squares regression of nitrogen concentrations between the 750-mL and 1750-mL volume points. Instantaneous flow at 75% of expired volume (FEF75%), average flow between the 25% and 75% volume points (FEF25%-75%), and delta N2 were the principal outcomes. Variance components were estimated with a nested random effects model with adjustments for important covariates. The average within-subject coefficients of variation (+/-SD of distribution of means) for male subjects were: FEV1 1.2 (+/-0.8); FEF25%-75% 3.2 (+/-2.3); FEF75% 5.8 (+/-5.0); and delta N2 17.9 (+/-12.3); for female subjects they were: FEV1 1.4 (+/-0.9); FEF25%-75% 3.0 (+/-2.2); FEF75% 6.2 (+/-5.2); and delta N2 19.9 (+/-17.0). The variance attributed to test session was less than 1% for all measures. The percentages of variance due to within-subject variation for each measure (adjusted for sex, area of residence, ethnicity, and height) were: FVC 3.6%; FEV1 3.0%; FEF25%-75% 5.2%; FEF75% 8.9%; and delta N2 23.9%. Of all subjects tested, 234 (97.9%) could provide at least two acceptable MEFV curves, but only 218 (91.2%) could provide at least two acceptable SBNW curves. The results were unchanged by recent history of acute, respiratory illness.(ABSTRACT TRUNCATED)     

Sex differences and nonadditivity in heritability of the Multidimensional Personality Questionnaire Scales.

A sex-limitation model was applied to the Multidimensional Personality Questionnaire (MPQ) data from the Minnesota Twin Family Registry. The sample included 626 monozygotic (MZ) twin pairs, 517 same-sex dizygotic (DZ) twin pairs, and 114 opposite-sex DZ twin pairs ranging in age from 27 to 64 years (mean age?=?37.8). In addition, whenever possible, family members of the twins were also assessed: 1,690 spouses, 495 parents, 322 siblings, and 535 offspring. The goals of the present investigation were to analyze the covariance matrices to determine whether (a) there was evidence for sex limitation of heritability of the MPQ scales and (b) there was evidence for nonadditive genetic influences on these scales. Significant sex differences in heritability were found for 3 of the scales: Alienation, Control, and Absorption. In addition, evidence for dominance was found for all scales except Traditionalism and Absorption. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical trial of two inhalation techniques for pressurized aerosols

The clinical effects of a bronchodilator, terbutaline sulphate, were compared after administration in the beginning of the inhalation by means of a standard inhaler and administration by actuating 2 seconds before starting the inhalation by means of an inhaler furnished with a 32 X 100 mm tube. No differences could be seen in the parameters measured-forced vital capacity (FVC), 1-second forced expiratory volume (FEV1), forced mid-expiratory flow (FMF), and oscillatory resistance (Ros). The results indicate that when attaching a tube to the standard inhaler co-ordination of inhalation and actuation of the aerosol is not of vital importance.     

Follow-up study of changes in respiratory function in the same workers after an additional 6 years of exposure to pollutants in the rubber industry

Follow-up study of respiratory function was carried out in a group of 311 male workers employed in one rubber industry. The prevalence of respiratory symptoms and ventilatory capacity were recorded over te period of six years. Lung function was measured by recording maximum expiratory flow-volume (MEFV) curves on which forced vital capacity (FVC), one-second forced expiratory volume (FEVI) and flow rates at 50% and the last 25% of the vital capacity (FEF50, FEF25) were read. The prevalence of all chronic respiratory symptoms was higher during the follow-up study although not statistically significant (p > 0.05). During both studies smokers had significantly higher prevalence of chronic cough, chronic phlegm and chronic bronchitis than nonsmokers (p < 0.05 or < 0.025). Measured values of ventilatory capacity were significantly lower than predicted normal values during both studies (p < 0.01). Percentage of predicted values were lower during the follow-up study in comparison to that during the initial study. The mean lowest percentages were obtained for FEF25 (initial study: 77.4%; follow-up study: 70.5%). Smokers had larger mean annual decrease of FVC: 0.073 L; FEVI: 0.063 L; FEF50: 0.100 L/s; FEF25: 0.085 L/s than nonsmokers (FVC: 0.063 L; FEVI: 0.058 L; FEF50: 0.083 L/s; FEF25: 0.058 L/s). Workers exposed for more than 10 years had larger mean annual decrease of ventilatory capacity tests than hose with shorter exposure. Our data indicate that exposure to noxious agents in rubber industry may be responsible for the development of chronic respiratory symptoms and chronic lung function changes.     

Lung function among black and white children

Racial differences in ventilatory lung function were evaluated in a community study of 393 children (158 blacks, 235 whites). Mean forced vital capacity was 18 per cent larger in nonsmoking white males than in nonsmoking black males, and 11 per cent larger in nonsmoking white females than in nonsmoking black females. Similar differences were observed for the 1-sec forced expiratory volume and for the maximal expiratory flow at 50 per cent of the vital capacity. However, when adjusted for lung size (on the basis of forced vital capacity), 1-sec forced expiratory volume and maximal expiratory flow at 50 per cent of the forced vital capacity were larger in the black children compared to the white children. Lung function prediction equations based on race, sex, age, height and weight are presented for healthy nonsmoking children; these allow for an evaluation of normal lung function in both black and white children.     

Indices from flow-volume curves in relation to cephalometric, ENT- and sleep-O2 saturation variables in snorers with and without obstructive sleep-apnoea

In a group of 37 heavy snorers with obstructive sleep apnoea (OSA, Group 1) and a group of 23 heavy snorers without OSA (Group 2) cephalometric indices, ENT indices related to upper airway collapsibility, and nocturnal O2 desaturation indices were related to variables from maximal expiratory and inspiratory flow-volume (MEFV and MIFV) curves. The cephalometric indices used were the length and diameter of the soft palate (spl and spd), the shortest distance between the mandibular plane and the hyoid bone (mph) and the posterior airway space (pas). Collapsibility of the upper airways was observed at the level of the tongue base and soft palate by fibroscopy during a Müller manoeuvre (mtb and msp) and ranked on a five point scale. Sleep indices measured were the mean number of oxygen desaturations of more than 3% per hour preceded by an apnoea or hypopnoea of more than 10 s (desaturation index), maximal sleep oxygen desaturation, baseline arterial oxygen saturation (Sa,O2) and, in the OSA group, percentage of sleep time with Sa,O2 < 90%. The variables obtained from the flow-volume curves were the forced vital capacity (FVC), forced expiratory and inspiratory volume in 1 s (FEV1 and FIV1), peak expiratory and peak inspiratory flows (PEF and PIF), and maximal flow after expiring 50% of the FVC (MEF50). The mean of the flow-volume variables, influenced by upper airway aperture (PEF, FIV1) was significantly greater than predicted.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationship between external resistances, lung function changes and maximal exercise capacity

In upper airway obstruction (UAO) the relationship between the degree of obstruction, exercise limitation and lung function indices is not well established. Therefore, we investigated in nine healthy subjects (age 36+/-9 yrs) the effects of two added resistances at the mouth (R1 = added resistance with 7.8 mm diameter; R2 = 5.7 mm) on forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), airway resistance (Raw) and maximal breathing capacity (measured during 15 s = measured maximum breathing capacity (MBCm); calculated as FEV1x37.5 = calculated maximum breathing capacity (MBCc)) on the one hand, and maximum exercise capacity (W'max), minute ventilation (V'E) and CO2 elimination (V'CO2) on the other. We found that R1 had almost no influence on FEV1 but decreased PEF by approximately 35% and increased Raw by almost 300%; it decreased W'max by merely approximately 10% while maximal exercise ventilation (V'Emax) was only 65% of control and only reached approximately 40% MBCc and approximately 70% MBCm; yet V'E and V'CO2 were significantly reduced at high exercise levels indicating hypoventilation. With R2, FEV1 was reduced by 25% and PEF by 55%, and Raw was increased by 600%; W'max was approximately 60% of control, V'Emax was only 35% of control and reached approximately 30% MBCc and approximately 60% MBCm, V'E was already reduced at moderate exercise levels. We conclude that: 1) an upper airway obstruction of 6 mm diameter (but not of 8 mm) had a marked influence on maximum exercise capacity due to hypoventilation; 2) calculated maximum breathing capacity markedly overestimated measured maximum breathing capacity because the forced expiratory volume in one second is an insensitive index of upper airway obstruction and because it does not take inspiratory flow limitation into account; and 3) a 10% decrease in maximum exercise capacity was linearly related with a 7% decrease in the forced expiratory volume in one second and a 150% increase in airway resistance. A 10% decrease in maximal exercise ventilation was related to a 8.5% decrease in peak expiratory flow and 9% decrease in measured maximum breathing capacity.