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PubMed1984

Pulmonary function before and after prolonged continuous positive airway pressure by mask.

This investigation examined whether prolonged continuous positive airway pressure (CPAP) applied by face mask could sustain an increase in functional residual capacity (FRC). Before median sternotomy, nine adults performed multiple-breath nitrogen washout to determine FRC and spirometry. The day after operation, lung volumes were measured before and 10 min after the 4-h application of 7.5 cm H2O of CPAP with a mask. Mean FRC, forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), and FEV1/FVC after CPAP were similar to pretreatment values. Although CPAP can restore FRC to preoperative values, and did increase FRC in these patients, FRC deteriorates within 10 min after CPAP is removed. Therefore, when a sustained increase in FRC is desired after median sternotomy, CPAP should be applied without interruption.

Critical Care↗
PubMed1980

Hiatal hernia and pulmonary function impairment: incidence or coincidence?

The high incidence of respiratory symptoms in patients with reflux esophagitis reported in the literature supports a cause-effect relationship between esophageal reflux and pulmonary symptoms. Analysis of the results of routine preoperative pulmonary function tests on 90 patients with reflux esophagitis and on 277 patients having nonthoracic elective surgery revealed that although the incidence of obstructive lung disease was high in both groups, it was higher in the general surgical population (51.9%) than in the patients with reflux esophagitis (37.7%). Thus a cause-and-effect relationship cannot be established between reflux esophagitis and obstructive lung impairment. This study indicates that the incidence of significant obstructive lung impairment in the general surgical population is greatly underestimated.

Adolescent↗
PubMed1978

Differences in pulmonary function tests among whites, blacks, and American Indians in a textile company.

Normal standards for pulmonary function in nonwhite populations are not presently available to occupational health workers. The present study examined differences in %FVC, FVC, FEV1/FVC, FEF 200-1200 and FEF 25-75% among whites, blacks, and American Indians. The sample consisted of 4209 job applicants to a textile company in southeastern United States. Multiple regression and analyses of covariance were employed to control differences in age, height, weight, and smoking status. Blacks were significantly lower in five of the six comparisons but higher in FEV1/FVC%. The pulmonary function measures of Indians fell generally between those of whites and blacks. Differences were observed between blacks and whites of both sexes regarding the effects of cigarette smoking. The need for race specific stardards was confirmed and the question of using smokers in the acquisition of normative data was raised.

Adult↗
PubMed2002

Functional evaluation in patients with chronic obstructive pulmonary disease: pulmonary function test versus cardiopulmonary exercise test.

The pulmonary function test (PFT) alone may be inadequate for predicting work-related exercise capacity in patients who file workers' compensation claims for respiratory limitation and compensation. Two hundred sixteen ambulatory patients with chronic obstructive pulmonary disease (forced expiratory volume in 1 second = 54.1 +/- 16.8% predicted) were administered the PFT and cardiopulmonary exercise test, and the results were analyzed by categorical statistical comparison, based on standard medical impairment classifications. Sixty-five patients (30.1%) were similarly classified by the two methods. Of the remaining patients, 132 (61.1%) were found to be less impaired according to the cardiopulmonary exercise test than according to the PFT, and 19 (8.8%) were more impaired according to the PFT. The results favor the use of the cardiopulmonary exercise test for the routine evaluation of respiratory impairment in patients with chronic obstructive pulmonary disease, particularly for patients with mild or moderate impairment revealed by the PFT. The large discrepancy between the two procedures emphasizes the need for a novel approach.

Aged↗
PubMed2003

Lung function in Pakistani welding workers.

Our objective was to study the effects of welding fumes and their duration of exposure on lung function. This was a matched case-control cross-sectional study of spirometry in 50 nonsmoking manual metal arc welders who work without the benefit of welding fume control ventilation or respiratory protective devices. Welding workers, with exposures longer than 9 years, showed a significant reduction in spirometry (forced expiratory volume in one second [FEV1], FEV1/forced vital capacity [FVC%], and peak expiratory flow [PEF]) relative to controls. Lung function in nonsmoking welding workers is impaired and stratification of results shows a dose-effect of years of welding on lung function. This effect primarily shows an obstructive pattern of airways disease. Preventive measures in developing countries have to be adopted to avert long-term lung damage in welders.

Adult↗
PubMed2004

Respiratory symptoms and lung function of coke oven workers: a lung function surveillance system from 1990-2000.

This study investigated the association of exposure to coke oven emissions with respiratory symptoms and with lung function. Data for respiratory symptoms and lung function were repeatedly collected from 764 male coke oven workers between 1990 and 2000. The data were analyzed cross-sectionally and longitudinally. Working in "Operation" increased the risk for cough (odds ratio [OR] = 2.37), phlegm (OR = 2.55), and shortness of breath (OR = 1.52). Cross-sectionally, each year of working in Operation was associated with a reduction in FEV1 of approximately 10 mL (P = 0.006) and in FVC of around 21 mL (P = 0.0001). From longitudinal analysis, each year of working in Operation was associated with an extra annual decline in FEV1 of 1.5 mL (P = 0.0012) and in FVC of around 1.8 mL (P = 0.0017). Exposure to coke oven emissions increased the risk for respiratory symptoms and adversely affected lung function.

Adult↗
PubMed2005

Simulation of lung function evolution after heart-lung transplantation using a numerical model.

A morphometry-based computational model for expiratory flow in humans was used to study the unusual configuration of the maximum expiratory flow-volume (MEFV) curve associated with alterations in lung function after heart-lung transplantation (HLT). The postoperative MEFV curve showed a peak, followed by a gently sloping plateau over the midvolume range, ending in a knee where the flow suddenly fell, instead of the usual observed uniform decrease in expiratory flow. We have tested several hypotheses about the relationship between the pattern of changes in the configuration of the MEFV curve and pathological changes in the airway mechanics through computer simulations. Principally, effects of lung denervation and airway obstruction, associated with the development of bronchiolitis obliterans in the lung periphery, have been investigated. The calculated curves are similar in appearance to the measured postoperative flow-volume curves and confirm reliability of the earlier hypotheses. We conclude that the plateau-knee configuration of the MEFV curve can result from flow limitation in one of the first airway generations, that this flow limitation coupled with an increase in peripheral airway resistance results in plateau shortening, and that flows exceeding predicted values during the second part of expiration may be produced by lung denervation. Additionally our results demonstrate that airways larger than the transitional and respiratory bronchioles can be involved in pulmonary function deterioration observed in patients affected with obliterative bronchiolitis. Our findings indicate that the computational model, based on a symmetrical dichotomous branching structure of the bronchial tree, along with pathological data, can be employed to evaluate the effects of heterogeneous changes in the lung periphery. Index Terms-Airway mechanics, forced expiration, lung transplantation, mathematical modeling, maximal expiratory flow-volume curve.

Computer Simulation↗
PubMed1977

Forced expiratory flow-volume relationships. Changes after upper abdominal surgery.

Forced expiratory flow-volume relationships have been used to investigate changes in lung mechanics caused by upper abdominal operations. The slope of the 'effort independent' portion of the flow-volume curve increases after operation, suggesting that restriction of respiratory movement is associated with an increase in lung recoil.

Abdomen↗
PubMed2006

Plethysmography and impulse oscillometry assessment of tiotropium and ipratropium bromide; a randomized, double-blind, placebo-controlled, cross-over study in healthy subjects.

AIMS: Spirometry, plethysmography and impulse oscillometry (IOS) measure different aspects of lung function. These methods have not been compared for their ability to assess long- and short-acting anticholinergic agents. We therefore performed a double-blind, placebo-controlled, four-way cross-over study in 30 healthy subjects. METHODS: Single doses of tiotropium bromide (Tio) 54 and 18 mcg, ipratropium bromide (IB) 40 mcg and placebo were administered. Specific conductance (sGaw), total lung capacity (TLC), inspiratory capacity (IC) and residual volume (RV) were measured using plethysmography, while IOS measured resistance (R5-25) and reactance (RF and X5). Pulmonary function was measured for 26 h post dose. RESULTS: Tio caused significant improvements in sGaw, forced expiratory voume in 1 s (FEV(1)), maximum mid-expiratory flow (MMEF) and R5-R25 at time points up to 26 h, with no clear differences between doses. IB improved the same parameters, but only up to 8 h. The weighted mean change (0-24 h) caused by Tio 54 mcg compared with placebo for FEV(1) was 240 ml (95% confidence interval 180, 300), while for sGaw the ratio of geometric means (Tio compared with placebo) was 1.35 (1.28, 1.41). Neither drug caused consistent statistically significant changes in RF, forced vital capacity, TLC or IC over 26 h. RV was significantly improved from 8 to 24 h by Tio 54 mcg only. CONCLUSIONS: In addition to spirometry, IOS resistance measurements and sGaw can distinguish between the effects of long- and shortacting anticholinergic effects in healthy subjects.

Adult↗
PubMed1986

Bronchial responsiveness to methacholine during airway cooling in normal subjects.

In order to investigate the effects of airway cooling on bronchial responsiveness in normal subjects, we measured bronchial responsiveness to inhaled methacholine with and without the inhalation of cold air. Two out of seven subjects showed an increase in baseline respiratory resistance (Rrs) during cooling of the airway but the other five subjects showed little change in their baseline Rrs. All subjects increased bronchial responsiveness to methacholine. Additionally, the threshold dose of methacholine decreased to one-third of the control dose with cooling of the airway. We speculate that airway cooling increased bronchial responsiveness to methacholine in normal subjects presumably due to increased vagal tone, increased alpha-adrenergic activity and/or a release of chemical mediators.

Adult↗
PubMed1995

Influence of budesonide on the response to inhaled terbutaline in children with mild asthma.

The aim of this study was to evaluate if continuous treatment with budesonide or salmeterol influences the bronchodilator response to terbutaline in children with asthma; 23 children, aged 7 to 16 years (mean = 11 years), with mild asthma were treated with inhaled budesonide 100 micrograms b.i.d. and placebo for three weeks in a randomized, double blind crossover study. These treatments were followed by treatment with inhaled salmeterol 50 micrograms b.i.d. for 3 weeks. On the last day of each period a cumulative dose-response experiment with terbutaline in the doses 50, 100, 250 and 500 micrograms (cumulative dose 900 micrograms) was performed. Lung function was measured before and 20 min after each terbutaline inhalation. Baseline pulmonary functions after budesonide treatment were significantly higher than the baseline measured after the two other treatments (p < 0.05). After budesonide treatment, the dose-response curve was shifted vertically upwards but otherwise parallel to the dose-response curve after placebo. The increase from baseline after the first cumulative dose of terbutaline was significantly lower after salmeterol treatment than after the two other treatments (p < 0.01). Maximal lung functions after 900 micrograms terbutaline also differed significantly between the three dose-response days; budesonide being significantly higher and salmeterol significantly lower than placebo (p = 0.02 and p < 0.001, respectively). It is concluded that budesonide treatment does not enhance the brochodilator response to terbutaline. Further studies are needed to assess if long-term continuous salmeterol treatment reduces the response to terbutaline.

Administration, Inhalation↗
PubMed2005

Additive effect of eosinophilia and atopy on exhaled nitric oxide levels in children with or without a history of respiratory symptoms.

Although atopy and blood eosinophilia both influence exhaled nitric oxide (eNO) measurements, no study has quantified their single or combined effect. We assessed the combined effect of atopy and blood eosinophilia on eNO in unselected schoolchildren. In 356 schoolchildren (boys/girls: 168/188) aged 9.0-11.5 yr, we determined eNO, total serum IgE, blood eosinophil counts and did skin prick tests (SPT) and spirometry. Parents completed a questionnaire on their children's current or past respiratory symptoms. Atopy was defined by a SPT >3 mm and eosinophilia by a blood cell count above the 80th percentile (>310 cells/ml). eNO levels were about twofold higher in atopic-eosinophilic subjects than in atopic subjects with low blood eosinophils [24.3 p.p.b. (parts per billion) vs. 14.1 p.p.b.] and than non-atopic subjects with high or low blood eosinophils (24.3 p.p.b. vs. 12.2 p.p.b. and 10.9 p.p.b.) (p <0.001 for both comparisons). The additive effect of atopy and high eosinophil count on eNO levels remained unchanged when subjects were analyzed separately by sex or by a positive history of wheeze (n=60), respiratory symptoms other than wheeze (n=107) or without respiratory symptoms (n=189). The frequency of sensitization to Dermatophagoides (Dpt or Dpf) was similar in atopic children with and without eosinophilia (66.2% and 67.4%, respectively); eosinophilia significantly increased eNO levels in Dp-sensitized children as well in children sensitized to other allergens. In a multiple linear regression analysis, eNO levels were mainly explained by the sum of positive SPT wheals and a high blood eosinophil count (t=4.8 and 4.3, p=0.000), but also by the presence of respiratory symptoms (especially wheeze) and male sex (t=2.6 and 2.0, p=0.009 and 0.045, respectively). Measuring eNO could be a simple, non-invasive method for identifying subjects at risk of asthma in unselected school populations.

Analysis of Variance↗
PubMed1982

Hyperinflation on hyperventilation-a simple test to detect early airway disease.

The hypothesis was raised that an increased end-expiratory lung volume when switching over from normal to hyperventilation (positive delta FRC) can be used as a criterion of early obstructive lung disease. In 20 normal subjects and in 24 patients with suspect or manifest lung disease delta FRC at breathing frequencies of 40, 60 and 80 min-1, forced expiratory volume in one second (FEV1), vital capacity (VC), maximal expiratory flow at 50 and 25% of VC (MEF50 and MEF25) and closing volume (CV) were determined. FEV% (FEV1 X VC-1 X 100) and CV% (CV X VC-1 X 100) were calculated. delta FRC40 correlated negatively with FEV%, MEF50 and MEF25 for normals and patients separately with no difference between the groups. The residual standard deviation of delta FRC40 on FEV% was significantly reduced when MEF50 and MEF25 was included. delta FRC40 did not correlate with CV or CV%. delta FRC60 and delta FRC80 did not correlate with MEF50 and MEF25. The reproducibility of delta FRC40 was of the same order as the other variables studied. A delta FRC40 of +0.31 corresponded to MEF50 and MEF25 values 2 SD below the reference value. This suggests that a positive delta FRC40 of more than 0.31 indicates airway obstruction.

Adolescent↗
PubMed2003

Computational model for forced expiration from asymmetric normal lungs.

We present a computational model to predict maximal expiration through a morphometry-based asymmetrical bronchial tree. A computational model with the Horsfield-like geometry of the airway structure, including wave-speed flow limitation and taking into consideration separate airflows from several independent alveolar compartments has been derived. The airflow values are calculated for quasistatic conditions by solving a system of nonlinear differential equations describing static pressure losses along the airway branches. Calculations done for succeeding lung volumes result in the semidynamic maximal expiratory flow-volume (MEFV) curve. Simulations performed show that the model captures the main phenomena observed in vivo during forced expiration: effort independence of the flow-volume curve for the most of vital capacity, independence of limited flow on the properties of airways downstream to the choke points, characteristic differences of lung regional pressures and volumes, and a shape of their variability during exhalation. Some new insights into the flow limitation mechanism were achieved. First, flow limitation begins at slightly different time instants in individual branches of the bronchial tree, however after a short period of time, all regional flows are limited in a parallel fashion. Hence, total flow at the mouth is limited for most of the expired lung volume. Second, each of the airway branches contribute their own flow-volume shape and just these individual flows constitute the measured MEFV curve. Third, central airway heterogeneity can play a crucial role in modification of the entire flow. Fourth, the bronchial tree asymmetry is responsible for a nongravitational component of regional volume variability. Finally, increased inhomogeneity yields results that cannot be explained nor re-created with the use of a symmetrical structure of the bronchial tree.

Air Pressure↗
PubMed2003

Nonlinear mechanisms determining expiratory flow limitation in mechanical ventilation: a model-based interpretation.

A nonlinear model of breathing mechanics, in which the tracheobronchial airways are considered in three serial segments, is presented to obtain insights into the mechanisms underlying expiratory flow limitation (EFL) in mechanically ventilated patients. Chronic obstructive pulmonary disease (COPD) and normal conditions were simulated and EFL was detected by application of negative expiratory pressure at the mouth or resistance reduction of the expiratory circuit. Simulation results confirm that both techniques reveal remarkable differences in the flow-volume curves between normal subjects and COPD patients, the former showing absence of EFL and the latter exhibiting EFL over most of the expiration. To interpret the role of different nonlinear mechanisms in producing EFL, different flow-volume curves obtained by changing model parameter values were analyzed. An increase in lower-airway resistance did not give rise to EFL, whereas a change in the pressure-volume characteristic of the intermediate-airway segment, towards increased resistance and easier collapse, significantly modified system behavior. In particular, EFL was observed when this intermediate-segment change was combined with an increase in lower-airway resistance. This evidence suggests that modifications, producing loss of radial traction and consequent narrowing of the airways in the peribronchial region, may play a leading role in EFL in COPD patients.

Air Pressure↗
PubMed1984

Mycoplasma pneumoniae: acute illness, antibiotics, and subsequent pulmonary function.

One hundred and eight children presenting with Mycoplasma pneumoniae infection were assessed during the acute illness and followed for three years. The incidence of wheezing with the acute infection (40%) was greater than expected in a normal childhood population. The initial illness precipitated wheezing for the first time in some subjects but others wheezed only with the acute illness. In non-asthmatic subjects significant bronchodilator responsiveness was present one month after infection. Children given erythromycin during the first seven days of their illness had a significantly shorter fever duration compared with those treated inappropriately. No significant effects of treatment were noted on pulmonary function three years later but non-asthmatic children had abnormal mean forced expiratory volume in one second and forced expiratory flow after 50% of the expired vital capacity compared with 64 healthy controls. These findings indicate impaired function three years after initial infection.

Adolescent↗
PubMed1996

Effects on symptoms and lung function in humans experimentally exposed to diesel exhaust.

OBJECTIVES: Diesel exhaust is a common air pollutant made up of several gases, hydrocarbons, and particles. An experimental study was carried out which was designed to evaluate if a particle trap on the tail pipe of an idling diesel engine would reduce effects on symptoms and lung function caused by the diesel exhaust, compared with exposure to unfiltered exhaust. METHODS: Twelve healthy non-smoking volunteers (aged 20-37) were investigated in an exposure chamber for one hour during light work on a bicycle ergometer at 75 W. Each subject underwent three separate double blind exposures in a randomised sequence: to air and to diesel exhaust with the particle trap at the tail pipe and to unfiltered diesel exhaust. Symptoms were recorded according to the Borg scale before, every 10 minutes during, and 30 minutes after the exposure. Lung function was measured with a computerised whole body plethysmograph. RESULTS: The ceramic wall flow particle trap reduced the number of particles by 46%, whereas other compounds were relatively constant. It was shown that the most prominent symptoms during exposure to diesel exhaust were irritation of the eyes and nose and an unpleasant smell increasing during exposure. Both airway resistance (R(aw)) and specific airway resistance (SR(aw)) increased significantly during the exposures to diesel exhaust. Despite the 46% reduction in particle numbers by the trap effects on symptoms and lung function were not significantly attenuated. CONCLUSION: Exposure to diesel exhaust caused symptoms and bronchoconstriction which were not significantly reduced by a particle trap.

Adult↗