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PubMed1980

Chronic bronchitis and decreased forced expiratory flow rates in lifetime nonsmoking grain workers.

To determine whether clinical symptoms and pulmonary function abnormalities were more common in lifetime nonsmoking grain elevator workers exposed to grain dust than in lifetime nonsmoking community control subjects who were not occupationally exposed to dust, we obtained an occupational health questionnaire, spirometric variables, and flow-volume curves on 90 lifetime nonsmoking grain workers and 90 lifetime nonsmoking community control subjects. For these groups we calculated the prevalence of chronic bronchitis, defined as daily production of phlegm for 3 months/yr for at least 2 yr. The prevalence of chronic bronchitis was higher in nonsmoking workers (23.1%) than in nonsmoking control subjects (3.3%) (p less than 0.01). Nonsmoking grain workers had lower mean values than did nonsmoking control subjects for maximal mid-expiratory flow rate (p less than 0.01) and for maximal expiratory flow at 50% of vital capacity (p less than 0.01). We conclude that exposure to grain dust inlifetime nonsmoking grain workers is associated with an increased prevalence of chronic bronchitis and evidence of airflow obstruction.

Adult↗
PubMed1975

Intraindividual variability in maximal expiratory flow-volume and closing volume in asymptomatic subjects.

The variability of the parameters derived from analysis of the forced vital capacity and the expired nitrogen trace after a vital capacity inhalation of oxygen (closing volume) within a day, from day to day, and from week to week, has been determined. Effort-dependent tests as vital capacity and peak expiratory flow showed the least variability. The greatest variability was seen in effort-independent tests of function such as the maximal expiratory flow rate at 25 per cent (75 per cent of expired vital capacity) and 50 per cent of vital capacity, as well as closing volume. The degree of variability in the tests used was uninfluenced by the periodicity of the tests or the age or smoking habits of the subjects tested. It is suggested that variability of tests of respiratory function should be taken into account in their interpretation.

Adolescent↗
PubMed2005

Monitoring of expiratory flow rates and lung volumes during a high altitude expedition.

BACKGROUND: Data on lung volumes and changes in flow-volume spirometry at high altitude are few and do not provide comprehensive assessment of the occurring changes. This study characterizes alterations of the forced expiratory flow-volume curve (FEFV-curve) and lung volumes at increasing altitude. METHODS: FEFV-curve and lung volumes at increasing altitude were characterized by daily assessment of peak expiratory flow (PEF), forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and maximal expiratory flow rates (MEF 25, 50, 75) at 25%, 50% and 75% of the FEFV-curve with a portable spirometer (turbinometric method) three times a day during an expedition to Mustagh Ata (7545m) in 15 healthy mountaineers. RESULTS: With increasing altitude FVC and FEV1 were reduced by up to 25% (74.8% / 74.6% of baseline) and MEF25 was reduced to 81.5% of baseline values. PEF initially increased up to 4451m and returned to baseline values above 5000m. After descent below 2000m, all values normalized within one day. There were weak negative correlations between AMSS and FEV1, FVC and PEF (r = -0.23, p<0.001). CONCLUSIONS: We found increasing pulmonary restriction at high altitude without a marked reduction of PEF. Assessment of the FEFV-curve at high altitudes with a portable spirometer is a practical method reflecting the true field situation and may provide clinically relevant information (impending pulmonary edema).

Adult↗
PubMed1976

Amantadine effect on peripheral airways abnormalities in influenza. A study in 15 students with natural influenza A infection.

Amantadine HCl administration has resulted in accelerated resolution of influenza A illness. Prolonged abnormalities in pulmonary function have been described in uncomplicated influenza A. To study the effect of amantadine on these changes, we evaluated young adults with documented natural influenza A with clear chest examinations and X rays. Subjects received placebo or amantadine in random, double-blind fashion. Physiologic studies included maximal expiratory flow volume curves with air and helium-oxygen mixtures. Air flow rates were unchanged in all subjects throughout. Initially, both groups showed comparable decreases in mean helium-oxygen maximal expiratory flow rates. The amantadine group showed accelerated physiologic improvement: significant increase in helium-oxygen flow rates occurred within 7 days (P less than 0.05). The rate of improvement in the helium-oxygen flow rates in the placebo group was not statistically significant. These studies confirm peripheral airways dysfunction after uncomplicated influenza A and suggest that amantadine is associated with accelerated resolution of this dysfunction.

Adult↗
PubMed2006

Effects of theophylline on pulmonary function in patients with traumatic tetraplegia.

BACKGROUND/OBJECTIVES: To assess the effects of theophylline on pulmonary function in patients with chronic traumatic tetraplegia, we conducted a double-blind placebo-controlled crossover study in 10 patients. METHODS: The patients (age: 41 +/- 3 years; time from injury: 16 +/- 3 years; neurological levels: C3 to C7-T1) were randomized to receive oral theophylline or placebo for 6 weeks. After 2 months of washout, the patients received the medication not taken in the first trial for an additional 6 weeks. We measured lung volumes, expiratory flow rates, maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) at both baseline and at the end of each treatment arm. Theophylline blood serum assays were measured during the first week of the treatment and on the day of respiratory measurements. RESULTS: Mean theophylline level on the day of treatment completion was 12.6 +/- 1.4 microg/mL. In analyzing the data from the group of 10 patients, the percent changes from baseline in total lung capacity, forced vital capacity, forced expiratory volume at 1 second, MIP, and MEP did not differ significantly between the two treatment arms (P > 0.05 in all). CONCLUSION: These data show that in this small group of 10 subjects with chronic tetraplegia, administration of oral theophylline did not improve pulmonary function.

Adult↗
PubMedDate not supplied

Within- and between- subject variability of indices from the closing volume and flow volume traces.

The within-subject variability of consecutive measurements of indices derived from the closing volume (CV) trace and from the maximal expiratory flow volume (MEFV) curve was studied in 24 subjects. The variability of the closing volume and of the maximal expiratory flow rates at 50 percent (Vmax. 50) and 75 percent (Vmax. 75) of the expired vital capacity was about three to eight times greater than that of the FEV1, FVC or FEV1 percent. The lung volume measured from total lung capacity to the onset of airway closure (OAC) was about five times more reproducible than the CV. The coefficients of variation for the CV (as a percentage of the vital capacity), the Vmax. 75, and the OAC, both in litres and as a percentage of the vital capacity, were significantly correlated with age. No difference in the mean coefficients of variation for the CV, OAC, Vmax. 50 or Vmax. 75 were found with respect to sex, smoking habit or previous experience with the test routines. The between-subject variability of the FEV1, FVC, FEV1 percent, transfer factor, diffusion coefficient, Vmax. 50, Vmax. 75, CV and OAC was evaluated from a study of 75 asymptomatic lifetime non-smokers. The variability of the Vmax. 50, Vmax. 75 and CV was about two to eight times greater than that of the other tests used, irrespective of sex. The OAC (percent VC) was three to four times less variable than the CV. The variability of the Vmax. 50 and Vmax. 75 was reduced by, on average, 7 percent when these flow rates were expressed per litre of FVC.

Adult↗
PubMed1998

Mechanisms by which COPD affects exercise tolerance.

In view of the recent advances in our understanding of the pathophysiology of COPD, we felt that it would be appropriate to examine the contribution of several abnormalities, not hitherto examined, to exercise limitation in this disease. These included: (1) The ability to exceed maximum expiratory flow (determined during forced maneuvers from TLC) during partial expiratory maneuvers. This is referred to as deltaFEV1. (2) Shape of the flow-volume curve (Shape). (3) Susceptibility to develop dynamic hyperinflation (dynamic hyperinflation index, DHI). (4) Ventilatory response to exercise (VEmax/VEpred). Twenty-four COPD patients (FEV1 = 42 +/- 13% pred) underwent symptom-limited progressive exercise. DeltaFEV1, shape, DHI and VEmax/VEpred were determined. All values were normalized to eliminate the effects of age, sex, and body size. Shape had no impact on peak VO2 (r = 0.8). DeltaFEV1 (r = 0.50), DHI (r = 0.50) and VEmax/VEpred (r = 0.46) correlated significantly with peak VO2 with all three exceeding FEV1 (r = 0.43). DHI and deltaFEV1 correlated significantly with each other (r = 0.43) suggesting that the latter exerts its beneficial effects by reducing the tendency to develop DH. We conclude that variability among patients in ventilatory response to exercise and in deltaFEV1 (likely an expression of extent of regional mechanical heterogeneity) contribute importantly to variability of exercise tolerance in COPD.

Aged↗
PubMedDate not supplied

A comparative study of a few tests of dynamic lung function.

A variety of tests like FEV0-76, FEV1, PFR, MEFR is in use for assessment of ventilatory function of the lungs. Each of them has some marginal advantage over the other. It is, therefore, necessary to find out their relative merits and choose the one which can provide the maximum information in a reasonably short time. In this project, a norm of all the above tests for the people of Gujarat of age group 18-20 years has been found, the relative merit of the tests has been discussed and the velocity of air flow at 0.3 sec of expiration has been suggested as the single measurement which may conveniently replace all the other above.

Adolescent↗
PubMed1986

The value of the forced expiration technique with and without postural drainage in adults with cystic fibrosis.

The effect of the Forced Expiration Technique (FET) with or without Postural Drainage (PD) was examined in eight adults with cystic fibrosis. On four mornings the patients followed a 30-min physiotherapy session consisting in a randomized order of either FET in a sitting position following a night of horizontal sleep ("FET"), or FET in a postural drainage position following sleep including postural drainage ("FET/PD"). The lung function parameters studied did not change during either of the two treatments. Sputum yield over 22.5 h before the physiotherapy sessions and over 24 h increased with PD during sleep in patients with more than 30 g of sputum per 24 h (p less than 0.05). PD during the treatment sessions did not further increase sputum production. This study indicates that sleeping head-down improves expectoration in patients with copious sputum. PD during FET is not needed after sleeping in the head-down position.

Adolescent↗
PubMed1982

Respiratory mechanics in supine subjects during progressive partial curarization.

Respiratory mechanics were studied in six supine conscious volunteers during progressive muscle weakness produced by infusion of d-tubocurarine. Partial curarization was carried out to the point of abolishing head lift ability and handgrip strength. At all levels of partial paralysis, expiratory muscle strength was significantly more impaired than inspiratory strength. Despite this, subjects maintained relatively normal maximal expiratory flow rates, whereas inspiratory flows decreased significantly. The diminished inspiratory flows are not fully explained by decreased driving pressures during force inspiration, since inspiratory resistance increased significantly with the decreased flow. Inspiratory flow patterns suggest a variable extrathoracic obstruction most likely due to the absence of normal airway abductor activity during inspiration. Maximal respiratory muscle weakness decreased forced vital capacity by 29% and total lung capacity by 15%. The decreased level of lung inflation did not alter lung elastic recoil. Functional residual capacity was unchanged, but inspiratory capacity decreased by 25% and residual volume increased by 38%. These changes are in accord with predictions based on the decreased muscle strength and normal respiratory system recoil.

Adult↗
PubMed1976

[Stability and variation of the maximal ventilation and maximal expiratory volume ratios].

The level of stability of the ratio (alpha coefficient) of maximal ventilation (MBC) over maximal expiratory volume per second (FEV1) was continued statistically for its practical value in estimating the respiratory functional incapacity. Three observations were made: --the mean value of the alpha coefficient=MBC/FEV1 is independent of the sex, age, size or weight in the normal subject; alpha was slightly higher than that found from theoretical values of MBC (CECA) and FEV1 (BALDWIN and COURNAND); --the alpha coefficient varied with the vital capacity (VC) and with FEV1; --there was a particularly simple relation between alpha and VC: alpha decreased from 38 to 30 when VC increased from 1 to 6 litres.

Age Factors↗
PubMedDate not supplied

Comparison of the ventilation response to CO2 rebreathing in healthy smokers and nonsmokers and subjects with bronchitis.

A comparison of ventilatory tests and the response to carbon dioxide rebreathing was made in healthy smokers, nonsmokers, and in subjects with bronchitis. The response to carbon dioxide (CO2) rebreathing was the same in the healthy population but diminished in the bronchitic group. Effects of smoking on maximal expiratory flow rates did not correlate with the results of carbon dioxide rebreathing. A consistent pattern of relationship of ventilation response to carbon dioxide and age of the subject was apparent.

Adult↗
PubMed1989

Inverse correlation of expiratory lung flows and sputum eosinophils in status asthmaticus.

Seventy-six consecutive patients admitted to Los Angeles County General Hospital with acute asthma were studied. Blood and sputum smears for cell counts were obtained on all patients within 12 hours of admission. Fifty-one (67%) patients were able or willing to perform spirometry and flow/volume curves in the first 24 hours of hospitalization. The severity of airway obstruction as assessed by forced expiratory volume in one second (FEV1), maximum mid-expiratory flow rate (MMFR), and forced vital capacity (FVC) was compared with blood and sputum eosinophil counts. Although there was no relation between the blood eosinophilia and airway obstruction, an inverse relationship between the number of eosinophils in the sputum and airway flow rates was observed. Higher percentages of sputum eosinophils were associated with diminished flow rates. We believe that sputum eosinophils may be helpful in the initial assessment of severe bronchial asthma.

Adolescent↗
PubMed1980

The immediate effect on lung function of smoking filtered and nonfiltered cigarettes.

We measured and compared the effect of smoking a filtered and a nonfiltered cigarette on instantaneous maximal expiratory flow rates (Vmax50 and Vmax25) and airway resistance (Raw). We found a significant increase in Raw after both cigarettes, and a small decrease in Vmax50 after smoking the nonfiltered cigarette. The change in Vmax50 after smoking the filtered cigarette was not significant. We suggest, on the basis of these data, that filtered cigarette smoke reduces some of the constituents that cause bronchoconstriction in the large and central airways.

Adolescent↗
PubMed1975

Reproducibility of dynamic compliance and flow-volume curves in normal man.

To evaluate methods proposed for the early detection of small airways obstruction. we have compared the precision of the forced expiratory flow-volume curve and of measurements of the frequency dependence of lung compliance in normal subjects, in 10 of whom these measurements were made on four occasions, and in 5 on two occasions. The maximal expiratory flow rate was highly reproducible, revealing consistent differences between these normal subjects, particularly when measured at 60% of TLC and corrected for differences in body size. The frequency-dependence measurements, expressed as the slope of the regression line relating dynamic compliance to frequency, showed much greater variation between repeated measurements in the same subject. Comparison with earlier published accounts is difficult in view of lack of quantitative data, but the variability between single measurements on different normal subjects appears to be similar to that which we have found when the results are expressed in a comparable manner. Dynamic compliance at a frequency of 1 Hz lay between 48% and 141% of the value obtained by extrapolation to zero frequency.

Adult↗
PubMed1982

Acute respiratory effects of exposure to diesel emissions in coal miners.

A study was conducted to determine if acute respiratory effects, measured in terms of changes in forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and maximal expiratory flow rate at 50% of forced vital capacity (Vmax50), were related to exposure to diesel emissions in coal miners. Sixty coal miners exposed to diesel emissions and 90 miners not exposed were tested before and after a work shift for ventilatory function changes. Significant work shift decrements in ventilatory function did occur in miners in both groups who smoked cigarettes, but there were no significant differences in the ventilatory function changes between those miners exposed to diesel emissions and those not exposed either in the aggregate or under control by smoking status.

Adult↗
PubMed1999

Major genetic effects on airway-parenchymal dysanapsis of the lung: the Humboldt family study.

We examined familial resemblance and performed segregation analysis for the maximal expiratory flow rate at 50% of vital capacity (Vmax50) and the ratio of Vmax50 to forced vital capacity (FVC), based on data from 309 nuclear families with 1,045 individuals in the town of Humboldt, Saskatchewan, in 1993. Vmax50 is considered as an index of airway function and Vmax50/FVC is considered as an index of airway-parenchymal dysanapsis. Both Vmax50 and Vmax50/FVC were preadjusted for host characteristics (age, height, and weight), environmental factors, and history of respiratory symptoms and diseases in four separate groups (mothers, fathers, daughters, and sons). Both Vmax50 and Vmax50/FVC showed low father-mother correlations and significant parent-offspring and sibling-sibling correlations. Segregation analysis indicated that for residual Vmax50, the model of no-parent-offspring transmission with possible heterogeneity between two generations fitted the data as well as did the general model with arbitrary transmission probabilities. The Mendelian hypothesis for Vmax50 was rejected, which was consistent with our previous findings for other indexes of airway function. For residual Vmax50/FVC, however, a single locus explained all the familial resemblance and both no-parent-offspring-transmission hypotheses [tau(AA) = tau(AB) = tau(BB) = qA and tau(AA) = tau(AB) = tau(BB)] were rejected. The study provides evidence for a single locus influencing airway-parenchymal dysanapsis.

Consanguinity↗