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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↗
PubMed1986

Pulmonary function in relapsing polychondritis.

The pulmonary mechanics and bronchoscopic findings in 5 patients with relapsing polychondritis were studied to evaluate the mechanism of obstruction. Two of the patients did not have clinical symptoms referable to the respiratory tract: pulmonary function was normal in 1 patient and was suggestive of mild restriction in the other. Three patients had dyspnea; pulmonary function studies revealed expiratory and inspiratory obstruction in all 3. The maximal flow-static recoil curves demonstrated that the expiratory obstruction was due predominantly to airway abnormality and not to loss of elastic recoil forces of the lung. The bronchoscopic appearance of the extrathoracic airway during quiet breathing did not accurately reflect pulmonary function results. One patient had a visually normal upper airway but greatly reduced maximal inspiratory flow rates, whereas another patient had pronounced narrowing of the upper airway but only a modest reduction of maximal inspiratory flow rates. The bronchoscopic appearance of the intrathoracic airway during quiet breathing did relate well to maximal expiratory flow rates. We conclude that in our group of patients the predominant mechanism of expiratory obstruction in relapsing polychondritis is due to airway abnormality. Although the bronchoscopic and radiographic findings are useful, spirometry is more important in determining functional abnormality.

Adrenal Cortex Hormones↗
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↗
PubMed1991

Mechanical constraints on exercise hyperpnea in a fit aging population.

We studied 12 physically fit (VO2 max = 44 ml.kg-1.min-1) older subjects (age = 63 to 77 yr) who showed the usual age-related declines in lung function (i.e., reduced maximal expiratory flow rates, vital capacity and increased functional residual capacity, closing capacity, and residual volume). We measured the optimal transpulmonary pressures for maximal expiratory airflow and the capacity of the muscles of inspiration for developing pleural pressure (taking into account the effects of lung volume and flow rate). Within these mechanical constraints to ventilation we plotted tidal pleural pressure-volume loops for mild through maximal exercise according to a measured end-expiratory lung volume (EELV). We found EELV to decrease a mean of 0.26 +/- 0.09 L and maximal effective pleural pressures to be reached in nine subjects near EELV with only light to moderate exercise intensities, whereas peak inspiratory pressure was only 45% of the capacity for pressure generation. With progressive increases in exercise intensity, EELV increased, and pleural pressures encroached to a greater extent on the maximal effective pressures; however, they remained effective in the majority of subjects. During maximal exercise EELV was 0.13 +/- 0.10 L greater than resting values, 20% of the Vt reached maximal effective pressures, and 83% of the capacity for inspiratory pressure was achieved. Three subjects significantly surpassed their maximal effective expiratory pressures, and four subjects achieved 95 to 100% of the capacity for inspiratory pressure generation. These subjects also showed no further increase in ventilation while breathing 0.02 to 0.05 FICO2 at maximal exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
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↗
PubMed1982

Bronchodilatation, lung recoil, and density dependence of maximal expiratory flow.

Using normal human subjects we have measured maximal expiratory flow rates with air (Vmaxair) and after a washin of 80% He-20% O2 (VmaxHeO2) and static elastic recoil pressures of the lung [Pst(L)] both before and after administration of a beta-agonist, terbutaline. The effects of inhaled drug were compared with those of the subcutaneously administered agent, each given in doses to produce maximal bronchodilatation as assessed by increases in Vmaxair in the mid-vital capacity. Although there was a significant yet modest decrease in Pst(L) only after injection of the agent, density dependence (DD), assessed as the ratio of VmaxHeO2 to Vmaxair, increased significantly and comparably after either route of administration. A modest decrease in Pst(L), therefore, did not affect the changes in DD.

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↗
PubMedDate not supplied

A normal FEV1/VC ratio does not exclude airway obstruction.

BACKGROUND: A decreased forced expiratory volume in 1 s/vital capacity (FEV(1)/VC) ratio is the hallmark of the definition of airway obstruction. We recently suggested that a lung function pattern, we called small airways syndrome (SAOS), has a normal FEV(1)/VC and total lung capacity (TLC) and reflects obstruction of small airways. OBJECTIVES: To substantiate our hypothesis we measured and compared lung function tests including maximal expiratory flow rates (MEFR), sensitive indicators of airway obstruction, in SAOS subjects and in matched controls. METHODS: We selected 12 subjects with the pattern of SAOS, but without chronic lung or heart disease (average age: 40.7 +/- 7.8 years) and 36 age-matched subjects with normal lung function (42.8 +/- 6.3 years). We measured static and dynamic lung volumes, MEFR and lung diffusing capacity (DL(CO)). RESULTS: SAOS subjects were heavier smokers (p < 0.05) and body mass index was less than in control subjects (p < 0.01). Both FEV(1)/VC ratio and TLC were comparable in the two groups. However, FEV(1), VC, DL(CO), and MEFR were lower and residual volume (RV) and RV/TLC ratio were higher (p < 0.05) in the SAOS group than in the control one. Furthermore, the MEFR curve of the SAOS group was displaced to the left without any change in slope, suggesting premature airway closure. CONCLUSION: Our results suggest that a normal FEV(1)/VC ratio does not exclude airway obstruction. A decrease of FEV(1), provided TLC is normal, reflects small airway obstruction.

Adult↗
PubMed1984

Verofylline, a methylxanthine bronchodilator, in asthma.

Verofylline, a long-acting polysubstituted methylxanthine bronchodilator, was taken orally by eight adult patients with asthma in a double-blind, crossover tolerance study. Peak expiratory flow, forced vital capacity, and its subdivisions were measured weekly 2, 4, and 6 hr after oral dosing with drug or placebo. Peak drug activity developed between 4 and 6 hr after dosing. Subject tolerance was good at the doses used. Dose-response curves for mean forced expiratory volume in one second, peak expiratory flow rate, and forced expiratory flow at the end of 4 hr were greater after 0.05 mg/kg verofylline than after placebo or higher doses of verofylline. Mean percent change in forced vital capacity remained increased as long as 6 hr after 0.15 mg/kg active drug. Verofylline was not very effective as a bronchodilator at the doses used.

Administration, Oral↗
PubMed2004

Effect of salmeterol on the ventilatory response to exercise in chronic obstructive pulmonary disease.

This study examined the effects of bronchodilator-induced reductions in lung hyperinflation on breathing pattern, ventilation and dyspnoea during exercise in chronic obstructive pulmonary disease (COPD). Quantitative tidal flow/volume loop analysis was used to evaluate abnormalities in dynamic ventilatory mechanics and their manipulation by a bronchodilator. In a randomised double-blind crossover study, 23 patients with COPD (mean +/- SEM forced expiratory volume in one second 42 +/- 3% of the predicted value) inhaled salmeterol 50 microg or placebo twice daily for 2 weeks each. After each treatment period, 2 h after dose, patients performed pulmonary function tests and symptom-limited cycle exercise at 75% of their maximal work-rate. After salmeterol versus placebo at rest, volume-corrected maximal expiratory flow rates increased by 175 +/- 52%, inspiratory capacity (IC) increased by 11 +/- 2% pred and functional residual capacity decreased by 11 +/- 3% pred. At a standardised time during exercise, salmeterol increased IC, tidal volume (VT), mean inspiratory and expiratory flows, ventilation, oxygen uptake (VO2) and carbon dioxide output. Salmeterol increased peak exercise endurance, VO2 and ventilation by 58 +/- 19, 8 +/- 3 and 12 +/- 3%, respectively. Improvements in peak VO2 correlated best with increases in peak VT; increases in peak VT and resting IC were interrelated. The reduction in dyspnoea ratings at a standardised time correlated with the increased VT. Mechanical factors play an important role in shaping the ventilatory response to exercise in chronic obstructive pulmonary disease. Bronchodilator-induced lung deflation reduced mechanical restriction, increased ventilatory capacity and decreased respiratory discomfort, thereby increasing exercise endurance.

Administration, Inhalation↗