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Results for “Forced Expiratory Flow Rates”

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At least 19 recordsLinked to original sources
PubMed1975

Comparison of the bronchial response to running and cycling in asthma using an improved definition of the response to work.

The bronchial responses to treadmill running and ergometer cycling have been compared in 13 adults with asthma. The exercises were performed on separate days with an interval ranging from three days to six months. The study was designed to ensure that the time course of oxygen consumption during running was replicated during cycling. The response to exercise was estimated by taking serial measurements of the maximum forced expiratory flow rate and forced expiratory volume in one second before and after work. Indices used to describe the response were (b-a)/b and a/b, where b and a were the average lung function before and the lowest value after exercise respectively. There was no significant difference in the lung function of the subjects before running and cycling nor did the duration of exercise or oxygen consumption differ between the two exercises. Eleven of the 13 patients showed a reduction in ventilatory capacity after both forms of exercise. Differences in the lung function responses to the two forms of standard work were trivial and not statistically significant, amounting to only about 1%. It is suggested that previous reports of larger responses to running than cycling were probably due to higher energy expenditures during running. General problems regarding the description and comparison of the responses to exercise are discussed.

Adult↗
PubMed1979

Changes in pulmonary function after naturally acquired respiratory infection in normal persons.

Changes in pulmonary function due to naturally occurring respiratory tract infection were examinated in 26 normal healthy volunteers during a period of 6 months. Forced expiratory maneuvers in each volunteer were recorded at 2-wk intervals throughout the study and daily during illness. Significant impairment of peak expiratory flow rate, forced vital capacity, forced expiratory volume in one second, and maximal mid-expiratory flow rate at 50% of the vital capacity was observed during infection, whereas changes in the maximal expiratory flow rate at 75% of vital capacity were nonsignificant. From these results, we conclude that large airways are certainly affected during uncomplicated respiratory infections in normal healthy persons and from the changes observed in FVC we suggest that more widespread involvement of the small airways may occur.

Adolescent↗
PubMed1975

Forced expiratory time--its reliability as a lung function test.

Three studies of factors affecting variability of forced expiratory time (FET) have been carried out. In the first, different observers or repeated measurements over a few minutes were shown to make no significant contribution to FET variability. Time of day was also relatively unimportant. In the second study, FET was shown to vary considerably more than peak flow rate, forced expiratory volumes, and mid expiratory flow rates over the course of five days. In the third study, FET was shown to correlate with other measurements of airways obstruction though the correlation coefficients were relatively low. The measurement of FET is thought to be too variable to be of practical use as a screening test for small airways disease, though its clinical value is not questioned.

Adolescent↗
PubMed1975

Evaluation of bronchial drainage in patients with cystic fibrosis.

Examined in this study are the results of six tests of pulmonary function immediately preceding and following bronchial drainage in twenty-six patients with cystic fibrosis. Highly significant increases averaging 5.67, 4.13, 13.47, and 6.98 percent occurred in peak expiratory flow rate, forced vital capacity, expiratory reserve volume, and inspiratory capacity respectively. Significant increases in peak expiratory flow rate, forced vital capacity, and inspiratory capacity were observed in a subgroup of six of the above patients who had evidence of bronchospasm. The authors conclude that bronchial drainage will produce significant increases in routine pulmonary function values. The results suggest that this treatment is most effective in clearing the larger, more proximal, airways and is of benefit even in the presence of clinical bronchospasm.

Adolescent↗
PubMed1992

Evaluation of mean transit time in children as an indicator of airways obstruction.

Mean transit time was evaluated as a test of pulmonary function in normal and asthmatic children. It was found to be independent of body size and negatively correlated with PEFR, FEV1 and FVC in normal children. Mean transit time was less sensitive in detecting the effects of bronchodilator therapy in asthmatic children than other simpler tests of lung function. The range of normal was so wide that there was no clear demarcation between normal and abnormal. The degree of overlap makes isolated tests of mean transit time of little diagnostic value. It is therefore concluded that mean transit time though it theoretically offers the attractive advantage of being a sensitive indicator of both large and small airways obstruction, is unlikely to play a major part in the routine evaluation of lung function in asthmatic children.

Adolescent↗
PubMed1976

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.

Adolescent↗
PubMedDate not supplied

[Technical and experimental study of two electronic spirometers (author's transl)].

Two electronic spirometers which use standard pneumotachographs were evaluated for their static and dynamic response, and clinically compared in 20 subjects to a reference flow channel. In the Pneumoscreen the data are digitalized and stored, permitting to play back the flow-volume curves at low or high speed. The instrument provides a direct read-out of forced vital capacity and of five indexes of forced expiration. It was found perfectly adequate with respect to linearity and frequency response. However, due to some systematic error in digital processing, maximum flow at low lung volumes appeared substantially over-estimated. Besides forced vital capacity and a number of indexes of forced expiration, the Medistor type M 010 may be used to measure ventilation, tidal volume, frequency and maximum breathing capacity. The data are processed by an analog computer. The transducer was found poorly linear with inadequate frequency response. However, no systematic bias in the measurements was found, except for peak flow and maximum breathing capacity.

Airway Obstruction↗
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↗
PubMed1979

Comparison of various methods for reading maximal expiratory flow-volume curves.

To determine the best procedure for reading maximal expiratory flow-volume curves 2 sets of 5 curves were obtained one hour apart in 89 subjects and processed digitally according to 8 different methods. Four indices were considered: the forced expiratory flows at 25, 50, and 75 per cent of the forced vital capacity, and the maximal mid-expiratory flow. When selecting the curve yielding the largest forced vital capacity or the largest sum of forced vital capacity and forced expiratory volume in 1 sec, flow values were significantly lower (P less than 0.001) and were often less reproducible than those obtained with most of the other methods. Computing the mean of the indices among the curves with the 2 largest forced vital capacities also provided comparatively low values, but with with better reproducibility. In contrast, maximal flows were probably overestimated by using the highest values among the curves having forced vital capacity or a surface area within 5 per cent of the largest, or when reading the indices on a composite curve obtained by superimposing individual breaths at residual volume. More reproducible and, probably, unbiased data may be drawn from the composite curves obtained by superimposing the breaths either at total lung capacity or on the descending limb.

Adult↗
PubMed1979

Inhaled atropine in asthma.

Ten adult asthmatics inhaled atropine and isoproterenol to determine the site of action in the airways and relative effectiveness of the two drugs. The two agents were equal in their effect on lung volumes and airway resistance but isoproterenol produced significantly better flows. Atropine was shown to be an effective bronchodilator with a predominant site of action in large airways. The authors believe atropine and atropine derivatives deserve ongoing investigation, especially regarding potential side effects of retarding mucociliary clearance and the clinical significance of apparent failure to dilate small airways.

Administration, Intranasal↗
PubMed1976

[Critical analysis of the diagnostic value of the flow-volume curve].

Changes in the flow-volume curve after administration of a bronchodilator were studied in reversible bronchial obstruction. The concept of isovolume is used in analysis of the curve indices, i.e. it is felt that the index (75, 60, 50, 25% FVC) after administration should be fixed on the curve at the same volume as on the basic curve to enable an indirect account to be taken of changes in flow in function of time, since, if resistance is reduced, the emitted volume varies in the same period even though the conditions promoting the flow are unchanged.

Bronchodilator Agents↗