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Results for “Maximal Expiratory Flow Rate”

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PubMedDate not supplied

Expiratory function in complete tetraplegics: study of spirometry, maximal expiratory pressure, and muscle activity of pectoralis major and latissimus dorsi muscles.

Respiratory complications, such as pneumonia and atelectasis, are major causes of mortality and inhibit rehabilitation programs in spinal cord injury. Tetraplegic patients cannot cough enough to clear their sputum because of expiratory muscle weakness, mainly of the abdominal muscles. However, tetraplegics are still able to activate some muscles during coughing. Some tetraplegics, even though they cannot contract the abdominal muscles, can cough effectively. It was supposed that some accessory expiratory muscles were activated during coughing in tetraplegics. We, therefore, studied the peak expiratory flow rate, expiratory muscle strength, and the activities of the pectoralis major and latissimus dorsi muscles in 11 complete tetraplegics. Peak expiratory flow rate was measured by spirometry. Expiratory muscles strength was assessed by maximal expiratory mouth pressure; muscle activity was assessed by means of the root mean square voltage obtained by surface electromyography. The results showed that peak expiratory flow rate, maximal expiratory mouth pressure, and root mean square of these two muscles were correlated with neurological level. Peak expiratory flow rate was correlated with peak expiratory flow rate. Peak expiratory flow rate was correlated with the root mean square voltage of the pectoralis major and latissimus dorsi muscles. It was supposed that these two muscles were activated as accessory expiratory muscles and play an important role in expiratory function in tetraplegic patients.

Adult↗
PubMed1976

Evaluation of lung function indices for bronchodilator trials. Results of a cross-over study of fenoterol.

In 10 patients with airway obstruction, spirographic indices and maximal expiratory flow rates were measured before inhalation of fenoterol and at different time intervals, for 5 h, following the inhalation of 200 mug of this substance. 10 min after inhalation of fenoterol, there was a statistically significant increase in all lung function indices. A further increase was observed later. 3 h after inhalation of fenoterol, all indices were still significantly higher than control values. No side effects were observed. At all time intervals, the increase of the forced expiratory volume in 1 sec (FEV1.0), peak expiratory flow rate (PEFR) and maximal expiratory flow rate at 50 and 75% of the vital capacity reached a similar level of statistical significance. It is concluded that for the trial of the bronchodilator drugs, any of these indices may be used, and for practical purposes FEV1.0 and PEFR are best suited.

Adult↗
PubMed1983

Influence of second-order data filtering on common forced expiration indices.

Forced expiratory manoeuvres are extensively recorded using flow meters coupled to pressure transducers, which usually behave like second-order filters. To assess what should be the dynamic characteristics of such equipment for accurate determination of common forced expiration indices, 125 curves were obtained from 25 healthy subjects in the best technical conditions. The flow-time curves were then submitted to various degrees of second-order filtering, and the indices derived from filtered and unfiltered curves were compared. Considering that experimental error is acceptable if it does not exceed 20% of the normal interindividual variability for 95% of the curves, the following conclusion was drawn; with an optimal damping ratio (r) of 0.7, forced expiratory volume in one second, maximum midexpiratory flow rate and maximal expiratory flow at 25% of the forced vital capacity (MEF25) are still correctly measured when the resonant frequency (fn) is as low as 3 Hz. The corresponding figures are 5 Hz for MEF50, 20 Hz for peak expiratory flow rate and above 20 Hz for MEF75. Higher values of fn are usually required when r is higher or lower than 0.7.

Adult↗
PubMed1980

Usefulness of forced expiration slope ratios for detecting mild airway abnormalities.

To assess their value for early recognition of airway abnormalities, forced expiration slope ratios as recently defined by Mead, were measured at 5 lung volumes in 114 healthy nonsmokers and in 76 cigarette smokers. In healthy nonsmokers, slope ratios were independent of sex and body height, but were significantly correlated with age. They tended to be higher at low lung volume, particularly in older subjects. In male smokers with a tobacco consumption of less than 5 pack-years, slope ratios were increased at both ends of the volume range, suggesting nonhomogeneous lung emptying and peripheral airway obstruction. With increasing tobacco consumption, slope ratios tended to return to normal values at low lung volume, perhaps because of airway closure. In female smokers, slope ratios were decreased at high lung volume and increased at low lung volume, suggesting that both central and peripheral airways were abnormal. Mead's analysis appeared to be a useful tool for discussing the data in terms of functional abnormalities. However, because of their large variability, slope ratios were not as successful as transit time indices for recognizing abnormal subjects.

Adult↗
PubMed1975

Functional abnormalities in young asymptomatic smokers with special reference to flow volume curves breathing various gases.

Functional abnormalities have been described in healthy, asymptomatic young smokers. Fifteen subjects between 22 and 30 years of age, who smoked but were completely asymptomatic, were compared with 10 nonsmokers of the same age group using lung volumes, maximal expiratory flow rates, closing volumes, and maximal expiratory flow volume curves breathing air and a helium-oxygen mixture. Lower maximal mid-expiratory flow rates, higher closing volumes, and significant differences in flow volume curves with the helium-oxygen mixture were found in smokers. Special attention was given to the volume expressed as percentage of vital capacity at which the flows with air and the helium-oxygen mixture were equal for each subject ("equal-flow volume"). This volume was found to be significantly higher for smokers than nonsmokers. The authors offer explanations for these differences and suggest that smoking may alter compliance, as reflected by abnormal closing volumes, and resistance of the small airways as determined by differing responses in flow rates after helium-oxygen breathing at low volumes.

Adult↗
PubMed1988

Respiratory symptoms and the maximum expiratory flow-volume curve; a multivariate approach.

Information on the size and shape of about 8500 maximum expiratory flow-volume (MEFV) curves was related multivariately to respiratory symptoms to construct a sensitive measure of airflow limitation. The data were obtained in an epidemiological follow-up study of a normal population in The Netherlands. Using non-linear canonical correlation analysis, thirteen variables from each curve yielded two uncorrelated variates which were optimally related to two variates simultaneously derived from all respiratory data. Curves with different size and shape may yield the same probability for respiratory symptoms. In this context the scores of individuals on the scales of the two curve-derived variates do not have to be corrected for body or lung size. Using FEV1 and standing height about half as much of the variability in respiratory symptoms is explained as when using the whole MEFV-curve. Moreover, the distribution of the scores for the MEFV-curves allows the differentiation between three patterns of airflow limitation graphically. These three types suggest different pathophysiological mechanisms related to airways resistance and lung elastic recoil and may be used to characterize individual curves. One type relates to subjects with symptoms of 'asthma', one to airflow limitation as found among people with dyspnoea and elderly subjects and another to bronchitic symptoms. In females, the association of the MEFV-curve with 'asthma' is stronger than in males but much weaker with bronchitic symptoms. Curves found to be more related to 'asthma' or bronchitic symptoms, but not to dyspnoea, are more prevalent among current than among never smokers in males.

Adolescent↗
PubMedDate not supplied

[Asthma-tobacco interaction and alterations of maximal expiratory flow in air and in helium-oxygen (author's transl)].

The eventual interaction between tobacco and asthma and the sensitivity of different functional tests on small airways are compared in 4 groups of subjects (n = 49): non-smokers and control smokers, asthmatic non-smokers and smokers. All subjects have a normal vital capacity (VC) and a normal forced expiratory volume in one second (FEV1). The measurement of mid expiratory time (MET) and maximal flow at 50% (V Max 50) and at 25% (V Max 25) of the flow volume curve in air (FEMV) does not have any discriminating advantages over the simple measurement of the ratio FEV1/VC. The latter, although always normal, differentiates the controls from the asthmatic non-smokers. Besides, helium independency (characterized by an increase in the V Max 50 air-helium less than 20% and an increase of volume iso flow [V iso V] beyond 20% of VC) is mostly linked to tobacco addiction but is definitely worsened when associated to asthma.

Air↗
PubMedDate not supplied

Maximal expiratory flow-volume loop in a southern Indian college sportsmen.

Flow volume loops using computerised pulmonary function testing equipment were analysed in twenty sportsmen of Loyola College, Madras. There was no significant difference in mean P.E.F.R. (P greater than 0.2) and VE 25% (P greater than 0.2) in sportsmen, compared to Indian or American normals. On the other hand, the mean VE 50% (P less than 0.05) and VE 75% (P less than 0.001) were significantly higher in sportsmen compared to Indian values, but was similar to those reported in American normals (P greater than 0.1). Inspiratory flow rates were similar to those reported in Indians. Our results show that there is an increase in maximal expiratory flow rates at lower lung volumes in Southern Indian College Sportsmen compared to Indian normals.

Adult↗