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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↗
PubMed1980

[Scale of normal values of peak expiratory output in healthy children and adolescents based on flow-volume curves (author's transl)].

The authors present scales of reference theoretical values for children and peak expiratory output (V 50 and V 25), as well as FEV1 and vital capacity obtained by flow-volume curves. After a description of the equipment (adaptable to on-the-spot epidemiological studies), the reference population (537 children, male and female, 6-16 years old), and the method of curve applications, the statistical basis for devising the scale was analyzed. Under study were the following topics: assuming an exponential regression model, advantages of the consideration of two reference parameters (age and size), or of one (size), which was the solution adopted finally to construct the scale. The comparison of our work with that described in the literature for groups of children with widely diversified origins points out the differences in certain functional parameters themselves. Thus, the interest of establishing scales for an epidemiological program based on populations with features as close as possible to those of the groups under study is justified.

Adolescent↗
PubMed2001

Effect of salbutamol on lung function parameters of healthy children.

UNLABELLED: In the present study, the effect of 200 microg salbutamol compared to placebo was evaluated on lung function parameters of 37 healthy children aged 7-14 years. Salbutamol or placebo were administered, using a single blind study design, and spirometry was performed before and after 10 min of inhalation. At the time of the study, all children were symptom-free and had not suffered from any respiratory infection during the previous 4 weeks. The administration of salbutamol resulted in a significant increase of mean forced expiratory volume in 1 s (111%-115%, P<0.05), maximal expiratory flow at 50% of forced vital capacity (101%-110%, P<0.05) and maximal expiratory flow at 25 % of forced vital capacity (96%-115%, P<0.05). The administration of placebo resulted in no significant change in lung function parameters. CONCLUSION: The administration of 200 microg salbutamol results in the occurrence of a small but significant bronchodilation in healthy, non-asthmatic children.

Adolescent↗
PubMed1984

Characterization of the late response in exercise-induced asthma.

Nine young adult subjects who developed asthma after a standard treadmill exercise test were studied. Pulmonary function tests were performed before and after exercise and serially for at least 6 hr afterwards. The subjects performed pulmonary function tests while breathing room air and after breathing an oxygen-helium mixture with each test. Although pulmonary function returned to normal within 3 hr after exercising in all subjects, eight of the nine had late asthmatic reactions 3 to 5 hr afterward. In general the late response was less severe than the initial response. Two subjects, however, noticed clinical asthma. In the immediate response, eight of the nine subjects were helium "responders," suggesting that the immediate response involved both large and small airways. In the late response, seven of eight subjects were helium "nonresponders," suggesting that the late response occurred primarily in small airways.

Adult↗
PubMed1990

Peak flow measurement as a screening test for restrictive pulmonary disorders.

We tested whether measurement of peak flow was useful in determining the presence and severity of restrictive pulmonary disorders in addition to its recognized use in the diagnosis and management of airflow obstruction. In 102 patients with various causes of restriction of lung volumes, we found that peak expiratory flow correlated well with forced vital capacity. As a diagnostic test it was useful in restrictive disorders, except in fibrosing alveolitis where it consistently failed to detect abnormality.

Forced Expiratory Flow Rates↗
PubMed1999

Ventilatory function of healthy, urban, non smoking, Pakistani young adults aged 18-24 years.

Age may have a different contribution to normal lung function values in those aged less than 25 years, as compared to older individuals. We report regression equations predicting ventilatory parameters in this age group, as none have been reported from Pakistan. The study was conducted on students of King Edward Medical College Lahore, Pakistan. Participants had never smoked and reported no respiratory symptoms. In addition to anthropometric data, forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and forced expiratory flow at 50% of FVC (FEF50) were measured. Equations predicting normal values of these parameters were derived using SPSS (Chicago, Illinois, U.S.A.) P < or = 0.05 was treated as statistically significant. Of the students, 519 took part in the study. All four parameters correlated significantly (P < 0.001) and positively with height. FEF50 had a negative correlation with age in both sexes (P < 0.05). The correlation of other parameters with age was variable and not statistically significant. On multiple regression, height featured as an independent predictor in equations for all parameters. The contribution of age as an independent predictor of ventilatory function was, once again, variable. Independent variables were retained in the raw form as their transformation did not improve the goodness of fit of the derived equations. Only height and age emerged as independent predictors of ventilatory function. Values derived from the equations presented in this study were less than those for height and age matched white Caucasians. Such differences were greater than the 'Asian correction factors'.

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

[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↗
PubMed1993

An algorithm for measurement of expiratory flow rate parameters on the partial expiratory flow-volume curve.

Partial expiratory flow-volume (PEFV) curves are a useful tool in airway challenge studies, but unlike the maximal expiratory flow-volume (MEFV) curve, lung function parameters require manual calculation from the flow-volume tracing. We describe an algorithm written in QuickBASIC that analyzes a PEFV curve superimposed on a MEFV curve by (1) identifying the PEFV curve, (2) locating the maximal expiratory flow at the point on the PEFV curve that corresponds to 60% of the baseline forced vital capacity (FVC) below total lung capacity (TLC), termed MEF40%(P), and (3) identifying the size of the PEFV curve along the TLC axis. A report of these parameters is also provided. This algorithm was validated using flow-volume curves from a clinical study in which eight subjects performed two sets of MEFV and PEFV curves separated by approximately 1 hr. Paired comparison of MEF40%(P) determined by the algorithm and two independent manual calculations correlated strongly and yielded no statistically significant differences between the two methods. We conclude that this algorithm provides rapid and accurate determinations of PEFV parameters.

Algorithms↗
PubMedDate not supplied

Pulmonary function studies in healthy non-smoking women of Calcutta.

Pulmonary function measurements were made in 230 healthy non-smoking women from Calcutta with an age range of 20-59 years. The tests consisted of vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory volume in one second as a percentage of forced vital capacity (FEV1%), forced expiratory time (FET), maximum voluntary ventilation, uncontrolled frequency (MVVF), forced expiratory flow (FEF200-1200ml), forced mid-expiratory flow (FEF25-75%), forced end-expiratory flow (FEF75-80%) and peak expiratory flow rate (PEFR). Except for PEFR, all the measurements were made with the help of two 9-litre closed-circuit-type expirographs using standard spirometric techniques. PEFR was recorded with the help of two Wright peak flow meters. Prediction formulae were derived on the basis of physical characteristics. Age and height were found to be the significant predictor variables for VC, FVC and FEV1, while only age was significant for FEV1%. The FVC and FEV1 values of the subjects, standardized for age and height, are much lower than those of Americans, Europeans and Jordanians. On comparison with data reported from other parts of India, it was revealed that the VC and FEV1 values of the current study, after adjustment for age and height, were much higher than those of Southern Indians but comparable with those of North-Western Indians.

Adult↗
PubMed1996

Effect of pattern of preceding inspiration on FEV1 in asthmatic children.

In adults, both peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1) are significantly influenced by the time course of the inspiration preceding the forced expiration. The aim of this study was to evaluate the effects of three different inspiratory manoeuvres on PEF, FEV1, and forced vital capacity (FVC) in asthmatic children. Twenty five symptomless asthmatic children performed forced expiration preceded by three different inspiratory manoeuvres, which consisted of: a rapid inspiration with a 2 s end-inspiratory breathhold (Manoeuvre No. 1); a rapid inspiration without an end-inspiratory breathhold (Manoeuvre No. 2); and a slow inspiration lasting about 5 s with an end-inspiratory breathhold of at least 4 s (Manoeuvre No. 3). All manoeuvres were performed in a randomly assigned sequence each morning for three consecutive days. In each session, the manoeuvres were repeated three times and the highest value was chosen. Both FVC and FEV1 obtained with Manoeuvre No. 3 were significantly lower than the corresponding values obtained with Manoeuvre Nos. 1 and 2. The mean (SD) FVC values were 2.76 (0.66) L with Manoeuvre No. 1, 2.67 (0.58) L with Manoeuvre No. 2 and 2.52 (0.52) L with Manoeuvre No. 3. The corresponding values of FEV1 were 2.25 (0.53), 2.22 (0.53) and 2.07 (0.44) L, respectively. By contrast, the values of PEF, obtained with a portable peak flow meter, were similar with the three different inspiratory manoeuvres. The results of this study show that in symptomless asthmatic children the preceding inspiratory manoeuvre may influence forced vital capacity and forced expiratory volume in one second. Hence, in order to reduce variability due to interference by physiological factors and so improve reproducibility of pulmonary function tests, the inspiratory manoeuvres must be accurately standardized.

Asthma↗
PubMed1992

Frequency and correlates of the saw-tooth pattern of flow-volume curves in an epidemiological survey.

The object of this report was to assess the possibility of identifying saw-tooth patterns on flow-volume curves in men aged 28 to 58 years. We studied the frequency of these patterns and their relationships with two indirect signs of UAO increase in FEV1/PEF and FEF50%/FIF50% ratios--as well as with clinical and functional data. Twenty-six of the 360 subjects surveyed, ie, 7.2 percent, had flow oscillations in the inspiratory and/or expiratory part of flow-volume curves, corresponding to the definition of the saw-tooth pattern. We observed significant relationships between the saw-tooth pattern and the mean FEV1/PEF ratio. In 97 subjects, the proportion of those with saw-tooth patterns was 13.4 percent, and the mean FEF50%/FIF50% ratio was 1.53 in those with the pattern vs 1.07 in those without it. These results show that the saw-tooth pattern was not rare in these men.

Adult↗