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Results for “Maximal Expiratory Flow Rate”

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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

Spirometric reference values from a Mediterranean population.

Maximal expiratory flow-volume (MEFV) curves were measured in 1044 healthy nonsmoking volunteers living in the Barcelona area, as part of a larger interhospital project to obtain reference values of pulmonary function tests. Forced vital capacity (FVC), one-second forced expiratory volume (FEV1), FEV1/FVC, %, forced maximal mid-expiratory flow (FEF25-75%), peak expiratory flow rate (PEF) and maximal expiratory flow at 50 and 75% of FVC (MEF50% and MEF25% respectively) were obtained and expressed at BTPS conditions. Techniques and equipments followed both the recommendations of the American Thoracic Society (ATS) and of the European Community for Coal and Steel (ECCS). Prediction equations for age 20 through 70 were calculated for both sexes from a final sample composed of 870 adult subjects, 443 males and 427 females. Simple linear equations using height, age and body weight predicted all spirometric variables as well as more complex equations except MEF25%. Logarithmic equations were proposed for MEF25% to correct for the heteroscedasticity shown in a simple linear model. To our knowledge, this study provides reliable spirometric equations from a large urban Mediterranean sample which were lacking so far in the literature.

Adolescent↗

PubMed1998

Respiratory findings in synthetic textile workers.

We studied 308 female and 92 male textile workers employed in a factory that produced synthetic fiber hosiery. The mean age of the women was 38 years, their mean duration of employment 16 years. The mean age of the men was 39 years with a mean duration of employment of 16 years. A control group of 160 female and 78 male nonexposed workers was also studied. Chronic and acute work related symptoms were recorded for all workers. Ventilatory capacity was measured by recording maximum expiratory flow-volume (MEFV) curves from which the forced vital capacity (FVC), the 1-sec forced expiratory volume (FEV1) and maximum expiratory flow rates at 50% and the last 25% (FEF50, FEF75) were read. There was a higher prevalence of all chronic respiratory symptoms in exposed than in control workers, although the differences were statistically significant only for dyspnea, sinusitis, and nasal catarrh (P < 0.01) in female synthetic textile workers, and for nasal catarrh (P < 0.01) in male synthetic textile workers. Occupational asthma was recorded in 3 (0.9%) of the women textile workers, and in 1 (1.1%) of male textile workers. There was a high prevalence of acute symptoms during the work shift, which was greatest for cough (female: 46%; male: 59%), dryness of the throat (female: 49%; male: 40%), dryness of the nose (female: 53%; male: 43%) and eye irritation (female: 46%; male: 36%). Ventilatory capacity data among the synthetic textile workers demonstrated significantly decreased FEF75 compared to predicted (P < 0.05). Our data suggest that inhalation of dust in synthetic textile plants causes the respiratory impairment.

Adult↗

PubMed1996

Pulmonary function in Sardinian fire fighters.

Our study examined the respiratory function of 92 firemen whose main activity is fire fighting in forests and open country. Such fire fighting activities are to be considered a risk to the respiratory tract, taking into account studies already in the literature that have evaluated the nature and quantity of inhalable toxins present in activities of this kind. The control group was composed of 51 Carabinieri (policemen), who were asked to fill in a questionnaire about their work activities. Forced expiratory volume and flow, total lung capacity, respiratory volume, and the permeability of the alveolar-capillary barrier were measured. Firemen and Carabinieri (policemen) showed FVC rates higher than the European Community for Coal and Steel standards. The firemen showed a significant reduction in forced expiratory volume in 1 second (FEV1)[3.90 (0.50) vs. 4.04 (0.44); p < 0.05] and forced expiratory flow at 75% of forced vital capacity (FVC) (FEF75) [8.37 (4.11) vs. 8.38 (1.67) p < 0.05] and more markedly in the FEV 1/FVC relationship [80.07 (5.89) vs. 83.89 (1.67) p < 0.001] and in FEF50 [4.73 (1.34) vs. 5.54 (1.44) p < 0.01] and FEF25[1.58 (.47) vs. 1.99 (.69) p < 0.001]. There were no marked differences in air-blood exchanges. No correlation was found between respiratory function data and years of service or the number of fires extinguished during work experience.

Adult↗

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↗

PubMed2001

Comparison of normal infants and infants with cystic fibrosis using forced expiratory flows breathing air and heliox.

SUMMARY. The detection of early airway disease in infants with cystic fibrosis (CF) may lead to earlier intervention and an improved prognosis. We hypothesized that the ratio of maximal expiratory flows while breathing a mixture of helium and oxygen (heliox) and air, referred to as density dependence (DD), would identify early airway disease in infants with CF who have normal lung function. We also hypothesized that these infants with CF might be better differentiated from normal infants when the flows breathing heliox are compared instead of room air flows. We evaluated 10 infants with CF and 21 infants without CF and with normal lung function, defined as a forced vital capacity (FVC) and forced expiratory flows between 25-75% of expired volume (FEF(25-75)) of greater than 70% predicted (z-score > -2.0). Full forced expiratory maneuvers by the rapid thoracic compression technique were obtained while breathing room air and then heliox. Flow at 50% and 75% of expired volume (FEF(50), FEF(75)), FEF(25-75), and FVC were calculated from the flow volume curve with patients and control subjects breathing each gas mixture. The ratio of heliox to air flow at FEF(50) and FEF(75) was calculated (DD(50), DD(75)), and the point where the two flow-volume curves crossed (V(iso) V') was also measured. DD parameters did not distinguish the infants with CF from the infants without CF; length-adjusted FEF(50) breathing air was significantly lower in the infants with CF compared to the infants without CF (P < 0.05). Length-adjusted flows breathing heliox did not distinguish the two groups. We conclude that the lower FEF(50) value may reflect early airway obstruction in healthy infants with CF, and that measurements obtained with the less dense gas mixture did not improve detection of airway disease in this age group.

Air↗

PubMed1997

Urinary eosinophil protein X in relation to disease activity in childhood asthma.

The clinical use of urinary eosinophil protein X (U-EPX) measurements in monitoring inflammation in childhood asthma was investigated. U-EPX and pulmonary function were assessed in 80 children with bronchial asthma and 24 healthy, age-matched controls. In addition, 14 patients with asthma were re-examined after 1-2 months. U-EPX levels were increased in children with asthma compared with controls (median 68.4 vs 35.3 micrograms/mmol creatinine; P < 0.0001). In addition, U-EPX levels were higher in symptomatic than in asymptomatic patients (median 123.5 vs 48.9 micrograms/mmol creatinine; P < 0.0001) independent of treatment modalities (i.e., inhaled steroids or disodium cromoglycate) or atopy (median 65.1 vs 86.0 micrograms/mmol creatinine). Furthermore, U-EPX levels were significantly correlated with pulmonary function. During the follow-up period, changes in U-EPX values were significantly related to changes in pulmonary function. In conclusion, our findings demonstrate that eosinophil activation can be measured in urine in childhood asthma. Concentrations of U-EPX are related to disease activity and pulmonary function, as shown in both cross-sectional and longitudinal analyses, but are independent of atopy and treatment modalities. Measurement of U-EPX may be useful in assessing the inflammatory process and therefore in the management of childhood asthma.

Adolescent↗

PubMed1985

Measurement of reversibility of airways obstruction: which parameters to use?

Maximum expiratory flow-volume (MEFV) curves recorded before and after salbutamol inhalation on 100 patients with various lung diseases were studied. Improvement was found to occur more frequently in MEF50, FEF25-75, FVC and MEF25, than in FEV1, FEV1/FVC%, or MTT. If improvement in only one of the first four parameters was taken as a measure of reversibility of airways obstruction, many cases showing improvement in the others were missed. Improvement in any of the last three parameters was rarely missed if improvement in any of the first four was present. It was concluded that there is no single best measurement for assessment of bronchodilator response. FVC, FEF25-75, MEF50 and MEF25 should all be measured. A flow-volume record of forced expiration from which all these measurements can be derived would therefore be preferable for this purpose to the time-volume spirometer record from which only FVC and FEF25-75 can be determined.

Adolescent↗

PubMed1997

Short-term variations in oscillatory and spirometric lung function indices among school children.

The aim of this study was to compare immediate, daily and weekly variation in respiratory resistance measured by means of the forced oscillation technique (Rrs,FOT) to spirometric indices in 7-12 year old children with chronic respiratory symptoms. The lung function measurements were performed in 19 children on 4 days, i.e. two consecutive days during two consecutive weeks. On each day, the measurements were carried out at the same time of day and always repeated three times. In addition, Rrs,FOT and spirometric lung function indices were compared with an exercise challenge test in 12 children. Intrasubject coefficients of variation (CoVs) for Rrs,FOT were larger than those for spirometric indices. Only in the immediately repeated measurements was the CoV of maximal expiratory flow at 25% vital capacity larger than that of Rrs,FOT (16.6 vs 14.9%). At all time intervals, the smallest CoVs were observed in forced vital capacity (FVC) or in the ratio of forced expiratory volume in one second to FVC (2.0-2.6%). When excluding Rrs,FOT values which were not within 2 SD (0.11 kPa.L-1.s) of the differences between the immediately repeated measurements, the CoV of the immediately repeated measurements of Rrs,FOT was reduced to 9.1%, being smaller than that of maximal mid-expiratory flow (10.1%). However, even then the day-to-day variation in Rrs,FOT was clearly larger (16.0%) than those of the airflow indices at specified lung volumes (7.2-8.3%). This was also true for the weekly variation. In the exercise challenge test, there were larger changes in Rrs,FOT values than in the spirometric indices, but Rrs,FOT was the most sensitive index to detect changes in the respiratory system. In conclusion, the variation in Rrs,FOT values was larger than that of most spirometric indices. When a reliability index was applied, the immediate variation in Rrs,FOT values was comparable to those of the airflow indices at specified lung volumes. Rrs,FOT was also the most sensitive index in the exercise challenge test, and therefore it seems to be suitable for detection of short-term functional changes in the respiratory system. However, the relatively low repeatability of Rrs,FOT over days and weeks may limit its applicability to longer-term follow-ups.

Airway Resistance↗

PubMed1991

[Standards in evaluating the test of obstruction reversibility based on the flow-volume curves].

The study analyzed the changes in the shape of the flow-volume curve after fenoterol (Berotec) inhalation in school age healthy children. Significant increase of FEF25-75%, FEF50%, FEF25% values were seen. The authors demonstrated that bronchodilatation was not related to sex, height, weight and children's age, but it's value is indirectly proportional to the at-rest state of the airways. It seems, basing on results of this study, that FEV1 and FEF25-75% are the best indexes of dilatation tests. Increases of 10% and 30% are significant of bronchodilatation.

Adolescent↗

PubMedDate not supplied

Obstructive flow-volume loop contours after single lung transplantation.

The development of spirometric airflow obstruction may be a diagnostic dilemma in recipients of single lung allografts. The contribution of bronchial anastomotic stenosis to the observed spirometric obstruction may be clinically difficult to distinguish from that of obliterative bronchiolitis. Similarly, differentiating the "normal" obstructive defect after single lung transplantation for emphysema from obliterative bronchiolitis may be clinically challenging. We retrospectively reviewed the maximum inspiratory and expiratory flow-volume loop contours of lung transplant recipients with either obliterative bronchiolitis (n = 7) or bronchoscopically diagnosed severe bronchial anastomotic stenosis (n = 3). Five patients underwent single lung transplantation for obstructive native lung diseases and underwent observation before and after development of obliterative bronchiolitis. Bronchial anastomotic stenosis-maximum inspiratory and expiratory flow-volume loops were analyzed both before and after correction of stenosis by niobium: yttrium-aluminum-garnet laser photoresection or endobronchial silicone stent placement. Measures of airflow derived from maximum inspiratory and expiratory flow-volume loops, such as peak expiratory flow, peak inspiratory flow, forced expiratory flow at 50% vital capacity, forced inspiratory flow at 50% vital capacity, and forced expiratory volume in 1 second/peak expiratory flow ratio could not differentiate patients with bronchial anastomotic stenosis versus obliterative bronchiolitis. The most clinically useful index was the maximum inspiratory and expiratory flow-volume contour, which was characterized by terminal plateaus during exhalation and inhalation in patients with bronchial anastomotic stenosis. This index was reflected in a lower forced inspiratory flow at 75% vital capacity and forced inspiratory flow at 75% vital capacity/peak inspiratory flow ratio in bronchial anastomotic stenosis that increased after elimination of the anastomotic obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Obstruction↗

PubMed1988

Cough capacity in patients with muscular dystrophy.

Cough capacity was evaluated in 22 patients with muscular dystrophy (MD) using subjective cough assessment, cough flow-volume curves, maximum expiratory pressures (MEP), forced vital capacity (FVC), and peak expiratory flow rates (PEFR). In ten of the 22 patients transients of peak flow were generated during cough flow-volume maneuvers, indicating dynamic compression of the airways, which is considered important in the physiology of an efficient cough. Patients who could not generate peak flow transients had significantly reduced PEFR, FVC, and MEP values. Measurement of MEP was the most sensitive predictor of flow transient production during coughing; all of the patients who exhibited transients had MEP values of above 60 cmH2O, whereas the highest value of MEP recorded in patients without transients was 45 cmH2O. Three of the 12 patients who were unable to generate flow transients were considered to have an adequate cough by subjective assessment. We concluded that the measurement of MEP is extremely useful for assessment of cough strength in patients with MD.

Adolescent↗

PubMed1996

Comparison of respiratory inductance plethysmography with thoracoabdominal compression in bronchial challenges in infants and young children.

Respiratory inductance plethysmography measuring thoracoabdominal asynchrony (TAA) has been claimed to be a useful tool for measuring changes in airway resistance in infants. In this study we evaluated the response to methacholine by thoracoabdominal compression and respiratory inductance plethysmography. Seventeen infants (mean age, 13.1 +/- 4.7 mo) with recurrent episodes of cough or wheeze underwent bronchial challenge with inhaled methacholine. Lung function was evaluated by measuring maximal expiratory flow at resting lung volume (VmaxFRC), and the degree of TAA was measured by phase angle (theta). Methacholine was inhaled for 1 min during tidal breathing using increasing doubling concentrations until a fall of at least 40% in VmaxFRC was achieved (final concentration). All infants responded to the final concentration of methacholine by a significant fall in VmaxFRC (from 31 +/- 10 to 12 +/- 5 ml/s/kg, p < 0.001). All but one infant responded to methacholine at the final concentration with a significant increase in phase angle (median theta increased from 11.7 to 31.7 degrees, p < 0.001). In two other infants there was an early response in theta compared with the response in VmaxFRC. Phase angle increase after methacholine was expressed as Z-scores (the difference between postmethacholine theta and postbuffer theta divided by the standard deviation of postbuffer theta). An increase of at least 2.0 Z-scores in theta was observed at the same concentration of methacholine when VmaxFRC fell by at least 40% in 15 of the 17 infants (88%). We conclude that respiratory inductance plethysmography is a sensitive method to measure bronchial reactivity to methacholine in most of the infants studied (14 of 17, 82%). A concentration of methacholine causing an increase in theta of at least 2.0 standard deviations above baseline is equivalent to the concentration causing a 40% fall in VmaxFRC.

Airway Resistance↗

PubMed1994

Inhaled platelet-activating factor increases airway sensitivity but not maximal airway narrowing to methacholine in normal subjects.

To examine the effect of inhaled platelet-activating factor (PAF) on airway sensitivity and on maximal airway narrowing, we measured airway response to doubling concentrations of methacholine (MCh) 48 h before and 48 h after inhalation of 10, 50 and 100 micrograms of PAF in six nonatopic, nonasthmatic subjects. The forced expiratory volume in one second (FEV1) and airflow at 30 percent of vital capacity (V30) from partial forced expiration were used to assess changes in airway calibre. Inhalation of PAF caused only minor changes in FEV1. In contrast, inhalation of 100 micrograms of PAF caused a significant fall in V30 from 2.64 +/- 0.35 to 1.35 +/- 0.43 l.min-1 (p < 0.05). Two days after PAF inhalation a leftward shift of the concentration-response curve to MCh was observed. The MCh concentration causing a 20% fall in FEV1 (PC20FEV1) was 11.25 +/- 1.78 and 2.38 +/- 1.29 mg.ml-1 (geometric mean +/- GSEM; p < 0.05) before and after PAF inhalation, respectively. PAF did not affect the maximal airway response to MCh. The maximum percentage fall in FEV1 was 36.2 +/- 1.9% at baseline and 37.6 +/- 1.8% after PAF inhalation. Likewise, maximum percentage change in V30 was 72.8 +/- 3.7% at baseline and 73.6 +/- 3.4% after PAF inhalation. The results of this study show that PAF inhalation increases airway sensitivity without altering the maximal bronchoconstrictive response to MCh in normal subjects.

Administration, Inhalation↗

PubMed1997

[Forced expiration. Various current concepts, 50 years after Robert Tiffeneau].

One hundred and fifty years after the original description of spirometry by Hutchinson and 50 years after the definition of his famous ratio by Tiffeneau, a certain number of physiological advances have enabled a better understanding of the determinants of the forced expired manoeuvre and to mitigate some of its inconveniences. This review focuses on three of these advances. The first is the influence of an inspiratory manoeuvre which precedes a forced expiration, on the expiratory flow. This influence is probably a consequence of viscoelastic phenomena and impose some strains on standardisation in current practice. The second is the possibility of detecting in a reproducible and simple fashion, without the need for co-operation on the part of the subject, a limitation in expiratory flow by the application of a negative expiratory pressure at the opening of the airways (NEP for negative expiratory pressure). The third is the possibility to verify in a simple fashion the quality of the expiratory performance achieved by the patient and thus to detect an insufficient effort in the force of a falling expiratory flow.

Dyspnea↗

PubMed1976

Effect of wool dust on respiratory function.

A group of 252 workers (176 women and 76 men) employed in two wool mills was studied. The mean age of 36 years; mean exposure, 11 years. All women were nonsmokers, and 47 per cent of the men were regular smokers. Ventilatory function was measured by recording maximal expiratory flow-volume curves and forced expiratory volume in 1 sec on the first working day of the week (Monday) before and after the work shift. On maximal expiratory flow-volume curves the flow rates at 50 per cent of the control vital capacity were read. Workers exposed to wool dust for more than 10 years had a higher prevalence of chronic respiratory symptoms than did those with less than 10 years' exposure, but the difference was not significant. Significant reductions during the work shift were found in maximal expiratory flow rates at 50 per cent of the control vital capapity and 1-sec forced expiratory volume, the first test being considerably more sensitive. Workers exposed to wool dust for more than 10 years had signficantly lower than predicted pre-shift values for maximal expiratory flow rates at 50 per cent of the control vital capapcity. Inhalation of wool dust extract caused a significant decrease of maximal expiratory flow rates at 40 per cent of the control vital capacity on partial expiratory flow-volume curves during the 100 min after exposure. Comparison with the same concentration of cotton dust extract revealed a similar effect during the first 40 min after exposure but a significantly larger effect of the cotton dust extract after 40 min. The data suggest that preventive measures, especially medical supervision, are necessary in wool-processing mills to protect workers sensitive to dust.

Adult↗

PubMed1986

Selection of effective maximal expiratory parameters to differentiate asthmatic patients from healthy adults by discriminant analysis using all possible selection procedure.

Maximal expiratory volume-time and flow-volume (MEVT and MEFV) curves were drawn for young male nonsmoking healthy adults and for young male nonsmoking asthmatic patients. Eleven parameters, two MEVT (%FVC and FEV1.0%), six MEFV (PFR, V75, V50, V25, V10 and V50/V25), and three MTC parameters (MTC75-50, MTC50-25 and MTC25-RV) were used for the multivariate analysis. The multivariate analysis in this study consisted of correlation coefficient matrix computation, the test for mean values in the multivariates, and the linear discriminant analysis using the all possible selection procedure (APSP). Correlation coefficients among flow rate parameters and flow rate related parameters in high lung volumes were different between the two groups. In the eleven-parameter discriminant analysis by APSP using single parameters, PFR, V75 (flow rate at 75% of forced vital capacity), and FEV1.0% were considered to be the effective parameters. In the seven-parameter discriminant analysis using the parameter groups, the group of all parameters and the %FVC and flow rate-related parameter group were considered to be the effective numerical alternatives to MEFV curves discriminating between healthy adults and asthmatic patients.

Adult↗

PubMed1980

Evaluation of pulmonary mechanics in guinea pigs during respiratory anaphylaxis.

Guinea pigs sensitized to ovalbumin exhibit signs of respiratory impairment when exposed to an aerosol of the antigen. This response was investigated in anesthetized guinea pigs by determining forced pulmonary mechanics to derive peak expiratory flow rate, forced vital capacity, forced expiratory volume in 0.1 sec, maximal mid-expiratory flow rate and respiratory rate. Measurement of these parameters allows qualitative comparisons to be made with changes that are routinely determined during investigations of human asthma. Exposure of anesthetized guinea pigs to a 3% ovalbumin aerosol for 2 min produced an increase in respiratory rate, a 20% fall in peak expiratory flow rate and maximal mid-expiratory flow rate, a 50% fall in forced vital capacity and a 40% fall in forced expiratory volume in 0.1 sec. This response was reversed by aminophylline. In these respects the response appears to be similar to the acute asthmatic response in humans.

Aminophylline↗