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Results for “Maximal Midexpiratory Flow Rate”

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PubMed1979

An assessment of cardiorespiratory adjustments of asthmatic adults to exercise.

The cardiorespiratory adjustments of asthmatic adults to submaximal and maximal workloads were investigated. Cardiorespiratory variables were measured every 2 min during exercise and at the end of maximal physical effort. Exercise-induced asthma (EIA) occurred in all asthmatic subjects while normal subjects maintained normal spirometry. The results suggest that asthmatic adults have no cardiac reserve or oxygen delivery limitations. They work under less efficient ventilatory conditions at submaximal workloads and have a significantly lower functional work capacity. The high degree of correlation between preexercise maximal midexpiratory flow rate (MMF) and maximum O2 consumption (max Vo2) suggests that the smaller airways contribute significantly to the observed abnormalities. We recommend that evaluation of antiasthmatic medications in exercise-induced asthma should take into consideration their effect upon smaller airways and cardiorespiratory variables.

Adult↗

PubMed1992

Five cross-sectional studies of grain elevator workers.

Five cross-sectional studies were conducted on grain workers in all the terminal elevators in British Columbia, Canada, at 3-year intervals from 1976 to 1988. Civic workers were studied in the same manner as a referent group. The studies consisted of questionnaires, spirometry using the same spirometers, allergy skin tests, and measurement of dust concentration by personal sampling. Although the dust concentration in the elevators was reduced progressively over the years, grain workers had more respiratory symptoms and lower lung function compared with the civic workers in each of the five cross-sectional studies. Exposure to grain dust was associated with significant reduction in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) but not in maximal midexpiratory flow rate or FEV1/FVC, suggesting reduction in volume which may be due to lesions in the lung parenchyma or in the small airways. Cigarette smoking was associated with significant reduction in FEV1, maximal midexpiratory flow rate, and FEV1/FVC due to airflow obstruction, but had no influence on FVC. Workers who took part in all five surveys tended to be a "healthier" selected group, but the grain workers still had lower lung function compared with the civic workers. This study confirmed previous findings that grain dust has adverse effects on the lungs. Cross-sectional study of the grain elevator workers proved to be a consistent and useful method to evaluate occupational health hazards.

Adult↗

PubMed1976

Comparison of an electronic spirometer with a pediatric Wright Peak Flow Meter and their relationship to clinical symptomatology in asthmatic children.

To evaluate the correlations between the Wright Peak Flow Meter and an Electronic Spirometer with clinical symptomatology in chronic asthmatic chidlren, objective measurements of Peak Flow (PF) on both electronic (Vanguard Electric Spirometer) and mechanical (Wright Peak Flow Meter) Spirometers, Forced Vital Capacity (FVC), Forced, Expiratory Volune 1/2 second (FEV 0.5), Forced Expiratory Volume 1/2 per cent (FEV 0.5%), AND Maximal Midexpiratory Flow Rate (MMEFR) were obtained. Subjective observations of clinical wheezing were recorded immediately before each flow rate by trained nurses. PF determinations of both the mechanical and electronic spirometers were in close agreement. PF on the electronic spirometer correlated best with clinical wheezing in this study. The MMEFR calculated from the electronically produced graphys had the nex best coefficient of corelation. These were followed by the PF measured mechanically on the WPFM.

Adolescent↗

PubMed1984

Upper respiratory tract infections and airway reactivity in normal and asthmatic subjects.

To assess the effect of an upper respiratory tract infection (URTI) on airway reactivity, histamine inhalation tests (HITs) were performed prospectively in 44 nonsmoking asthmatic (14) and nonasthmatic (30) volunteers. Fifteen of the subjects developed an URTI during the following 4 months. Pulmonary function-forced expiratory volume in one second (FEV1), maximal midexpiratory flow rates (MMEFR) and maximal flow at 50% vital capacity (V50), and HITs, were studied at onset and 2, 3, and 4 wk after infection. There were no significant changes in pulmonary function during the total study period. For the 15 subjects, the mean provocative concentration of histamine causing a 20% fall in FEV1, (PC20H) was 8.73 mg/ml prior to onset of URTI, and at 1, 2, 3, and 4 wk after URTI was 7.97, 8.68, 8.13, and 8.61 mg/ml. These were not significantly different for the group as a whole, nor for the subgroups of asthmatics and nonasthmatics. Small changes in PC20H outside the normal range of variability occurred in 5 of 15 subjects. These were short-lived and no predictive factor for change in PC20H was identified in this group. Thus, URTI was not associated with significant changes in PC20H in this group of asthmatic and nonasthmatic subjects.

Adult↗

PubMed1988

Environmental exposure to tobacco smoke and lung function in young adults.

The relationship between lung function and environmental exposure to tobacco smoke (passive smoking) was studied in 293 nonsmoking young men and women, 15 to 35 yr of age. A self-administered mailed questionnaire was used to assess the lifetime environmental exposure to cigarette smoke at home and at work for each subject. Lung function information used here had been gathered in the course of a previous study of the determinants of lung function in early adulthood. In men, maximal midexpiratory flow rate (FEF25-75) decreased in relation to an index of cumulative lifetime environmental exposure to tobacco smoke at home, after taking into account the effects of cumulative exposure at work as well as age, height, body size, respiratory pressures, and cooking fuels used at home. The components of this exposure index most closely related to the reduction in FEF25-75 were maternal smoking habits and exposure to second-hand smoke during childhood. In women, the diffusing capacity of the lung (DLCO) decreased in relation to cumulative exposure to tobacco smoke at work, after accounting for the effects of cumulative lifetime exposure at home and the other factors mentioned above. These findings contribute to the gathering evidence that environmental exposure to tobacco smoke is harmful to respiratory health, and suggest that the effects are not insignificant. For instance, the FEF25-75 of a young man 20 yr of age who had never smoked and always lived at home would be 800 ml less if both his parents smoked than if they did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1980

Lung growth and airway function after lobectomy in infancy for congenital lobar emphysema.

To characterize the outcome of lobectomy in infancy and the low expiratory flows which persist after lobectomy for congenital lobar emphysema, 15 subjects with this history were studied at age 8-30 yr. Total lung capacity was normal in all, but higher values (P < 0.05) were observed in nine subjects with upper lobectomy than in five subjects with right middle lobectomy. Ratio of residual volume to total lung capacity was correlated (P < 0.05) with the amount of lung missing as estimated from normal relative weights of the respective lobes. Xe(133) radiospirometry in eight subjects showed that the operated and unoperated sides had nearly equal volumes at total lung capacity, but that the operated side was larger than the unoperated side at residual volume. Perfusion was equally distributed between the two sides. Similar findings were detected radiographically in four other subjects. Forced expiratory volume in 1 s and maximal midexpiratory flow rate averaged 72 and 45% of predicted, respectively. Low values of specific airway conductance and normal density dependence of maximal flows in 12 subjects suggested that obstruction was not limited to peripheral airways. Pathologic observations at the time of surgery and morphometry of the resected lobes were not correlated with any test of pulmonary function. These data show that lung volume can be completely recovered after lobectomy for congenital lobar emphysema in infancy. The volume increase occurs on the operated side, and probably represents tissue growth rather than simple distension. The response to resection is influenced by the particular lobe resected and may be associated with decreased lung recoil near residual volume. Low expiratory flows in these subjects could be explained by several mechanisms, among which a disproportion between airway and parenchymal growth in infancy (dysanaptic growth) is most compatible with our data.

Adolescent↗

PubMed1997

Evaluation of supported upper limb exercise capacity in patients with cystic fibrosis.

Physiological responses to upper limb exercise have not been well documented in patients with cystic fibrosis (CF). This is the first study to quantify ventilatory responses to supported incremental upper limb exercise in this patient group. Twenty-four subjects with CF, with a wide range of pulmonary impairment, and ten normal control subjects were studied. Subjects performed pulmonary function tests and incremental arm and leg exercise to peak work capacity on an arm crank and bicycle ergometer. All subjects performed less work with the arms than legs. At an equivalent oxygen consumption, ventilation was higher for arm work than leg work. This higher ventilation was achieved mainly through a higher frequency of breathing. Only CF subjects with severe pulmonary impairment (FEV1 < 40% predicted, FEF25-75% < 20% predicted) had a reduced arm work capacity compared with control subjects. At peak arm work, these subjects had a mean ventilation to maximum voluntary ventilation ratio (VE/MVV) of 106% +/- 25, while maximum heart rate was less than 80% predicted. Despite the high ventilatory requirement for arm exercise, arm work capacity was well maintained in subjects with CF until severe lung disease impaired the ability to further increase ventilation.

Adolescent↗

PubMed1980

Effectiveness of a portable face mask in attenuating exercise-induced asthma.

Recent investigations have demonstrated that exercise-induced asthma (EIA) can be prevented by inspiration of warm, fully humidified air during exercise. We evaluated the success of a surgical face mask, used to retain warm, humidified, expired air, in preventing EIA in ten asthmatic children. subjects underwent six minutes of exercise on a treadmill during two sessions, in one session breathing room air and in another wearing a mask covering the nose and mouth. On the control day, average group forced expiratory volume in 1 s (FEV1) and maximal midexpiratory flow rate (MMEF) decreased from the preexercise baseline value to 66% and 47% of baseline, respectively, at six minutes; on the mask day, FEV1 and MMEF were 91% and 82% of the baseline values (increased in all subjects). A simple face mask may be an inexpensive, nonpharmacologic alternative for alleviation of EIA.

Adolescent↗

PubMed1982

Analysis of antigen-induced changes in pulmonary mechanics in sensitized inbred rats.

An inbred line of rats was derived which develop marked and consistent dyspnea following sensitization and then exposure to aerosolized antigen. This pulmonary response was investigated in detail by determining forced pulmonary mechanics to derive respiratory rate, peak expiratory flow rate (PEFR), forced vital capacity (FVC), forced expiratory volume in 0.1 s (FEV0.1), and maximal midexpiratory flow rate (MMFR). Challenging anesthetized rats for 5 min with an aerosol of 3% egg albumin produced minimal change in respiratory rate, a 20% fall in PEFR, a 50% fall in FVC, and a 30% decrease in FEV0.1 and MMFR. The response could be inhibited or reversed by salbutamol (0.5 mg/kg, i.v.) and aminophylline (25 mg/kg, i.v.) administered either before or after challenge. The pulmonary changes are consistent with antigen-induced asthma in the rats. The response shows similarities to human asthma and may provide a relevant experimental model.

Albuterol↗

PubMed1984

Respiratory response to formaldehyde and off-gas of urea formaldehyde foam insulation.

In 18 subjects, 9 of whom had previously complained of various nonrespiratory adverse effects from the urea formaldehyde foam insulation (UFFI) in their homes, pulmonary function was assessed before and after exposure in a laboratory. On separate occasions formaldehyde, 1 part per million (ppm), and UFFI off-gas yielding a formaldehyde concentration of 1.2 ppm, were delivered to each subject in an environmental chamber for 90 minutes and a fume hood for 30 minutes respectively. None of the measures of pulmonary function used (forced vital capacity, forced expiratory volume in 1 second or maximal midexpiratory flow rate) showed any clinically or statistically significant response to the exposure either immediately after or 8 hours after its beginning. There were no statistically significant differences between the responses of the group that had previously complained of adverse effects and of the group that had not. There was no evidence that either formaldehyde or UFFI off-gas operates as a lower airway allergen or important bronchospastic irritant in this heterogeneous population.

Allergens↗

PubMed1982

Are the small airways really quiet?

The results of recent epidemiological studies and of functional-pathological correlations suggest that morphologic alterations, specifically inflammatory lesions, of the peripheral airways (with an interval diameter of 2 mm or less) influences the values of FEV1, of the FEV1/VC ratio and of the maximal midexpiratory flow rate, also in the incipient stages of these lesions. Between the so-called tests of small airways obstruction and FEV1 there would only be a difference in sensitivity. This implies that the small airways are not as silent as postulated previously. This is corroborated by measurements of resistance of peripheral airways performed on excised human lungs, showing that with normal lungs as well as in cases of airways obstruction, the peripheral resistance constitutes 50 to 90% of the total resistance between the main bronchus and the pleura.

Airway Resistance↗

PubMed1991

Silicosis, chronic airflow limitation, and chronic bronchitis in South African gold miners.

In a cross-sectional study of a working population of black South African gold miners, 1,197 men were studied with respiratory and occupational questionnaires, lung function tests, and chest radiographs. The study was designed to examine the effects of silicosis on respiratory symptoms and lung function. A total of 857 men with chronic, simple silicosis and 340 men without silicosis were included in the sample. Other determinants of lung disease including the duration and intensity of underground dust exposure and tobacco smoking were also examined. Three distinct pulmonary disorders could be discerned: silicosis-associated pulmonary dysfunction with dyspnea on effort; chronic airflow limitation, which was related to the duration of underground exposure; and a chronic bronchitic symptom complex, which reflected the intensity of dust exposure in the workplace. Chronic, uncomplicated silicosis was found to be associated with significant loss of lung function, and all of the measured indices, FVC, FEV1, FEV1/FVC%, maximal midexpiratory flow rate (MMEF), and lung diffusion for carbon monoxide measured by the single-breath method (DLCO) were reduced. When comparing men with Category 3/3 nodule profusion with men without silicosis, reductions of FVC of 351 ml, FEV1 of 447 ml, MMEF of 1.04 L/s, and DLCO of 4.7 ml/min/mm Hg (p = 0.0001) were detected after controlling for age, height, the direct effects of the underground environment, and tobacco smoking. Dyspnea on effort was more common in the men with silicosis (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2006

Same efficacies of ipratropium and salbutamol in reversing methacholine-induced bronchoconstriction.

Efficacy of salbutamol (S) was compared to that of ipratropium (I) or to their association, after methacholine challenge testing (MCT). MCT was performed in 4 groups of 10 patients suspected to suffer from asthma; mean changes in FEV1, maximal midexpiratory flow rate (MMFR), and airway resistance (Raw) were the same in all groups. After MCT, the group 1 patients inhaled S and then I, 10 min later; both drugs were given in the reverse order to the group 2 patients. The group 3 patients inhaled a mixture of both drugs just after MCT; the group 4 patients were not given any bronchodilator till the 20th min after MCT, when they inhaled S. Short-term (10 min) bronchodilator effects of S, I or S + I on spirometric variables were of the same magnitude and Raw returned to its baseline value. Further improvement (10-20 min) in FEV1 was mainly due to spontaneous recovery, whereas further increase in MMFR was due also to bronchodilator actions of drugs. It is concluded that ipratropium could be proposed as an alternative bronchodilator to salbutamol after MCT.

Adult↗

PubMed1997

Effects of obesity and fat distribution on ventilatory function: the normative aging study.

OBJECTIVE: Although the influence of obesity on ventilatory function has long been recognized, the nature of the relationship and the mechanisms are not yet clear. The purpose of this report was to examine the effects of overall obesity and fat distribution on ventilatory function. METHODS: Multiple measurements over > 30 years from 507 subjects with lifelong tobacco consumption of < or = 1 pack-year were analyzed separately in five age decades from 30 to 79 years. FVC, FEV1, ratio of FEV1 to FVC, and maximal midexpiratory flow rate (MMEF) were each adjusted for age and stature. Relative adiposity (or obesity) was assessed using the body mass index (BMI). Subscapular skinfold thickness, abdominal girth, and the ratio of abdominal girth to hip breadth (AG/HB) were used as measures of body fat distribution. Multiple linear regression was used to explore the effects of overall adiposity and body fat distribution on ventilatory function. RESULTS: BMI was positively associated with the ratio of FEV1 to FVC at all ages (p < 0.01), and negatively with FVC and MMEF between 40 and 69 years (p < 0.01). After adjustment for BMI, subscapular skinfold thickness was negatively associated with both FVC and FEV1 (p < or = 0.02) among men aged 30 to 59 years, whereas AG/HB was negatively associated with FVC and FEV1 in men aged 50 to 59 years only (p < or = 0.0004). CONCLUSIONS: Body fat distribution has independent effects on ventilatory function after adjustment for overall obesity in men. The finding that age modifies this association has implications for future research.

Adipose Tissue↗

PubMed1977

Effects of dry and humid climates on exercise-induced asthma in children and preadolescents.

Among factors which possibly influence the responses of asthmatic children to exercise, climate has received little attention. This study was performed to determine whether the level of air humidity is a factor to be considered. Twenty asthmatic (extrinsic perennial) girls and boys, 6 to 14 yr of age, with unverified history of exercise-induced asthma (EIA) took part. They rested and exercised in a climatic chamber in dry (25% relative humidity) and humid (90%) sessions at 25 degrees to 26 degrees C. One to three weeks separated the sessions, the order of which was counterbalanced. No changes in pulmonary functions (FVC, FEV 1.0, MMEF, MBC) were found following a sitting period of 60 min in either climate. Five and ten minutes following the treadmill run, however, bronchoconstriction was distinctly more pronounced in the dry than in the humid climate. Exercise heart rate and the subjective rating of effort were not affected by climate. It was concluded that, under the above experimental conditions, EIA is more likely in dry air than in humid air, possibly due to heat loss at the airway mucosa caused by evaporation. High humidity of inspired air could be the reason why EIA is less prevalent in swimming, as compared with other modes of exercise.

Adolescent↗

PubMed1993

Pulmonary function parameters, arterial blood gases and flow volume curves of dental technicians.

Dental technicians working in laboratories are exposed to different doses of various dusts. Disorders of pulmonary function may occur before radiographic changes are evident. If these pulmonary function disorders are found at an early stage, the risk may be reduced by early, adequate local ventilation and by appropriate individual protective methods. Unless adequate preventive measures are taken, pulmonary disorders will increase, finally leading to obstructive or restrictive ventilatory disorders, or progressive massive fibrosis. Results of pulmonary function tests provide objective criteria for prognosis, and are a measure of disease disability. In this situation, abnormal pulmonary function results should be considered as alarm signs.

Adolescent↗

PubMed2007

Evaluation of pulmonary function and bicycle ergometry tests in patients with Behçet's disease.

Behçet's disease (BD) has well-defined pulmonary complications, but cardiopulmonary exercise testing and the strength of the respiratory muscles have not been studied in detail. We aimed to investigate the pulmonary functions tests, inspiratory and expiratory muscle strength and endurance, cardiopulmonary exercise test response, and the relationship of these parameters in patients with BD. Forty BD patients and 20 healthy control subjects were recruited for this study. Mean age was 32.95 +/- 7.66 years for the BD group and 33.85 +/- 6.63 years for the control group with no statistically significant difference. The ratios of slight obstructive ventilatory impairment were 32.5% for the BD group. When the values of pulmonary function tests were compared, no statistically significant difference was found in FEV(1)/FVC (Forced expiratory volume during the first second/forced vital capacity), or maximal midexpiratory flow rate (all in percent) values between patient and control groups. Maximal inspiratory and expiratory pressures, peak expiratory flow rate (in percent) and maximal voluntary ventilation (in percent) values were significantly lower than those of the control group. Body's consumption of peak oxygen (VO(2peak)), oxygen consumption (milliliters per kilogram per minute), anaerobic threshold (AT), maximum exercise ventilation (VE(max)), work load values, and exercise test time in the bicycle exercise test were significantly higher in control groups than in patients with BD. The values of heart rate reserve, breathing reserve, and VE/VCO(2) at the AT of BD patients were within normal limits We conclude that respiratory and aerobic exercise may be recommended to improve respiratory muscle strength and endurance as well as the aerobic capacity and maximal ventilatory capacity in patients with BD.

Adult↗

PubMed1982

Effects of cardioselective and nonselective beta-adrenergic antagonists on pulmonary mechanics.

After a 7-day lead-in period, one of three beta-adrenergic antagomists was taken for 2 wk by 10 healthy male subjects. The drugs were metoprolol (cardioselective) and propranolol and nadolol (both nonselective). Dosage was according to currently recommended regimens and was increased after the first week (50 to100 mg b.i.d., 20 to 40 mg q.i.d., and 80 to 160 mg q.d.). Pulmonary mechanics and density dependence (DD) of maximal expiratory flow were measured before and at the end of the placebo lead-in period and the low- and high-dose treatment weeks. Total lung capacity (TLC), residual volume (RV), and RV/TLC all rose (P less than 0.05) after high-dose nadolol. Forced vital capacity (FVC) and expiratory reserve volume fell (P less than 0.05) after high-dose nadolol. Forced vital capacity (FVC) and expiratory reserve volume fell (P less than 0.05) after high-dose metoprolol. There was no change in forced expiratory volume in 1.0 sec (FEV1), FEV1/FVC, maximal midexpiratory flow rate, or airway resistance with any of the beta-antagonists. Decreases (P less than 0.05) in maximal expiratory flow determined at 50% of the vital capacity occurred after propranolol and metoprolol, but not after nadolol. A dose-related decrease in DD at 50% of the vital capacity accompanied nadolol dosing, but was significant only after the high-dose regimen. The decreases in DD with nadolol, as well as its effect on RV/TLC, are consistent with small airway narrowing. The findings with metoprolol and propranolol suggest that they affect central as well as peripheral airways.

Adrenergic beta-Antagonists↗