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Results for “Maximal Midexpiratory Flow Rate”

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PubMed1979

Effects of oxone inhalation on work performance and VO2 max.

Ozone (O3) at near ambient smog alert levels has previously been shown to cause alterations in pulmonary function and exercise response in humans. The present study was designed to investigate the effects of O3 administered during graded bicycle exercise to volitional fatigue on work performance and maximal oxygen uptake (VO2max). Nine subjects performed three tests each while breathing either 0.00, 0.15, or 0.30 ppm O3. Forced vital capacity, residual volume, maximal midexpiratory flow rate, and forced expiratory volume in 1 s were assessed before, immediately after, and 4 h after exercise. O3 exposure resulted in no significant effect on maximal work rate, anaerobic threshold, or any pulmonary function parameter. However, maximal expired minute ventilation was decreased (P less than 0.05) in a dose dependent fashion. Thus, exercise ventilation during maximal work was a more sensitive indicator of the effects of O2 exposure than were standard pulmonary function tests. Although subjective symptoms of discomfort were reported more frequently with increased O2 level, it was concluded that exposure of healthy young men to as much as 0.30 ppm O2 for no more than 30 min of progressively incremented exercise to volitional fatigue, is insufficient to cause a significant decrease in work capacity or V02 max.

Adult↗

PubMed1996

Effects of bronchomotor tone and gas density on time dependence of forced expiratory vital capacity maneuver.

It has been shown that in normal subjects and chronic obstructive pulmonary disease (COPD) patients the maximal expiratory flows and FEV1 are significantly higher if the FVC maneuver is preceded by a rapid inspiration without an end-inspiratory pause (maneuver 1) compared with a slow inspiration with an end-inspiratory pause of approximately 5 s (maneuver 2). This time dependency of FVC was attributed primarily to loss of lung recoil (stress relaxation) during breath-holding at TLC, in association with time constant inequality within the lungs, and changes in bronchomotor tone. To examine the role of bronchomotor tone on time dependency of FVC, 11 COPD and 10 asthmatic patients performed FVC maneuvers 1 and 2 before and after administration of a bronchodilator drug (salbutamol). In addition, using the same approach, the effects of changing airway resistance per se were assessed in another group of 10 COPD patients and 10 normal subjects, while breathing air and after equilibration with 80% helium in oxygen. Main findings were: peak expiratory flow (PEF), FEV1, and maximal midexpiratory flow rate (MMF) were significantly larger with maneuver 1 than 2; after salbutamol administration and during helium-oxygen breathing, all indices increased significantly with both maneuvers but the relative differences between maneuvers 1 and 2 were unchanged. We conclude that time dependency of maximal expiratory flow-volume (MEFV) curves, as indexed by PEF, FEV1, and MMF, is largely independent of bronchomotor tone and gas density, and probably reflects mainly stress relaxation of the respiratory tissues. The relevance of time dependency of FVC maneuver in the assessment of bronchodilator response and density dependence is discussed.

Adult↗

PubMed2001

Respiratory effects of relocating to areas of differing air pollution levels.

We studied 110 children (59 boys and 51 girls, who were 10 yr of age at enrollment and 15 yr of age at follow-up) who had moved from communities participating in a 10-yr prospective study of respiratory health (The Children's Health Study [CHS]) to determine whether changes in air quality caused by relocation were associated with changes in annual lung function growth rates. The subjects were given health questionnaires and underwent spirometry in their homes across six western states, according to a protocol identical to evaluations performed annually on the CHS cohort in school. Changes in annual average exposure to particulate matter with a mean diameter of 10 microm (PM(10)) were associated with differences in annual lung function growth rates for FEV(1), maximal midexpiratory flow, and peak expiratory flow rate. As a group, subjects who had moved to areas of lower PM(10) showed increased growth in lung function and subjects who moved to communities with a higher PM(10) showed decreased growth in lung function. A stronger trend was found for subjects who had migrated at least 3 yr before the follow-up visit than for those who had moved in the previous 1 to 2 yr. We conclude that changes in air pollution exposure during adolescent growth years have a measurable and potentially important effect on lung function growth and performance.

Adolescent↗

PubMedDate not supplied

[The late sequelae of the systematic action of a complex of real diving factors on the pulmonary ventilatory function of deep-sea divers].

Parameters which characterize lung volumes, absolute and relative flow rates, breathing reserve, were found unchanged with increasing age and record of active dive service, and in some deep-divers these parameters were growing up. This was disclosed due to comparative analysis of lung ventilatory function changes in divers through certain amount of years of professional occupation. At the same time a significant decrease in small to middle calibre bronchi patency was noted. In 30% of experienced deep-divers the mean maximal forced expiratory flow at 75% forced vital capacity (FEF75) decreased to 39% of predicted value at one-second forced expiratory volume (FEV1) being normal. Maximal expiratory flow at 50% forced vital capacity (FEF50) were in inferior normal limit (52% of predicted value).

Arctic Regions↗

PubMed2000

Effects of weight loss on peak flow variability, airways obstruction, and lung volumes in obese patients with asthma.

STUDY OBJECTIVES: To clarify the pathophysiologic features of the relation between asthma and obesity, we measured the effects of weight reduction on peak expiratory flow (PEF) variability and airways obstruction, compared to simultaneous changes in lung volumes and ventilatory mechanics in obese patients with stable asthma. METHODS: Fourteen obese asthma patients (11 women and 3 men; aged 25 to 62 years) were studied before and after a very-low-calorie-diet period of 8 weeks. PEF variability was determined as diurnal and day-to-day variations. FEV(1) and maximal expiratory flow values were measured with a flow-volume spirometer. Lung volumes, airways resistance (Raw), and specific airways conductance were measured using a constant-volume body plethysmograph. Minute ventilation was monitored in patients in supine and standing positions. RESULTS: As patients decreased their body mass index (SD) from 37.2 (3.7) to 32.1(4.2) kg/m(2) (p < 0. 001), diurnal PEF variation declined from 5.5% (2.4) to 4.5% (1.5) (p = 0.01), and day-to-day variation declined from 5.3% (2.6) to 3. 1% (1.3) (p < 0.005). The mean morning PEF, FEV(1), and FVC increased after weight loss (p = 0.001, p < 0.005, and p < 0.05, respectively). Flow rate at the middle part of FVC (FEF(25-75)) increased even when related to lung volumes (FEF(25-75)/FVC; p < 0. 05). Functional residual capacity and expiratory reserve volume were significantly higher after weight loss (p < 0.05 and p < 0.005, respectively). A significant reduction in Raw was found (p < 0.01). Resting minute ventilation decreased after weight loss (p = 0.01). CONCLUSION: Weight loss reduces airways obstruction as well as PEF variability in obese patients with asthma. The results suggest that obese patients benefit from weight loss by improved pulmonary mechanics and a better control of airways obstruction.

Adult↗

PubMed1985

Methylprednisolone and troleandomycin in treatment of steroid-dependent asthmatic children.

Oral methylprednisolone combined with troleandomycin has been reported to be successful in treating poorly controlled, severe asthma in adults. We found this drug combination to be effective in treating 11 steroid-dependent children with poorly controlled asthma who were aged 7 to 13 years, for 12 to 28 months. Improvement of clinical and pulmonary functions was achieved within seven days, with the forced expiratory volume in 1 s increasing by 38% and the maximal midexpiratory flow rate increasing by 55% over the baseline value. By one year, the former improved to 98% of predicted value and the latter, to 79% of predicted value. Compared with the prior 12 months, patients at this time required fewer emergency visits, missed fewer days of school, and had fewer hospitalizations. Side effects included transient-increased cushingoid features, abdominal pain, and liver enzyme level elevation. Patients showed less evidence of adrenal suppression.

Administration, Oral↗

PubMed1998

Pulmonary function of workers in the aluminum industry.

The effects of aluminum on the pulmonary function of aluminum workers were investigated in this study. Serum aluminum levels and spirometry were measured in 55 male workers and 30 male controls. The mean serum aluminum level of workers (72.7 +/- 9.9 ng/ml) was significantly high compared to that of controls, indicating aluminum toxicity. Spirometric parameters were significantly lower in workers than in controls and correlated negatively with both exposure time and serum aluminum levels. The impairment in pulmonary function may be due to exposure time and insufficient protection.

Adult↗

PubMedDate not supplied

Obstructive pulmonary disease in rheumatoid arthritis.

Twenty-six of 43 patients (60.5%) with classic rheumatoid arthritis (RA) participating in a controlled, prospective study were found to have maximal midexpiratory flow rates (MMEFs) suggestive of obstructive pulmonary disease. Cigarette smokers with RA had significantly lower MMEFs than either nonsmokers with RA or smokers with degenerative joint disease. There was an increased prevalence of the Pi phenotype MS among the RA patients. Interstitial fibrosis, tobacco smoking, and protease inhibitor deficiencies were all significant factors in producing airway obstruction in patients with RA.

Adult↗

PubMed1993

Evolution of pulmonary function during an acute exacerbation in hospitalized patients with cystic fibrosis.

Few objective criteria have been validated for serial clinical monitoring in patients with cystic fibrosis (CF) during pulmonary exacerbations. While pulmonary function tests (PFT) are often used to monitor clinical improvement, it is not known which test correlates most closely with clinical improvement. To answer this, we measured routine PFT in 58 patients with CF before, during, and at discharge after 2-3 week hospital admission in 71 episodes of pulmonary exacerbation. Patients with CF were discharged based on clinical, radiological, and laboratory criteria. In general, all PFTs improved at midadmission and improved further by discharge, at which time forced expiratory volume in 1 second (FEV1), forced expiratory flow between 25% and 75% of forced vital capacity (FEF25-75), vital capacity (VC), maximal voluntary ventilation (MVV), and oxygen saturation by pulse oximetry (SPO2) increased. The residual volume to total capacity ratio (RV/TLC) and the slope of phase 3 in the single breath N2 washout curve (SP3 N2) decreased. The change in SP3 N2 was significantly greater than in any other PFT (P < 0.01 vs. VC and FEV1; P < 0.02 vs. RV and P < 0.001 vs. SPO2). A calculated optimal cut-off value for SP3 N2 improvement was significantly more sensitive in identifying patient improvement at discharge than any other pulmonary function test (P = 0.005). We speculate that clinical improvement in patients with CF is closely linked to improved distribution of ventilation.

Acute Disease↗

PubMed2005

Long-term pulmonary morbidity in survivors of congenital diaphragmatic hernia.

Our objective was to study long-term respiratory outcomes of congenital diaphragmatic hernia (CDH) treated in the perinatal period. This was a cohort study with 26 adolescent survivors and age- and gender-matched controls. Medical histories were retrieved from hospital charts and questionnaires. Pulmonary function testing included measurement of maximum inspiratory and expiratory pressures (MIPS and MEPS) and maximum voluntary ventilation (MVV). Unpaired two-tailed t-test and nonlinear regression were used for statistical analysis. Significant differences were found in forced expiratory volume in one second (FEV(1)) (79% +/- 16% vs. 94% +/- 10%, P < 0.001), FEF(25-75) (62% +/- 24% vs. 84% +/- 15%, P < 0.001), FRC (114% +/- 20% vs. 95% +/- 13%, P < 0.001), RV/TLC (31% +/- 10% vs. 22% +/- 6%, P < 0.001), MVV (74% +/- 16% vs. 90% +/- 13%, P < 0.001), and MIPS (69% +/- 19% vs. 84% +/- 16%, P < 0.01), with numbers indicating percent predicted of reference values +/- SD. Reduction of MVV was not independent from FEV1 (r = 0.83). Forty-eight percent of patients vs. 4% of controls showed significant improvement of FEV1 after bronchodilators (86% +/- 15 vs. 98% +/- 10, P < 0.01). Forty-six percent of patients had abnormalities of the chest wall or spinal column such as pectus excavatum, pectus carinatum, and scoliosis, mostly mild or moderate. In conclusion, long-term respiratory outcome in adolescent CDH is associated with mild to moderate airway obstruction, a high prevalence of response to bronchodilators, and decreased inspiratory muscle strength. This should guide follow-up scheduling and should be taken into account for perioperative and critical care management.

Adolescent↗

PubMed1977

Comparison of aerosolized atropine sulfate and SCH 1000 on exercise-induced bronchospasm in children.

The new anticholinergic compound Sch 1000 (ipratropium bromide) has been reported to be an effective bronchodilator without significant atropine-like side effects. We evaluated the effectiveness of different doses of nebulized Sch 1000 (40 microgram and 80 microgram) aerosolized atropine sulfate (1 mg) and placebo in the prevention of exercise-induced bronchospasm (EIB) in 20 children with atopic bronchial asthma. A random, crossover double-blind protocol was used. Standard exercise on a cycloergometer was used to induce EIB. Pulmonary function was determined before and after drug administration and exercise. Following no treatment or placebo, exercise resulted in average reductions of 33% to 43% in plethysmographic specific airway conductance (SGaw), of 20% to 25% in forced expiratory volume in 1 sec (FEV1), and of 25% to 32% in maximal midexpiratory flow rate. Exercise following no treatment or placebo resulted in average increases of 23% to 30% in thoracic gas volume (Vtg). Prior to exercise atropine and either dose of Sch 1000 caused significant increases in SGaw (48% to 59%). After pretreatment with Sch 1000 or atropine, exercise caused SGaw to fall to values that were not significantly different from pretreatment medication values, but were significantly higher than values following exercise without pretreatment or after pretreatment with placebo. No significant differences were noted between the effects of atropine and Sch 1000 on EIB. We conclude that at the doses used atropine and Sch 1000 cause equivalent degrees of bronchodilation but neither drug specifically inhibits EIB.

Adolescent↗

PubMed1976

Echocardiographic assessment of cor pulmonale in cystic fibrosis.

The early clinical recognition and assessment of cor pulmonale are frequently difficult. To evaluate the usefulness of echocardiographic measurement of right ventricular dimension and septal motion in assessing cor pulmonale, we studied 94 patients with cystic fibrosis of varying severity. There was a significant relationship between increasing right ventricular dimension index (RVDI) and (1) decreasing clinical score, vital capacity, forced expiratory volume in one second (FEV1), and maximal midexpiratory flow rate (MMFR); and (2) increasing residual volume and thoracic gas volume. There was no correlation between right ventricular dimension index and PaO2. These findings were supported by electrocardiogram and pathologic evidence of right ventricular involvement. Abnormal septal motion was observed more frequently in patients with severe obstructive airway disease as measured by decreased vital capacity, FEV1, and MMFR. The data show that there is echocardiographic evidence of mild right ventricular enlargement and/or hypertrophy much earlier in the course of cystic fibrosis than previously suspected and that the echocardiogram is a useful tool in the evaluation of cor pulmonale in patients with cystic fibrosis.

Adolescent↗

PubMed1980

Release of mast-cell mediators and alterations in lung function in patients with cholinergic urticaria.

Cholinergic urticaria was elicited in seven subjects by experimental challenge that consisted of running on a treadmill in a plastic occlusive suit. A sensation of generalized warmth of the skin was followed by pruritus, erythema, urticaria, and transient respiratory-tract symptoms consisting of shortness of breath or wheezing or both. Statistically significant falls in one-second forced-expiratory volumes (FEV1), maximal midexpiratory flow rates (MMF), and specific conductance (SGaw) and a rise in residual volume were detected. The serum histamine concentration rose, with an augmentation of eosinophil and neutrophil chemotactic activities. Gel-filtration chromatography showed that the eosinophil chemotactic activity consisted of at least two principles. The chemotactic activities are similar in magnitude to those recognized in other skin disorders dependent on mast cells. These observations extend to the lungs the manifestations of a condition previously thought to be restricted to the skin.

Adult↗

PubMed2006

Reduced lung function at birth and the risk of asthma at 10 years of age.

BACKGROUND: Reduced lung function in early infancy has been associated with later obstructive airway diseases. We assessed whether reduced lung function shortly after birth predicts asthma 10 years later. METHODS: We conducted a prospective birth cohort study of healthy infants in which we measured lung function shortly after birth with the use of tidal breathing flow-volume loops (the fraction of expiratory time to peak tidal expiratory flow to total expiratory time [t(PTEF)/t(E)]) in 802 infants and passive respiratory mechanics, including respiratory-system compliance, in 664 infants. At 10 years of age, 616 children (77%) were reassessed by measuring lung function, exercise-induced bronchoconstriction, and bronchial hyperresponsiveness (by means of a methacholine challenge) and by conducting a structured interview to determine whether there was a history of asthma or current asthma. RESULTS: As compared with children whose t(PTEF)/t(E) shortly after birth was above the median, children whose t(PTEF)/t(E) was at or below the median were more likely at 10 years of age to have a history of asthma (24.3% vs. 16.2%, P=0.01), to have current asthma (14.6% vs. 7.5%, P=0.005), and to have severe bronchial hyperresponsiveness, defined as a methacholine dose of less than 1.0 micromol causing a 20% fall in the forced expiratory volume in 1 second (FEV1) (9.1% vs. 4.9%, P=0.05). As compared with children whose respiratory-system compliance was above the median, children with respiratory compliance at or below the median more often had a history of asthma (27.4% vs. 14.8%; P=0.001) and current asthma (15.0% vs. 7.7%, P=0.009), although this measure was not associated with later measurements of lung function. At 10 years of age, t(PTEF)/t(E) at birth correlated weakly with the maximal midexpiratory flow rate (r=0.10, P=0.01) but not with FEV1 or forced vital capacity. CONCLUSIONS: Reduced lung function at birth is associated with an increased risk of asthma by 10 years of age.

Asthma↗

PubMed2004

Pulmonary function, diffusing capacity, and inflammation in healthy and asthmatic subjects exposed to ultrafine particles.

Particulate air pollution is associated with asthma exacerbations and increased morbidity and mortality from respiratory causes. Ultrafine particles (particles less than 0.1 microm in diameter) may contribute to these adverse effects because they have a higher predicted pulmonary deposition, greater potential to induce pulmonary inflammation, larger surface area, and enhanced oxidant capacity when compared with larger particles on a mass basis. We hypothesized that ultrafine particle exposure would induce airway inflammation in susceptible humans. This hypothesis was tested in a series of randomized, double-blind studies by exposing healthy subjects and mild asthmatic subjects to carbon ultrafine particles versus filtered air. Both exposures were delivered via a mouthpiece system during rest and moderate exercise. Healthy subjects were exposed to particle concentrations of 10, 25, and 50 microg/m(3), while asthmatics were exposed to 10 microg/m(3). Lung function and airway inflammation were assessed by symptom scores, pulmonary function tests, and airway nitric oxide parameters. Airway inflammatory cells were measured via induced sputum analysis in several of the protocols. There were no differences in any of these measurements in normal or asthmatic subjects when exposed to ultrafine particles at concentrations of 10 or 25 microg/m(3). However, exposing 16 normal subjects to the higher concentration of 50 microg/m(3) caused a reduction in maximal midexpiratory flow rate (-4.34 +/- 1.78% [ultrafine particles] vs. +1.08 +/- 1.86% [air], p =.042) and carbon monoxide diffusing capacity (-1.76 +/- 0.66 ml/min/mm Hg [ultrafine particles] vs. -0.18 +/- 0.41 ml/min/mm Hg [air], p =.040) at 21 h after exposure. There were no consistent differences in symptoms, induced sputum, or exhaled nitric oxide parameters in any of these studies. These results suggest that exposure to carbon ultrafine particles results in mild small-airways dysfunction together with impaired alveolar gas exchange in normal subjects. These effects do not appear related to airway inflammation. Additional studies are required to confirm these findings in normal subjects, compare them with additional susceptible patient populations, and determine their pathophysiologic mechanisms.

Adult↗

PubMed1989

The Quality of Well-being Scale. Applications in AIDS, cystic fibrosis, and arthritis.

The Quality of Well-being (QWB) Scale combines preference-weighted measures of symptoms and functioning to provide a numerical point in-time expression of well-being that ranges from zero (0) for death to 1.0 for asymptomatic optimum functioning. The QWB includes three scales of function: mobility, physical activity, and social activity. Each step of these scales is associated with preference weights. Preference adjustments for symptoms are also included. This paper describes how this general system was used to evaluate outcomes in three different clinical conditions: acquired immune deficiency syndrome (AIDS), cystic fibrosis, and arthritis. In one study, the QWB was administered to 31 patients participating in evaluation of azidothymidine (AZT) treatment for AIDS. The QWB system demonstrated substantial benefits of AZT treatment in comparison to placebo. In a second study, the QWB and a series of pulmonary function measures were administered to 44 patients with cystic fibrosis. The QWB was demonstrated to be significantly correlated with measures of pulmonary function, including FEV1 and maximal midexpiratory flow rate (MMEFR). In addition, there were significant associations between the QWB and measures of exercise tolerance. In the third study, the QWB and an arthritis-specific measure were administered to 83 arthritis patients before and after their treatment. The QWB was at least as capable of detecting clinical change in this population as was the disease-specific measure. For all three conditions, the QWB considered side effects and benefits of treatment in a common unit. Clinical trial data are cited to suggest that the QWB is a valuable outcome measure in arthritis treatment evaluation. We conclude that the QWB has substantial validity as a general health outcome measure and that the system can be used with different populations.

Acquired Immunodeficiency Syndrome↗

PubMed1996

Airway reactivity in welders: a controlled prospective cohort study.

In a 3-year survey, respiratory symptoms, spirometry, and methacholine reactivity were measured annually in welders (n = 51) and non-welder controls subjects (n = 54) to determine whether welding-related symptoms are associated with accelerated decline in lung function or changes in airway reactivity. In the cross-workshift study, maximal midexpiratory flow rate declined reversibly during a welding day, whereas 1-second forced expiratory volume and forced-vital capacity were unchanged. In the longitudinal study, the welders had significantly more reversible work-related symptoms of cough, phlegm, wheeze, and chest tightness than the non-welder shipyard control subjects. In this group of actively working welders, across-workshift changes in midflow and reversible symptoms were related to the welding occupation, but evidence for chronic irreversible effects on spirometry or airway reactivity was not seen over the 3 years of observation. The short period of observation was not optimal for detecting a chronic effect on lung function. Work practices and engineering controls may be successfully preventing irreversible respiratory effects, but not mild reversible effects, in this group of welders.

Adult↗

PubMed1978

Effects of exercise, vitamin E, and ozone on pulmonary function and lipid peroxidation.

Expired pentane, an index of lipid peroxidation, and pulmonary function were measured as a function of exercise for 1 h with and without exposure to 0.3 ppm ozone. In experiment 1, 10 subjects who exercised on a bicycle ergometer at 50% of maximal oxygen consumption while being exposed to 0.3 ppm ozone had increased lung residual volume and decreased vital capacity, maximal midexpiratory flow rate, and forced expiratory volume in 1 s. In experiment 2, breath collected into a spirometer filled with hydrocarbon-scrubbed air showed increased pentane from the stress of exercise but no effect of ozone. During rest and exercise in experiment 3, two of six subjects had higher pentane levels than the other subjects. Following daily supplementation with 1,200 IU dl-alpha-tocopherol for 2 wk, the mean production of pentane during rest and exercise was significantly lowered, and there was no difference in pentane production among the subjects. It was concluded that lipid peroxidation occurs during exercise and that it is attenuated by vitamin E.

Adult↗