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Results for “Maximal Expiratory Flow Rate”

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PubMed1980

Upper and lower airway hyperreactivity in recurrent croup.

Seventeen children with recurrent croup, who had their last episode within the previous 12 months, were evaluated clinically by allergy skin tests, pulmonary function tests, and a histamine inhalation challengae. Fourteen showed airway hyperreactivity. Flow-volume loops were obtained after a positive histamine response and compared with post histamine tracings of children with asthma and health control subjects. Children with recurrent croup as well as those with asthma showed a significantly greater fall in maximal expiratory flow rates than that shown in healthy control subjects. Those recurrent croup also had a significantly greater fall in maximal inspiratory flow rates when compared to those with asthma and to the control subjects. A specific type airway hyperreactivity suggestive of involvement of both upper and lower respiratory tract was seen in children with recurrent croup.

Adolescent↗

PubMed1985

Carbon monoxide diffusing capacity: a reliable indicator of bleomycin-induced pulmonary toxicity.

Seventy-seven untreated patients with germ-cell tumors, of whom 20 had no pulmonary involvement, no clinical or radiological evidence of pulmonary disease, received 6 courses of cisplatin, vinblastine and bleomycin. Pulmonary function tests were performed before, every 3 weeks during treatment, and once a month from then on. The carbon monoxide diffusion capacity tests were normalized with respect to the actual hemoglobin concentration. During treatment a nonsignificant decrease (P greater than 0.05) was seen in the flow volume relationships, but as it was reversible it was attributed to the strenuous treatment. In contrast a significant decrease of 35% (P less than 0.01) in the corrected carbon monoxide diffusion capacity was seen in 15 of 18 evaluable patients with neither clinical nor radiological signs of pulmonary toxicity. The decrease was correlated to the increasing dose of bleomycin (r = 0.63).

Adolescent↗

PubMed1981

Pulmonary mechanisms and work of breathing at maximal ventilation and raised air pressure.

Pulmonary ventilation (V) and the interrelationships of airflow, transpulmonary pressure, and lung volume during inspiration and expiration were studied in eight healthy subjects who performed maximal exercise (MEx; 140% VO2 max), 15-s maximal voluntary ventilation (MVV), and forced inspiratory and expiratory vital capacity (FVC) maneuvers at 1, 3, and 6 ATA. Maximal exercise ventilation and MVV amounted to 149 +/- 7 (mean +/- SE) and 193 +/- 9 l . min-1, respectively, at 1 ATA and were both reduced by approximately 37% at 3 ATA and by 50% at 6 ATA. Expiratory peak flows during MEx and MVV were equal to the maximal flows obtained during FVC at comparable lung volumes, whereas inspiratory peak flows during MEx were 20% less than the FVC flows. Despite a sixfold increase in gas density, the rate of mechanical work of breathing decreased when the pressure was raised to 6 ATA, during MEx from 8 +/- 1 to 6 +/- 1 W, and during MVV from 28 +/- 5 to 18 +/- 3 W. With increasing gas density there was a shift of lung volumes in the inspiratory direction with consequent reductions of inspiratory-to-expiratory flow ratios. We conclude that depletion of energy stores in the inspiratory muscles contributed to limiting V during MEx at raised air pressure.

Adult↗

PubMed1991

[Correlation of parameters of the flow-volume curve for the assessment of bronchial hyperreactivity].

The association of maximal expiratory flow-volume curve and the response of nonspecific bronchial responsiveness was studied in 265 normal and asthmatic subjects. Bronchial hyperresponsiveness to acetylcholine was found in 143 subjects. These hyperreactive persons had already significantly reduced maximal expiratory flow rate at 75%, 50% and 25% vital capacity before the test started. Besides, we found a significant correlation between the provocative dose and the flow-volume parameters, although resistance was in the normal range. We concluded that the flow rates at middle and low lung volumes may be an important determinant of bronchial sensitivity to acetylcholine.

Acetylcholine↗

PubMed1997

Effects on pulmonary function of daily exposure to dry or humidified hyperbaric oxygen.

The purpose of this study was to examine the effects of breathing dry or humidified hyperbaric oxygen on pulmonary function. Pulmonary function tests were performed before and after each of 10 hyperbaric oxygen exposures at 2.5 atmospheres absolute (ATA) for 95 min in a group of 13 patients treated daily by hyperbaric oxygen for problem wounds. Patients breathed dry oxygen during five successive sessions and humidified oxygen during the remaining five. No differences were found between forced vital capacities (FVC) and maximal expiratory flows before and after hyperbaric oxygen exposure while breathing dry or humidified oxygen. Significant differences were found for the changes in the percentage of FVC expired in 1 s (FEV1%) and mean forced mid-expiratory flow rate during the middle half of the FVC (FEF25-75%) on day 1 alone: decrements of 1.42 and 2.96%, respectively, under dry oxygen, vs. increments of 3.93 and 34.4%, respectively, for humidified oxygen. Day-to-day decrements in the percent changes in FEV1% and FEF25-75% were observed while breathing humidified hyperbaric oxygen. These results demonstrate that repeated daily exposure to humidified hyperbaric oxygen abolishes the initial beneficial effect of humidification on peripheral airways flow characteristics.

Adult↗

PubMed2006

Pulmonary function in children after a single scuba dive.

This study evaluated the respiratory effects of a single dive in children. Eighteen young divers and 18 controls participated in our study (age range: 9 - 13 years). Volumes and expiratory flow rates were measured 20 minutes before and 10 minutes after one air dive (3 meters, 25 minutes). Before the dive, no differences were noted regarding pulmonary parameters. Ten minutes after the dive, decreases were noted in forced expiratory volume in 1 s (FEV1) and maximal voluntary ventilation (- 8 %, - 5.3 %, respectively; p < 0.01), peak expiratory flow, maximal expiratory flow rates at 50 % of FVC (MEF(50 %)) and MEF(25 %), forced mid-expiratory flow rate (FEF(25 - 75 %)), and FEV1/FVC(- 5.9 %, - 14.3 %, - 21.4 %, - 4.2 %, - 3.5 %, respectively; p < 0.05). The respiratory pattern observed 10 minutes after a single dive to three meters indicated airway narrowing. However, no association between diving experience and lung function was obtained.

Age Factors↗

PubMed1987

Assessment of the usefulness of helium-oxygen maximal expiratory flow curves in epidemiologic studies of lung disease in children.

Density dependence of maximal expiratory air flow (DD) has been used in adults as a test of early obstructive airway disease (OAD). Whether DD is useful as an epidemiologic tool to identify childhood risk factors for OAD is not known. In a population-based sample of 133 children 8 to 23 yr of age, we calculated density dependence at 50 and 25% of vital capacity (DD50 and DD25) (the ratios between maximal expiratory flow rates breathing helium-oxygen and air gas mixtures at each of these lung volumes), and the volume of isoflow (VisoV) (the lung volume, expressed as a percentage of vital capacity, at which maximal flow rates when breathing each gas mixture are equal), measured airway responsiveness using eucapnic hyperventilation with cold air, and obtained health and household information with questionnaires. Mean levels (+/- SD) of DD50, DD25, and VisoV were: 1.49 +/- 0.14, 1.37 +/- 0.18, and 10.7 +/- 10%. The DD50 significantly increased with age in these growing children (p less than 0.05), but DD50 was found to be significantly lower (1.42 +/- 0.14 versus 1.52 +/- 0.13; p less than 0.01) among children with nonspecific bronchial hyperresponsiveness. The DD50 also was significantly reduced among children with a history of a recent upper respiratory tract illness (URI) (p less than 0.01). There were no significant associations of DD with history of asthma, personal smoking, parental smoking, or respiratory illness during infancy. The reproducibility of DD50 was assessed on a subsample of 90 subjects in whom DD was measured during 2 surveys 1 yr apart.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Pulmonary function tests--a comparison between urban industrial and rural agricultural workers of Andhra Pradesh.

Physical parameters and pulmonary function tests (VC, FEV1, FEV1% and FEF25-75%) were collected in 112 urban industrial workers and 104 rural agricultural workers. These average values, values according to age and smoking habits were compared between urban and rural workers. Inspite of no differences in age, rural workers average height, weight, BSA is significantly lower than urban workers. A significant increase in VC value to the extent of 0.22 lit (7.1%), significantly lower FEV 1% value by 4.7% and reduce FEF25-75% value (4.7%) is demonstrated in rural than urban workers. Smoking is shown to produce airway obstruction in both urban and rural workers. A wide variation of PFT values between the present workers and other reported values in India is observed. This study indicates rural workers have better pulmonary capacity and less flow rates than their urban counterpart.

Adult↗

PubMed2000

Maximal inspiratory flow rates in patients with COPD.

OBJECTIVES: To assess the relevance of maximal inspiratory flow rates (MIFR) in the assessment of airway obstruction in COPD. SETTING: University teaching hospital. PARTICIPANTS: Ten consecutive COPD patients (O group; mean [+/- SD] age, 58.5+/-8.3 years) and 10 matched healthy subjects (H group; mean age, 58.7+/-7.4 years). MEASUREMENTS: Lung volumes, FEV(1), specific airway conductance, single-breath lung diffusing capacity, MIFR, and maximal expiratory flow rates (MEFR). RESULTS: Mean FEV(1)/vital capacity (VC) was 74.7% in the H group and 37.8% in the O group (p<0.001). Total lung capacity was higher (p<0.001) in the O group compared with the H group. Lung diffusing capacity was less than half in the O group compared with the H group (p<0.001). MEFR at all lung volumes were lower in the O group (p<0.001). MIFR were comparable in the two groups, except at 25% inspired VC, where MIFR were lower in the O group (p< 0.05). CONCLUSION: MIFR are less sensitive than MEFR to detect airway obstruction in COPD patients. Yet, the interest of MIFR lay in the possibility to separate intrinsic from extrinsic involvement of airways. A normal MIFR associated with low MEFR, as in the present study, suggests either a lack of parenchymal support, an increased collapsibility of the airways, or a reversible peripheral airway narrowing. A fixed, generalized airway narrowing would be associated with a decrease of both MIFR and MEFR.

Forced Expiratory Flow Rates↗

PubMed1977

Airway response to short-term inhalation of tobacco smoke. Lack of racial differences.

Airway response to short-term inhalation of cigarette smoke was studied in healthy black subjects. We have measured thoracic gas volume, airway resistance, maximum expiratory flow rates, and closing volume in 12 healthy black volunteers before and after smoking a cigarette. We found a significant reduction in airway conductance and midexpiratory flow rate after smoking the cigarette. The results are similar to those previously observed in white subjects. We conclude from our study that the response to short-term inhalation of cigarette smoke is identical in both white and black subjects.

Adult↗

PubMedDate not supplied

Post-exercise reduction in diffusing capacity of the lung after moderate intensity running and swimming.

A reduction in transfer factor of the lung for carbon monoxide (Tl(co)) is a consistent finding after saturation dives and is reported after some open sea air dives. Several diving associated factors may contribute to this reduction in Tl(co) including hyperoxia, venous gas microembolism, increased breathing resistance and immersion. Exercise, which inevitably is associated with open sea diving, may itself cause a reduction in Tl(co) up to at least 12 hours post-exercise. Six trained swimmers and six trained runners who had never dived performed 30 min moderate intensity swimming and running on different days and in random order at approximately 75% of their maximal heart rate. Lung function including a flow-volume loop and Tl(co) was measured 30 min before and 60-90 min after exercise. There were no significant changes in dynamic lung volumes or maximal expiratory flow rates, but there was a reduction in Tl(co) of 4.5 (SD = 4.8) and 4.7 (SD = 4.6) % after swimming and running respectively (p < 0.01). There was no difference in this response between runners and swimmers, and the response was not associated with lung size. Even moderate exercise preceding measurements of Tl(co) should generally be accounted for, and this effect may contribute significantly to lung function changes immediately after open sea dives.

Adult↗

PubMed1993

Importance of inspiratory load in the assessment of severity of airways obstruction and its correlation with CO2 retention in chronic obstructive pulmonary disease.

Different aspects of mechanical loading were analyzed in a group of 25 patients with chronic obstructive pulmonary disease (COPD) who all had severe expiratory airflow limitation but different arterial CO2 values. It was found that the maximal expiratory flow rates (V75, V50, V25, VFRC), functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), specific airways conductance (SGaw) measured during inspiration or expiration, and lung recoil pressure (PLel) were not correlated to the PaCO2. Only five parameters were significantly linked to the PaCO2; they were the peak inspiratory flow (PIF) (r = -0.57, p < 0.002), the inspiratory vital capacity (IVC) (r = -0.46, p < 0.01), the maximal voluntary ventilation (MVV) (r = -0.49, p < 0.01), the total SGaw (r = -0.40, p < 0.03), and the forced expiratory flow volume in one second (FEV1) (r = -0.36, p < 0.05). It was concluded that the airflow limitation during the inspiratory phase has an important contribution to the CO2 retention in patients with COPD, and therefore analysis of both phases of the respiratory cycle is necessary to assess the severity of airway obstruction in this disease.

Aged↗

PubMed1999

Clickhaler (a novel dry powder inhaler) provides similar bronchodilation to pressurized metered-dose inhaler, even at low flow rates.

STUDY OBJECTIVE: Comparison of the bronchodilator response to an albuterol novel dry powder inhaler (DPI) (Clickhaler [CH]; ML Laboratories PLC; St. Albans, UK) activated at various inspiratory flow rates and to an albuterol pressurized metered-dose inhaler (pMDI) by patients with moderate to moderately severe stable asthma. DESIGN: Randomized, double-blind, placebo-controlled comparison of the bronchodilator response to albuterol DPI (200 microg) at inspiratory flow rates of approximately 15, 30, and 60 L/min in patients with stable asthma with demonstrated reversibility to albuterol. Active (albuterol via pMDI inhaled at 30 L/min) and placebo controls were included. SETTING: Single center study at the chest/allergy unit of a teaching hospital in Canada. PATIENTS: Sixteen patients with moderate to moderately severe stable asthma. MEASUREMENTS AND RESULTS: Efficacy end points were FEV1, FVC, FEV1/FVC, maximum expiratory flow, and forced expiratory flow between 25% and 75% of vital capacity. Safety end points included heart rate, BP, and tremor. There was no significant difference between the bronchodilator response to albuterol via the CH at 15, 30, and 60 L/min inspiratory flow rate and, at all flow rates, no significant difference was found comparing albuterol CH with the pMDI. All of the techniques for delivering albuterol provided significantly better bronchodilatation than placebo. Adverse events were minimal and did not differ between CH and pMDI or between the various flow rates inhaled through the CH. CONCLUSION: A novel passive albuterol DPI (CH) provides a similar bronchodilator response at 15, 30, and 60 L/min inspiratory flow rates compared with a pMDI used optimally.

Administration, Inhalation↗

PubMed1988

Ribavirin aerosol in the elderly.

Ribavirin aerosol is effective in treating respiratory syncytial virus and influenzal infections in children and young adults. It has not been studied in elderly patients. We evaluated the safety of ribavirin aerosol in eight elderly volunteers at high risk for influenza. Their mean age was 64 years; seven subjects had chronic obstructive pulmonary disease (COPD). Subjects received ribavirin aerosol for two or six hours with six hours between treatments. Regimens were continued for 96 hours. The drug was well tolerated. Subjects receiving ribavirin for 2 hours demonstrated a significant decrease in their forced expiratory volume in one second, peak expiratory flow rate and flow over the middle 50 percent of the forced vital capacity. These changes were small and the subjects' symptoms remained stable. Subjects receiving ribavirin for 6 hours had no significant changes in pulmonary function. We conclude that ribavirin aerosol is safe in elderly patients with underlying COPD.

Aerosols↗

PubMed2004

[Suspended particulates and lung health].

Based on several severe air pollution episodes, a temporal correlation between high concentrations of particulate matter (PM) and SO2 pollution and acute increases in respiratory and cardiopulmonary mortality had been established in Vienna for the 1970's. After air pollution had decreased in Austria in the 1980's--as documented by data on SO2, and total suspended particles (TSP)--no such associations between day-to-day changes of SO2 and TSP and mortality have been documented any more, however, traffic related pollutants like fine particles and NO2 remained a problem. Therefore, short term effects of PM on lung function, morbidity and mortality were investigated in Vienna, Linz, Graz and a rural control area. Long-term exposure and chronic disease--even more important for public health--were studied in repeated cross-sectional, a mixed longitudinal and a birth cohort study on school children in the city of Linz. Lung function growth was found impaired from long-term exposure to air pollutants and improved in districts where ambient air pollution had decreased. Where only TSP and SO2 had decreased, no continuous improvement of small airway function was found and end-expiratory flow rates stayed impaired where NO2-reduction from technical improvements of cars and industry was counterbalanced by increase of motorized (diesel) traffic. Remaining acute effects of ambient air pollution in 2001 from PM, NO2 and co-pollutants found in a time series study also show that continuing efforts are necessary. Active surface of particles inhaled several hours to days before spirometry was found related to short-term reductions in forced vital capacity-FVC (p<0.01), forced expiratory volume in one second-FEV1 (p<0.01) and maximal expiratory flow rate at 50% of vital capacity-MEF50 (p<0.05). In pupils with asthma or previous airway obstruction 4-week-diaries proved that the following symptoms increased with acute exposure to higher active surface of particles: wheezing (p<0.01), dyspnea, cough when going to sleep, cough at night (p<0.05). Efforts to reduce exposure to fine particles from motor traffic and passive smoking have to be increased if we want to achieve full recovery of children from air pollution effects and best respiratory performance in adulthood. Surveillance seems to be necessary not only for particle mass but also for particle number and surface. Little is known on the mechanisms of irreversible long-term effects of PM such as myocardial infarction and cancer. In a prospective cohort study on 1630 dust-exposed and 1630 non dust-exposed workers matched for smoking we found an increase of lung cancer related to nonfibrous insoluble PM. Other studies were able to relate lung cancer to specific particles like those from diesel engines, and a large prospective study of the American Cancer Society was able to link lung cancer in the general population with long-term exposure to fine particles from combustion processes. All these recent epidemiological findings will have consequences for occupational and ambient air PM standards.

Adult↗

PubMed1978

A forced expiration end-segment flow rate to improve diagnosis of reversible bronchial obstruction: a spirographic examination.

An inhalatory bronchodilatory test was performed in two groups of 130 healthy and 89 asthmatics comparable in age, height and weight. All were males aged about 20 years. The bronchodilatory response was assessed by the percent increase after bronchodilation of FEV1, MEF200-1200, MMEF25-75 MEF50-75 (E50-75) and MEF75-90--at last three flow rate percent increases measured before and after bronchodilation at the same level of control FVC. It was found that only MEF75-90, measured as described, could probably significantly improve the diagnostic value of a bronchodilatory test if used in cases in which the FEV1 percent increase remains within the normal range.

Adult↗

PubMed2002

Lung function of school children with low levels of alpha1-antitrypsin and tobacco smoke exposure.

Exposure to environmental tobacco smoke (ETS) and other air pollutants has been associated with small decrements in lung function. The susceptibility to pollution exposure may, however, vary substantially between individuals. Children with an impaired protease-antiprotease balance may be particularly vulnerable. Therefore this study aimed to investigate the effects of ETS exposure on children with reduced levels of alpha1-antitrypsin (alpha1-AT). Random samples of school children (aged 9-11 yrs) (n=3,526) were studied according to the International Study of Asthma and Allergies in Childhood (ISAAC) phase II protocol, including parental questionnaires, pulmonary function and allergy testing. Blood samples were obtained to measure plasma levels of alpha1-AT and to genotype for pleomorphic protein inhibitor (Pi)Z and PiS alleles. Children with low levels of alpha1-AT (< or = 116 mg x dL(-1)) showed significant, albeit small decrements in baseline lung function. When exposed to ETS, pronounced decrements of pulmonary function, particularly in measures of mid- to end-expiratory flow rates, were seen in these children as compared to exposed children with normal levels of alpha1-AT. The mean levels of % predicted+/-SE in both groups were: maximum expiratory flow at 50% of vital capacity 79.4+/-7.2 versus 99.0+/-1.5, maximum expiratory flow at 25% of vital capacity 67.4+/-10.0 versus 100.3+/-2.1, maximal midexpiratory flow 73.7+/-8.6 versus 99.9+/-1.7. These findings suggest that school children with low levels of alpha1-antitrypsin are at risk of developing pronounced decrements in pulmonary function, particularly if they are exposed to environmental tobacco smoke. Parents of children with heterozygous alpha1-antitrypsin deficiency resulting in significantly reduced blood concentrations should be advised to prevent their children from being exposed to environmental tobacco smoke and dissuade them from taking up smoking.

Child↗

PubMed1993

Relation of passive smoking as assessed by salivary cotinine concentration and questionnaire to spirometric indices in children.

BACKGROUND: Previous studies of the effects of passive exposure to smoke on spirometric indices in children have largely relied on questionnaire measures of exposure. This may have resulted in underestimation of the true effect of passive smoking. Biochemical measures offer the opportunity to estimate recent exposure directly. METHODS: The relation between spirometric indices and passive exposure to tobacco smoke was examined in a large population sample of 5-7 year old children from 10 towns in England and Wales. The effects of passive exposure to smoke on lung function were assessed by means of both salivary cotinine concentration and questionnaire measurements of exposure. Analyses of the relation between spirometric values and cotinine concentrations were based on 2511 children and of the relation between spirometric values and questionnaire measures on 2000 children. RESULTS: Cotinine concentration was negatively associated with all spirometric indices after adjustment for confounding variables, which included age, sex, body size, and social class. The strongest association was with mid expiratory flow rate (FEF50), the fall between the bottom and top fifths of the cotinine distribution being 6%, equivalent to a reduction of 14.3 (95% confidence limits (CL) 8.6, 20.0) ml/s per ng/ml cotinine. Salivary cotinine concentrations were strongly related to exposure to cigarette smoke at home but 88% of children who were from non-smoking households and not looked after by a smoker had detectable cotinine concentrations, 5% being in the top two fifths of the cotinine distribution. A composite questionnaire score based on the number of regular sources of exposure was as strongly related to mid and end expiratory flow rates as the single cotinine measure. The fall in FEF50 per smoker to whom the child was exposed was 51.0 (26.5, 75.5) ml/s. The relationships between the questionnaire score and forced vital capacity (FVC) or forced expiratory volume in one second (FEV1) were not statistically significant. CONCLUSIONS: These effects of passive smoking on respiratory function are consistent with the results of previous studies and, although small in absolute magnitude, may be important if the effects of exposure are cumulative. In children aged 5-7 years the use of a single salivary cotinine concentration as a marker of passive exposure to smoke resulted in clear relationships between exposure and FVC and FEV1, whereas the associations were much weaker and not significant when based on the questionnaire score. The associations between exposure and mid or end expiratory flow rates were of similar magnitude for cotinine concentration and the questionnaire score. The use of salivary cotinine concentration in longitudinal studies may help to determine the extent to which these effects are cumulative or reversible.

Biomarkers↗