PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Forced Expiratory Flow Rates”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed1997

Changes in respiratory function after one and three hours of exposure to formaldehyde in non-smoking subjects.

OBJECTIVE: To determine the changes in respiratory function within one hour and three hours of exposure to formaldehyde and investigate the relation between exposure to formaldehyde and acute changes in respiratory function. METHOD: Respiratory function of 50 non-smoking medical students exposed to formaldehyde in a gross anatomy laboratory were compared with respiratory function of 36 non-exposed, non-smoking physiotherapy students. Formaldehyde concentrations were measured in the breathing zone of each exposed subject and in the general work environment. RESULTS: Formaldehyde concentrations in the breathing zone of exposed subjects generally exceeded recommended standards. On average, the variables of respiratory function of both the exposed and the control subjects increased significantly within one hour and from one to three hours after exposure. The increase in respiratory function of the exposed subjects was significantly less than that of the control subjects. There was no meaningful correlation between concentration of formaldehyde in the breathing zone and changes in the respiratory function of exposed subjects. CONCLUSION: As the increase in the respiratory function of the subjects can be attributable to normal diurnal variation, the significantly lower increase in respiratory function of the exposed group than in the control group is probably due to exposure to formaldehyde. The results of this study do not, however, support a dose-response relation.

Adult↗
PubMed2002

Cross sectional study on lung function of coke oven workers: a lung function surveillance system from 1978 to 1990.

AIMS: To determine the association between lung function of coke oven workers and exposure to coke oven emissions. METHODS: Lung function data and detailed work histories for workers in recovery coke ovens of a steelworks were extracted from a lung function surveillance system. Multiple regressions were employed to determine significant predictors for lung function indices. The first sets of lung function tests for 613 new starters were pooled to assess the selection bias. The last sets of lung function tests for 834 subjects with one or more year of coke oven history were pooled to assess determinants of lung function. RESULTS: Selection bias associated with the recruitment process was not observed among the exposure groups. For subjects with a history of one or more years of coke oven work, each year of working in the most exposed "operation" position was associated with reductions in FEV(1) of around 9 ml (p = 0.006, 95% CI: 3 ml to 16 ml) and in FVC of around 12 ml (p = 0.002, 95% CI: 4 ml to 19 ml). Negative effects of smoking on lung function were also observed. CONCLUSIONS: Exposure to coke oven emissions was found to be associated with lower FEV(1) and FVC. Effects of work exposure on lung function are similar to those found in other studies.

Adolescent↗
PubMed2002

Respiratory morbidity in a population of French dental technicians.

AIMS: To compare wage earner dental technicians with non-exposed salaried subjects for the prevalence of respiratory symptoms and function, and chest x ray abnormalities. METHODS: A total of 134 dental technicians and 131 non-exposed subjects participated. A medical and an occupational questionnaire were filled in to evaluate the prevalence of respiratory symptoms and occupational exposures. Subjects underwent respiratory tests and chest x ray examination. RESULTS: Mean age of the dental technicians was 36.6 years with a mean duration of dental work of 16.5 years. There was a significant risk of cough (day and night) and usual phlegm in dental technicians. Respiratory function parameters were lower in dental technicians with a significant difference between exposed and non-exposed groups for % FVC (forced vital capacity), % FEF(25) (forced mid expiratory flow), and % FEF(50). The prevalence of small opacities increased with age. Small opacities were significantly related to an exposure to asbestos in the past. CONCLUSIONS: Our young population of dental technicians is at risk of respiratory morbidity. They should benefit from adequate technical prevention measures.

Adolescent↗
PubMed2001

Effect of gas cooking on lung function in adolescents: modifying role of sex and immunoglobulin E.

BACKGROUND: A study was undertaken to investigate the effect of gas cooking on the lung function of adolescents while considering serum IgE level as a possible effect modifier. METHOD: The cross sectional study was performed in 702 subjects aged 11-13 years from primary and secondary schools in Civitavecchia and Viterbo ( Latium region in Central Italy), categorised according to how often they were in the kitchen while the mother cooked (never, sometimes, often). Data were collected by questionnaire and lung function was measured by spirometric tests. Bronchial hyperresponsiveness was evaluated by the methacholine test, atopic status by a skin prick test, and a blood sample was collected to determine serum IgE levels. The results were analysed separately for boys and girls. Multiple regression analysis was performed, taking functional parameters (FEV(1), FEV(1)/FVC, FEF(25-75), FEF(50), FEF(75)) as the dependent variables and age, height, parental smoking, and father's education as independent variables. RESULTS: There was no association between time spent in the kitchen and lung function level in boys, but a reduction in lung function was detected in girls which was statistically significant for FEF(75) (sometimes -10.3%, often -11.1%). After stratifying boys and girls into four groups on the basis of the IgE serum level (below and above the median value of IgE), the reduction in lung function was significant in girls with a high IgE value whereas no significant deleterious effects were evident in girls with a low IgE value or in boys with either a low or high IgE. The results remained substantially unchanged after excluding girls with a response to methacholine below the concentration of 4 mg/ml, asthmatic patients, and those with positive skin prick tests. CONCLUSION: Gas cooking has a harmful effect on the lung function of girls with a high serum level of IgE. We do not know whether serum IgE, a marker of allergic susceptibility, is a simple indicator that an inflammatory process is in progress or whether it is involved in the pathogenesis of injury leading to bronchial obstruction.

Adolescent↗
PubMed2002

Airway and systemic effects of hydrofluoroalkane fluticasone and beclomethasone in patients with asthma.

BACKGROUND: With the transition to hydrofluoroalkane-134a propellants in metered dose inhalers, it is important to consider the efficacy and safety profiles of formulations containing inhaled corticosteroids. We examined the airway and systemic effects of hydrofluoroalkane-134a fluticasone propionate (FLU-HFA) and beclomethasone dipropionate (BEC-HFA) at recommended labelled doses. METHODS: Twenty mild to moderate asthmatics were randomised in crossover fashion to receive 6 weeks of 500 micro g/day followed by 1000 micro g/day FLU-HFA and BEC-HFA. Measurements were made at baseline after placebo run in and washout, and after each randomised treatment. The primary airway outcome for benefit was the dose of methacholine provoking a fall in forced expiratory volume in 1 second (FEV(1)) of 20% or more (methacholine PD(20)) and for systemic adverse effects was overnight urinary cortisol/creatinine (OUCC). RESULTS: For mean responses, both doses of BEC-HFA and FLU-HFA produced significant improvements in PD(20) compared with baseline. The improvement was not significantly greater with 1000 micro g/day FLU-HFA versus BEC-HFA, a 1.69 fold difference (95% CI 0.94 to 3.04). Both doses of BEC-HFA but not FLU-HFA caused significant suppression of OUCC compared with baseline, with significantly (p<0.05) lower values at 1000 micro g/day for BEC-HFA versus FLU-HFA (1.97 fold difference (95% CI 1.28 to 3.02)). CONCLUSION: There was no difference in the airway and systemic effects in patients with mild to moderate asthma between FLU-HFA and BEC-HFA at a dose of 500 micro g/day. At 1000 micro g/day there was increased systemic bioactivity with BEC-HFA compared with FLU-HFA, without any gain in airway efficacy.

Adult↗
PubMed2002

Volume effect and exertional dyspnoea after bronchodilator in patients with COPD with and without expiratory flow limitation at rest.

BACKGROUND: A study was undertaken to investigate whether bronchodilators are associated with less breathlessness at rest and during light exercise in patients with moderate to severe chronic obstructive pulmonary disease (COPD) with resting tidal expiratory flow limitation (EFL; flow limited (FL)) compared with those without EFL (non-flow limited (NFL)). METHODS: Twenty subjects (13 men) of mean (SD) age 65 (8) years (range 43-77) suffering from COPD with forced expiratory volume in 1 second (FEV(1)) 47 (18)% predicted were studied before and after inhalation of salbutamol (400 microg). Routine pulmonary function tests were performed in the seated position at rest. EFL was assessed by the negative expiratory pressure (NEP) method and changes in end expiratory lung volume (EELV) were inferred from variations in inspiratory capacity (IC). Dyspnoea was measured using the Borg scale at rest and at the end of a 6 minute steady state exercise test at 33% of the maximal predicted workload. RESULTS: EFL occurred in 11 patients. Following salbutamol IC did not change in NFL patients but increased by 24% (95% CI 15 to 33) in FL patients (p<0.001). Maximal inspiratory pressure (PImax) improved at EELV from 45 (95% CI 26 to 63) to 55 (95% CI 31 to 79) cm H(2)O (p<0.05) in FL patients after salbutamol but remained unchanged in NFL patients. The workload performed during exercise amounted to 34 (95% CI 27 to 41) and 31 (95% CI 21 to 40) watts (NS) for patients without and with EFL, respectively. After salbutamol, dyspnoea did not change either at rest or during exercise in the NFL patients, but decreased from 0.3 (95% CI -0.1 to 0.8) to 0.1 (95% CI -0.1 to 0.4) at rest (NS) and from 3.7 (95% CI 1.7 to 5.7) to 2.6 (95% CI 1.1 to 4.0) at the end of exercise (p<0.01) in FL patients. CONCLUSIONS: Patients with COPD with EFL may experience less breathlessness after a bronchodilator, at least during light exercise, than those without EFL. This beneficial effect, which is closely related to an increase in IC at rest, occurs even in the absence of a significant improvement in FEV(1) and is associated with a greater PImax.

Administration, Inhalation↗
PubMed2002

Effect of CPAP on intrinsic PEEP, inspiratory effort, and lung volume in severe stable COPD.

BACKGROUND: Intrinsic positive end expiratory pressure (PEEPi) constitutes an inspiratory threshold load on the respiratory muscles, increasing work of breathing. The role of continuous positive airway pressure (CPAP) in alleviating PEEPi in patients with severe stable chronic obstructive pulmonary disease is uncertain. This study examined the effect of CPAP on the inspiratory threshold load, muscle effort, and lung volume in this patient group. METHODS: Nine patients were studied at baseline and with CPAP increasing in increments of 1 cm H(2)O to a maximum of 10 cm H(2)O. Breathing pattern and minute ventilation (I), dynamic PEEPi, expiratory muscle activity, diaphragmatic (PTPdi/min) and oesophageal (PTPoes/min) pressure-time product per minute, integrated diaphragmatic (EMGdi) and intercostal EMG (EMGic) and end expiratory lung volume (EELV) were measured. RESULTS: Expiratory muscle activity was present at baseline in one subject. In the remaining eight, PEEPi was reduced from a mean (SE) of 2.9 (0.6) cm H(2)O to 0.9 (0.1) cm H(2)O (p<0.05). In two subjects expiratory muscle activity contributed to PEEPi at higher pressures. There were no changes in respiratory pattern but I increased from 9.2 (0.6) l/min to 10.7 (1.1) l/min (p<0.05). EMGdi remained stable while EMGic increased significantly. PTPoes/min decreased, although this did not reach statistical significance. PTPdi/min decreased significantly from 242.1 (32.1) cm H(2)O.s/min to 112.9 (21.7) cm H(2)O.s/min). EELV increased by 1.1 (0.3) l (p<0.01). CONCLUSION: High levels of CPAP reduce PEEPi and indices of muscle effort in patients with severe stable COPD, but only at the expense of substantial increases in lung volume.

Aged↗
PubMed2003

Passive smoking and lung function in alpha(1)-antitrypsin heterozygote schoolchildren.

BACKGROUND: A study was performed to determine whether Pi heterozygotes exposed to smoking have a higher risk of reduced lung function than Pi M homozygotes. METHODS: The effect of passive smoking on lung function was investigated in a cross sectional study of 997 primary and secondary schoolchildren aged 11-13 years categorised by Pi phenotype as either PiM homozygotes or Pi heterozygotes. Data on respiratory health and risk factors were collected by questionnaire, lung function was measured by spirometric tests, bronchial hyperresponsiveness was evaluated by methacholine test, atopic status was evaluated by skin prick testing, and a blood sample was collected to determine Pi phenotype. Urinary cotinine and creatinine concentrations were determined and assessment of exposure was made from questionnaire data and urinary cotinine concentrations. The results were analysed by multiple regression analysis. RESULTS: Sixty one subjects (6.1%) were found to be Pi heterozygotes. Lung function did not differ between homozygotes and heterozygotes. There was a reduction in lung function in subjects exposed to parental smoking in the overall sample: FEV(1)/FVC ratio (-0.78%), FEF(25-75) (-0.11 litres), and FEF(75) (-0.13 litres). Interaction terms between parental smoking and Pi status were significant with regard to FEV(1)/FVC ratio (p=0.035) and FEF(50) (p=0.023). In subjects exposed to parental smoking the decrement in lung function in Pi heterozygotes tended to be greater (FEV(1)/FVC ratio = -2.57, FEF(25-75) = -0.30, FEF(50) = -0.43, and FEF(75) = -0.29) than in PiM homozygotes. These results did not change significantly when the urinary cotinine concentration was used as an exposure variable. CONCLUSIONS: The detrimental effect of environmental tobacco smoke on lung function in schoolchildren is confirmed. This harmful effect is greater in Pi heterozygotes than in PiM homozygotes.

Adolescent↗
PubMed1975

Intravenous prednisolone in chronic bronchial asthma.

A single injection of 40 mg prednisolone phosphate was given to 10 patients with chronic bronchial asthma. Changes in pulmonary function were followed over a 30-hour period. Statistically significant changes occurred in the tests employed one hour after the injection of prednisolone. The maximum change for the group as a whole was seen to occur after eight hours. This time course of response is very similar to that obtained in previous studies on similar groups of patients with oral prednisolone where the peak effect occurred nine hours after the drug had been given. Intravenous hydrocortisone produces a much earlier peak effect, at five hours, when it is administered to chronic asthmatic patients.

Adolescent↗
PubMed1979

Effective time of the forced expiratory spirogram in health and airways obstruction.

We have calculated the effective time (t eff) of the forced expiratory spirogram in healthy non-smokers, in patients with simple chronic bronchitis, and in patients with chronic obstructive lung disease. Effective time was obtained by dividing the area underneath the forced expiratory spirogram by the forced vital capacity (FVC) and is equal to the time constant of lung emptying if the FVC-time curve is a single exponential. In 75 healthy non-smoking adults, t eff showed a linear increase with age but no difference between the sexes. In 37 patients with low forced expiratory volume in one second (FEV1)/FVC ratios, t eff, as expected, was increased. In 19 subjects with simple chronic bronchitis and normal FEV1/FVC ratios, t eff was longer than or at the upper limit of 2 SE above the mean for healthy subjects of the same age. A comparison of t eff with FEV1/FVC suggested that in most normal subjects and patients the forced expiratory spirogram was a multiple exponential and that t eff was a more sensitive index for the evaluation of airway obstruction than the FEV1/FVC ratio.

Adult↗
PubMed1982

Repeatability of the moments of the truncated forced expiratory spirogram.

It is proposed that if the spirogram is truncated for moment analysis, this should be done with respect to volume and not time. Errors are incurred when the moments of one spirogram are compared with those of another. These errors are maximal with no truncation and are reduced by truncation. A method is described for deriving sequential truncated moments of the forced expiratory spirogram. The repeatability and discriminatory power of the truncated moments were assessed over five consecutive days in 21 symptom-free subjects and were compared with conventional spirometric tests. The first and second moments about the origin of the spirogram (alpha 1 and alpha 2), the moment ratio (square root alpha 2/alpha 1) and the forced expiratory time to truncation (FET) are progressively less repeatable within individuals the later the truncation point. The discriminatory power of alpha 1 and alpha 2 and FET declines with later truncation but the discriminatory power of the moment ratio is maximal with truncation at 85% forced vital capacity (FVC) an diminishes sharply if truncation is beyond 95% FVC. At 75% FVC truncation alpha 1 is as good as FEV1% in discriminating between our subjects, whereas alpha 1 at 100% FVC is only half as good as FEV1%. The moment ratio at 90% FVC truncation is highly reproducible (mean within person coefficient of variation 2.1%), has important discriminatory power and is little influenced by events early in the spirogram (correlation with FEV1% r = -0.61, p less than 0.001). The moment ratio at 90% of FVC has attributes which may be useful in detecting early airway obstruction and its further study is warranted in order to establish its normal range and predictive value.

Adult↗
PubMed1988

Forced expiratory indices in normal Libyan men.

Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory ratio in the first second (FEV1% VC), forced expiratory flow between 200 and 1200 ml (FEF200-1200), and forced mid expiratory flow between 25% and 75% of FVC (FMF) were measured in 275 Libyan men ranging from 20 to 60 years. All values were lower with increasing age and, apart from FEV1% VC, were positively correlated with standing height. This study can be used as a source of reference for Libyan men.

Adult↗
PubMed1988

Forced expiratory indices in normal Libyan children aged 6-19 years.

Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured in 796 Libyan children (386 boys and 410 girls) with ages ranging from 6 to 19 years. Values in girls were significantly less than those in boys after allowance had been made for age and height. FVC and FEV1 correlated best with standing height but were also correlated with body weight. These results may be used as a source of standard values for Libyan children.

Adolescent↗
PubMed1990

Effects of passive smoking on the pulmonary function of adults.

The effects of exposure to environmental tobacco smoke (passive smoking) on pulmonary function of non-smoking, healthy Iranian men (n = 167) and women (n = 108) were investigated. There were significant reductions in % predicted FEV1 (5.7%), forced vital capacity (FVC, 4.6%) and forced expiratory flow 25-75% (FEF25-75, 9.9%) among men exposed to cigarette smoke (n = 78). The adverse effect of passive smoking was greatest among men exposed at the workplace (reduction in % predicted FEV1 9.4%, FVC 7.6%, and FEF25-75 15.3%). No significant difference in pulmonary function was found among the 54 women exposed to passive smoke, but only eight women had smoke exposure at work. It is concluded that exposure to environmental tobacco smoke, particularly at the workplace, adversely affects the pulmonary function of adults.

Adult↗
PubMed1999

Oxidative stress during acute respiratory exacerbations in cystic fibrosis.

BACKGROUND: Patients with cystic fibrosis experience chronic systemic oxidative stress. This is coupled with chronic inflammation of the lung involving bronchial polymorphonuclear neutrophil accumulation and activation. We hypothesised that, during periods of acute respiratory exacerbation, free radical activity and consequent damage would be most marked and that intensive treatment of the infection would result in improvement towards values found during stable periods. METHODS: Plasma and red blood cells were collected from 12 healthy normal volunteers and from 12 patients with cystic fibrosis with an acute respiratory exacerbation (increased respiratory symptoms, reduction in forced expiratory volume in one second (FEV1) of more than 10%, and a decision to treat with intravenous antibiotics). Further samples were collected from patients following two weeks of treatment. Samples were analysed for inflammatory markers, markers of free radical damage, and aqueous and lipid phase scavengers. RESULTS: During respiratory exacerbations FEV1 and forced vital capacity (FVC) were lower than in controls (mean differences -2.82 (95% CI -2.12 to -3.52) and -3. 79 (-3.03 to -4.55) l, respectively) but improved following treatment (mean change 0.29 (95% CI 0.18 to 0.40) and 0.33 (0.23 to 0.43) l, respectively). Inflammatory markers during exacerbations were significantly higher in patients than in controls with the following mean (95% CI) differences: C reactive protein (CRP), 46 (17 to 75) g/l; neutrophil elastase alpha1-antiprotease complexes (NEAPC), 4.4 (1.77 to 7.07) mg/l; white cell count (WCC), 5.3 (4.7 to 5.9) x 10(9)/l. These markers decreased significantly following treatment with the following mean (95% CI) changes: CRP -26 (-10 to -42) g/l; NEAPC -3.1 (-1.3 to -4.9) mg/l; WCC -1.5 (-1.3 to -1.7) x 10(9)/l. Malondialdehyde (MDA) as a marker of free radical activity was significantly higher in patients during exacerbations than in controls with a mean (95% CI) difference of 193 (107 to 279) which improved with treatment (mean change -56 (95% CI -28 to -84) nmol/mmol cholesterol). Red blood cell polyunsaturated fatty acids were significantly lower in patients than in controls with a mean difference of -4.4(95% CI -2.6 to -6.2) moles percent, but did not improve significantly after treatment. Protein carbonyls during exacerbations were not different from controls but did increase with treatment compared with levels during the exacerbation (mean change 0.39 (95% CI 0.11 to 0.67) micromol/g protein). Aqueous and lipid phase scavengers in patients during exacerbations were significantly lower than in controls with the following mean (95% CI) differences: ascorbate, -19.0 (-2.7 to -35.3) micromol/l; sulphydryls, -122 (-77 to -167) micromol/l; retinol, -237 (-47 to -427) nmol/mmol cholesterol; beta-carotene, -52.8 (-11.8 to -93.8) nmol/mmol cholesterol; luteine, -50.4 (-10.4 to -90.4) nmol/mmol cholesterol; lycopene, -90.1 (-30.1 to -150.1) nmol/mmol cholesterol. Treatment resulted in improvement with the following mean (95% CI) changes: sulphydryls, 50 (32 to 68) micromol/l; retinol, 152 (47 to 257) nmol/mmol cholesterol; alpha- and beta-carotene, 0.6 (0.0 to 1.2) and 7.6 (0.0 to 15.2) nmol/mmol cholesterol, respectively; alpha-tocopherol, 839 (283 to 1405) nmol/mmol cholesterol; and lycopene, 8.2 (0.0 to 16.2) nmol/mmol cholesterol. CONCLUSIONS: Abnormalities of markers of inflammation, free radical activity, and radical scavengers were significantly more extreme during acute respiratory exacerbations and showed improvement with treatment. The need to provide protection from inflammation and free radical damage should therefore be dynamic and related to the inflammatory and oxidative processes.

Acute Disease↗
PubMed2003

Beta-thalassemia major: thin-section CT features and correlation with pulmonary function and iron overload.

PURPOSE: To describe and quantify thin-section computed tomographic (CT) features of the lung in patients with beta-thalassemia major (beta-TM) and determine the correlation between thin-section CT findings, pulmonary function test (PFT) results, and iron overload. MATERIALS AND METHODS: Forty-one patients with beta-TM (mean age, 24.5 years) underwent thin-section CT (during full inspiration and expiration) and PFTs. Two radiologists in consensus recorded the presence of focal bronchial and parenchymal abnormalities and air trapping. A semiquantitative air trapping score (ATS) was used, and patients were separated into air trapping-negative (ATS between 0 and 3) and air trapping-positive (ATS > 3) groups for statistical analysis. Iron overload was estimated by calculating the ratio of the signal intensity (SI) of the liver to the SI of paraspinous muscle by using magnetic resonance imaging in 27 patients (66%). We performed multiple logistic regression analysis to study the influence of age, PFT findings, and SI ratio on the presence of air trapping at CT and multivariate regression analysis to study the simultaneous influence of the presence of air trapping on obstructive PFT indexes. RESULTS: Air trapping was the predominant thin-section CT finding and was seen in 10 (24%) of 41 patients. No patient had interstitial lung disease at CT, although 11 (27%) had a restrictive spirometric pattern. Simple logistic regression analysis revealed significant associations between ATS and forced expiratory volume in the first second (FEV1), FEV1/forced vital capacity (FVC), forced expiratory flow (FEF) in the midexpiratory phase (FEF25%-75%), FEF at 50% of the FVC (FEF50%), and FEF at 75% of the FVC (FEF75%) (P =.019,.030,.007,.034, and.021, respectively) but not between ATS and SI ratio. At multiple logistic regression analysis, only FEF25%-75% was significantly associated with ATS (P =.019, adjusted odds ratio = 0.86, R2 = 41.8%). Multivariate analysis revealed that ATS did not have a significant influence on lung function indexes (P =.104), although significant effects were found with FEV1, FEF25%-75%, FEF50%, and FEF75% when examined separately. CONCLUSION: Air trapping may be present at expiratory thin-section CT in patients with beta-TM and is associated with reduced FEF25%-75% values but not hepatic iron overload.

Adolescent↗