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PubMed2005

Are ethnic differences in lung function explained by chest size?

BACKGROUND: Ethnic differences in lung function (LF) are recognised in adults and children. Most prediction equations for LF are derived from whites, so non-whites are at risk of erroneous assessment. It was hypothesised that differences in chest dimensions would explain differences in LF between Asian (Indian) and white schoolchildren. AIMS: To quantify the impact of chest dimensions on LF, which would inform our understanding of ethnic differences that have implications for health care. METHODS: Children aged 6-11 were studied in school. A questionnaire provided information on ethnicity and respiratory health. Spirometry was used to record FVC, FEV1, FEF25-75, and PEF. Weight, height, sitting height, and chest dimensions (chest height, circumference, antero-posterior and transverse diameters) were measured. RESULTS: Data were obtained from 294 healthy children. Standing height was the most important predictor of LF. Ethnicity was an independent predictor for all LF measures except PEF, where the effect was marginal. FVC in whites was 13.4% bigger than in Asians of the same height, and the FEV1 was 10.6% greater in whites. The influence of chest dimensions on lung function was trivial. Body mass index was smaller in Asians but did not explain differences in LF. CONCLUSIONS: Differences in chest dimensions did not explain the substantial effect of ethnicity on LF. Mechanisms whereby ethnicity exerts its influence may include differences in inspiratory muscle strength or lung compliance but remain speculative. Nevertheless it remains imperative that ethnic differences are recognised when interpreting LF tests.

Anthropometry↗
PubMed1976

[Critical analysis of the diagnostic value of the flow-volume curve].

Changes in the flow-volume curve after administration of a bronchodilator were studied in reversible bronchial obstruction. The concept of isovolume is used in analysis of the curve indices, i.e. it is felt that the index (75, 60, 50, 25% FVC) after administration should be fixed on the curve at the same volume as on the basic curve to enable an indirect account to be taken of changes in flow in function of time, since, if resistance is reduced, the emitted volume varies in the same period even though the conditions promoting the flow are unchanged.

Bronchodilator Agents↗
PubMed1996

A five year follow-up of lung function among chemical workers using flow-volume and impedance measurements.

Impedance of the respiratory system, measured using the forced oscillation technique (FOT), has repeatedly been proposed as a tool for occupational health screening. The aim of this study was to compare the outcome of impedance measurements and flow-volume curves, and to study relationships between lung function decline and specific exposures and smoking. Both measurements were applied in 136 chemical workers from seven main production/personnel groups during a 5 year follow-up (1990-1995). The prevalence of airway obstruction (forced expiratory volume in one second (FEV1) < 80% of predicted) at both time-points was about 5% but did not necessarily include the same subjects. The average decline in FEV1 over 5 yrs was 200 mL (predicted decline 160 mL). Although most impedance parameters correlated to flow-volume parameters in both years, a rapid 5 year decline of FEV1 (> 330 mL) was only accompanied by a significant decrease in the reactance at 8 Hz (X8) and an increase in the resonance frequency (f0). Interestingly, decline in FEV1 was significantly dependent on age, years of employment, pack-years, FEV1, and all impedance parameters at the start in 1990 (r = 0.35; p = 0.01). Similarly, the increase in f0 was significantly dependent on age, years of employment, pack-years, f0, FEV1, forced vital capacity (FVC), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF) at the start (r = 0.56; p < 0.01). Those with a rapid decline in FEV1, were relatively more represented among acid workers (relative risk (RR) = 2.14), maintenance workers (RR = 2.1) and bulk/transport workers (RR = 1.78), but none of these was significant. Lung function, however, was significantly lower in the bulk/transport workers (n = 14) compared to the rest, based both on flow-volume (FEV1, FVC) and impedance (X8, f0) measurements. Smoking had a significant effect on most flow-volume parameters but only for frequency dependence among the impedance outcomes. It is concluded that alterations in impedance parameters do reflect changes in flow-volume curves induced by age. smoking and occupational exposure. Therefore, these data are a valuable extension to current cross-sectional data.

Acids↗
PubMed1989

Effects of thoracic gas compression on maximal and partial flow-volume maneuvers.

Airway hysteresis can be evaluated by comparing maximal (MEFV) and partial (PEFV) expiratory flow-volume curves. The maneuvers are often obtained from pulmonary function systems that are subject to gas-compression artifacts. Because gas-compression artifacts might differentially affect PEFV vs. MEFV curves, we simultaneously obtained MEFV and PEFV curves by use of a spirometer and a volume-displacement plethysmograph (a method not subject to gas-compression artifacts) in normal and asthmatic subjects. Plethysmographic flow rates exceeded spirometric flow rates on all MEFV and PEFV maneuvers. When maximal flow exceeded partial flow (or vice versa) in the plethysmograph, the same result was virtually always observed for spirometric measurements. Alveolar pressure (PA) was higher on MEFV than on PEFV maneuvers in asthmatic subjects; comparisons between PA (on PEFV and MEFV maneuvers) in normal subjects varied at different lung volumes. Ratios of Vmax on PEFV maneuvers to Vmax on MEFV maneuvers (Vmax-p/Vmax-c) obtained from a volume-displacement plethysmograph differ quantitatively from ratios determined in systems subject to gas-compression artifacts; qualitatively, however, failure to account for thoracic gas compression ordinarily will not influence the ability to identify airway hysteresis (or lack thereof) by use of Vmax-p-to-Vmax-c ratios.

Adult↗
PubMed1989

Comparison of PEFR and FEV1 in patients with varying degrees of airway obstruction. Effect of modest altitude.

Measurements of FEV1 and PEFR performed on a Jones Pulmonor Spirometer (JPF) were compared with PEFR obtained with a mini-Wright peak flow meter (WPF) in 102 patients. Data were converted to percent predicted. Standard deviations of triplicate measurements were: FEV1, 3.01 percent; JPF, 7.22 percent; and WPF, 5.12 percent. Correlation of best of three measurements was FEV1-JPF r = .758; FEV1-WPF r = .744; and JPF-WPF r = .846. The mean percent predicted of the best of three values of FEV1 was 74.8 percent, JPF 91.4 percent, and WPF 94 percent. These higher values for percent predicted PEFR were obtained throughout the range of FEV1 values. Studies on nine normal volunteers in an atmospheric chamber suggested that higher altitudes may account for higher PEFR values. We conclude that PEFR, measured by either waterless spirometer or mini-Wright peak flow meter, has greater intrasubject variability than FEV1, and it tends to underestimate the degree of pulmonary impairment.

Adolescent↗
PubMed2003

Pulmonary function parameters in patients with allergic rhinitis.

Rhinitis patients may have abnormal airway function as demonstrated by an obstruction in large or small airways and increased bronchial reactivity to inhaled nonspecific provocating agents. The nonspecific bronchial hyperreactivity (BHR) is particularly important in patients with rhinitis because they are more prone to develop asthma. However, the factors associated with BHR in rhinitis patients have not yet been explained. Therefore, we performed this study to determine the differences in airflow rates, and bronchial and nasal resistance between nonasthmatic rhinitis patients with or without BHR, and to evaluate the relationship between these parameters and bronchial reactivity to methacholine. A total of 66 patients with allergic rhinitis but not asthma were selected for the study and divided into two groups; Group 1 (40 patients with allergic rhinitis and negative mechacholine provocation test) and Group 2 (26 patients with allergic rhinitis and positive methacholine provocation test). Pulmonary function tests, methacholine provocation tests, anterior rhinomanometry, and skin prick tests were performed on the patients. The study groups were homogeneous with regard to gender, age, duration of illness, and smoking ratio. Expiratory airflow parameters including FVC, FEV1, PEFR, and FEF25 were similar in both groups, however FEV1/FVC, FEF25-75, FEF50, and FEF75 were significantly lower in Group 2. Additionally, sRaw was significantly higher in Group 2 and negatively correlated with the expiratory airflow parameters for small airways. Total nasal resistance was not different between the groups. There was no correlation between nasal resistance and BHR to methacholine or airway resistance. The present study suggests that nonasthmatic rhinitis patients with BHR may have mild but significant changes in the small airways. Clinical and functional follow-up of these patients should assess the long-term consequences of these parameters and their clinical importance.

Adolescent↗
PubMed2002

Importance of drug delivery system in steroid aerosol therapy via nebulizer.

Aim of our study was to evaluate if the type of nebulizer can influence the effects of steroid aerosol therapy. We considered 27 asthmatics allergic to grasses with FEV1<80% of the predictive value or methacholine PD20 FEV1<750 mcg. The patients were divided into three groups in relation to the type of nebulizer they used and treated 9 weeks by aerosol therapy with beclomethasone dipropionate bid (800 mcg). Respect to the values recorded at the beginning and at the end of the therapy we found different variations of spirometric indeces and PD20 values among the three groups. We can conclude that the type of nebulizer influences steroid aerosol therapy and, particularly, jet nebulizers seem more efficient than ultrasonic nebulizers.

Adult↗
PubMed1983

Changes in the normal maximal expiratory flow-volume curve with growth and aging.

On the basis of their answers to a self-administered questionnaire, 697 nonsmoking healthy subjects were chosen from a randomly selected sample representative of the white non-Mexican-American population of Tucson, Arizona, enrolled in a longitudinal study of respiratory health. For each subject, the first satisfactory set of flow-volume data obtained during the first 3 consecutive surveys was selected for analysis. For forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), the single best value for each subject was selected. Other flow-volume measurements were derived from the single test with the best sum FEV, plus FVC. These data were used to derive improved prediction equations for each sex by age group for 5 spirometric and flow-volume variables. The resulting predicted values demonstrate the effects of development, maturation, and senescence on ventilatory function. "Normal" limits are proposed that take into consideration the between-subject variability and non-Gaussian distribution of the various measurements.

Adolescent↗
PubMed1990

Late pulmonary sequelae of bronchopulmonary dysplasia.

BACKGROUND: Bronchopulmonary dysplasia is a chronic lung disease that often develops after mechanical ventilation in prematurely born infants with respiratory failure. It has become the most common form of chronic lung disease in infants in the United States. The long-term outcome for infants with bronchopulmonary dysplasia has not been determined. METHODS: We studied the pulmonary function of 26 adolescents and young adults, born between 1964 and 1973, who had bronchopulmonary dysplasia in infancy. We compared the results with those in two control groups: 26 age-matched adolescents and young adults of similar birth weight and gestational age who had not undergone mechanical ventilation, and 53 age-matched normal subjects. RESULTS: Sixty-eight percent of the subjects with bronchopulmonary dysplasia in infancy (17 of the 25 tested) had airway obstruction, including decreases in forced expiratory volume in one second, forced expiratory flow between 25 and 75 percent of vital capacity, and maximal expiratory flow velocity at 50 percent of vital capacity, as compared with both control groups (P less than 0.0001 for all comparisons). Twenty-four percent of the subjects with bronchopulmonary dysplasia in infancy had fixed airway obstruction, and 52 percent had reactive airway disease, as indicated by their responses to the administration of methacholine or a bronchodilator. Hyperinflation (an increased ratio of residual volume to total lung capacity) was more frequent in the subjects with a history of bronchopulmonary dysplasia than in either the matched cohort (P less than 0.0006) or the normal controls (P less than 0.0004). Six of the subjects who had bronchopulmonary dysplasia in infancy had severe pulmonary dysfunction or current symptoms of respiratory difficulty. CONCLUSIONS: Most adolescents and young adults who had bronchopulmonary dysplasia in infancy have some degree of pulmonary dysfunction, consisting of airway obstruction, airway hyperreactivity, and hyperinflation. The clinical consequences of this dysfunction are not known.

Adolescent↗
PubMed1989

Effects of an external resistance on maximum flow in chronic obstructive lung disease: implications for recognition of coincident upper airway obstruction.

To determine how the presence of generalised airflow limitation due to chronic obstructive lung disease affects the recognition of simulated upper airway obstruction, a study was carried out in 12 patients (mean (SD) age 57 (7) years) with chronic obstructive lung disease (FEV1% predicted 53 (22), range 21-70) and 12 matched control subjects. Patients and control subjects performed maximal inspiratory and expiratory flow-volume curves in a variable volume plethysmograph with and without upper airway obstruction simulated at the mouth with a series of polythene washers of internal diameter 4, 6, 8, 10, and 12 mm. In patients, as in normal subjects, peak expiratory flow (PEF) and maximum inspiratory flow at 50% of vital capacity (Vmax50) were more sensitive to upper airway obstruction than were FEV1 or maximum expiratory flow at 50% VC (VEmax50); but the reductions in all indices caused by simulated upper airway obstruction were smaller in the patients than in the controls. The fall in PEF (whether expressed in absolute units or as a percentages) consequent on severe (4 mm) upper airway obstruction became smaller with increasing severity of chronic obstructive lung disease. The subjects also produced flow-volume curves with and without 6 mm upper airway obstruction while breathing helium and oxygen (heliox). In both groups the effects of heliox on PEF and Vmax50 were increased when upper airway obstruction was simulated. It was confirmed that the functional recognition of upper airway obstruction is more difficult in patients with chronic obstructive lung disease than in normal subjects and this difficulty increases with severity of disease; an unusually large increase in PEF or Vmax50 while the patient is breathing heliox should raise the suspicion of coexisting upper airway obstruction, but such a pattern is not specific.

Aged↗
PubMed1980

The decay of thoracic gas volume during forced expiration.

The MEFV curve has been analysed for the mechanical time constant distribution through the lungs, and it has been transformed into the forced decay of the thoracic gas volume (FVtD). The best regression formula to express the FVtD was the exponential in respect to the linear one, and this difference was statistically significant only in asthmatic patients. It seems likely that the FVtD will prove to be useful for detecting, already in the simple routine functional investigation, the airways obstruction due to asthma as interlobular inhomogeneity of ventilation.

Airway Obstruction↗
PubMed1988

Variability of maximal expiratory flow-volume curve in young volley players.

In order to assess the variability of forced expiratory flows, 15 male players (age 16-19 years, height 182-201 cm) of the Italian National Junior Volley team were studied twice with the pneumotachygraph of the computerized Hewlett-Packard Pulmonary System. The first time (April), but not the second (July), all the subjects were physically trained. Each subject performed at least three acceptable forced vital capacity (FVC) maneuvers, following the standard of the American Thoracic Society, with the exception of the criterion for determining the FVC end point. Mean values of forced mid- and end-expiratory flows were significantly higher in April than in July. Inter- and intrasubject coefficients of variation were lower for FVC and forced expiratory volume in 1 s (FEV1) than for the flows. However, the within-subject variability of expiratory flows is lower in our athletes than in the subjects described by other authors. Our findings indicate the importance of forced expiratory flows in detecting even minor intra-subject variations related to physical training and suggest that flow in the terminal portion of the FVC curve may be at least moderately dependent upon effort.

Adolescent↗
PubMed1985

Density-dependence of maximal expiratory flow and its correlation with small airway disease in smokers.

Density-dependence of maximal expiratory flow was measured in 110 patients prior to resection for peripheral coin lesions. The resected lung or lobe was examined morphologically and graded for emphysema, membranous bronchiolitis, and respiratory bronchiolitis. Density dependence did not decrease with increasing airway obstruction, and there was no relationship between density-dependence and peripheral airway abnormality or emphysema in the group as a whole. When patients were arbitrarily divided into those with forced expiratory volume in one second (FEV1) greater than 80% predicted (n = 80) and FEV1 less than 80% predicted (n = 30), density-dependence correlated significantly and negatively with membranous bronchiolitis in those with FEV1 greater than 80% predicted and significantly but positively in those with more advanced airway obstruction. We conclude that density-dependence of maximal expiratory flow is not an accurate predictor of peripheral airway abnormality in patients with mild to moderate air-flow obstruction.

Aged↗
PubMed1991

Individualized aerobic and high intensity training for asthmatic children in an exercise readaptation program. Is training always helpful for better adaptation to exercise?

In order to define the role of individualized training intensity in a conditioning program for asthmatic children, we have trained seven asthmatics (age = 11.4 +/- 1.8 years) at their ventilatory threshold (VTh) intensity level for a three-month period (aerobic training) and at maximal intensity also for three months (high intensity training). VTh is the point at which a nonlinear increase of VE occurs. Another group of seven asthmatics (age = 11.4 +/- 1.5) served as control subjects. Cardiopulmonary fitness was determined on a cycle ergometer before and after each training session. This study demonstrated that aerobic training, correctly adapted to the child's physical ability, induces the following: (1) a rapid and marked cardiovascular fitness increase; and (2) a decrease in VE over a given work range so that VTh is increased. This is of great importance because hyperventilation is a major determinant of exercise-induced bronchospasm. In contrast, even if high intensity training is well tolerated in an indoor swimming pool, the long-term effects are unsuitable for asthmatic children because the decrease of VTh will involve an increase of hyperventilation, even when exercise is performed at submaximal intensity.

Adaptation, Physiological↗