Spirometric reference equations for European females and males aged 65-85 yrs.

The aim of this study was to describe spirometric reference equations for healthy never-smoking European adults aged 65-85 yrs and to compare the predicted values of this sample with those from other studies including middle-aged and/or older adults. Reference equations and normal ranges for forced expiratory volume in one second (FEV1), forced vital capacity (FVC), forced expiratory volume in six seconds (FEV6), FEV1/FVC ratio and FEV1/FEV6 ratio were derived from a healthy subgroup of 458 subjects aged 65-85 yrs. Spirometry examinations followed the 1994 American Thoracic Society recommendations and the quality of the data was continuously monitored and maintained. Reference values and lower limits of normal were derived using a piecewise polynomial model with age and height as predictors. The reference values of FEV1 and FVC from the present study were higher than those given by prediction equations from the European Community for Coal and Steel. By contrast, use of prediction equations from Caucasian-American elderly subjects (Cardiovascular Health Study) consistently overpredicted FVC and FEV1 in females by 8.5 and 2.1%, respectively. In males, equations from the Cardiovascular Health Study overpredicted FVC by 2.8%, whilst underpredicting FEV1 by 2.5%. In conclusion, these results underscore the importance of using prediction equations appropriate to the origin, age and height characteristics of the subjects being studied.     

A comparison of spirometric values with subjects in standing and sitting positions.

Spirograms obtained from 235 subjects in standing and sitting positions revealed small differences for the forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). No statistically significant differences were found for the mean forced expiratory flow during the middle half of the FVC (FEF25-75%, or maximal midexpiratory flow) and FEV1/FVC. Sitting values were, on the average, higher for determinations greater than FVC of 2.14 L, FEV1 of 1.68 L, FEF25-75% of 2.16 L/sec, and FEV1/FVC of 75.7 percent. On the average, subjects with less than these values performed slightly better in the standing position.     

Obstructive and restrictive spirometric patterns: fixed cut-offs for FEV1/FEV6 and FEV6.

The purpose of this study was to determine fixed cut-off points for forced expiratory volume in one second (FEV(1))/FEV(6) and FEV(6) as an alternative for FEV(1)/forced vital capacity (FVC) and FVC in the detection of obstructive and restrictive spirometric patterns, respectively. For the study, a total of 11,676 spirometric examinations, which took place on Caucasian subjects aged between 20-80 yrs, were analysed. Receiver-operator characteristic curves were used to determine the FEV(1)/FEV(6) ratio and FEV(6) value that corresponded to the optimal combination of sensitivity and specificity, compared with the commonly used fixed cut-off term for FEV(1)/FVC and FVC. The data from the current study indicate that FEV(1)/ FEV(6) <73% and FEV(6) <82% predicted can be used as a valid alternative for the FEV(1)/FVC <70% and FVC <80% pred cut-off points for the detection of obstruction and restriction, respectively. The statistical analysis demonstrated very good, overall, agreement between the two categorisation schemes. For the spirometric diagnosis of airway obstruction (prevalence of 45.9%), FEV(1)/FEV(6) sensitivity and specificity were 94.4 and 93.3%, respectively; the positive and negative predictive values were 92.2 and 95.2%, respectively. For the spirometric detection of a restrictive pattern (prevalence of 14.9%), FEV(6) sensitivity and specificity were 95.9 and 98.6%, respectively; the positive and negative predictive values were 92.2 and 99.3%, respectively. This study demonstrates that forced expiratory volume in one second/forced expiratory volume in six seconds <73% and forced expiratory volume in six seconds <82% predicted, can be used as valid alternatives to forced expiratory volume in one second/forced vital capacity <70% and forced vital capacity <80% predicted, as fixed cut-off terms for the detection of an obstructive or restrictive spirometric pattern in adults.     

A comparison of a new transtelephonic portable spirometer with a laboratory spirometer.

The Spirophone is a new, portable transtelephonic spirometer which records the slow and the forced expiratory vital capacity tests. Data can be transmitted via the telephone to a remote receiving centre, where a volume-time curve and the flow-volume curve are displayed on screen in real time. The aim of this study was to compare the newly developed transtelephonic spirometer, with a laboratory spirometer according to the American Thoracic Society (ATS) testing guidelines. Spirometry indices (slow vital capacity (SVC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), forced expiratory flow at 25, 50 and 75% of FVC (FEF25, FEF50, and FEF75, respectively)) were measured from the SVC and the FVC tests in 45 subjects (30 patients, 15 healthy volunteers) according to the ATS standards. The data obtained with the laboratory system were compared to those from the Spirophone. The Spirophone measurements of SVC, FVC, FEV1, PEF, FEF25, FEF50 and FEF75 correlated closely (r=0.91-0.98) to those from the laboratory system, whereas FEF25, FEF50, and FEF75 were significantly higher with the Spirophone. It is concluded that the Spirophone is comparable to the standard spirometry for home monitoring of slow vital capacity, forced vital capacity, forced expiratory volume in one second and peak expiratory flow. The validity of the manoeuvre can be assessed on screen in real time.     

Working in swine-confinement buildings causes an accelerated decline in FEV1: a 7-yr follow-up of Danish farmers.

Work in swine confinement units causes exposure to high levels of organic dust and is associated with a high prevalence of work-related respiratory symptoms and probably with accelerated decline in forced expiratory volume in one second (FEV1). A 7-yr follow-up on FEV1, forced vital capacity (FVC), bronchial reactivity, and respiratory symptoms was performed on 181 Danish farmers. The participation rate was 76.3% and nonparticipants had more symptoms, were more likely to be current-smokers and had lower lung function in the first survey than participants in both surveys. Farmers who worked exclusively with pigs in the follow-up had an accelerated decline in FEV1 but not in FVC compared with dairy farmers, where the observed decline in FEV1 was close to the expected. For a nonsmoking pig farmer compared to a nonsmoking dairy farmer the mean additional decline in FEV1 was 17 mL x yr(-1) (53.0 mL x yr(-1) versus 36.1 mL x yr(-1)). The authors conclude that working in swine confinement units causes an accelerated decline in forced expiratory volume in one second but not in forced vital capacity. The mean decline is approximately 0.5 L during a working life and some farmers will develop clinically significant airway obstruction due to work in swine confinement units.     

Ventilatory parameters in healthy nonsmoking adults of Adriatic islands (Yugoslavia).

Forced expiratory volumes and flows (forced vital capacity (FVC), forced expiratory volume in one second (FEV1) peak expiratory flow (PEF), maximal expiratory flow at 25% (MEF25%), 50% (MEF50%) and 75% (MEF75%) of the FVC) have been measured in 909 healthy nonsmoking men and women, ranging in age from 18-86 yrs, who live on Eastern Adriatic islands (Yugoslavia). This area is essentially free from air pollution. The results have been analysed in terms of age and height and regression equations for each sex were derived. The equations for FVC and FEV1 were reliable and those for forced expiratory flows were not. Comparisons were made with prediction equations derived for other populations, especially with those which are commonly used in daily medical practice.     

Annual lung function changes in young patients with chronic lung disease.

Reference equations for ventilatory function that use different statistical models may introduce artifacts that affect the estimated change of lung function during growth in young subjects. The effect of differently modelled reference equations on the estimated annual change of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in young patients with chronic lung disease was assessed. Four frequently used reference equations were used to describe the longitudinal changes of FEV1 and FVC in 52 patients (23 females) with cystic fibrosis (CF) during a mean follow-up of 3.9 yrs. Choice of reference equations directly affected value and, most importantly, estimated annual change of FVC and FEV1. Mean+/-SD annual change of FEV1 varied from 2.2+/-6.2 to -2.2+/-3.6% of predicted. For two reference equations the estimated individual changes of FEV1 and FVC in CF were positively correlated with mean individual age. This probably reflects underestimation of deteriorating lung function. Variability of annual change was independent of age only when reference equations that were designed to accurately predict lung function during the pubertal growth spurt were used. These findings have implications for patient care and clinical research.     

Long- and medium-term ozone effects on lung growth including a broad spectrum of exposure.

The effects of semi-annual and 3.5 yr mean ozone (O3) concentrations on children's forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were assessed over a study period of 3.5 yrs in 2,153 schoolchildren from 15 study sites in South Western Germany and Lower Austria. Spirometric parameters were assessed twice a year, and differences between consecutive measurements divided by days were considered as a measure of lung growth. Exposure was analysed in four classes, separately for winter and summer (semi-annual mean O3 concentrations 22-30, 30-38, 38-46, 46-54 parts per billion (ppb) in summer and 4-12, 12-20, 20-28, 28-36 ppb in winter). Regression methods for repeated measurements were used, and these revealed a significantly lower FVC (FEV1) increase estimated at -19.2 (-18.5) mL x 100 days(-1) for semi-annual mean O3 exposure in summer between 46 and 54 ppb compared to exposure between 22 and 30 ppb. However, in winter, the estimated difference in FVC (FEV1) was 16.4 (10.9) mL x 100 days(-1) between the semi-annual O3 class 28-36 ppb and the 4-12 ppb class. By means of linear regression the study found that there was no association between growth rates and mean summer O3 for FVC and FEV1 over a 3.5 yr period. The authors conclude that medium-term effects on schoolchildren's lung growth are possibly present, but are in the long-term not detectable for forced vital capacity and forced expiratory volume in one second over a 3.5 yr period due to partial reversibility.     

Should forced expiratory volume in six seconds replace forced vital capacity to detect airway obstruction?

It has been suggested that forced expiratory volume in six seconds (FEV(6)) should be substituted for forced vital capacity (FVC) to measure fractions of timed expired volume for airflow obstruction detection. The present authors hypothesised that this recommendation might be questionable because flow after 6 s of forced expiration from more diseased lung units with the longest time constants was most meaningful and should not be ignored. Furthermore, previous studies comparing FEV(6) and FVC included few subjects with mild or no disease. The present study used spirometric data from the USA Third National Health and Nutrition Evaluation Survey with prior published ethnicity- and sex-specific equations for FEV(1)/FEV(6), FEV(1)/FVC and FEV(3)/FVC, and new equations for FEV(3)/FEV(6), all derived from approximately 4,000 adult never-smokers aged 20-80 yrs. At 95% confidence intervals, 21.3% of 3,515 smokers and 41.3% of smokers aged >51 yrs had airway obstruction; when comparing FEV(1)/FEV(6) with FEV(1)/FVC, 13.5% were concurrently abnormal, 1.5% were false positives and 4.1% were false negatives; and when comparing FEV(3)/FEV(6) with FEV(3)/FVC, 11.6% were concurrently abnormal, 3.3% were false positives and 5.7% were false negatives. Substituting forced expiratory volume in six seconds for forced vital capacity to determine the fractional rates of exhaled volumes reduces the sensitivity of spirometry to detect airflow obstruction, especially in older individuals and those with lesser obstruction.     

FEV6 as a surrogate for FVC in detecting airways obstruction and restriction in the workplace.

Compared with measurements of forced vital capacity (FVC), using the forced expiratory volume in six seconds (FEV(6)) reduces test time and frustration. It was hypothesised that using FEV(6) in the workplace setting would result in an acceptably low misclassification rate for detecting airways obstruction and spirometry-defined restriction when compared with using the traditional FVC. Experienced technicians from the National Institute for Occupational Safety and Health performed spirometry using dry rolling-seal spirometers as per American Thoracic Society guidelines in four workplace investigations. Airways obstruction was defined as an FEV(1)/FVC % below the lower limit of normal (LLN) using National Health and Nutrition Examination Survey III reference equations. Restriction was defined as an FVC below the LLN with a normal FEV(1)/FVC %. These "gold standard" definitions were compared with definitions based on FEV(6) (obstruction: FEV(1)/FEV(6) below the LLN; restriction: FEV(6) below the LLN with a normal FEV(1)/FEV(6)). The median (range) age of the 1,139 workers was 37 yrs (18-71 yrs) and 51.4% were male. A significantly high overall agreement was obtained between the two definitions. In conclusion, the current results confirm that forced expiratory volume in six seconds can be used as a surrogate for forced vital capacity in detecting airways obstruction and restriction in workers, although with some misclassification when compared to obtaining American Thoracic Society-acceptable manoeuvres of longer duration.     

Spirometry and maximal expiratory flow-volume curve reference standards for Polynesian, European, and Chinese teenagers

Lung function was compared and reference standards were determined in 1,007 Polynesian, European, and Chinese teenagers attending school in Tahiti (517 boys, 490 girls; mean age, 14.4 years). Spirometric study results and maximal expiratory flow-volume curves were measured using techniques recommended by the American Thoracic Society. Age, standing height, and weight were chosen as the independent variables for males, and age and standing height for females. Regression equations constructed with logarithmically transformed dependent variables provided accurate predictions. We observed significant racial differences: in the Europeans, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were higher than the mean values predicted for the whole study population, while forced expiratory flow during the middle half of the FVC (FEF25-75%) and maximal expiratory flows after 25, 50, and 75 percent of FVC had been exhaled (V max 25, 50, and 75, respectively) were about equal to the mean values; in the Polynesians, volumes and flows were mostly lower than the mean; in the Chinese, FVC in boys and girls, and FEV1 in girls only, were lower, while the other flows were higher. The FEV1/FVC, FEF25-75%/FVC, Vmax25/FVC, Vmax50/FVC, and Vmax75/FVC were significantly higher than the mean in the Chinese boys and girls and often lower in the Europeans.     

Post-bronchodilator spirometry reference values in adults and implications for disease management

RATIONALE: International guidelines promote the use of post-bronchodilator spirometry values in the definition and severity classification of chronic obstructive pulmonary disease. However, post-bronchodilator reference values have not yet been developed. OBJECTIVES: To derive reference values for post-bronchodilator forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC, and to compare these reference values with locally derived and existing pre-bronchodilator reference values. METHODS: Based on a random sample of a general adult population, 2,235 subjects (70% of invited subjects) performed spirometry with reversibility testing. A reference population of healthy never-smokers constituted 23% of the study population (n=515). Reference values for median and lower-limit-of-normal pre- and post-bronchodilator lung function and bronchodilator response were modeled using quantile regression analyses. MAIN RESULTS: The reference population had equal proportions of men and women in the age range 26-82 yr. Both FEV1 and FVC decreased with age and increased with height. FEV1/FVC decreased with age, although this trend was not statistically significant for men after bronchodilatation. Linear models gave the best overall fit. Lower-limit-of-normal post-bronchodilator FEV1/FVC exceeded 0.7 for both sexes. Post-bronchodilator prediction equations gave higher predicted FEV1 and FEV1/FVC than both locally derived and existing pre-bronchodilator equations. The bronchodilator response decreased with age. CONCLUSIONS: The present study is the first to develop reference values for post-bronchodilator lung function. Post-bronchodilator prediction equations can facilitate better management of patients with chronic obstructive pulmonary disease by avoiding falsely high FEV1% predicted with a subsequent underestimation of disease severity.     

Pulmonary function testing. What is 'normal'?

For many years, confusion has existed concerning the normal range for pulmonary function test results. Using statistical guidelines that have been traditionally applied to the interpretation of measured forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1), we have redefined normal limits for the most common pulmonary function test values, including those for FVC, FEV1, mean forced expiratory flow during the middle half of the FVC, FEV1 as a proportion of FVC, residual volume, functional residual capacity, total lung capacity, diffusion capacity, maximum voluntary ventilation, and peak expiratory flow. Our goal is to provide a simple and consistent scheme for interpretation of pulmonary function test data. We consider the assumptions used to achieve this simplification to be reasonable, as long as their limitations are understood.     

COPD和哮喘患者支气管舒张实验用力肺活量和呼气容积的变化

目的 探讨COPD和哮喘患者支气管舒张实验用力肺活量和呼气容积变化.方法 随机选取COPD急性加重期78例和哮喘急性发作期64例,采用支气管舒张实验比较COPD和哮喘患者实验前后用力肺活量(FVC)、一秒用力呼气容积(FEV1)的增加量和增加率.结果 支气管舒张实验后,COPD患者的用力肺活量(FVC)的增加量191 ml,较舒张前增加12.93%,而一秒用力呼气容积(FEV1)的增加量63 ml,较舒张前增加10.01%;哮喘患者的用力肺活量(FVC)的增加量363 ml,较舒张前增加15.34%,而一秒用力呼气容积(FEV1)的增加量289 ml,较舒张前增加23.57%.结论 COPD患者支气管舒张试验后用力肺活量的增加幅度大于呼气容积的增加幅度,而哮喘患者正好相反,因此用力肺活量可鉴别COPD和哮喘患者病情的客观指标.     

Static lung volumes in patients with Cushing's disease.

OBJECTIVE: Numerous clinical manifestations have been described in association with Cushing's syndrome. There are no eligible data on pulmonary function tests in Cushing's disease (CD). We aimed to asses pulmonary function tests including spirometry in a series of patients with active CD. MATERIALS AND METHODS: This cross-sectional study comprised 10 patients with Cushing's disease (F/M, 9/1). The forced expiratory volume in 1st second (FEV1), the forced vital capacity (FVC), the FEV1/FVC ratio and the forced expiratory flow over the middle half of the FVC (FEF 25-75%) values and predicted values were determined by spirometry. RESULTS: Mean age, height, weight, body mass index were 36.7+/-12.6 yrs (range 22-63 years), 156.9+/-8.4 cm, 74.1+/-10.7 kg, 29.6+/-3.8 kg/m(2), respectively. Spirometric abnormalities (impairment of FEV1, FVC, FEV1/FVC and FEF 25-75 values) were not detected, and there were no significant differences compared to reference values. Disease duration and cortisol concentrations by HDDSTs were negatively correlated with predicted FEV1/FVC values and the percentage of predicted FEV1 ratios, respectively. DISCUSSION: The lung volume and ventilatory performance by spirometry were not disturbed in patients with endogenous hypercostisolism due to Cushing's disease.     

Clinical comparison of two electronic spirometers with a water-sealed spirometer.

Two electronic spirometers which use a hot-wire anemometer to measure air flow were clinically compared with a water-sealed spirometer. The forced vital capacity (FVC), the forced expiratory volume in one second (FEV1), the FEV1/FVC%, the mean forced expiratory flow between 200 and 1,200 ml of the FVC, the mean forced expiratory flow during the middle half of the FVC, the mean forced expiratory flow between 75 and 85 percent of the FVC, and the maximum voluntary ventilation were determined for a group of 67 subjects. Techniques are described for connecting the spirometers in series to permit evaluation by human subjects or by syringe injection. High correlation coefficients generally were obtained when comparing the electronic spirometers with the water-sealed spirometer, but the actual range of percent difference was greater than 11 percent in all spirometric tests. The results indicate the need for systematic evaluation of electronic spirometers to characterize their deviation from accented standards. Frequent calibration is necessary to maintain consistent performance.     

Forced expiratory parameters in healthy preschool children (3-6 years of age)

In a group of 173 healthy preschool children 3-6 years of age (body height, 90-130 cm; 102 boys and 71 girls) out of total 279 children examined, maximum expiratory flow-volume (MEFV) curves were recorded in cross-sectional measurements. The majority (62%) of preschool children were able to generate an MEFV curve as correctly as older children. From the curves, maximum expiratory flows at 25%, 50%, and 75 % of vital capacity (MEF(25), MEF(50), and MEF(75)), peak expiratory flow (PEF), forced expiratory volume in 1 sec (FEV(1)), forced vital capacity (FVC), and area delineated by MEFV curve (A(ex)) were obtained. The purpose of the study was to establish reference values of forced expiratory parameters in preschool children suitable for assessment of lung function abnormalities in respiratory preschool children. The values of the studied parameters increased nonlinearly and correlated significantly with body height (P < 0.0001); the correlation was much lower with age. A simple power regression equation was calculated for the relationship between each parameter and body height. A best-fit regression equation relating functional parameters and body height was a power function. Based on the obtained regression equations with upper and lower limits, we prepared tables listing reference values of forced expiratory parameters in healthy Caucasian preschool children, against which patients can be compared. No statistically significant gender differences were observed for MEF(25), MEF(50), MEF(75), PEF, FEV(1), FVC, and A(ex) by extrapolation. The reference values were close to those obtained in our older children. A decline of the ratios PEF/FVC, FEV(1)/FVC and MEF/FVC with increasing body height suggested more patent airways in younger and smaller preschool children.     

Pulmonary function in normal south Indian children aged 7 to 19 years

There are only a few studies that have established reference standards for pulmonary function of Indian children. Reference standards for pulmonary function that are reported for Indian children are mainly from northern and western parts of the country and there is a paucity of data on pulmonary function in normal South Indian children. Therefore, pulmonary function tests (spirometry and maximal expiratory flow rates) were carried out in 469 South Indian healthy children (246 boys and 223 girls) between 7-19 years of age to derive regression equations to predict pulmonary function. The correlations of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were, in general highest with height followed by weight and age. Peak expiratory flow rate (PEFR), forced mid-expiratory flow (FMF) and forced expiratory flow rates at 25%, 50% and 75% of FVC (FEF25% FVC, FEF50%FVC and FEF75%FVC) were also significantly correlated with physical characteristics (age, height and weight). With a view to find out regression equations to predict spirometric functions based on physical characteristics (age, height and/or weight), the functions were regressed over all possible combinations of regressor variables, i.e. age, height and weight separately for boys and girls. The height influences the prediction equation in males to a great extent, whereas age and weight had greater influence in girls. Regression equations were derived for boys and girls for predicting normal pulmonary functions for children in South India. The pulmonary function measurements in South Indian children were similar to those reported for subjects from Western India and lower than those reported for Caucasians.     

Predictive nomograms for forced expiratory volume, forced vital capacity, and peak expiratory flow rate, in Chinese adults and children

A survey of three indices of ventilatory capacity, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR), was undertaken on 3490 Chinese inhabitants of Hong Kong. Nomograms have been constructed for the prediction of these three indices for subjects between the ages of 5 and 75 years.     

To clip or not to clip? Noseclips for spirometry.

The use of noseclips for open-circuit spirometry is sporadic, despite guidelines encouraging their use. The authors aimed to evaluate whether noseclips significantly affected measurements of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) in children attending a tertiary, paediatric respiratory centre. Children attending the asthma and cystic fibrosis (CF) clinics were asked to perform two sets of spirometry, one with and one without noseclips in random order, 20-min apart. Paired data was obtained on 62 patients (32 asthma, 30 CF) with a median age of 11.4 yrs (range 7.2-17.2 yrs). There were no systematic differences in FEV1 or FVC measured with and without noseclips, although seven children (11%) had clinically significant differences in FEV1 of >190 mL. There is no clear advantage to wearing noseclips when performing open-circuit spirometry. Individuals should be assessed to ascertain their optimal technique, which should then be used consistently in clinical practice. Noseclips should probably be retained for research protocols.