Selection of reproducible forced expirograms: percentage or fixed-volume criterion.

The aim of this study was to evaluate whether the intrasession reproducibility of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) depends on height and lung volume. FVC tracings of 740 subjects (350 males) from a general population sample living in North Italy were analyzed. Subjects filled out a standardized questionnaire and performed three acceptable FVC maneuvers following the American Thoracic Society recommendations. The differences between the largest and the second largest FVC and FEV1 were computed as absolute (DeltaFVC, DeltaFEV1) and as percentage values (DeltaFVC%, DeltaFEV1%). The higher the tertiles of the largest FVC and FEV1 were, the higher were DeltaFVC and DeltaFEV1. Regarding FVC, borderline differences in both sexes for DeltaFVC and in males significant differences for DeltaFVC% were found among the tertiles. Regarding FEV1, in both sexes DeltaFEV1 significantly differed among the tertiles. DeltaFVC and DeltaFEV1 correlated with height and lung volume in both sexes, except for DeltaFVC versus the largest FVC in females. When DeltaFVC and DeltaFEV1 were analyzed with respect to respiratory symptoms/diseases and smoking habit, no significant differences were observed in both sexes, except for DeltaFEV1 between ever- and never-smoking males. It may be concluded that the intrasession within-subject variability of FVC and FEV1 is proportional to lung volume and height, regardless of the sex, presence of symptoms and smoking habit. Thus, our results confirm the usefulness of a reproducibility criterion based on a percentage rather than on a fixed volume.

Residual volume in a general population. Effects of body size, age, cigarette smoking, and respiratory symptoms.

Residual volume (RV) was obtained by subtracting vital capacity from total lung capacity determined by the single breath helium dilution (TLCsb) to measure CO diffusing capacity in 2,680 subjects (8 to 64 years old) of a general population sample. There were 712 normal subjects (243 male and 469 female subjects) selected to evaluate the pattern of RV by age and to derive reference values for internal comparisons. From 8 to 20 years old, RV showed an increase because of the cross-sectional body size effect; after 20 to 30 years, RV was still increasing, however, at a lower level. Age and height coefficients were significantly related to RV in younger and older ages, both in male and female subjects. The RV percent predicted and RV/TLC percent were higher in smokers when compared to nonsmokers and exsmokers (the difference was significant in male subjects). A dose-response effect was observed between RV percent predicted, RV/TLC percent, and pack-years. The RV percent predicted and RV/TLC percent were significantly higher in smokers and nonsmokers with FEV1 percent predicted below the normal limit (the difference was significant in male subjects). Moreover, higher values of RV percent predicted and RV/TLC percent were observed in subjects with wheezy symptoms in male smokers and nonsmokers. A negative significant correlation was observed between RV/TLC percent and the diffusing capacity adjusted for lung volume (DL/VA) in smokers, exsmokers and nonsmokers of both sexes, confirming the hypothesis that the decrease in DL/VA may be ascribed to the enlargement of terminal air spaces. In conclusion, determination of RV by the single breath helium dilution method is suitable in epidemiology, and it allows additional important information for understanding the physiopathologic mechanisms related to the pathogenesis of chronic obstructive lung disease.

Prevalence rates of respiratory symptoms in Italian general population samples exposed to different levels of air pollution.

We surveyed two general population samples aged 8 to 64 living in the unpolluted, rural area of the Po Delta (northern Italy) (n = 3289) and in the urban area of Pisa (central Italy) (n = 2917). Each subject filled out a standardized interviewer-administered questionnaire. The Pisa sample was divided into three groups according to their residence in the urban-suburban areas and to outdoor air pollution exposure (automobile exhaust only or industrial fumes as well). Significantly higher prevalence rates of all the respiratory symptoms and diseases were found in Pisa compared with the Po Delta. In particular, rhinitis and wheezing symptoms were higher in all the three urban zones; chronic cough and phlegm were higher in the zone with the automobile exhaust and the additional industrial exposure. Current smoking was more frequent in the rural area, but the urban smokers had a higher lifetime cigarette consumption. Childhood respiratory trouble and recurrent respiratory illnesses were evenly distributed. Exposure to parental smoking in childhood and lower educational level were more frequent in Po Delta, whereas familial history of respiratory/allergic disorders and work and indoor exposures were more often reported in the city. Multiple logistic regression models estimating independently the role of the various risk factors showed significant odds ratios associated with residence in Pisa for all the symptoms but chronic phlegm. For example, those living in the urban-industrial zone had an odds ratio of 4.0 (4.3-3.7) for rhinitis and 2.8 (3.0-2.6) for wheeze with respect to those living in the Po Delta.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional results of bronchial sleeve lobectomy.

The primary purpose of this study was to evaluate whether preservation of lung function parallels preservation of anatomy following elective bronchial sleeve-lobectomy (BSL). Between January 1984 and July 1988, 21 male patients (median age 51 years) with non-small cell lung cancer (n = 18), atypical carcinoid (n = 2) and inflammatory stenosis (n = 1) entered the study. Pulmonary function tests were performed pre- and postoperatively (at 3 and 12 months) and included spirometry, a quantitative perfusion lung scan and arterial blood gas analysis. The majority of operations were performed on the right lung (n = 15, 71%), with no operative deaths or major complications. Three months after surgery, the values of PaO2, PaCO2 and overall perfusion improved significantly (P less than 0.05), while there was a non significant improvement of the forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). The only parameter correlating (r = 0.46) and significantly (p = 0.032) predicting outcome after resection was overall perfusion. The preserved, reimplanted lobe rather than contralateral lobe(s) significantly (p = 0.014) contributed to remaining overall function. In 16 patients examined 12 months post-operatively a further improvement in pulmonary function occurred. The data presented demonstrate that preservation of pulmonary function parallels preservation of anatomy following BSL and that the functional contribution of reimplanted, ipsilateral lobe(s) is of paramount importance.

Single breath nitrogen test in an epidemiologic survey in North Italy. Reliability, reference values and relationships with symptoms.

The usefulness of single breath nitrogen test (SBN2) was evaluated in a cross-sectional epidemiologic survey on a general population sample (n = 3,289) of North Italy. Each subject was submitted to CNR standardized questionnaire and to lung function testing using automated equipment (Hewlett-Packard 47804S). Acceptable closing volume (CV) and slope of alveolar plateau (DN2%/L) tracings were performed by only 1,370 and 1,982 subjects respectively, in comparison with the 2,638 diffusing capacity and the 3,079 forced vital capacity acceptable maneuvers. Prediction equations were computed on normal subjects for CV indices, with the exception of DN2%/L: they were similar to those found in other studies. Significant differences among smoking categories were found for all the SBN2 parameters in males, but only for DN2%/L in females. The latter was also able to distinguish either subjects with airway obstruction from those without it or symptomatic from asymptomatic individuals, but DN2%/L did not give more information than Vmax75, a sensitive index of flow volume curve. Our results suggest that the place of SBN2 in large scale epidemiologic testing has not been justified.

Prevalence of respiratory symptoms in an unpolluted area of northern Italy.

Using a multistage stratified geographic cluster sample of households living in an unpolluted area of Northern Italy (near Venice), we enrolled 3289 inhabitants (aged 8-64 yr) for a longitudinal respiratory study. During the first cross-sectional survey, before the start of operation of a large oil-burning thermoelectric power plant, they completed a standardized administered questionnaire and performed several lung function tests. In the whole sample, dyspnoea grade 1 (11%), chronic cough and chronic phlegm (9%) were the most frequent respiratory symptoms; all the symptoms except dyspnoea were more prevalent in males than in females. Smokers (S) showed higher prevalence rates than ex-smokers (ES) and nonsmokers (NS), especially in males. In both sexes, the frequency of respiratory symptoms increased with increasing smoking as assessed by pack-years. An inverse relationship between prevalence of symptoms and socio-economic status was also observed. All tests of lung function were significantly impaired in S compared with NS in males; single-breath CO diffusing capacity and slope of alveolar plateau but not spirometric indices were significantly impaired in female S compared to female ES and NS. Finally, our prevalence rates were lower than in other epidemiological surveys: this result may be ascribed to the low levels of air pollution measured in the area.

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.

A computer-based method for on-line acquisition and analysis of bronchial challenge test.

We developed a computer program for the optimization and management of data collection in order to compute the change of forced expiratory volume in the first second (delta FEV1), provocative doses and to plot the dose-response curve for bronchial challenge test. Doses of methacholine are entered via the keyboard and forced vital capacity (FVC) with the highest FEV1 value obtained in each step is selected. When the imposed threshold of response has been reached, doses of administered methacholine and corresponding spirometric parameters are displayed and printed. Dose-response relationships are analysed: the increase of delta FEV1 for each unit of metacholine is computed in the interval between the two doses where delta FEV1 reached one of the imposed values (i.e. 15% or 20% or 30%). Finally spirometric values, dose-response curve and provocative doses are shown in a print-out. Computer values of provocative doses are higher than those obtained manually. This difference may be ascribed to the incorrect manual linear extrapolation. In conclusion the computer program is able to reduce consistently the time spent to analyze data from bronchial challenge test and allows a more precise determination of provocative doses by avoiding also inter-intra individual errors.

Comparison of algorithms for determining the end-point of the forced vital capacity maneuver.

The criteria of the American Thoracic Society (ATS) for determining the end-point of the forced vital capacity (FVC) maneuver were compared with an algorithm employed by a computer system (Hewlett-Packard), which yields a later end-point. The 150 subjects tested were divided into five groups of 30 on the basis of the following spirometric diagnoses: normal; small airways' obstruction (SAO); mild airways' obstruction (MAO); severe chronic obstructive pulmonary disease (COPD); or restrictive disease. The subjects performed a minimum of three maneuvers according to ATS standards, and the flow-volume curves with the greatest sum of FVC and forced expiratory volume in one second (FEV) were chosen for analysis by the two algorithms. Hewlett-Packard (HP) values for FVC and FVC time were always higher than the corresponding ATS values, and the HP values for flows were always lower than the corresponding ATS values. The higher differences were observed in the SAO group. In the group with severe COPD, high FVC differences and low flow differences were observed; on the contrary, in the restrictive group, low FVC differences and high flow differences were present. These results, in addition to the different location of the FVC end point, may be explained by the different morphology of the flow-volume curves. In conclusion, the ATS algorithm caused a systematic underevaluation of FVC and a systematic overevaluation of flows, which cause practical consequences only in the SAO group. In fact, 28 percent (17/60) of the subjects with SAO characteristics were considered "normal" using ATS criteria for the end-point.

Reference values for vital capacity and flow-volume curves from a general population study.

A longitudinal epidemiological respiratory study has been started in the North of Italy to investigate the natural history of obstructive airways disease and the long-term effect of SO2 exposure. The first cross-sectional study was completed in this unpolluted area before the activation of a thermoelectric power plant (500 tons of SO2 produced daily). Follow-up surveys are planned after pollution emission starts for a period of ten years. A sample (n = 3289) representative of the general population was drawn from the villages of the area according to the different risks of pollution exposure. Subjects completed questionnaires and performed lung function tests, including forced expiratory (FVC) manoeuvres. For 801 'normal' subjects, prediction equations have been derived in age/sex groups for slow vital capacity (VC) and variables from the FVC manoeuvre. Comparisons with predictions of other studies are reported. Differences among FVC predictions were found, indicating that the use of different criteria for determination of the FVC manoeuvre end-point can affect results. In 'normals' VC was higher than FVC in older subjects. The difference between VC and FVC may be hypothesized as an epidemiological indication of the ageing effect on the mechanical properties of the ventilatory system.

[Cross-over epidemiologic study of symptoms and respiratory function in workers at a furniture factory]. / Indagine epidemiologica trasversale sui sintomi e la funzione respiratoria nei lavoratori di un mobilificio.

An epidemiological survey on symptoms and diseases (collected with CNR standardized questionnaire) and on lung function (forced vital capacity and derived indexes; CO diffusing capacity) has been carried on in workers of a furniture plant in Arezzo. Significantly higher prevalence rates of cough in smokers than in non smokers, and of cough, phlegm, wheeze in non smoker workers than in the control group from a general population sample were present. A not significant relationship of symptoms and working years was also found. Lung function indices were in the normal range; smokers had significantly lower values than non smokers. A lower FEV1%, after adjusting for age and smoking, was shown by subjects with more working years. Thus, in a modern furniture plant the risk of adverse health effect seems to be slight: this conclusion may be confirmed by the ongoing longitudinal survey.

Reference equations for the single-breath diffusing capacity. A cross-sectional analysis and effect of body size and age.

A longitudinal study was implemented in an unpolluted rural area of northern Italy (near Venice), before the start of the operation of a large oil-burning thermoelectric power plant, in order to investigate the effects of the future exposure to air pollution and to elucidate the natural history of obstructive airways diseases. During the first cross-sectional survey, a sample of the general population (n=3,300, 8 to 64 yr of age) performed several lung function tests, and information on risk factors and on the presence of respiratory symptoms were obtained by a standardized questionnaire. There were 712 subjects who were classified as normal on the basis of rigid criteria and who were able to perform satisfactorily a single-breath CO diffusing capacity (DLCOsb) test. The DLCOsb values showed an increase with height and age early in life and a later decrease with age. Two age groups were selected to determine an age at which DLCOsb stopped increasing and began to decline. Reference equations were computed (using age and height) in these 2 different age groups in each of the sexes. Similar equations were calculated for the total lung capacity derived from single-breath helium dilution measurements. The DLCOsb values in this study were higher than reported by other investigators. The method of selection of the study population, the strict criteria for normal, as well as technical, differences probably explain this finding. Reference equations for diffusing capacity corrected to lung volume (DL/VA) were computed only for adults (much greater than 20) in both sexes, because age and height coefficients in young subjects were insignificant.(ABSTRACT TRUNCATED AT 250 WORDS)

[Respiratory function in chemical workers]. / Funzione respiratoria in lavoratori chimici.

The authors have evaluated the trend of the forced expiratory flows at low lung volumes and of the diffusing capacity for CO in a group of chemical workers of a dye factory, exposed to mineral dusts, organic pigments and solvents. Prevalences of chronic bronchitis and dyspnea, as evaluated by CNR questionnaire, were 15 and 32%. FEF25-75, MEF50 and MEF75 showed statistically significant differences with reference values. The reduction of KCO% was almost completely accounted for by smoking habit. During exercise, DLCOSS2 did not reach the expected values. 71% of the subjects with a diagnosis of COLD had worked more than 15 years in the dye factory. These results suggest a negative effect of the working environment, together with cigarette smoking, on lung function of subjects with a medium-long-term exposure.