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The measurement of arterial blood oxygen tension (PaO2) in 54 patients with chronic nonspecific lung disease with a FEV1.0 of 1.51 or less, in a stable clinical state, at rest, indicated subnormal results to be more frequent among "bronchitics" (79 per cent with hypoxemia) than than among "emphysematous" patients (63 per cent with hypoxemia). The patients were classified according to a mixed clinical-roentgenologic-biological "score" (Nash et al., 1965). A significant correlation was found between PaO2 and the "emphysema score" (r=0.36; p less than 0.01). The average PaO2 was significantly (p less than 0.02) lower in "bronchitics" (65.5 +/- 8.8 mmHg; n = 14) as compared to the "emphysema" group (71.8 +/- 5.7; n = 19), in agreement with the data of the literature.

'Conventional' (lung volumes, airway conductance, CO transfer factor) and 'small-airway dysfunction' (single-breath N2 washout, maximal expiratory flows with air and a helium-oxygen mixture) tests were performed in a group of asymptomatic male ex-smokers (n = 20) with normal spirometry and compared to those of a similar group of middle-aged nonsmokers (n = 41). The study group had a mean life-long consumption of 13.2 +/- (SD) 8.8 pack-years and had stopped smoking 1-21 years ago, mean 7.3 +/- (SD) 5.8 years. Among the conventional tests, a minimal increase in residual volume and residual volume/total lung capacity ratio was found. Ex-smokers had a steeper phase III slope, a higher closing volume/vital capacity ratio, lower forced flows with air and a higher volume of isoflow, but neither difference between the group means was significant. There was a trend to more abnormal small-airway tests as a function of increased smoking, but only the correlation between percent of predicted closing volume and pack-years reached significance (r = +0.51, p less than 0.05). We conclude that small-airway function normalizes in the long term in most ex-smokers if they become asymptomatic, with less than 10% still having abnormal results years after they stopped smoking.

Two simple indices of pulmonary mixing (helium mixing time in a closed circuit, and mixing ventilation) were measured in 274 patients (mostly miners) with silicosis, aged 50 years or less (mean 42.4 years); the results were analysed in respect to silicosis category and type, presence of co-existent chronic bronchitis and ventilatory performance, and were compared to those of a group of normal subjects to assess statistical significance. The average results for the whole group were 5.81 min for mixing time (tmix) and 62.3 1 for mixing ventilation (Vmix), representing 1.8 times and 2.4 times the normal, respectively; the results were higher for patients with co-existent chronic bronchitis within each radiological category, except the last ("C" opacities), but the differences were significant only for patients with small opacities and with "suspect pneumoconiosis". Among patients with small rounded opacities the co-existence of healed tuberculosis (apical fibrous nodules) or of other X-ray changes did not influence the pulmonary mixing; no difference was found between the three types of small opacities. A slight tendency towards lower values in patients with early conglomeration ("A" opacities) allows the suggestion of conglomeration starting in "slow" lung spaces. The best results were those of patients with normal ventilatory function followed by those with a restrictive and then by those with an obstructive ventilatory impairment. The most severe mixing disturbance was found among patients with chronic bronchitis and obstructive defect with "suspect pneumoconiosis", who are not covered by occupational disablement compensation.

"Sensitive" and "conventional" lung function tests were compared in a group of 114 males, aged 35-55 years, including healthy non-smokers, asymptomatic smokers with normal spirometry, and smokers with chronic bronchitis with or without mild airflow limitation. In non-smokers, with the exception of a MEF vs. FEV1 correlation, "sensitive" and "conventional" tests were independent of each other. In asymptomatic smokers the phase III slope and the closing volume were significantly related to FEV1, RV/TLC and CO transfer factor. In smokers with chronic bronchitis all the "sensitive" tests were related to the "conventional" tests (with the exception of the total lung capacity). Hyperinflation and CO transfer impairment suggest that early emphysema may accompany mucus hypersecretion in smokers.

Pulmonary function variables (forced expiratory flows and vital capacity, static lung volume, alveolar N2 slope, closing volume and closing capacity) were compared in a group of 10-16 year old children with (n = 65) and without (n = 440) symptoms or signs of mild acute respiratory infection ('common cold'). Symptomatic children had a significant impairment of forced expiratory vital capacity and flows, with no change in static volumes, alveolar N2 slopes and closing volumes. The effect was present only in boys (in whom RV/TLC and phase III slope were borderline abnormal), was more evident in older children (13 to 16 years) and was independent of the smoking habits or the presence of chronic respiratory symptoms. The results are in favour of a predominant involvement of upper airways, but signs of lower airways dysfunction are present in boys and in children 13 to 16 years old.

At the request of its inhabitants, an epidemiological survey was conducted among the children of Carling, a particularly polluted industrialized town in the department of the Moselle in North-East France. Contrary to all expectations, no major toxic effect of industrial pollution on the respiratory health of the children was found. There was some correlation between the fact of living in a polluted area and a claimed respiratory morbidity. However, the potentially harmful effect of atmospheric pollution could not be translated in terms of abnormalities of respiratory function. In contrast, a significant effect of the smoking habits of the parents, and particularly of the mothers, on respiratory symptoms and spirographic data of their children was observed.

Two mini-peak flow meters, the Airmed (mini-Wright) and the Medicheck (Pulmonary Monitor), were assessed against a reference electronic spirometer (Spiromatic, based on a pneumotachograph, integrator and an Apple II computer) in a series of 10 healthy subjects and 20 patients with chronic obstructive lung disease. The devices to be tested were mounted in series with the reference instrument; each subject did five trials. It was found that the Airmed instrument overestimated the flows up to 9 l X s-1 (i.e. in patients, average difference 0.86 l X s-1, p less than 0.001; in healthy subjects, average difference 0.35 l X s-1, p less than 0.001). The correlation with the results of the reference instrument was high (r = 0.992) in healthy subjects, whose regression slope was less than unity (0.763). In patients the correlation was satisfactory (r = 0.974), and the slope close to 1 (1.05). The Medicheck overestimated slightly the results of patients (difference 0.17 l X s-1, p less than 0.01); in normal subjects the overestimation was present only below 10 l X s-1 and the difference with the reference instrument nonsignificant (average 0.19 l X s-1). The results were closely related to those of the reference spirometer in both healthy subjects (r = 0.960) and patients (r = 0.936). As for the first instrument the slope of the regression was below 1 in healthy subjects (0.751) and practically one (1.01) in patients.(ABSTRACT TRUNCATED AT 250 WORDS)

A patient with pronounced dyspnoea and cyanosis was found to have severe hypoxaemia with normal spirographic values. His past history included arterial hypertension, myocardial infarction and phlebitis of the lower limb. Airways resistance was normal, but maximal expiratory flow rates at low lung volume (Flow-volume curves) were reduced, suggesting "peripheral" airways obstruction. This was confirmed by the presence of pulmonary hyperinflation and mechanical non-homogeneity accompanied by unevenly distributed ventilation, as shown by alveolar nitrogen gradient. There was marked hyperventilation with hypocapnia. Since transfer values (measured by the CO single-breath method) and lung distensibility values were normal, emphysema could be ruled out as a cause of obstruction. Analysis of pressure-flow relationship confirmed that the obstruction of peripheral airways was "intrinsic" in character. It could be due to an increase in lung extravascular fluid (interstitial oedema due to left cardiac failure), or to repeated micro-emboli in the lungs, or to hypocapnia, these three mechanisms possibly being associated.

Peripheral airways obstruction (PAO) is a pathophysiologic syndrome combining normal values of the usual tests (one-second forced expiratory volume, airway resistance) and abnormalities of "sensitive" tests (dynamic compliance, closing volume, forced expiratory flows, response to helium-oxygen mixtures). Clinical data are scarce, and the radiological aspects nonspecific. The natural history of the PAO is not fully understood. Therapeutic measures could be useful, but their efficacy was not yet systematically evaluated. From the theoretic point of view, the notion of bronchiolar obstruction is important in as much as it represents the initial phase of any obstructive process. In practice, the detection of a PAO identifies the "at risk" subject allowing the application of efficient preventive measures.

In an attempt to identify patterns of variation in airflow obstruction and to detect patients with marked bronchial lability, a factor reported to be associated with an increased risk of sudden asthma death, we obtained serial peak expiratory flow rate (PEFR) recordings from out-patients with chronic, clinically stable, asthma (N = 27) for one week. Similar recordings were obtained for comparison from out-patients with chronic obstructive pulmonary disease (COPD) (N = 14) and from healthy controls (N = 14). Analysis of the recordings disclosed patterns of PEFR variation for 20 asthmatics but not for COPD patients or healthy subjects. Ten asthmatics were classified as "brittle" asthmatics (BA), nine as morning dippers (MD) and one as a gradually deteriorating (GD) asthmatic. Patients were considered at risk when their diurnal fall (DF) in PEFR was greater than 50% on at least one occasion during the survey. This was the case for seven BA, three MD and one GD patient. Diurnal falls in PEFR of this magnitude were not observed among asthmatics without a discernible pattern of variation of airflow obstruction or COPD patients. A relationship was found between the amplitude of PEFR fluctuations and the frequency of significant DF in PEFR (greater than 25%) during half or more days of the survey. A significant fraction of out-patients with chronic, clinically stable asthma may present patterns of variation in airflow obstruction and diurnal falls in PEFR of a magnitude such as has been associated with sudden asthma death.

The interrelationships of breath holding lung transfer factor (TCO) and transfer coefficient (KCO) with ventilatory obstruction (FEV1.0) and FEV1.0/VC) and hyperinflation (RV and RV/TLC) were studied in 37 patients with chronic nonspecific lung disease with a FEV1.0 of 1.5 litre or less classified as "bronchitic", "emphysematous" or "intermediate" according to Nash, Briscoe and Cournand (1965). No relationships could be found between TCO and airway obstruction or hyperinflation. KCO tended to decrease as RV increased (r=-0.26) and was weakly related to the FEV1.0/VC ratio in "intermediate" (r=0.34) and "emphysema" (r=0.29) patients but these relationships were nonsignificant.

The respiratory health of 138 arc welders and 106 control subjects in the same company was studied in 1981 and in 1986. Most of the subjects welded mild steel using the Metal Inert Gas (MIG) process. The controls were workers in the same company, not exposed to any known pulmonary risk. The welders and controls in the analysis had not changed their professional activity nor their smoking habits during these five years. The examinations consisted of a questionnaire on respiratory symptoms, a thoracic auscultation, a chest X-ray and lung function tests: flow-volume curve and steady state CO transfer test. The examinations in 1986 confirmed the risk of non specific radiological impairment (pulmonary reticulo-micronodulation) and of obstruction in the small bronchi, which had already been observed in 1981 in the arc welders in this company. These impairments did not seem to have evolved more than in the controls, but do however justify regular surveillance of the respiratory health of arc welders.

The variability and reproducibility of maximal static respiratory pressure measurements was evaluated in 22 healthy subjects and 17 patients with chronic respiratory disease. The difference between consecutive measurements represented 4 to 8 per cent of the result in healthy subjects and 10 to 11 per cent in patients. The difference between the first and the second measurement was not significant and the two values were highly correlated. At 1 to 3 days interval, the results may differ by 10 to 15 per cent in healthy subjects and 20 to 22 per cent in patients. These differences tend to be greater for expiratory (as compared to inspiratory) pressures and for females (as compared to males). A preliminary assessment of the variability and reproducibility of maximal respiratory pressures is compulsory for a valid interpretation of their change in clinical studies.