Bulletin de physio-pathologie respiratoire最新文献

Seventeen of an original cohort of 25 non-smoking working coal miners and 6 age-matched controls studied in 1969 were re-examined in 1973. Measurements included lung volumes, maximal expiratory flow-volume curves, and closing volumes. Miners, when compared with controls, showed a marked decline in maximal expiratory flow at mid-vital capacity (V 50%) over the 4-year period which took place without significant change in the 1-second forced expiratory volume (FEV1). Frequency dependence of dynamic compliance (Cdyn) in association with an increased upstream airways resistance (Rus), and also loss of lung elastic recoil (PL(St)) which were present at the time of the original study led to similar declines in V 50%. An abnormally elevated closing capacity expressed as a percentage of total lung capacity (CC/TLC)% was found in 9 miners (53%) and none of the controls. Closing volume as a percentage of vital capacity (CV/VC)% was abnormal in 4 miners (23.5)% and no controls. Measurement of closing volume did not relate well to the variety of mechanical abnormality present on the original study; namely, loss of recoil or small airways obstruction. The presence of an elevated (CC/TLC)% and (CV/VC)% correlated mainly with the presence of hyperinflation as indicated by an elevated residual volume.

Respiratory mechanics were studied in 7 patients with vocal cord paralysis (Group A), 7 with laryngeal or sublaryngeal obstruction (Group B) an in 3 with intrathoracic tracheal obstruction (Group C). Group A showed decrease in FIV1.0, PIFR and VI50 when compared with corresponding expiratory parameters. Group B only showed a decrease in PIFR compared with PEFR. In all patients the high flow area near TLC in expiratory V/V curves was replaced by a flat flow pattern, extending variably into lower lung volumes. Predominant inspiratory flow reduction was present in Group A. Usually the normal expiratory plateau (IVPF curves) was absent even at very low lung volumes (about 25% VC) in the 8 patients studied (Group A, B, C). In Group B, inspiratory and expiratory resistances (IVPF curves) were similar up to about 50-60 cm H2O Palv; above this level inspiratory resistance was higher. The flow-pressure pattern (IVPF curves) of a normal subject with a relatively low resistance added at the mouth (9 mm i.d.) was very close to that of the resistance alone throughout inspiration. Above 60 cm H2O Palv expiratory resistance appeared to be lower, as in Group B. Calculated pressure drop due to convective acceleration across the resistance coincides with its pressure-flow relationship. These results do not support the hypothesis of inspiratory reduction in tracheal caliber as a contributing cause to inspiratory flow decrease. The difference PEFR-PIFR at highest Palv was inversely related to the degree of obstruction. Consequently, flow-volume curves of moderate sublaryngeal lesions may show disproportionate reductions in VI (like Group A) despite its fixed nature. Results obtained in six patients submitted to surgical treatment are discussed.

The functional residual capacity (FRC) was measured in 24 healthy subjects, 1-by the helium dilution method using a closed system and an open system during washout, and 2-using a constant pressure plethysmograph. Results obtained with the three methods were not significantly different. Furthermore, FRC was determined by helium dilution in 177 healthy men and in 100 healthy women, aged between 18 and 77 years. In both sexes, FRC was dependent on age, height (H) and weight, being greater in the taller, older subjects. For a given height and age, FRC decreased with increasing weight. Correlation coefficients between logarithm of (FRC/H3) and age and/or weight were highly significant. From these allometric relationships, it was possible to calculate FRC reference values, and then, reference values for other functional tests such as steady state TLCO and lung compliance.

The authors have worked out an adaptation to microsamples (200-400 mul) of the DUVELLEROY et al. method, allowing the continous registration of the O2-Hb association curve. The microsample being diluted in buffer solution, it is possible to predetermine its pH and PCO2. The prefixed conditions are maintained during the initial deoxygenation phase, and all along the curve registration. Moreover, the adjustment to the desired values of the pH and PCO2 allows the quantification of total BOHR effect, proton BOHR effect and carbamino-formation, during the course of oxygenation.

A modified technique for continuous recording of the Hb-O2 association curve for blood samples is proposed. The following alterations to the classical method of Duvelleroy et al. (5) were studied and validated: 1) dilution of blood micro-samples (200-400 mul) to 10 ml of a buffered phosphate solution; 2) use of a (CO2, O2) mixture allowing the maintenance of standard conditions (pH=7.40, PCO2=40 Torr) during the entire oxygenation process. The advantages of such modifications were: 1) reducing the time necessary for both deoxygenation and drawing Hb-O2 association curve (to about 20 min), hence permitting to work out large series of samples; 2) avoiding the necessity of imprecise a posteriori corrections, thus permitting analysis of the different components of the BOHR effect.