Prediction formulas f o r s t a t i c and dynamic spirometry, gas distribution, s t a t i c lung mechanics and the transfer t e s t were derived from measurements in healthy men. The measurements included total lung capacity, residual volume, airways resistance, s t a t i c elastic recoil pressure of the lung, s t a t i c compliance, closing volume, slope of the alveolar plateau (phase 1111, flow-volume variables (including mean t r a n s i t time) during breathing of a i r or a helium/oxygen mixture, and conventional spirometric indices. The results from 146 smokers and 124 never-smokers were evaluated separately and combined. For a l l lung function t e s t s a single regression equation was obtained. The prediction formulas included time-re1 ated smoking variables and were Val id for both smokers and never-smokers. For many lung function t e s t s , a nonlinear age coefficient resulted in a significant reduction in variance compared with.. simple linear models. Heavy tobacco smoking influenced most lung function t e s t s less than ageing from 20 t o 70 years, b u t for airways resistance, transfer factor and phase 111 the opposite was found.
Prediction equations for respiratory function tests were obtained by multiple regression of data from 263 healthy males. The material was evenly distributed in the ages 20-70 years, about one third each of non-smokers, smokers and ex-smokers. Measurements were done of lung volumes (with body plethysmograph), airways resistance, ventilatory capacity including flow-volume registration, gas distribution and closing volume, transfer factor and static elastic recoil pressures of the lung with calculation of static compliance. The parameters age, height, weight, years of tobacco smoking and grams of tobacco smoked each day showed significant correlation with the outcome of the test in most of the respiratory function tests. Therefore a set of basic regression equations including these parameters were calculated. In addition an 'extended' set of equations was calculated for prediction of some tests with inclusion of nonlinear terms and the parameter 'years of abstinence from smoking.' The reduction in variance which followed inclusion of tested parameters was moderate (20-69%). There were significant differences between results of the present study and several previously published regression formulas.
Bilateral block of the 5th through the 11th intercostal nerves was induced in 16 healthy men. In eight of the men, bupivacaine 0.25% was used and in the other eight, etidocaine 0.5%. Before and after induction of the block flow/volume curves, maximal airway pressures, and pulmonary compliance, were recorded, and helium spirometry and multiple and single breath nitrogen wash-outs were performed. There were no differences between the results in the two groups, and the material was therefore pooled. Total lung capacity was decreased by 4%. There was no increase in residual volume, though the maximal expiratory airway pressure decreased by 7%. There was an 8% decrease in functional residual capacity. Pulmonary recoil appeared to be unchanged, as also did the effort-independent peak expiratory flow rates. According to the pulmonary nitrogen clearance index, the overall pulmonary time constant did not alter, while the slope of the alveolar plateau in the single breath nitrogen wash-out test increased by 9%. The significance of the latter finding is unclear, but it is concluded that the nerve block had no obvious effects on pulmonary mechanics, the changes observed rather being attributable to effects on the chest wall.
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