[Effect of obesity on the ventilatory capacity of the respiratory system. II. Reference spirometry values of VC and FEV1 for overweight males].

642 persons without respiratory and circulatory diseases were selected from 1087 steel mill workers. The examined persons were classified according to the intervals of relative body mass. The relations between spirometric parameters (VC and FEV1) and degree of obesity were studied. For each interval the equations of multiple regression were calculated, taking into account the dependence of VC and FEV1 on age, height and present body mass. The numeric factor from the equation of multiple regression of coefficient describing the dependence of VC on the present body mass was positive in 90-114% and 115-124% intervals but negative in 125-134% and 135% of body mass. In case of FEV1 the negative factor of the same coefficient was not negative until 135% of body mass. A positive correlation of VC and FEV1 with the present body mass in the whole population was shown. If the group of obese persons was formed on the basis of Wot anthropometric index (which included skinfolds thickness, present body mass and height), significantly lower values of VC and FEV1 were found in comparison to non-obese counterparts. For the persons with morbid obesity a new method of calculation of predicted VC and FEV1 values was presented. The equation of multiple regression used for this purpose takes into account the dependence of spirometric values on age and Wot index.