Biomedical subjects
Publications and source records attributed to U Smidt.
Five meters of six models of peak flowmeters have been checked by 40 measurements each in series with a pneumotachograph. There were no substantial differences between the five meters of one type, but the various models showed a different scatter, partly due to differences in the applied flow pattern. We prefer those peak flowmeters with less influence of the flow pattern.
There is no comprehensive theory for the various reasons for dyspnea. It is proposed to regard the disproportion between "input" and "output" as the common cause of the various forms. This disproportion may be located between psychological drive and neural response or between neural excitation and muscular response or between muscular activity and ventilatory effect. Thus insufficient perfusion of respiratory muscles--as in cardiac failure--may cause dyspnea. Arterial oxygen pressure as the criterion of sufficient ventilation is misleading in anemia and CO-poisoning, so that there is no dyspnea despite of insufficient O2-transport.
Against the background of the working hypothesis of the 1-parametric Siregnost FD 5 forced oscillation technique-phase angle psi may be invariant in a clinical reference population-the hypothetical straight Ros-P line is in good agreement with the crowd of extremely nonlinear Rre-P-lines only within narrow limits. Neglecting phase angle measurements it might be useful to insert a known linear resistor into the airway to determine the pertaining Rre-P relation. In spite of selective tuning to the oscillation frequency of 10 Hz there is full sensitivity to stationary flow; alinear stationary flow characteristics of resistors can be readily determined by forced oscillation. There is a marked improvement in the P-psi/Rre-phi-evaluating system with respect both to the symmetry of phase angle and unequivocality of pressure when the reference phase angle alpha is shifted from 81 degrees to 0 degrees. Using digital data acquisition and processing, a flexible evaluation technique with monitor-oriented test management, automatical calculation of secondary values and multidimensional presentation of results on a graphical display is provided, which has proved its worth in experimental and clinical-physiological studies.
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A review is given about various epidemiologic and pathologic studies in coal workers and foundry workers, regarding the prevalence of respiratory symptoms, chronic bronchitis and pulmonary emphysema in those workers in the Rhine-Ruhr-area. It is evident that these diseases are much more frequent in dust-exposed workers than in the other population.
The washing-in of a low density gas (80% He, 20% O2) into the lung is being eased by greater diffusibility and diminished work of breathing. Helium analysis was performed by means of the oscillation method with an equipment suitable for the assessment of resistance to breathing. The density of helium gas mixture is being compared to the density of ambient air.
In 34 subjects--coal workers with pneumoconiosis, patients with collagenic diseases and healthy subjects--the daily urinary excretion of hydroxyproline (HP) and the plasma concentrations of HP and of collagenic peptidase have been measured during one week under HP-free and HP-enriched diet. It is shown that a 24-hour period of HP-free diet is necessary and sufficient before collecting urine or plasma for diet independent measurements of total or non-protein bound HP. Concentrations in plasma correlate well with the amounts excreted in urine. Collagenic peptidase is independent from the diet and well suited for assessment of the activity of the metabolism of collagene. There are no differences between healthy subjects and coal workers with pneumoconiosis.
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The correlation between barometric pressure and arterial oxygen pressure has been investigated in 3,054 coal miners. Furthermore, the correlation between alveolar oxygen pressure and alveolar-arterial oxygen pressure difference and barometric pressure has been investigated in 1,669 coal miners. For low and for high pO2a there are significant correlations to barometric pressure, in particular for the young age groups. PO2A and AaDO2 show closer correlations to barometric pressure in the middle range of pO2a (65--84 mm Hg). This points to different regulating mechanisms. A correction with a uniform factor is not possible and, for clinical purposes, unnecessary, since the influence of changing barometric pressure on pO2a is only about 1--3 mm Hg.
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In 15 patients with chronic bronchitis with or without emphysema breathing of room air was compared with breathing of 20.9% O2 in helium and in argon. Minute ventilation and alveolar ventilation showed no differences, whereas the alveolar and arterial pO2 and PCO2 showed an improvement of the CO2 gas exchange and a deterioration of the O2 gas exchange. This contradictory behaviour cannot be explained by shunts or inhomogeneities or influence of gaseous or alveolo-capillary diffusion. Perhaps the physicochemical properties of the alveolo-capillary membrane change by the depletion of nitrogen. The recommendation of helium-oxygen breathing, proposed by other authors for patients with obstructive airway diseases, cannot be supported, when the gas exchange for O2 is deteriorated.
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