Ventilation and gas-dynamic work of breathing during CO2 stimulation in patients with airways obstruction prior to and following bronchodilation with reproterol (author's transl)

A new, non-invasive method for measuring chemo-sensitivity of the respiratory center is described, one that may sensibly be applied in patients with airways obstruction. It is used for measurement of ventilation and gas-dynamic work of breathing in body plethysmography during a modified unsteady state of CO2 rebreathing technique. In 9 patients suffering from chronic obstructive bronchitis, a linear correlation between the end-expiratory CO2 partial pressure and the respiratory work rate vs. the airways resistance was established while between the end-expiratory PCO2 and the respiratory minute volume as well as the respiratory minute volume and the respiratory work rate vs. airways resistance, a non-linear correlation exists. In tests with 7-(3[2-(3 5-dihydroxyphenyl)-2-hydroxy-ethyl-amino]-propyl)-theophylline (reproterol, Bronchospasmin), a beta-phenylethyl-amino alkylxanthine, with known bronchodilating effects and a preparation for which pharmacological considerations of central-analeptic effects cannot definitely be excluded, this method revealed in patients with airways obstruction no breathing stimulation. In contrast, however, specific airways resistance in patients afflicted with bronchitis was statistically significantly reduced.