[A comparison of airway resistance in oral-endotracheal tubes, tracheotomy tubes and in normal noses (author's transl)].

Not only a decrease, but also an increase of airway resistance by spontaneous regulation in the larynx, nose, or mouth will improve lung function in some diseases. Therefore, pressure and airflow in oral-endotracheal tubes, tracheotomy tubes and in normal noses are analysed. Double-logarithmic divided diagrams, valid for the comparison of laminar, turbulent and unstable turbulent-laminar flows, are used. The airway resistance and therefore the work of breathing generally is lowered after tracheotomy, increased after intubation, if the tubes are not of unusual size. The possible influence of these test results toward the indication (tracheotomy or intubation) is discussed.