Messungen der Luftströmung im Bronchialsystem beim gesunden Menschen

Abstract

Information about the type of flow present in the bronchial tree is important for the assessment of resistance offered by the airways to the inspired and expired air current.

Data from the literature about the type of flow in the bronchial tree fail to provide definite answers to the question of whether regular — laminar flow, or irregular — turbulent flow constitutes the predominant type.

The reason for the diversity of published views rests, in the writers' opinion, in the measurement of type of flow, as a rule, either on a variety of models representing the bronchial tree, or in the indirect methods of evaluation used (such as mixing of gases etc.). For the reasons stated, the writers, in collaboration with experts on aerodynamics, devised a modification of a special apparatus (Constant temperature anemometer manuf. by Disa) and adapted it to measuring the velocity and type of flow in the bronchial tree.

It was found that in the trachea and bronchi belonging to the I.–IV. generation after Weibel only turbulent flow of a different degree of turbulence exists under physiological conditions and even during slow, quiet respiration (from Re 410,25). Laminar flow which, from a physiological viewpoint, may be considered less advantageous than turbulent flow, could not be demonstrated.

Zusammenfassung

Anhand von direkten Messungen wurde festgestellt, daß in der Trachea und den Luftröhren der 1.–4. Generation eine verwirbelte bzw. turbulente Exspirationsströmung existiert. Die mittlere Strömungsgeschwindigkeit in der Trachea betrug 98 ml/sec, das entspricht in etwa einer Reynoldschen von 410.