The Effects of Inner Diameter of Respiratory Valve on Pulmonary Ventilation

Abstract

The effects of the inner diameter of respiratory valve on the pulmonary ventilation and oxygen uptake were studyed.
Five healthy male subjects were asked to run on a treadmill with 8.6% slope. Each subject equiped a respiratory valve with five kinds of diameter (19mm, 24mm, 30mm, 34mm and two valves of 19mm) performed all-out running at a given speed at which he could run about 6 minutes. In all experiments, the inner diameter of the connective tubes in valve, stop cock and bag were 30mm. From the experiment, following results were obtained ; up to diameter of 30mm the larger the diameter of valve, the higher became the pulmonaly ventilation, accompanied with the increasing oxygen uptake. However, a large diameter of 34 mm did not produce further increase in ventilation. The difference in ventilation between 19mm and 30mm was found in such an intensive work that demanded over 5011/min. of ventilation and it increased related to the increment of work intensity.
It is concluded that in studying the respiratory function during severe work, it is better to use respiratory valve as large as 30mm in diameter.