Studies on the pulmonary diffusing capacity and the pulmonary circulation with special reference to the haemodynamic aspects of the average contact time.

Abstract

1) The method of estimating the average contact time through simultaneous measurements on the red cell component of the apparent pulmonary diffusing capacity and the effective pulmonary blood flow. 2) The physiological basis of the present method was introduced. 3) The average contact time in cases of normal healthy was ranged between 0.3-0.5 sec and that in cases of any cardiopulmonary diseases had revealed various degree of restriction. 4) The average contact time has been studied in relation with any haemodynamic factors of the pulmonary circulation and some physiological significance of the average contact time was reported. 5) As for the cause of the restriction of the average contact time, the authors have pointed out the following items : such as a) increase in cardiac output, b) decrease in effective pulmonary capillary beds, c) decrease in pulmonary blood volume, etc. 6) The importance and necessity of further investigations to give any definite conclusion on the physiological mechanism to cause any restriction of the average contact time was emphasized.