Measurement of Pulmonary Venous Blood Flow in Dogs

　The satisfactory measurement of pulmonary　venous blood flow depends on the resolution of a　number of problems that evolve from three rather　distinct aspects of the activity．　These are the　physiology of the flow phenomenon, the instru—mentation of the flow measurement, and the　technique of surgical preparation．　The solution of　the problems in all three areas is directly related　to the nature of the veins, as apposed to or in　contrast to the arteries．　Relatively, the arteries　are rigid vessels under, high internal pressure and　have known flow characteristics．