AT THE PRESENT time, indicator-dilution curves are one of the most important technics employed in the investigation of the circulation. The earliest of these studies were carried out by the rapid serial collections of blood samples and their subsequent photometric analysis.' This ingenious but cumbersome method was replaced by the continuous withdrawal of blood in front of a photoelectric cell,...

T HE accumulation of accurate iniformiation as regards operative mortality and results of surgery is basic to the advancement of the surgical management of any disease. It has been amply demonstrated by Lewis and Tauflc,1 Swan,2 Gross and associates,3 Bailey and associates,4 Bj6rk and Crafoord,5 Gibbon,6 Shumacker7 and ourselves8 that a number of technics of closure of atrial septal defects can...

• The indicator-dilution principle has been applied to studies of the circulation in order to provide estimates of flows and volumes in the vascular compartment. A sine qua non of validity of these estimates is that the indicator used remain within the confines of: the vascular compartment for the entire duration of the period required to obtain appropriate samples of blood. In such a symposium...