Detection and quantification of small right-to-left shunts by the phase-plane method.
In six anesthetized dogs 70 indicator-dilution curves and phase-plane plots were recorded. Indocyanine green was injected into the superior vena cava and sampled through a dichromatic cuvette densitometer from the femoral artery. Dye-dilution curves were recorded from dogs with normal cardiovascular systems and repeated after right-to-left shunts of different magnitude were surgically produced. The percent of blood shunting was calculated according to standard indicator-dilution equations and also by means of oximetric determination of blood samples. They were compared with shunt estimates based on phase-plane loop measurements. Good correlation was found with standard indicator-dilution procedures (r = 0.890) but not with oximetry (r = 0.466). The phase plane shows its utility in the detection and evaluation of small right-to-left shunts. These shunts affect the initial portion of the phase plane and the alterations appear to be more evident than in the corresponding concentration-vs.-time curves.
D000818:Animals; D001166:Arteriovenous Shunt, Surgical; D002302:Cardiac Output; D004285:Dogs; D005263:Femoral Artery / Q000502:physiology; D006321:Heart / Q000502:physiology*; D007208:Indocyanine Green; D012984:Software; D014683:Vena Cava, Superior / Q000502:physiology
D007208:Indocyanine Green