Resting hemodynamics and oxygen transport in unanesthetized adult cats

Characteristics of blood, oxygen transport were determined in seven adult female cats with inlying catheters in the pulmonary artery and a carotid artery. Measurements were made without anesthesia. Cardiac output averaged 167 ml.kg-1.min-1. Blood oxygen capacity averaged 11.6 ml.dl-1. Mean arterial oxygen saturation was 94% and mixed venous oxygen saturation was 49%. Mean oxygen tensions were 97.3% and 36.9 mm Hg in arterial and mixed venous blood, respectively. Mean arteriovenous oxygen concentration difference was 5.1 ml.dl-1, yielding a calculated oxygen consumption of 8.4 ml.kg-1 min-1, 5% higher than the value obtained by spirometric measurements on four of the animals. These data, when compared with previously reported values from species ranging widely in body size, show that the increased oxygen consumption per kg associated with decreasing body size is provided by progressive increases in cardiac output per kg and in arteriovenous oxygen concentration difference. Mixed venous oxygen tension is held within narrow limits in resting, unanesthetized animals.