Reproducibility of cardiac output measurements in the dog

¹ Departments of Biology and Physiology, University of Redlands, Redlands, California, and State University of Iowa, Iowa City, Iowa

Studies were performed on dogs to determine the constancy of the cardiac output during a 4-hour period beginning from the moment the animal was anesthetized. The cardiac output fell to varying quantities during the first hour but finally became stabilized at approximately 50–75% of the values obtained within the first 2–3 minutes following induction. Considerable variability in this response among different animals was noted. Similar studies on other animals, beginning approximately 1 hour following induction, indicated a similar pattern, i.e. that relatively stable cardiac outputs could be anticipated after this time period.