Lack of agreement between thermodilution and echocardiographic determination of cardiac output during normovolemia and acute hemorrhage in clinically healthy, anesthetized dogs

Objective and hypothesis: To determine whether or not there is agreement between the thermodilution and echocardiographic measurement of cardiac output (CO) during normovolemia and acute hemorrhage. The hypothesis was that there will be agreement between echocardiographic measurement of CO (ECO) and thermodilution measurement of CO (TDCO) during normovolemia and acute hemorrhage. Design: CO was measured by both thermodilution and echocardiography during α‐chloralose anesthesia in dogs before and 15 and 30 minutes following acute arterial hemorrhage. Setting: Laboratory investigation. Animals: Eighteen clinically healthy dogs, weighing 20–25 kg, anesthetized with α‐chloralose. Interventions: Acute arterial hemorrhage of approximately 50% of the total blood volume. CO was measured by thermodilution and echocardiography before and 15 and 30 minutes following hemorrhage. Measurements and main results: Acute hemorrhage resulted in a significant decrease in CO. There was a lack of agreement between the 2 methods to measure CO at each time and at all anatomic points of measurement in the aorta and pulmonary artery. Conclusion: There is a lack of agreement between the 2 methods; thus, determination of CO by echocardiography may not be a clinically useful tool following hemorrhage in dogs.