Objective—To evaluate the use of a transesophageal echo-Doppler ultrasonography (TED) technique for measurement of aortic blood flow (ABF) in relation to cardiac output (CO) measured by use of a thermodilution technique in anesthetized cats.
Procedures—Anesthesia was induced and maintained in cats by administration of isoflurane. A thermodilution catheter was placed in a pulmonary artery. The TED probe was positioned in the esophagus in the region where the aorta and esophagus are almost parallel. Five baseline values for ABF and CO were concurrently recorded. Cats were randomly assigned to a high or low CO state (increase or decrease in CO by at least 25% from baseline, respectively). Baseline conditions were restored, and the other CO state was induced, after which baseline conditions were again restored. For each CO state, ABF and CO were measured 5 times at 5-minute intervals. Correlation and agreement between the techniques were determined by use of the Pearson product-moment correlation and Bland-Altman method.
Results—CO ranged from 0.16 to 0.75 L/min and ABF from 0.05 to 0.48 L/min. Overall data analysis revealed a high correlation (r = 0.884) between techniques but poor agreement (limits of agreement, −0.277 to 0.028 L/min). During the low CO state, correlation between techniques was low (r = 0.413).
Conclusions and Clinical Relevance—TED did not accurately measure CO. However, it allowed evaluation of CO patterns and may be useful clinically in anesthetized cats.