Agreement between transthoracic echocardiography and esophageal Doppler on aortic flow variables in anesthetized mechanically ventilated dogs

The use of transthoracic echocardiography (TTE) and esophageal Doppler (ED) for the measurement of hemodynamic variables in anesthetized dogs was studied. Fourteen mixed-breed dogs, without cardiac disease, undergoing general anesthesia for diagnostic or therapeutic procedures were included in this prospective preliminary study. Dogs were premedicated with dexmedetomidine (3 μg/kg) and methadone (0.3 mg/kg), intramuscularly. General anesthesia was induced with propofol intravenously titrated to effect and maintained with isoflurane in oxygen. Animals were positioned in dorsal recumbency. Transthoracic echocardiography was performed using a 5-2 MHz cardiac ultrasound probe placed in the subcostal window, whereas esophageal Doppler was performed using a CardioQ probe (MP50; Deltex Medical, Chichester, UK). Once an appropriate view of the aortic flow was obtained, the variables peak velocity (PV) and velocity-time integral (VTI) were measured. Agreement between methods was evaluated using the Bland-Altman method with single observation per individual. The bias and the limits of agreement (LOA) between the two methods were determined. Mean (± SD) PV was 99.46 cm/s (± 42.73 cm/s) and 110.29 cm/s (± 35.86 cm/s), and VTI was 13.24 cm (± 4.33 cm) and 13.05 cm (± 4.47 cm), for TTE and ED, respectively. Mean differences and LOA were 10.83 cm/s (range: −20.50 to 42.16 cm/s) and −0.19 cm (range: −3.32 to 2.95 cm) for PV and VTI, respectively. No statistically significant differences were determined in the variables measured between TTE and ED in anesthetized dogs without cardiac disease, positioned in dorsal recumbency. This could be of clinical relevance when an evaluation of the intraoperative hemodynamic status of anesthetized dogs is desired.