The effects of isoflurane anaesthesia on some Doppler-derived cardiac parameters in the common buzzard (Buteo buteo)

In order to gain an initial overview of the influence of anaesthesia on the results of Doppler-derived blood flow measurements in raptors, the heart rate as well as three different sample volumes of pulsed-wave spectral Doppler-derived flow velocity (diastolic flow across the left and right atrioventricular valve, systolic flow across the aortic valve) were determined in 10 common buzzards (Buteo buteo). Measurements were taken once in conscious and once in anaesthetized birds. Anaesthesia was shown to produce significant changes in cardiac parameters recorded in the same birds whilst conscious. When comparing conscious birds with each other (with one exception for right sided ventricular inflow velocity) no correlation between the heart frequency and measured blood flow velocities was evident. This was also the case under anaesthesia. However, significant differences in these parameters were evident when comparing the results obtained before and under anaesthesia. The results suggest that the influence of anaesthesia in raptors is more than a simple reduction of heart rate and that there is also reduction in blood flow velocity.