Objective—To compare measurements of blood flow
in the common femoral artery obtained by duplex
Doppler ultrasonography (DDU) and a reference ultrasonic
transit-time flow (TTF) method and to examine
the impact of Doppler spectral waveform measurement
techniques on volumetric estimates.
Animals—5 healthy female pigs.
Procedure—Femoral arterial blood flow was measured
simultaneously in anesthetized pigs by use of a
TTF probe (left femoral artery) and transcutaneous
DDU (right femoral artery). A range of flow states was
induced pharmacologically by using xylazine,
bradykinin, dobutamine, and isoflurane. Volumetric
blood flow was calculated from DDU waveforms,
using the product of the flow velocity integral (FVI),
the cross-sectional vessel area, and heart rate. Three
calculations of FVI were obtained by manually tracing
the Doppler spectral envelopes at the outer envelope,
the modal, and the inner envelope of the spectral dispersion
pattern. Data analysis included calculation of
Pearson correlation coefficients and Bland-Altman
limits of agreement.
Results—Blood flow measured by DDU was more
closely correlated with TTF measurements when the
modal or inner envelope tracing method was used
( r, 0.76 and 0.78; limits of agreement, –100 to 54.2
and –48.5 to 77.0 mL/min, respectively). Limits of
agreement for the outer envelope tracing method
were –238.5 to 64 mL/min.
Conclusion and Clinical Relevance—Transcutaneous
DDU is a reliable noninvasive technique for
measuring blood flow in the femoral artery of pigs
over a range of flow states. Tracing the inner envelope
of the Doppler spectral dispersion pattern provided
the best estimate of blood flow in this study.
(Am J Vet Res 2003;64:43–50)