Doppler ultrasonography and single-fiber laser Doppler flowmetry for measurement of hind limb blood flow in anesthetized horses.
OBJECTIVE
To use Doppler ultrasonography and single-fiber laser Doppler flowmetry (LDF) to evaluate blood flow in the dependent and nondependent hind limbs of anesthetized horses and to evaluate changes in femoral arterial blood flow and microvascular skeletal muscle perfusion in response to administration of phenylephrine hydrochloride or dobutamine hydrochloride.


METHODS
6 healthy adult horses.


METHODS
Horses were anesthetized and positioned in left lateral recumbency. Doppler ultrasonography was used to measure velocity and volumetric flow in the femoral vessels. Single-fiber LDF was used to measure relative microvascular perfusion at a single site in the semimembranosus muscles. Phenylephrine or dobutamine was then administered to decrease or increase femoral arterial blood flow, and changes in blood flow and microvascular perfusion were recorded.


RESULTS
Administration of phenylephrine resulted in significant decreases in femoral arterial and venous blood flows and cardiac output and significant increases in mean aortic blood pressure, systemic vascular resistance, and PCV. Administration of dobutamine resulted in significant increases in femoral arterial blood flow, mean aortic blood pressure, and PCV. Significant changes in microvascular perfusion were not detected.


CONCLUSIONS
Results suggest that Doppler ultrasonography and single-fiber LDF can be used to study blood flows in the hind limbs of anesthetized horses. However, further studies are required to determine why changes in femoral arterial blood flows were not associated with changes in microvascular perfusion.
Raisis
A L
AL
Center for Equine Studies, The Animal Health Trust, Newmarket, Suffolk, UK.
Young
L E
LE
Taylor
P M
PM
Walsh
K P
KP
Lekeux
P
P
D000778:Anesthetics, Dissociative; D000818:Animals; D001158:Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology / Q000662:veterinary; D001794:Blood Pressure; D002316:Cardiotonic Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology; D005260:Female; D006400:Hematocrit / Q000662:veterinary; D006614:Hindlimb / Q000098:blood supply* / Q000000981:diagnostic imaging; D006736:Horses / Q000502:physiology*; D007649:Ketamine; D017078:Laser-Doppler Flowmetry / Q000662:veterinary*; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D011897:Random Allocation; D018608:Ultrasonography, Doppler / Q000662:veterinary*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014743:Videotape Recording
D000778:Anesthetics, Dissociative; D002316:Cardiotonic Agents; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D004280:Dobutamine; D007649:Ketamine