Doppler ultrasonography and single-fiber laser Doppler flowmetry for measurement of hind limb blood flow in anesthetized horses.

The research article discusses an experiment that used Doppler ultrasonography and single-fiber laser Doppler flowmetry (LDF) to measure the impact of phenylephrine and dobutamine on blood flow in the hind limbs of anesthetized horses.

Introduction

• The research involved experimenting with six healthy adult horses that were anesthetized and then placed in left lateral recumbency.
• Two types of procedures were used to evaluate the blood flow – Doppler ultrasonography to determine the velocity and volumetric flow in the femoral vessels, and single-fiber LDF to gauge the relative microvascular perfusion within the semimembranosus muscles (a part of the hind limb).

Administration of Drugs

• Two types of drugs were administered to the horses – phenylephrine hydrochloride, which is known to decrease femoral arterial blood flow and dobutamine hydrochloride, which tends to increase the same.
• The impact of these drugs on blood flow and microvascular perfusion were closely recorded and monitored during the course of the experiment.

Results

• The results showed clear evidence of the impact of these drugs. The administration of phenylephrine resulted in decreased femoral arterial and venous blood flows, cardiac output, along with increased mean aortic blood pressure, systemic vascular resistance, and PCV (Packed Cell Volume).
• On the other hand, dobutamine administration led to significant increases in femoral arterial blood flow, mean aortic blood pressure, and PCV.
• Despite these changes, no significant changes were observed in microvascular perfusion – a factor that left the researchers intrigued.

Conclusion

• The research concluded that Doppler ultrasonography and single-fiber LDF could be effectively used to understand and study the blood flow in the hind limbs of anesthetized horses.
• Nevertheless, the study has left an unanswered question about the relationship between the changes in femoral arterial blood flows and microvascular perfusion, indicating the necessity of further research.