Effect of a 30-minute infusion of dobutamine hydrochloride on hind limb blood flow and hemodynamics in halothane-anesthetized horses.

This research explored the effect of dobutamine hydrochloride on the blood flow and heart dynamics in horses under halothane anesthesia. The study found that the drug did not significantly change heart function but did increase blood flow in the hind limb arteries.

Research Objective

The primary goal of this study was to figure out how dobutamine hydrochloride, a drug used to treat heart failure and cardiogenic shock, impacts the blood flow and heart dynamics of horses anesthetized with halothane, a commonly used inhalation anesthetic for veterinary surgery.

Methodology

The study involved the following methods:

• Six adult Thoroughbred horses were anesthetized using romifidine and ketamine, and the anesthesia was maintained using halothane.
• Measurements of aortic, left ventricular, and right atrial pressures were taken using catheter-mounted strain gauge transducers.
• Cardiac output, velocity time integral, maximum aortic blood flow velocity and acceleration, and left ventricular preejection period and ejection time were determined using transesophageal Doppler echocardiography.
• Velocity waveforms were recorded from the femoral vessels using Doppler ultrasonography. The time-averaged mean velocity and early diastolic deceleration slope were measured. The pulsatility index and volumetric flow were calculated.
• The blood flow in small blood vessels of the semimembranosus muscles was measured using laser Doppler flowmetry.
• The data were recorded 60 minutes after the induction of anesthesia and then 15 and 30 minutes after the beginning of dobutamine infusion.

Results

The results showed that:

• The infusion of dobutamine significantly increased aortic pressures.
• There was no change observed in the indicators of left ventricular systolic function, including the cardiac output.
• The femoral arterial flow significantly increased, while the pulsatility index and early diastolic deceleration slope decreased.
• There was no change observed in the femoral venous flow or the microvascular perfusion.

Conclusions

From these results, the researchers concluded that the dosage of dobutamine utilized in this study did not affect left ventricular systolic function. However, it did increase blood flow in the femoral arteries due to local vasodilation. No significant changes were noted in femoral venous flow or in microvascular perfusion, implying that increased femoral flow does not necessarily lead to improved perfusion of skeletal muscles.