Effects of norepinephrine and a combined norepinephrine and dobutamine infusion on systemic hemodynamics and indices of renal function in normotensive neonatal thoroughbred foals.

This research studies how the application of norepinephrine and a joint infusion of norepinephrine and dobutamine impacts overall blood flow and kidney function in newborn, healthy Thoroughbred foals.

Objective and Methods

The main goal of this experiment was to investigate whether adding dobutamine to a norepinephrine infusion would affect the renal profile during the infusions without influencing the arterial blood pressure.

To conduct this research, eight conscious Thoroughbred foals were selected. Each foal was administered with norepinephrine (0.1 microg/kg/min), a blend of norepinephrine (0.1 microg/kg/min) and dobutamine (5 microg/kg/min), along with a control dose of saline, following a blinded and placebo-controlled study.
Various measurements were made including:

• Heart rate
• Arterial blood pressure (directly)
• Cardiac output (via lithium dilution)

The research team also computed the systemic vascular resistance, stroke volume, cardiac index, and stroke volume index. The output of urine, creatinine clearance along with the fractional excretion of sodium, potassium, and chloride were also gauged.

Results

The data revealed that both the infusion of norepinephrine and a combined infusion of norepinephrine and dobutamine escalates the arterial blood pressure and systemic vascular resistance while simultaneously reducing heart rate and cardiac index in comparison to saline. The combined infusion resulted in an increased arterial pressure compared to the norepinephrine alone.

Interestingly, there were no substantial differences in urine output, creatinine clearance, or the fractional excretion of electrolytes with either infusion when equated against saline.

Conclusion

The results of the study imply that norepinephrine and a combined norepinephrine and dobutamine infusion induce distinct hemodynamic attunements without influencing measurements of kidney function. The researchers suggest that these findings necessitate further exploration into the subject matter.