Effects of two different dosages of dobutamine on pulmonary artery wedge pressure, systemic arterial blood pressure and heart rate in anaesthetized horses.

The research investigated the impact of two different concentrations of dobutamine on pulmonary artery wedge pressure and mean systemic arterial blood pressure in anaesthetized horses. The results suggest that dobutamine improves circulation beyond its known peripheral effects.

Objective

The main objective was to study the effects of two different dobutamine concentrations on pulmonary artery wedge pressure (PAWP) and mean systemic arterial blood pressure (MAP) in horses anaesthetized with isoflurane.

Method

• The study involved eight healthy warm-blood horses that were subjected to general anesthesia twice with two different dosages of dobutamine administered.
• The dosages of dobutamine used were 3 and 5 microg/kg bw/min, infused over 15 minutes.
• Measurements such as heart rate, PAWP, and MAP were recorded after 10 minutes and then every 5 minutes until 15 minutes after cessation of dobutamine administration.
• The PAWP was measured using a right heart catheter positioned in the pulmonary capillaries.
• Mean systemic arterial blood pressure was monitored at the facial artery for the duration of general anaesthesia.

Results

• All parameters, including heart rate, PAWP, and MAP, increased at both dosage rates of dobutamine and decreased significantly when the administration of dobutamine ceased.
• The administration of 3 microg/kg bw/min dobutamine caused a significantly higher increase in heart rate compared to the dosage of 5 microg/kg bw/min dobutamine.
• The increase in MAP was also higher at this dosage but was not significantly different from the dosage of 5 microg/kg bw/min dobutamine.
• The greatest increase in PAWP was observed during administration of 5 g/kg bw/min dobutamine, though PAWP was not significantly different with the dosage of 3 microg/kg bw/min dobutamine.

Conclusion

The study concluded that the administration of dobutamine led to an increase in MAP and PAWP, denoting good peripheral circulation. Dobutamine was found to enhance circulation beyond its well-documented peripheral effects, which implies it could be used in managing anesthetized horses by enhancing their circulation while they are under general anesthesia.