Effects of dobutamine hydrochloride on cardiovascular function in horses anesthetized with isoflurane with or without acepromazine maleate premedication.

This research study explored the impact of the premedication drug acepromazine maleate on cardiovascular function in horses undergoing anesthesia with isoflurane and dobutamine hydrochloride treatment. The results indicated that while dobutamine increased oxygen delivery and femoral arterial blood flow indices, these changes were not significantly influenced by the use of premedication with acepromazine.

Research Methodology

• The research involved six healthy adult horses. Each horse was anesthetized twice, once with premedication with acepromazine and once without. This premedication was administered 30 minutes before the anesthetic induction.
• Anesthesia was induced via the intravenous administration of xylazine hydrochloride, ketamine hydrochloride, and diazepam. After positioning the horses, anesthesia was maintained using inhalable isoflurane given in oxygen.
• The researchers maintained a target mean arterial blood pressure of 60 mm Hg. Measurements of cardiac index, oxygen delivery index, and femoral arterial blood flow indices were taken 60 minutes after anesthetic induction (baseline).
• After the baseline measurements, the horses were then administered dobutamine to achieve a target mean arterial pressure of 80 mm Hg. Data collection pertaining to the cardiovascular functions was then repeated after 30 minutes of dobutamine administration.

Findings

• The data was successfully collected from five out of the six horses. The administration of dobutamine resulted in significant increases in oxygen delivery and femoral arterial blood flow indices, but there was no significant change in the cardiac index for each treatment.
• However, the findings for the treatments with and without acepromazine premedication did not differ either at baseline or 30 minutes after the start of dobutamine infusion.

Conclusions and Clinical Relevance

• The administration of dobutamine in isoflurane-anesthetized horses led to an increased oxygen delivery and femoral arterial blood flow indices. These changes, however, were not affected by whether the horse was premedicated with acepromazine or not.
• This suggests that acepromazine maleate premedication does not influence these cardiovascular functions during anesthesia, and its use may not be necessary in such cases.