Effects of dobutamine on cardiac index and arterial blood pressure in isoflurane-anaesthetized horses under clinical conditions.

This research investigates the impact of dobutamine, a drug frequently used to treat low blood pressure, on the heart rate and blood pressure of horses anesthetized with isoflurane.

Purpose and Methods of the Study

• The study sought to understand better the cardiovascular impact of dobutamine on horses put under anaesthesia with isoflurane; this was motivated by the fact that there’s currently little understanding of how dobutamine behaves under these conditions.
• The study included 44 horses that were anesthetized for surgical procedures, ranging from routine to complex operations.
• Each animal was pre-medicated with a combination of acepromazine, methadone and detomidine, before being anesthetized with a combination of ketamine, midazolam and isoflurane.

Use of Dobutamine and Monitoring During the Experiment

• Once under anaesthesia, each horse’s heart output was monitored; the research team checked blood pressure, heart rate, dobutamine infusion rate, and cardiac index just before the start of dobutamine infusion and then again 15 minutes after.
• The team aimed to maintain the mean arterial blood pressure above 70 mmHg using dobutamine infusion.

Results and Interpretation

• The findings indicated a considerable increase in arterial blood pressure after the commencement of dobutamine infusion. Additionally, the heart rate and cardiac index rose considerably only when dobutamine was coupled with a surgical stimulus.
• Despite isoflurane’s primary effect being vasodilation which lowers blood pressure, the researchers concluded that dobutamine effectively treats hypotension under clinical circumstances in isoflurane-anesthetized horses.
• The researchers noted that the effect of dobutamine was not directly proportional to the dose administered. The surgical stimulus probably contributed to the observed cardiovascular improvement.