Effects of a constant rate infusion of detomidine on cardiovascular function, isoflurane requirements and recovery quality in horses.

This research studied the effects of a continuous infusion of detomidine on horses’ heart functions, isoflurane (an anaesthetic) needs, and recovery quality during surgery, finding that the infusion led to expected cardiovascular effects but did not impact isoflurane needs or recovery times.

Study Details

• The experiment was designed as a prospective, randomized, blinded, and clinical trial carried out on twenty healthy adult horses.
• At the start, the horses were sedated using detomidine and the anaesthesia was induced using midazolam and ketamine. The anaesthesia was then maintained using isoflurane in oxygen/air.
• The researchers ensured the horses’ lungs were mechanically ventilated when required and dobutamine was administered if the mean arterial pressure dropped below 70 mmHg.

Experiment Design

• The horses were randomly divided into two groups, with one group receiving a constant rate infusion (CRI) of detomidine and the other group receiving saline CRI. The anaesthetist was not aware of the treatment group assignments.
• Various parameters were monitored during the experiment, including the end-tidal isoflurane concentration, arterial pH, arterial carbon dioxide pressure (PaCO2), arterial oxygen pressure (PaO2), dobutamine administration rate, heart rate, arterial pressure, cardiac index, systemic vascular resistance, stroke index, and oxygen delivery index.
• The researchers also administered detomidine intravenously to all horses during their recovery from anaesthesia and recorded the quality and duration of each horse’s recovery.

Results

• Results showed that the group receiving the detomidine CRI (group D), as compared to the saline group (group S), had a lower heart rate and oxygen delivery index but showed higher systemic vascular resistance. Furthermore, heart rate and arterial pH were observed to increase over time.
• Interestingly, no significant differences were noted in terms of isoflurane requirements, as well as the quality and duration of recovery between the two groups.

Conclusions

• The study concluded that a constant rate infusion of detomidine led to cardiovascular effects typical to α2-agonists. However, it did not affect the isoflurane requirements, duration of recovery, or quality of recovery in horses undergoing surgery.