Comparison of desflurane and propofol at equipotent doses in combination with a constant rate infusion of dexmedetomidine on global and peripheral perfusion and oxygenation in horses.

The research investigates the effects of desflurane and propofol, combined with dexmedetomidine, on overall and peripheral circulation and oxygenation in horses.

Objective and Methodology

• The primary aim of the study was to understand how anesthesia, administered with equal doses of desflurane and propofol, coupled with a stable dexmedetomidine infusion, affects overall and local blood flow and oxygenation in horses. The trial involved six warmblood horses, which were first given dexmedetomidine as premedication.
• Anesthesia was introduced with either propofol or ketamine and then sustained with desflurane or propofol, combined with a steady dexmedetomidine infusion. The unique design of these trials enabled every horse to be subject to each combination of anaesthetic.
• Before and after sedation and during anesthesia, the research team measured microperfusion and oxygenation of the rectal, oral, and esophageal mucosa. They also recorded heart rate, mean arterial blood pressure, respiratory rate, cardiac output, and blood gas pressures throughout the anesthesia.

Results

• The study found that peripheral microperfusion and oxygen saturation decreased significantly following dexmedetomidine administration under all tested conditions. While oxygenation returned to baseline values, tissue microperfusion remained low during anesthesia. The study noted no differences in peripheral tissue microperfusion and oxygenation between the two anesthesia treatments.
• During desflurane treatment, the researchers observed a significantly higher cardiac index and significantly lower systemic vascular resistance than during propofol treatment.
• For the propofol treatment, arterial oxygen pressure was significantly higher, and there was less dead space and venous admixture than for the desflurane treatment.

Conclusions and Clinical Relevance

• Dexmedetomidine resulted in a decrease in blood flow and oxygen saturation in peripheral tissues. Anesthesia with desflurane and propofol in combination with dexmedetomidine maintained proper oxygenation in peripheral tissues, albeit with reduced blood flow.
• The findings contribute valuable insights to the body of knowledge surrounding equine anesthesia and may inform improved clinical anesthesia practices to preserve blood flow and oxygen saturation in horses.