Anesthetic potency of desflurane in the horse: determination of the minimum alveolar concentration.

The study investigates the minimum alveolar concentration (MAC) of desflurane, an anesthetic, in horses and found that it provides a quick and smooth transition into and out of anesthesia.

Introduction and Methodology

• The research is a prospective study conducted on six healthy adult horses, equally divided by gender, with an average weight of around 370 kg and age of approximately 9 years.
• Anesthesia was induced in the horses using desflurane, which was vaporized in oxygen and administered using a face mask connected to an anesthetic circle system specifically designed for large animals.
• After the horse was anesthetized, it was intubated endotracheally and positioned on its right side. The levels of inspired and end-tidal desflurane were monitored using a specifically calibrated multigas analyzer.
• The purpose of the study was to establish the minimal concentration of desflurane needed in the alveoli (the tiny air sacs where gas exchange happens in the lungs) to prevent gross purposeful movement in the horse in response to 60 seconds of noxious electrical stimulation of the oral mucous membranes.

Results

• The researchers found that it took an average of about 6 minutes from the start of desflurane administration to the point where the horse would lay down on its right side.
• The MAC of desflurane that prevented purposeful movements in the horses studied was found to be approximately 7.6%.
• Following an anesthesia period that lasted on average about 98 minutes, the time required for the horse to regain an upright position on its sternum (chest) was on average about 6.5 minutes and for it to fully stand up was a little over 14 minutes.

Conclusions

• The study concluded that desflurane provides a quick induction into, and recovery from, anesthesia.
• The researchers posit that desflurane offers potential advantages of more precise control during anesthesia and potentially a smoother and faster recovery.
• The research underscores the importance of establishing the MAC of a particular inhalant for optimizing its clinical use.