Effects of desflurane and mode of ventilation on cardiovascular and respiratory functions and clinicopathologic variables in horses.

The study explored the impact of an anesthetic called desflurane and different ventilation modes on the cardiovascular and respiratory functions of horses. It also identified the changes in certain clinical and pathological factors associated with the use of desflurane anesthesia in horses.

Research Methodology

• The research was conducted on six healthy adult horses. Each of these horses was subjected to anesthesia on two different occasions for specific reasons.
• The first time was to determine the minimum alveolar concentration (MAC) of desflurane in Oxygen.
• The second time was to identify and characterize the effects of varying concentrations of desflurane and two different modes of ventilation – controlled and spontaneous – on the horses’ cardiovascular, pulmonary, and clinical-pathological responses.

Research Findings

• The determined minimum alveolar concentration of desflurane found in the horses was approximately 8.06%. The researchers noted that there didn’t appear to be any signs of airway irritation due to desflurane inhalation.
• During spontaneous ventilation, the mean partial pressure of carbon dioxide (PaCO2) observed in the horses was 69 mm Hg.
• It was discovered that arterial blood pressure, stroke volume, and cardiac output all decreased as the dose of desflurane increased.
• When the horses were subjected to conditions of intermittent positive pressure ventilation and eucapnia, further cardiovascular depression was observed.
• Despite the observed cardiovascular depression, horses were found to recover quickly from the anesthesia with little to no evidence of adverse clinical or pathological effects.
• The researchers also noted that the serum fluoride concentration, before and after the administration of desflurane, was below their detection limit of 0.05 ppm.

Conclusions Derived

• According to the results, it was concluded that desflurane, like other inhalation anesthetics, considerably causes hypoventilation in horses.
• The degree of cardiovascular depression is related to both the dose of desflurane and the ventilation mode utilized.
• The investigators noted less severe cardiovascular depression at doses of 1X to 1.5X the minimum alveolar concentration of desflurane, compared to the effects of other inhalation anesthetics under similar conditions.
• Lastly, it was established that desflurane does not significantly metabolize and did not prominently influence the renal function or hepatic cell integrity or function in the horses.