Predictors of arterial oxygen tension in anesthetized horses: 1,610 cases (1992-1994).

The research article focuses on the identification of factors associated with variations in partial pressures of arterial oxygen (Pao2) in horses during anesthesia. The study found that factors like low pulse pressure, emergency situations, dorsal recumbency and short duration of anesthesia significantly impacted the arterial oxygen tension.

Methods

In the study, data from 1,450 horses that underwent anesthesia 1,610 times with either isoflurane or halothane was used. The research mainly concentrated on the following:

• Analyzing anesthesia records, specifically the outcomes of blood gas analyses.
• Grouping horses based on the lowest recorded Pao2 during anesthesia.

Key Findings

Different categories of horses were found to be more likely to have varying degrees of Pao2 levels:

• For horses with a lowest Pao2 of less than 120 mm Hg, factors such as low pulse pressure, anaesthesia conducted on an emergency basis, and the horse being male were associated with a Pao2 level less than 80 mm Hg.
• In cases where the lowest Pao2 was less than 250 mm Hg, horses positioned in dorsal recumbency, those that underwent anesthesia on an urgent basis or those who had shorter durations of anesthesia were more likely to have a Pao2 of less than 120 mm Hg.
• For horses with a lowest Pao2 of less than 400 mm Hg, factors such as being positioned in dorsal recumbency, undergoing anesthesia on an emergency basis, having shorter periods of anesthesia, being older or heavier, or being subjected to mechanical ventilation were identified as being more likely to result in a Pao2 of less than 250 mm Hg.

Conclusion

From the study, it was concluded that low pulse pressure, emergency case status, dorsal recumbency, and short duration of anesthesia have significant relationships with lower Pao2 in anesthetized horses. Therefore, consideration of these factors is necessary during the anesthesia of horses to manage their arterial oxygen tension effectively.