The Effect of Inhaled Albuterol on PaO2 in Anesthetized Horses Receiving a FiO2 of 0.5 or >0.95.

This study investigates the effect of inhaled Albuterol, a short-acting β adrenergic agonist, on oxygen uptake in anesthetized horses. The researchers found that Albuterol improved arterial oxygen partial pressure (PaO2) for at least 40 minutes after being administered, potentially helping to correct hypoxemia conditions during anaesthesia.

Background

• The research focuses on the problem of hypoxemia, or low arterial oxygen levels, in horses under general anesthesia. This condition can potentially harm the animals, leading to a necessity for effective corrective measures.
• Previous studies have explored numerous treatments for this issue, with varying degrees of success. One promising remedy is Albuterol, which has demonstrated positive effects in clinical trials, particularly in cases resistant to other interventions such as mechanical ventilation modifications or positive inotropic drugs administration.
• However, these previous findings were based on anecdotal evidence and uncontrolled clinical situations. This study thus aims to provide a more controlled, systematic analysis focusing on healthy, nonhypoxemic horses under anesthesia.

Methods

• The research was a prospective study, involving 14 horses divided into two groups. One group received a fractional inspired oxygen (FiO2) of 0.5, while the other received a FiO2 higher than 0.95. Both groups were kept under similar anesthesia conditions.
• Each horse’s arterial oxygen partial pressure (PaO2) was measured as a baseline 15 minutes after anaesthetisation. Five horses in each group were then given inhaled Albuterol at a dose of 2 µg/kg. Two horses in each group were left untreated as a control.
• Subsequent PaO2 measurements were taken at 10-minute intervals for 40 minutes after the Albuterol treatment. The collected data was then analysed using repeated measures analysis of variance (ANOVA) with statistical significance set at a P-value of less than 0.05.

Results

• The results showed that the horses treated with Albuterol demonstrated increased PaO2 levels for at least 40 minutes after the baseline. This represents an improvement in arterial oxygen uptake during anesthesia as compared to the control group.
• These effects occurred in healthy, nonhypoxemic horses and were independent of the greater or lesser levels of FiO2 they received (0.5 or >0.95).
• The side effects of the Albuterol treatment were minimal, consisting only of increased heart rate and perspiration.

Conclusion

• In conclusion, inhaled Albuterol demonstrated effectiveness in improving arterial oxygen levels in anesthetized horses. Given the minimal side effects and the duration of its impact, this treatment offers a potential solution for managing hypoxemia conditions in anesthetised horses.