Arterial hypoxemia in exercising thoroughbreds is not affected by pre-exercise nedocromil sodium inhalation.

The research article evaluates whether pre-exercise inhalation of nedocromil sodium can alleviate exercise-induced arterial hypoxemia and subsequent desaturation of hemoglobin in racehorses. However, the study found that nedocromil sodium was ineffective in changing the severity or development of such conditions.

Introduction and Study Purpose

• The research was held based on previous studies and reports indicating that pre-exercise inhalation of a drug named nedocromil sodium helped mitigate exercise-induced arterial hypoxemia (EIAH) in humans.
• The EIAH condition refers to the decrease in oxygen levels in the blood during intense physical activity, reportedly associated with the pulmonary injury caused by capillary stress failure, which humans can manage by inhaling nedocromil sodium before exercise.
• This study aimed to see if the same effect could be seen in racehorses, which often suffer from exercise-induced pulmonary hemorrhage due to the same capillary stress failure.

Methodology

• Seven exercise-trained thoroughbred horses were selected for this investigation, which was divided into two sets of experiments.
• The first set was the placebo studies, followed by the nedocromil sodium inhalation experiments, which took seven days later.
• Both scenarios involved arterial and mixed-venous blood-gas/pH measurements at rest before and after placebo/drug inhalation, and during incremental exercise leading up to galloping at 14 m/sec on a 3.5% uphill grade.
• This high-intensity exercise was designed to cause pulmonary hemorrhage in all horses, indicating that capillary stress failure had occurred.

Results

• In both treatments, significant exercise-induced arterial hypoxemia (EIAH) of similar magnitude had developed within 30 seconds of maximal exertion, and it did not significantly change as exercise duration extended to 120 seconds.
• Therefore, the inhalation of nedocromil sodium proved to be ineffective in modifying the development and severity of EIAH in thoroughbred racehorses.

Conclusion

• The research concluded that pre-exercise inhalation of nedocromil sodium does not provide any significant improvements to EIAH and subsequent desaturation of hemoglobin.
• These findings challenge the hypothesis that arterial hypoxemia in racehorses is triggered by the release of airway inflammatory mediators, which can be regulated by nedocromil sodium inhalation before exercise.