Pulmonary distribution of aerosolized technetium Tc 99m pentetate after administration of a single dose of aerosolized albuterol sulfate in horses with recurrent airway obstruction.

This research investigates if a single dose of aerosolized albuterol sulfate enhances the pulmonary distribution of an aerosolized radioactive substance technetium Tc 99m pentetate in horses suffering from recurrent airway obstruction (RAO), also known as heaves. The findings indicate that the administration of aerosolized albuterol sulfate indeed improves pulmonary distribution of the radiolabeled pentetate, particularly in horses with heaves, but has no discernible effect on clinically normal horses.

Methods

• The study involved 10 horses in total, six of which had recurrent airway obstruction and four that had normal respiratory function.
• The horses underwent ventilation at baseline. The maximal change in pleural pressure during tidal breathing, denoted as deltaPpImax, was measured before the baseline scan and before and five minutes after albuterol sulfate administration.
• There was a 24-hour washout period between experiments. Aerosolized albuterol sulfate was administered to all the horses in a dosage of 360 micrograms.
• Images were captured and assessed through visual inspection using a semi-quantitative scoring system, and through histogram analysis.

Results

• The study found that horses with heaves had inconsistent and irregular pulmonary distribution of the radioactive material. It was also noted that the radionuclide poorly penetrated the peripheral lung fields, showing excess deposition in larger airways.
• Uniform deposition of the radionuclide was observed in control horses, while horses with heaves showed non-uniform deposition, particularly in the caudal parts of the lungs.

Conclusions

• The administration of a single dose of aerosolized albuterol sulfate was found to noticeably improve the dissemination of aerosolized radiolabeled pentetate in the lungs of horses with heaves.
• However, no alteration in pulmonary distribution was observed in clinically normal horses after the administration of aerosolized albuterol sulfate.
• The research leads to the implication that the administration of a bronchodilator preceding an aerosolized, surface-active anti-inflammatory preparation could potentially provide improved pulmonary distribution.