Abstract
Objective
To determine whether pulmonary distribution of aerosolized technetium Tc 99m pentetate is improved after inhalation of a single dose of albuterol sulfate in horses susceptible to recurrent airway obstruction (heaves).
Animals
6 horses with heaves and 4 horses with normal respiratory tract function.
Procedure
Images were obtained during ventilation of horses at baseline (maximal change in pleural pressure during tidal breathing [ΔPplmax] > 15 cm H2O) and after aerosolized albuterol sulfate (360 µg) administration, with a 24-hour washout period between experiments. The ΔPplmax was determined prior to the baseline scan, prior to albuterol sulfate administration, and 5 minutes after albuterol sulfate administration. Images were assessed by visual inspection (semiquantitative scoring system) and histogram analysis.
Results
Images obtained from horses with heaves had nonuniform pulmonary distribution of radionuclide characterized by poor penetration in peripheral lung fields and excess deposition in large airways. Histogram analysis of images of the caudal portions of the lungs revealed nonuniform radionuclide deposition in horses with heaves and uniform radionuclide deposition in control horses.
Conclusion
Administration of a single dose of aerosolized albuterol sulfate improved pulmonary distribution of aerosolized radiolabeled pentetate suspension in horses with heaves but did not alter pulmonary distribution in clinically normal horses.
Clinical Relevance
Precedent bronchodilator administration may improve pulmonary distribution of aerosolized, surface-active anti-inflammatory preparations. (Am J Vet Res 1999;60:764–769)
