THE EFFECT OF DOXAPRAM-INDUCED HYPERVENTILATION ON RESPIRATORY MECHANICS IN HORSES

To investigate the influence of increased respiratory frequency on res piratory mechanics in the horse, measurements were made in two groups of seven tracheostomised horses before and after the administration of doxapram. The horses in group I had normal base line values for respi ratory mechanics, whereas the horses in group II had significantly low er values of dynamic compliance (Cdyn), higher respiratory resistance (R), and a higher total change in pleural pressure (Delta P). The admi nistration of 0.3 mg kg(-1) doxapram intravenously resulted in a signi ficant increase in respiratory frequency (f(R)), R, Delta P, tidal vol ume (V-T), and peak to peak respiratory flow ((V) over dot), and a dec rease in Cdyn in both groups of horses. The group Il horses had signif icantly greater increases in Rand Delta P than the horses in group I.