Effects of inhaled dry powder ipratropium bromide on recovery from exercise of horses with COPD

The present study evaluated ventilatory, cardiovascular and metabolic param eters during recovery from strenuous exercise in horses suffering from a cr isis of chronic obstructive pulmonary disease (COPD) and to determine wheth er ipratropium dry powder inhalation (DPI) before exercise has an effect on these parameters. When 6 saddle horses, affected with COPD, developed airway obstruction, the y inhaled placebo and ipratropium (2400 mu g/horse), the order being random ly chosen. Pulmonary function tests were then recorded 15 min after inhalat ion. Following these tests, the horses underwent a strenuous treadmill exer cise, followed by a recovery period that consisted of a 10 min walk. Measur ements were made at the first and tenth min of recovery. Respiratory flow, O-2 and CO2 fractions in the respired gas, pleural pressure changes and hea rt rate were recorded. Arterial and mixed venous blood samples were analyse d for gas tensions, haemoglobin and plasma lactate concentrations. Oxygen c onsumption ((V) over dot O-2), CO2 production, tidal volume, alveolar oxyge n tension (PAO(2)), alveolar ventilation, the alveolar-pulmonary capillary oxygen difference ((A-a)dO(2)) and total pulmonary resistance (R-L) were me asured. The PAO(2) was the only parameter significantly improved during recovery fo llowing ipratropiun DPI. This improvement was not accompanied by evidence o f improvement of other ventilatory or cardiorespiratory parameters. The results showed that in horses suffering from a crisis of COPD, recovery is characterised by an exercise-induced bronchodilation. Secondly, ipratro pium DPI at a dose of 2400 mu g/horse is an effective bronchodilator in the se horses at rest but it has little effect on the airway calibre during the recovery period. It is suggested that the short term recovery period is st ill influenced by exercise-induced adjustments that may exceed the bronchod ilatory effect of inhaled ipratropium that are observed before exercise.