Effects of inhaled dry powderipratropium broide on reconvery from exercise of horses with COPD

The present study evaluated ventilatory, cardiovascular and metabolic parameters during recovery from strenuous exercise in horses suffering from a crisis of chronic obstructive pulmonary disease (COPD) and to determine whether ipratropium dry powder inhalation (DPI) before exercise has an effect on these parameters. When 6 saddle horses, affected with COPD, developed airway obstruction, they inhaled placebo and ipratropium (2400 pghorse), the order being randomly chosen. Pulmonary function tests were then recorded 15 min after inhalation. Following these tests, the horses underwent a strenuous treadmill exercise, followed by a ecovery period that consisted of a 10 min walk. Measurements were made at the first and tenth min of recovery. Respiratory flow, 0 2 and C02 fractions in the respired gas, pleural pressure changes and heart rate were recorded. Arterial and mixed venous blood samples were analysed or gas tensions, haemoglobin and plasma lactate concentrations. Oxygen consumption (Wz), C02 production, tidal volume, alveolar oxygen tension (PAOz), alveolar ventilation, the alveolar-pulmonary capillary oxygen difference ((A-a)dOz) and total pulmonary resistance (RL) were measured. The PA02 was the only parameter significantly improved during recovery following ipratropium DPI. This improvement was not accompanied by evidence of 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, ipratropium DPI at a dose of 2400 pghorse is an effective bronchoddator in these 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 still Muenced by exercise-induced adjustments that may exceed the bronchodilatory effect of inhaled ipratropium that are observed before exercise