EVALUATION OF PULMONARY VASODILATORY CAPACITY WITH INHALED NITRIC-OXIDE IN A DOG WITH PATENT DUCTUS-ARTERIOSUS

A female Maltese dog with patent ductus arteriosus (PDA) showing left congestive heart failure and moderate pulmonary hypertension was evalu ated for pulmonary vasodilatory capacity using low concentrations of i nhaled nitric oxide (NO) in comparison with oxygen during preoperative cardiac catheterization. Increasing the inspired oxygen concentration (FiO(2)) to 1.0 without adding NO did not reduce the mean pulmonary a rterial pressure (mPAP). However, inhalation of NO at FiO(2) 1.0 reduc ed mPAP rapidly without changing other hemodymamic and gas exchange pa rameters. From these results, inhaled NO caused selective pulmonary va sodilation without producing systemic vasodilation, which may provide a safe and effective mean of evaluating the pulmonary vasodilatory cap acity of dogs with PDA.