['The purpose of this study was to examine and compare the systemic and pulmonary hemodynamic effects of a central venous infusion of adenosine in cardiac surgical patients.', 'Prospective; each subject served as his/her own control.', "University Hospital and Veteran's Affairs Medical Center.", 'Ten cardiac surgical patients (age 56 +/- 6 years) were studied in the operating room under general anesthesia after weaning from cardiopulmonary bypass. Pulmonary vascular resistance (PVR), systemic vascular resistance (SVR), mean pulmonary arterial pressure (MPAP), and mean systemic arterial pressure (MAP) were determined before, during, and after central venous infusion of adenosine (50 micrograms/kg/min) for 15 min. Statistical analysis was by analysis of variance; significance was accepted at p < 0.05.', 'Adenosine produced selective vasodilation of the pulmonary vascular bed: both PVR and MPAP were significantly reduced during adenosine infusion without changes in either SVR or MAP. PVR and MPAP returned to preinfusion levels after cessation of the infusion. Adenosine effectively reduced PVR and pulmonary arterial pressure without decreasing SVR or systemic arterial pressure.'] Is adenosine a selective pulmonary vasodilator in cardiac surgical patients?