Adenosine spares platelets during cardiopulmonary bypass in man without causing systemic vasodilatation.

The effect of infusing adenosine during cardiopulmonary bypass (CPB) on platelet count and mean arterial blood pressure (MABP) was studied in 13 patients (age 42-74), with 12 patients (age 47-66) as controls. Adenosine infusion (0.1 mg/kg/min in a central vein) caused a ten- to twentyfold increase of the adenosine concentration in the venous blood to the oxygenator, while the arterial levels were close to basal values (0.3 +/- 0.1 microM). The platelet count was significantly higher in the treated than in the placebo group during and 30 min after CPB, but not on the postoperative day. The groups did not differ with regard to the postoperative blood loss from tube drainage. Adenosine did not cause major systemic vasodilation (MABP less than 30 mmHg) in any case, and the blood pressure levels showed no intergroup difference during CPB. However, seven control patients but none in the adenosine group required vasodilator treatment (sodium nitroprusside) during CPB to prevent MABP from exceeding 70 mmHg. We conclude that adenosine infusion during CPB in man spares platelets, with minor changes in blood pressure.