Does sodium nitroprusside improve tissue oxygenation during cardiopulmonary bypass?

Eight patients undergoing cardiopulmonary bypass with hypothermia received, during part of the hypothermic phase, an infusion of sodium nitroprusside (SNP). Oxygen consumption was measured during the infusion and during control periods. Despite causing a marked reduction of arterial pressure, SNP was not shown to have any significant effect upon whole-body oxygen consumption or lactate concentration in the blood.