A postoperative client is admitted to the intensive care unit (ICU) with an inflated pressure infuser containing a solution of heparin 2 units/ml attached to an intra-arterial (IA) cannula. Which finding indicates that the heparin infusion has achieved its therapeutic use?

A. Heparin is infused in less than four hours. The heparinized solution used in an intra-arterial (IA) pressure infuser is not intended for systemic anticoagulation but rather to maintain catheter patency. The infusion rate is typically slow and continuous, and completing the infusion in less than four hours is not an indicator of effectiveness. B. Systolic blood pressure greater than 120 mm Hg. Heparin in an IA pressure infuser does not directly affect blood pressure. Its purpose is to prevent clot formation within the catheter, ensuring uninterrupted arterial pressure monitoring. BP readings are monitored separately and are not an indicator of heparin’s therapeutic effect. C. No knee pain upon forced dorsiflexion. This assessment is used to evaluate deep vein thrombosis (DVT) (Homan's sign), which is not related to arterial catheter function. The low-dose heparin in the pressure infuser does not provide systemic anticoagulation, making this finding irrelevant. D. Intra-arterial cannula remains patent. The primary purpose of heparinized flush solutions in IA lines is to prevent clot formation within the catheter and maintain patency for continuous blood pressure monitoring or arterial blood sampling. A patent arterial line confirms that the heparin infusion is achieving its intended effect.