A client with a history of deep vein thrombosis (DVT) is receiving a continuous IV heparin infusion. The nurse notes that the client’s activated partial thromboplastin time (aPTT) is 120 seconds. Which action should the nurse take? Reference Range: aPTT [25 to 35 seconds, therapeutic range for heparin 1.5 to 2.5 times baseline, approximately 38 to 88 seconds].