A client with a deep vein thrombosis (DVT) is started on heparin infusion. After 24 hours, the aPTT is 140 seconds (therapeutic range 60-100 seconds). What is the PRIORITY nursing action?

HEPARIN MONITORING AND SAFETY is one of the most high-stakes pharmacology topics on the NCLEX. THERAPEUTIC aPTT RANGE: Typically 60-100 seconds (or 1.5-2.5 times the normal value of approximately 30-40 seconds); some institutions use anti-Xa levels instead. aPTT 140 SECONDS: This is well above the therapeutic range; risk of serious spontaneous bleeding is significantly elevated at this level; IMMEDIATE ACTIONS: (1) STOP THE HEPARIN INFUSION; (2) NOTIFY THE PROVIDER IMMEDIATELY; (3) ASSESS FOR BLEEDING: neurological changes (intracranial bleed); abdominal/back pain (retroperitoneal bleed); blood in urine, stool, vomit; decreased BP, tachycardia; unexplained bruising or bleeding from IV sites; (4) PREPARE FOR REVERSAL if ordered: PROTAMINE SULFATE is the specific antidote for heparin; dosing based on heparin units administered; given slowly IV (anaphylaxis risk — have resuscitation equipment ready); (5) REPEAT aPTT after interventions; (6) DOCUMENT. SUPRATHERAPEUTIC aPTT CAUSES: Too rapid an infusion rate; laboratory timing (drawn too soon after dose change); patient sensitivity; drug interactions. HEPARIN-INDUCED THROMBOCYTOPENIA (HIT): Monitor platelet count every 2-3 days; HIT is a paradoxical pro-coagulation reaction; platelets below 50% of baseline after starting heparin → stop heparin immediately.