The nurse is caring for a patient on bed rest. The patient receives low dose heparin daily for the prevention of DVTs. The nurse evaluates the patient's activated partial thromboplastin time (aPTT) level. Which of the following aPTT levels is below the therapeutic range?
• The reference range for aPTT is 30–40 seconds.
• For treatment of deep vein thrombosis with low-molecular-weight heparin (LMWH), a therapeutic range of aPTT ratio (patient/control) of 1.5 to 2.5 is generally recommended. This results in an aPTT ranging from 45–100 seconds.
• Anything under 45 seconds is under the therapeutic value.
• The activated partial thromboplastin time (aPTT) has replaced partial thromboplastin time (PTT). They both measure the efficacy of the intrinsic and common coagulation pathways in patients treated with heparin.