Therapeutic monitoring heparin

Cipolle RJ, Rodvold KA, and Seifert R (1983) Heparin-associated thrombocytopenia A prospective evaluation of 211 patients. Therapeutic Drug Monitoring 5 205-211. 

When used in full therapeutic doses, UFH must be monitored to determine the appropriate dose to administer. The choice of assay is based on chnician preference and institutional availabihty. The aPTT remains the most commonly used test to monitor UFH therapy in North America. In some European countries, anti-factor Xa heparin activity is used commonly. The aPTT should be measured prior to the initiation of therapy to determine the patient s baseline. When administered by intravenous infusion, the response to therapy... 

When anti-factor Xa activity is used to monitor LMWH therapy, the sample should be drawn approximately 4 hours after the subcutaneous injection, during the peak period of anti-factor Xa activity. A calibrated LMWH heparin should be used to establish the standard curve for the assay. The therapeutic range for anti-factor Xa activity is not well defined and to date has not been correlated clearly with efficacy or the risk of bleeding. Eor the treatment of VTE, an acceptable target range is 0.5 to 1.0 unit/mL. Specific algorithms for dosing adjustments based on anti-factor Xa activity are not available at the present time. 

ADMINISTRATION AND MONITORING FuU-dose heparin therapy usually is administered by continuous intravenous infusion. Treatment of venous thromboembolism is initiated with a bolus injection of 5000 units, followed by 1200-1600 units/h delivered by an infusion pump. Therapy routinely is monitored by the aPTT the target is an elevation to 1.8-2.5 times the normal value. The risk of recurrence of thromboembolism is greater in patients who do not achieve a therapeutic level of anticoagulation within the first 24 hours. Initially, the aPTT should be measured and the infusion rate adjusted every 6 hours dose adjustments may be aided by use of a nomogram. Once a steady dosage schedule has been established, daily monitoring is sufficient. 

Enoxaparin is a low-molecular-weight (LMW) heparin. LMW heparins have a longer half-Ufe than standard heparin and a more consistent relationship between dose and therapeutic effect. Enoxaparin is given subcutaneously, not intravenously. It is less— not more— likely to cause thrombosis and thrombocytopenia. Neither LMW heparins nor standard heparin l e teratogenic. The aPTT is not useful for monitoring the effects of LMW heparins. The answer is (A). 

The nurse is administering therapeutic heparin, an anticoagulant, for a client diagnosed with deep vein thrombosis. Which laboratory value should the nurse monitor ... 

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