An evaluation of empiric vs. nomogram-based dosing of heparin in an intensive care unit

Objective: To compare the time to achieve therapeutic anticoagulation with heparin using two dosing methods. Design: A retrospective before and after time series. Setting: An 11-bed medical-surgical intensive care unit of a tertiary, teaching hospital. Patients: Critically ill patients who required full dose anticoagulation as part of treatment of hemodynamic or respiratory failure. Intervention: The use of a weight-based dosing nomogram with independent adjustment of infusion rates by nursing staff utilizing the nomogram dosing directions. This nomogram was compared with prior empiric heparin dosing by physicians. Measurements and Main Results: The time to achieve a therapeutic activated partial thromboplastin time (PTT) (>60 sees) was significantly less during use of the nomogram than during use of the empiric dosing method. The number of adjustments required to achieve the therapeutic PTT was less during use of the nomogram. Heparin dosing using the nomogram resulted in larger initial heparin infusion rates (unit/kg) and significantly higher initial PTT results. There was no difference in the initial bolus dose, time to first measured PTT, number of PTT measurements outside the therapeutic range, or signs of toxicity from subtherapeutic or supratherapeutic anticoagulation. Conclusions: Use of a weight based heparin dosing nomogram by intensive care unit nursing staff can shorten the time to achieve therapeutic anticoagulation compared with empiric dosing by physicians.