Rapid heparin anticoagulation: use of a weight-based nomogram.

The rapidity with which heparin anticoagulation is achieved is essential to a positive clinical outcome in patients with deep venous thrombosis or pulmonary embolus. However, adequate anticoagulation is frequently not achieved, either as a result of dosing regimens that do not take heparin kinetics into account or because of clinicians' wariness of possible hemorrhagic complications associated with elevated activated activated partial thromboplastin times. Obese patients are at particularly greater risk for subtherapeutic heparin dosing because their pharmacokinetic volumes of distribution differ from those in nonobese patients. Traditional empiric heparin dosing schemes may have pitfalls; methods that take into account the patient's weight are more likely to allow rapid anticoagulation. A nomogram that uses pharmacokinetic and volume of distribution principles to predict therapeutic levels of anticoagulation is presented.