Achievement of anticoagulation by using a weight-based heparin dosing protocol for obese and nonobese patients

The need for different heparin dosing protocols for obese and nonobese patients was studied. A chart review was performed for all patients who received heparin over an eight-month period at an acute care hospital. Data collected included age, sex, height, actual body weight (ABW), ideal body weight (IBW), initial activated partial thromboplastin time (aPTT), initial heparin bolus dose, initial heparin i.v. infusion rate, time to initial targeted aPTT, and final infusion rate. Forty patients met criteria for inclusion: 20 obese patients (greater than 30% over IBW) and 20 nonobese patients (less than 20% over IBW). Mean +/- S.D. initial heparin infusion rates for the obese and nonobese groups were 14.44+/-1.29 and 15.04+/-0.42 units/kg/hr, respectively. Times to targeted aPTT for obese and nonobese patients were 25.86+/-12.83 and 25.18+/-14.76 hours, respectively; mean final infusion rates were 12.94+/-2.56 and 12.36+/-2.54 units/kg/hr; and percent changes from initial to final infusion rates were 11.84% and 17.76%. There were no significant differences in initial or final infusion rates or time to targeted aPTT between the two groups. It is appropriate to use ABW in a weight-based heparin dosing protocol for obese patients.