Safety of fixed-dose heparin titration boluses in underweight patients

At UNC, venous thromboembolism (VTE) patients are treated with a heparin nomogram including fixed-dose titration boluses to correct subtherapeutic heparin correlation values (HCVs). The bolus dose often exceeds the recommended loading dose in underweight patients, therefore raising concern for an increased bleeding risk. This evaluation aims to assess the safety of these titration boluses for underweight patients.

Adult patients receiving intravenous heparin for VTE treatment and requiring at least one titration bolus were included. The underweight patients had a body mass index (BMI) <18.5 kg/m² while the patients in the control group had a BMI of 18.5-29.9 kg/m². The primary outcome was the percentage of patients with a supratherapeutic HCV after the first titration bolus. Secondary outcomes included the percentage of patients with a supratherapeutic HCV requiring holding of the infusion, time to stable HCV, and clinically significant bleeding.

One hundred fifty-eight patients met inclusion criteria, with similar baseline characteristics between groups. There were 13.9 % of patients in both groups who had a supratherapeutic HCV after the first titration bolus. More underweight patients required holding of heparin. All patients took over 48 h to reach a stable HCV. There was no difference in clinically significant bleeding.

Despite finding no significant difference, there remains clinical concern for increased bleeding risk in underweight patients as this population required heparin to be held due to supratherapeutic HCVs more often. More evidence is needed to evaluate the safety of fixed-dose heparin titration boluses in underweight patients due to the limited scope of this study.