Continuous Heparin Infusions: Evaluation and Review of a Dosing Nomogram at Kingston Health Sciences Centre

Abstract

Background: KHSC uses the Heparin (Unfractionated) Standard Dose order set to titrate continuous heparin infusions using PTT monitoring. It was hypothesized that it may be failing to achieve therapeutic PTT values within 24 hours. Compared to other nomograms, KHSC uses conservative dose maximums, which may result in delays in achieving therapeutic PTT in certain patient populations. Objective: Determine if the KHSC heparin nomogram is effective at achieving a therapeutic PTT value for patients. Methods: A retrospective, cross-sectional study was completed. The primary outcome was the percentage of patients achieving a therapeutic PTT within 24 hours. Secondary outcomes included percentages of patients achieving a therapeutic PTT within 48 hours, achieving a second consecutive therapeutic PTT, unable to achieve a therapeutic PTT, median time to therapeutic PTT, and percentage of patients with supratherapeutic PTTs. Between-group analyses were conducted to identify patient-specific factors that may be associated with prolonged time to achieve therapeutic PTT or increased risk of supratherapeutic PTTs. Results: 50 patients, with 54 continuous heparin infusions, were included in the study. 53.7% and 90.7% of the patients achieved a therapeutic PTT value within 24 and 48 hours of initiating heparin, respectively. Between-group analyses determined there was a significant difference between those weighing <80 kg and ≥80 kg for the primary outcome. Conclusion: This study demonstrated that the heparin infusion nomogram is unable to achieve a therapeutic PTT for all patients within 24 hours, with patients weighing <80 kg at a higher risk. Most patients achieved a therapeutic PTT within 48 hours.