Intravenous heparin dosing: patterns and variations in internists' practices

Abstract

Objective: To characterize internists' dosing practices when administering and adjusting intravenous heparin regimens.

Design: A survey administered by physician-investigators.

Setting: Two community teaching hospitals and one Veterans Affairs Medical Center.

Subjects: Sixty-one attending physicians in internal medicine.

Measurements: Physicians' choices of therapeutic activated partial thromboplastin time (APTT) range, initial heparin bolus, initial infusion dose, and dose/infusion adjustments when APTT levels are < 1.2 x control (< 35 seconds), 1.2-1.5 x control (35-45 seconds), 1.5-2.3 x control (46-70 seconds), 2.3-3.0 x control (71-90 seconds), and > 3.0 x control (> 90 seconds).

Results: Physicians' dosing decisions and therapeutic ranges during heparin treatment varied widely. Responses to nontherapeutic APTT levels had especially high coefficients of variation (0.67-0.81). Two groups of physicians, together comprising a majority of all respondents, use mutually exclusive therapeutic ranges (mean 44-56 seconds and 60-83 seconds). These two groups differ significantly in several types of dosing decisions.

Conclusion: In the absence of generalizable standard guidelines for intravenous heparin therapy, internists' dosing practices vary widely. Because such practices may impede timely, effective anticoagulation, experimental studies comparing standardized dosing protocols are needed.