Reevaluation of a Weight-Based Heparin Dosing Nomogram: Is Institution-Specific Modification Necessary?

Abstract

Spanish

French

OBJECTIVE:

To compare a heparin dosing nomogram using an initial infusion rate of 18 units/kg/h with physician-directed heparin prescribing and with a modified version of the nomogram adjusted for institution-specific data.

METHODS:

During consecutive phases of this cohort study, patients' intravenous heparin therapies were initiated and adjusted by using one of the following three methods: (1) physician-directed dosing, (2) a body weight—based dosing nomogram with an initial infusion rate of 18 units/kg/h, and (3) a body weight—based dosing nomogram with an initial infusion rate determined by the median dose of heparin (in units/kg/h) required to achieve therapeutic activated partial thromboplastin times (aPTTs) during the first two phases. The time required to achieve therapeutic aPTTs as well as the percentage of initial aPTTs in the therapeutic range were compared for the three phases.

RESULTS:

The heparin dosing nomogram in which the initial infusion rate was adjusted for our individual institution resulted in a statistically shorter median time until aPTTs were in the therapeutic range than did either the physician-directed dosing or unmodified nomogram groups (6.1 h in the modified nomogram group, 10.5 h in the physician-directed group, 21.5 h in the unmodified nomogram group; p < 0.05 for all differences). Use of the institution-specific nomogram resulted in the greatest percentage of initial aPTTs in the therapeutic range (84% in the 13 units/kg/h nomogram group vs. 47% in the physician-directed group and 18% in the 18 units/kg/h nomogram group; p < 0.05 for all differences).

CONCLUSIONS:

Use of a heparin dosing nomogram with an initial infusion rate of 18 units/kg/h resulted in prolongation of the time to reach therapeutic aPTTs. By modifying the nomogram for use at an individual institution, we reduced the time to achieve therapeutic range of aPTTs while still reducing the likelihood of excessive anticoagulation of patients.

Keywords

heparin nomogram

Get full access to this article

View all access options for this article.

References

Raschke

Gollihare

Peirce

. The effectiveness of implementing the weight-based heparin nomogram as a practice guideline. Arch Intern Med 1996; 156: 1645–9.

Raschke

Reilly

Guidry

Fontana

Srinivas

. The weight-based heparin dosing nomogram compared with a “standard care” nomogram. Ann Intern Med 1993; 119: 874–81.

Gunnarsson

Sawyer

Montague

Williams

Dupuis

Caiola

. Appropriate use of heparin: empiric vs nomogram-based dosing. Arch Intern Med 1995; 155: 526–32.

Kaplan

Davison

Parker

Maybery

Feiereisel

Salinger

. Role of heparin after intravenous thrombolytic therapy for acute myocardial infarction. Am J Cardiol 1987; 59: 241–4.

Hull

Raskob

Hirsh

Jay

Leclerc

Geerts

. Continuous intravenous heparin compared with intermittent subcutaneous heparin in the initial treatment of proximal-vein thrombosis. N Engl J Med 1986; 315: 1109–14.

Basu

Gallus

Hirsh

Cade

. A prospective study of the value of monitoring heparin treatment with the activated partial thromboplastin time. N Engl J Med 1972; 287: 324–7.

Anand

Ginsberg

Kearon

Gent

Hirsh

. The relation between the activated partial thromboplastin time response and recurrence in patients with venous thrombosis treated with continuous intravenous heparin. Arch Intern Med 1996; 156: 1677–81.

Hull

Raskob

Rosenbloom

Lemaire

Pineo

Baylis

. Optimal therapeutic level of heparin therapy in patients with venous thromboembolism. Arch Intern Med 1992; 152: 1589–95.

Norman

Provan

, Control and complications of intermittent heparin therapy. Surg Gynecol Obstet 1977; 145: 338–42.

10.

Landefeld

Cook

Flatley

Weisberg

Goldman

. Identification and preliminary validation of predictors of major bleeding in hospitalized patients starting anticoagulant therapy. Am J Med 1987; 82: 703–13.

11.

Conti

Daschbach

Blaisdell

. A comparison of high-dose versus conventional-dose heparin therapy for deep vein thrombosis. Surgery 1982; 92: 972–7.

12.

GUSTO Ila Investigators. Randomized trial of intravenous heparin versus recombinant hirudin for acute coronary syndromes. Circulation 1994; 90: 1631–7.

13.

Neuhaus

von Essen

Tebbe

Jessel

Heinrichs

Maurer

. Safety observations from the pilot phase of the randomized rhirudin for improvement of thrombolysis (HIT-III) study. Circulation 1994; 90: 1638–42.

14.

Antman

. Hirudin in acute myocardial infarction: safety report from the thrombolysis and thrombin inhibition in myocardial infarction (TIMI) 9A trial. Circulation 1994; 90: 1624–30.

15.

Sobel

. Intracranial bleeding, fibrinolysis, and anticoagulation: causal connections and clinical implications. Circulation 1994; 90: 2147–52.

16.

Hirsh

Raschke

Warkentin

Dalen

Deykin

Poller

. Heparin: mechanism of action, pharmacokinetics, dosing considerations, monitoring, efficacy, and safety. Chest 1995; 108 (suppl): 258S–75S.

17.

Stevenson

Easton

Curry

Thomson

Poller

. The reliability of activated partial thromboplastin time methods and the relationship to lipid composition and ultrastructure. Thromb Haemost 1986; 55: 250–8.

18.

D'Angelo

Seveso

D'Angelo

Gilardoni

Dettori

Bonini

. Effect of clot-detection methods and reagents on activated partial thromboplastin time (aPTT): implications in heparin monitoring by aPTT. Am J Clin Pathol 1990; 94: 297–306.

19.

Brill-Edwards

Ginsberg

Johnston

Hirsh

. Establishing a therapeutic range for heparin therapy. Ann Intern Med 1993; 119: 104–9.