Maintaining Adequate Anticoagulation on Extracorporeal Membrane Oxygenation Therapy: Hemochron Junior Low Range versus Hemochron 400

¹ Division of Neonatal and Developmental Medicine, Stanford University, Palo Alto, California
² Division of Pediatric Surgery, Stanford University, Palo Alto, California

^* Address correspondence to: Christopher E. Colby, M.D., Division of Neonatal and Developmental Medicine, 725 Welch Road, Suite 315, Palo Alto, CA 94304. E-mail: christopher.colby@medcenter.stanford.edu

Received: 8 July 2002
Accepted: 27 January 2003

Abstract

Extracorporeal membrane oxygenation (ECMO) therapy requires that patients be anticoagulated to prevent clotting and thrombotic complications. There are several bedside whole blood microcoagulation systems available to determine activated clotting time (ACT) levels. Many ECMO centers use Hemochron (International Technidyne, Edison, NJ) products to determine ACT levels. During the study period, we used the Hemochron 400 and then changed to the Hemochron Junior Low Range. There were two specific aims of this study. First, to determine if there was a difference in ACT levels measured by these two distinct Hemochron products both marketed for the use in ECMO therapy. Second, to determine if the differing ACT levels produced by these two devices affected clinical outcomes. We compared ACT levels between two devices on 70 paired blood specimens obtained from four neonatal ECMO patients receiving heparin. A retrospective review of 77 ECMO patients was performed to analyze frequency of circuit emergencies and length of ECMO circuit life while using the two products. In lower ACT ranges, the Hemochron Jr. LR consistently yielded higher ACT values than the Hemochron 400. In higher ACT ranges, the Hemochron Jr. LR consistently yielded lower ACT values than the Hemochron 400. Without calibration, after changing devices, this discrepancy led to shorter circuit life and more circuit clotting complications. After calibration and adjustment in target ACT values, there was a trend toward longer circuit life, and there were fewer clotting complications. There is a difference in the ACT values produced by Hemochron 400 and Hemochron Jr. LR. Failure to calibrate target ACT levels after changing machines may lead to shorter circuit life and more clotting complications.