The effect of heparin-coated pulmonary artery catheters an activated coagulation time in cardiac surgical patients

Objective:To investigate the effect of heparin-coated pulmonary artery catheters (HPACs) on activated coagulation time (ACT) drawn through a non-heparin-coated introducer sheath. Design: A prospective, observational study. Setting: University teaching hospital. Participants: Patients scheduled for surgical procedures requiring cardiopulmonary bypass. Interventions: With institutional review board approval, 63 patients without prior coagulopathy undergoing procedures requiring cardiopulmonary bypass were studied. Jugular venous and radial arterial ACTs were measured before and immediately after insertion of an HPAC. Additional measurements were obtained 1 hour later and 4 minutes after completion of protamine infusion. Measurements and Main Results:The ACT drawn from the introducer after placement of an HPAC was 48 seconds greater than the ACT drawn before the HPAC was placed (p < 0.0001). This difference was still present 1 hour later but not after the administration of protamine or in blood drawn at any time from another site. Baseline ACTs drawn from radial arterial catheters, kept patent using a heparin flush system, resulted in elevated measurements, despite withdrawing seven times the deadspace before taking a sample. Conclusions: Blood obtained from an introducer with an HPAC in situ provides a spuriously high ACT. ACTs drawn from catheters kept patent using heparin flush also result in prolonged measurements. Baseline ACT measurement from an introducer should be obtained before placement of the HPAC. Copyright (C) 2000 by W.B. Saunders Company.