Masking of heparin activity in the activated coagulation time (ACT) by platelet procoagulant activity

Bode, Arthur P.; Lust, Robert M.

doi:10.1016/0049-3848(94)90025-6

Cited by 24 publications

(9 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other studies showed procoagulant activity of platelets in ACT determination (16). It was also reported that heparin activity in blood containing microparticles generated during blood circulation is masked rather than lost (17). An inverse relationship between ACT and the concentration of the platelet inhibiting agent C7E3 was observed (14).…”

Section: Discussionmentioning

confidence: 91%

See 1 more Smart Citation

Effect of Heparin, Platelets, Activated Platelets, Platelet Fragments, and Hematocrit on Activated Clotting Time

2000

View full text Add to dashboard Cite

Activated clotting time (ACT) is the most commonly used laboratory test to control the heparin effect during extracorporeal techniques. The study was undertaken in order to test in vitro the influence of heparin, platelet count, hematocrit, platelet fragmentation, and platelet activation on ACT. Blood was drawn from volunteer donors into syringes containing citrate. Platelet counts and hematocrit were modified. Platelets were fragmented by sonifier or activated by collagen and adenosine diphosphate (ADP). Different heparin final concentrations were created. Increasing concentrations of heparin had a significant effect on ACT. However, it was not predictable in every case in concentrations lower than 1.0 U/ml. Platelet count generally had no significant effect on ACT. The effect of hematocrit was detectable in a group but not in single cases. Fragmented platelets significantly shortened ACT only without addition of heparin, and the effect was only partly predictable. Activation of platelets by collagen and ADP induced no significant changes. Our results show that heparin is reflected by ACT but that effect is not predictable in every specific patient. Our results also show that other variables that may be altered during extracorporeal techniques such as platelet count, hematocrit, activation, and fragmentation of platelets do not severely influence the ACT.

show abstract

Section: Discussionmentioning

confidence: 91%

“…The aim of this study was to gain a more complete picture of the role that heparin, platelet counts, platelet fragments, activated platelets, and hematocrit play in ACT determination (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”

mentioning

confidence: 99%

Effect of Heparin, Platelets, Activated Platelets, Platelet Fragments, and Hematocrit on Activated Clotting Time

2000

View full text Add to dashboard Cite

show abstract

“…Although ACTs are widely used to monitor heparin activity during CPB, ACT values do not correlate to heparin concentrations during CPB (1, 46). The lack of correlation between heparin levels and ACT values can be explained by the fact that ACT values also reflect the effect of platelet activation, hypothermia and, most importantly, haemodilution (46,47). The major limitation of ACT values during CPB is that when a patient is bleeding, ACT values cannot differentiate whether the bleeding is due to excessive heparinization or acquired haemostatic defects.…”

Section: Discussionmentioning

confidence: 99%

Coagulation and Fibrinolytic Profile of Paediatric Patients Undergoing Cardiopulmonary Bypass

et al. 1997

View full text Add to dashboard Cite

SummaryThe haemostatic system and the use of heparin during cardiopulmonary bypass (CPB) have been studied extensively in adults but not in children. Results from adult trials cannot be extrapolated to children because of age-dependent physiologic differences in haemostasis. We studied 22 consecutive paediatric patients who underwent CPB at The Hospital for Sick Children, Toronto. Fibrinogen, factors II, V, VII, VIII, IX, XI, XII, prekallikrein, protein C, protein S, antithrombin (AT), heparin cofactor II, α2-macroglobulin, plasminogen, α2-antiplas- min, tissue plasminogen activator (tPA), plasminogen activator inhibitor, thrombin-AT complexes (TAT), D-dimer, heparin (by both anti-factor Xa assay and protamine titration) and activated clotting time (ACT) were assayed perioperatively. The timing of the sampling was: pre heparin, post heparin, after initiation of CPB, during hypothermia, post hypothermia, post protamine reversal and 24 h post CPB. Plasma concentrations of all haemostatic proteins decreased by an average of 56% immediately following the initiation of CPB due to haemodilution. During CPB, the majority of procoagulants, inhibitors and some components of the fibrinolytic system (plasminogen, α2AP) remained stable. However, plasma concentrations of TAT and D-dimers increased during CPB showing that significant activation of the coagulation and fibrinolytic systems occurred. Mechanisms responsible for the activation of haemostasis are likely complex. However, low plasma concentrations of heparin (<2.0 units/ml in 45% of patients) during CPB were likely a major contributing etiology. ACT values showed a poor correlation (r = 0.38) with heparin concentrations likely due to concurrent haemodilution of haemostatic factors, activation of haemostatic system, hypothermia and activation of platelets. In conclusion, CPB in paediatric patients causes global decreases of components of the coagulation and fibrinolytic systems, primarily by haemodilution and secondarily by consumption.

show abstract

“…The percent reduction of the ACT owing to the addition of PAF is related to the ability of platelets to be activated and to shorten clotting time. 69 The assay is performed using a specific cartridge in a Heparin Management System (HMS) (Medtronic Inc.) device. The Hemostatus cartridge has been approved by the US Food and Drug Administration (FDA) for monitoring platelet function during cardiac surgery.…”

Section: Tests Of Platelet Response To An Agonist Stimulusmentioning

confidence: 99%

Evidence Based Coagulation Monitors: Heparin Monitoring, Thromboelastography, and Platelet Function

Shore‐Lesserson¹

2005

Semin Cardiothorac Vasc Anesth

View full text Add to dashboard Cite

The hemostatic management of patients undergoing cardiac surgery is a unique challenge. Since its inception, cardiopulmonary bypass (CPB) has required meticulous attention to maintaining adequate anticoagulation. New anticoagulants and alternative monitoring techniques present an opportunity to investigate potential advances in the area of anticoagulation for CPB. Hemostasis after CPB is still a vexing problem, and the addition of antiplatelet medication to the platelet defect already incurred during CPB has led to hemorrhagic complications in cardiac surgery. The two opposing processes of anticoagulation and hemostasis must be managed carefully and modified with respect to the patient's hematologic status and desired hemostatic outcome. Cardiac surgical patients consume a much larger fraction of perioperative blood transfusions than the percentage of the surgical population they represent. Thus, during CPB, careful attention must be paid to optimal anticoagulation, platelet quiescence, biocompatible circuitry and interventions, and to monitoring hemostasis. The multifactorial etiology of the CPB-induced hemostatic defect requires a multimodal approach to blood conservation and hemostasis monitoring, including heparin maintenance and sophisticated point-of-care hemostasis monitoring. Each technology has its own attributes and each may be suitable for different populations based upon the expected defects being measured. This article reviews the evidence supporting the use of point-of-care monitors in coagulation and hemostasis management in cardiac surgical patients.

show abstract

Masking of heparin activity in the activated coagulation time (ACT) by platelet procoagulant activity

Cited by 24 publications

References 25 publications

Effect of Heparin, Platelets, Activated Platelets, Platelet Fragments, and Hematocrit on Activated Clotting Time

Effect of Heparin, Platelets, Activated Platelets, Platelet Fragments, and Hematocrit on Activated Clotting Time

Coagulation and Fibrinolytic Profile of Paediatric Patients Undergoing Cardiopulmonary Bypass

Evidence Based Coagulation Monitors: Heparin Monitoring, Thromboelastography, and Platelet Function

Contact Info

Product

Resources

About