Do you stop the heparin (Heparin Sodium) infusion when the Activated Partial Thromboplastin Time (APTT) level is elevated?

From the Guidelines

Yes, you should stop the heparin infusion when the Activated Partial Thromboplastin Time (APTT) level is significantly elevated above the therapeutic range, such as an APTT level of 192. When the APTT exceeds the target range (typically 1.5-2.5 times the control value or approximately 60-100 seconds, though this varies by institution), the infusion should be temporarily held to prevent excessive anticoagulation and bleeding risk, as supported by the American College of Chest Physicians evidence-based clinical practice guidelines 1. After stopping the infusion, recheck the APTT in 4-6 hours. Once the APTT returns to the therapeutic range, the heparin infusion can be restarted at a reduced rate (typically 10-25% lower than the previous rate). This approach is necessary because heparin has a relatively short half-life of 60-90 minutes, and its anticoagulant effect will diminish fairly quickly after stopping the infusion. The decision to hold heparin should be balanced against the patient's thrombotic risk, and in some high-risk situations, your physician may choose to continue the infusion at a reduced rate rather than stopping it completely, as suggested by the guideline for reversal of antithrombotics in intracranial hemorrhage 1. Some key points to consider when managing heparin infusion include:

• Monitoring the APTT level regularly to ensure it remains within the therapeutic range
• Adjusting the heparin dose based on the APTT results to minimize the risk of bleeding and thrombosis
• Being aware of the potential for variability in APTT results between different reagents and instruments used to measure the APTT, as noted in the study by the American College of Chest Physicians 1
• Considering the use of protamine sulfate to reverse heparin in the context of intracranial hemorrhage, as recommended by the Neurocritical Care Society and the Society of Critical Care Medicine 1. The goal of heparin therapy is to maintain the APTT within the therapeutic range to effectively prevent clot formation while minimizing bleeding complications. In clinical practice, the management of heparin infusion should prioritize the patient's safety and minimize the risk of adverse events, as supported by the highest quality evidence available 1.

From the Research

Heparin Infusion Management

• The decision to stop heparin infusion due to an elevated Activated Partial Thromboplastin Time (APTT) level, such as 192, depends on various factors, including the patient's condition, the target APTT range, and the clinical context 2.
• APTT is a surrogate marker that estimates heparin concentration, and its results can be influenced by patient variation, reagents, UFH composition, and concentration 2.
• The optimal strategy for managing heparin infusion and APTT levels is not fully established, but studies suggest that weight-based heparin dosing and regular APTT monitoring can help achieve therapeutic anticoagulation levels while minimizing the risk of bleeding complications 3, 4.

APTT Monitoring and Heparin Dosing

• APTT values can plateau between a minimal neutralizing dose of protamine and a protamine dose five times greater, and protamine can exert its own anticoagulant action at high doses 5.
• The APTT therapeutic range should be established for each laboratory, taking into account the specific reagents and UFH composition used 2.
• Weight-based heparin dosing regimens, such as a 60-U/kg bolus and 12-U/kg/h infusion, can result in a higher proportion of therapeutic APTT values 4.

Clinical Outcomes and APTT Levels

• Longer APTT values within the first 12 hours of heparin therapy have been associated with adverse outcomes, including increased risk of death, reinfarction, and bleeding complications 4.
• The relationship between APTT levels and clinical outcomes is complex and may be influenced by various factors, including patient weight, UFH composition, and the presence of comorbidities 3, 4.