Is it safe to initiate a heparin drip in a patient with an International Normalized Ratio (INR) of 2, who has failed a swallow evaluation and was previously taking Coumadin (warfarin), and has impaired renal function with a creatinine (Cr) level of 1.8?

From the Guidelines

Starting a heparin drip in a patient with an INR of 2 who failed a swallow evaluation and was taking Coumadin (warfarin) is not recommended due to the increased risk of bleeding, especially with impaired kidney function (creatinine 1.8). The safest approach would be to wait until the INR is below 1.5-1.7 before initiating heparin therapy to minimize the risk of bleeding complications 1. If anticoagulation is urgently needed, consider using a reduced initial heparin dose (e.g., no bolus and starting at 12 units/kg/hr instead of the standard 18 units/kg/hr) with more frequent aPTT monitoring (every 4-6 hours initially) 2, 3. Some key points to consider in this scenario include:

• The patient's impaired kidney function, which affects heparin clearance and increases the risk of accumulation and bleeding 1
• The need for careful monitoring of aPTT levels to avoid over-anticoagulation 2
• The importance of addressing the swallowing difficulty with alternative anticoagulation routes to minimize the risk of bleeding complications 3
• The recommendation to re-evaluate renal function prior to initiation of direct thrombin or factor Xa inhibitors, and to re-evaluate when clinically indicated and at least annually 2, 3 It is crucial to weigh the risks and benefits of anticoagulation therapy in this patient, considering the increased risk of bleeding due to the elevated INR and impaired kidney function. The decision to start heparin therapy should be made on a case-by-case basis, taking into account the patient's individual risk factors and the potential benefits of anticoagulation. In general, it is recommended to follow institutional standard operating procedures (SOP) for dosing schedules, and to use the American College of Chest Physicians (ACCP) recommendations if no SOP is available 1.

From the FDA Drug Label

To ensure therapeutic anticoagulation, continue full dose heparin therapy and overlap COUMADIN therapy with heparin for 4 to 5 days and until COUMADIN has produced the desired therapeutic response as determined by INR, at which point heparin may be discontinued As heparin may affect the INR, patients receiving both heparin and COUMADIN should have INR monitoring at least: 5 hours after the last intravenous bolus dose of heparin, or 4 hours after cessation of a continuous intravenous infusion of heparin, or 24 hours after the last subcutaneous heparin injection

The safe threshold for INR to start heparin drip is not explicitly stated in the provided drug labels. However, it is recommended to overlap heparin therapy with COUMADIN for 4 to 5 days and until COUMADIN has produced the desired therapeutic response as determined by INR. Key considerations:

• The patient's INR is 2, which is within the therapeutic range for some indications, but the labels do not provide a specific threshold for starting heparin.
• The patient has failed a swallow evaluation and is taking COUMADIN, which may affect the decision to start heparin.
• The patient's kidney function is not good, with a creatinine level of 1.8, which may increase the risk of bleeding with anticoagulant therapy. It is recommended to exercise caution and consider the individual patient's risk factors and clinical situation when deciding whether to start heparin therapy 4.

From the Research

Safety of Starting Heparin Drip with INR 2

• The safety of starting a heparin drip with an International Normalized Ratio (INR) of 2 in a patient who failed a swallow evaluation and was taking Coumadin is not directly addressed in the provided studies.
• However, study 5 investigated the efficacy and safety of a standardized periprocedural anticoagulation regimen with low-molecular-weight heparin during interruption of warfarin therapy.
• The study found that in patients undergoing a non-high-bleeding-risk procedure, the resumption of warfarin and low-molecular-weight heparin was associated with a low risk of thromboembolic and major bleeding complications.

Kidney Function and Anticoagulation

• Study 6 found that apixaban was favored over warfarin for treating venous thromboembolism in severe renal failure, reducing the risk of recurrence and bleeding.
• The study suggests that direct oral anticoagulants may be a safer option for patients with severe renal impairment, but does not provide guidance on the use of heparin in this population.
• Study 7 discusses the management of anticoagulation in patients with thrombotic antiphospholipid syndrome, including those with severe renal impairment, but does not provide specific guidance on the use of heparin in this context.

Safe Threshold for INR to Start Heparin Drip

• Study 5 found that in patients undergoing a non-high-bleeding-risk procedure, warfarin was resumed on the evening of the procedure, and low-molecular-weight heparin was resumed on the next day and continued until the INR was 2.0 or more.
• This suggests that an INR of 2.0 may be a safe threshold for starting a heparin drip, but this is not explicitly stated in the study.
• Study 8 highlights the importance of close monitoring of INR when switching between brands of warfarin, as small changes in systemic concentration can lead to significant variation in pharmacodynamic response.
• Study 9 found that low-molecular-weight heparin bridging was not associated with a significant reduction in the risk of thrombotic events, and may even be associated with a higher risk of thrombosis in some patients.