Guidelines for Reversal of Oral Anticoagulants (Vitamin K antagonists, e.g. Warfarin, Phenindione and Acenocoumarol).

Transcription

1 CLINICAL GUIDELINE (Vitamin K antagonists, e.g. Warfarin, Phenindione and Acenocoumarol). For use in (clinical areas): For use by (staff groups): For use for (patients): Document owner: Status: All clinical areas All clinicians All patients on oral anticoagulants Hospital Thrombosis Committee Approved 1. Purpose of guideline For the purposes of this guideline oral anticoagulants refer to oral vitamin K antagonists, which include warfarin, phenindione and acenocoumarol. This is a clinical guideline to aid decision making about the reversal of oral anticoagulation where the International Normalised Ratio (INR) is above the normal range, or if a patient is bleeding or undergoing an urgent invasive procedure. The management of oral anticoagulants in patients requiring elective surgery or invasive procedures is covered in a separate guideline. These guidelines provide a framework to aid decision making. Further advice is always available from the duty Haematology doctor, who should be informed if a patent is bleeding or the INR is not coming under control. Contents 1. Purpose of guideline Background Methods of Reversing Warfarin Stop warfarin or reduce the dose Vitamin K Prothrombin Complex Concentrate (Octaplex) Management of Bleeding & Excessive Anticoagulation with Warfarin Major bleeding basic principles Urgent surgery/invasive procedure Prosthetic heart valves Table 1: Summary of management of bleeding and excessive... anticoagulation Management of patients requiring Prothrombin Complex Concentrate (PCC) Management of patients after warfarin reversal References Development of the guideline...8 Appendix 1 Manufacturer s instructions for preparation of Octaplex...9 Source: Hospital Thrombosis Committee Issue date: April 2011 Page 1 of 9

2 2. Background Warfarin and other vitamin K antagonists work by inhibiting the production of the vitamin K dependent clotting factors II, VII, IX and X by the liver. A number of factors affect the dose of warfarin needed to achieve the therapeutic range. These include diet (amount of vitamin K), other drugs, liver disease (including the effect of alcohol and liver congestion in heart failure) and genetic factors. Patients are therefore monitored closely but can still be out of range or develop bleeding. While anticoagulation is beneficial to the patient, over anticoagulation is potentially life-threatening. A balance between the two must be made when reversing warfarin in a patient who is over anticoagulated or bleeding/requiring urgent surgery. Decisions need to be made about the target INR and whether to reduce or stop the warfarin and allow the INR to fall naturally or intervene to reverse warfarin quickly and whether to fully or partially reverse the warfarin (i.e. what INR to aim for). The decisions must be made on an individual basis and should consider:- the presence of major/minor bleeding risk of bleeding patient factors (including risk of falls) and external factors (need for urgent/semi-urgent invasive procedure and type of procedure) the current INR the risk of bleeding increases exponentially with an INR >5. the reason for anticoagulation e.g. atrial fibrillation, prosthetic heart valve the risk of thrombosis All patients with bleeding should be evaluated to identify if there is a local anatomical reason for bleeding. Bleeding may occur when patients are not over anticoagulated. In these circumstances it may still be necessary to reverse anticoagulation and identify the cause of bleeding. Advice is always available from the duty Haematology doctor. Source: Hospital Thrombosis Committee Issue date: April 2011 Page 2 of 9

3 3. Methods of Reversing Warfarin: 3.1 Stop warfarin or reduce the dose. The effect of warfarin will reverse over a period of 2-4 days. 3.2 Vitamin K Vitamin K is a specific antidote for warfarin. A sustained response is achieved with intravenous Vitamin K. Oral or intravenous administration of vitamin K can be expected to reverse warfarin 4 6 hours after administration. Only 0.5mg vitamin K is required to reduce the INR from about 5.0 to a target level of Vitamin K tablets usually contain >5mg which will completely reverse anticoagulation. When partial correction is required, consider intravenous vitamin K phytomenadione (Konakion MM) or give the intravenous preparation orally. Allergic reactions following intravenous vitamin K are rare with new preparations. If the INR is still too high at 24 hours, the dose of vitamin K can be repeated. For patients with prosthetic heart valves, full reversal of oral anticoagulants with vitamin K may result in prolonged oral anticoagulant resistance and the possibility of valve thrombosis and thromboemboli. The degree of reversal must therefore be decided on an individual basis. 3.3 Prothrombin Complex Concentrate (PCC) e.g. Octaplex Octaplex is a prothrombin complex concentrate (PCC) licensed for warfarin reversal. It is derived from human plasma (non-uk) and contains the clotting factors II, VII, IX and X. PCCs provide immediate reversal of warfarin but the effect will begin to wear off after 6-12 hours. Octaplex is a virally inactivated product which reduces the risk of transmission of viral infections especially enveloped viruses such as HIV. Like other plasma products however, there remains a risk of prion diseases namely variant Creutztfeldt-Jakob Disease (vcjd). Early PCCs were associated with a significant thrombotic risk due to the presence of phospholipids and activated clotting factor VII, as well as protein C & S. The newer products such as Octaplex carry a very low risk. See latest BNF for contraindications and cautions. The combination of vitamin K and a prothrombin complex concentrate (e.g.octaplex) is the treatment of choice for rapid reversal of warfarin. (NB Do not confuse with Octaplas, which is a commercial fresh frozen plasma) Note: Fresh frozen plasma (FFP) not recommended The British Committee for Standards in Haematology guidelines state that FFP should not be used to reverse warfarin unless no Prothrombin Complex Concentrate is available in the case of a severe bleed. FFP must be authorised by the duty Haematology doctor. Source: Hospital Thrombosis Committee Issue date: April 2011 Page 3 of 9

4 4. Management of Bleeding and Excessive Anticoagulation 4.1 Major Bleeding Basic principles Resuscitate the patient. Stop warfarin Transfer to hospital for immediate reversal with vitamin K and prothrombin complex concentrate (PCC), e.g. Octaplex units/kg (see Table 1). Establish the cause of bleeding and treat the cause. Monitor INR after reversal (4-6 hours after vitamin K; mins after PCC) and correct as necessary. Specific details are given in section 4.5 For cerebral bleeds there is evidence that the faster the warfarin is reversed the lower the chance of extension of the haematoma. The INR should therefore be corrected to <2.0 as soon as possible. 4.2 Urgent surgery/invasive procedure The INR should be corrected to at least <2.0 before surgery or <1.5 for high risk sites e.g. neurosurgery, lumbar puncture. The method of correction used will depend on how urgently surgery is required. a) Surgery/invasive procedure in 4-6 hours Stop warfarin Give vitamin K (phytomenadione (Konakion MM)) 5mg or 10mg by slow intravenous injection. Recheck INR 4-6 hours after administration and prior to surgery. b) Immediate surgery/invasive procedure As above Consider PCC (Octaplex) in addition. 4.3 Prosthetic heart valves Patients with prosthetic heart valves are at high risk of valve thrombosis and thromboemboli. Obtain consultant advice from cardiology as well as haematology. The risk varies according to valve position and type. Source: Hospital Thrombosis Committee Issue date: April 2011 Page 4 of 9

5 4.4 Table 1 Summary of management of bleeding and excessive anticoagulation. 3.0 <INR <6.0 (1) reduce warfarin dose or stop (target INR 2.5) (2) restart warfarin when INR <5.0 or 4.0 <INR <6.0 (target INR 3.5) No bleeding or minor bleeding 6.0 <INR <8.0 (1) stop warfarin No bleeding or (2) restart when INR <5.0 minor bleeding INR >8.0, (1) stop warfarin no bleeding or (2) restart warfarin when INR <5.0 minor bleeding (3) if other risk factors for bleeding give mg of vitamin K orally* 1 Major bleeding* 1 (1) stop warfarin (2) give Prothrombin Complex Concentrate (PCC), i.e. Octaplex units/kg* 2 (3) give 5mg or 10mg of vitamin K intravenously 4.5 * 1 For Vitamin K, use phytomenadione (Konakion MM) paediatric. This intravenous preparation may ge given orally or by slow IV injection. 4.6 * 2 For Octaplex, contact duty Haematology doctor to discuss indication/contraindications and dose of Octaplex, as well as degree of reversal required. The maximum dose is 3,000 units. Once bleeding has stopped and the situation is stable a plan will need to be discussed with the haematologists for reintroducing anticoagulation. If it is decided to stop warfarin indefinitely, inform the patients Anticoagulation Monitoring Service before discharge. Source: Hospital Thrombosis Committee Issue date: April 2011 Page 5 of 9

6 4.5 Management of Patients requiring Prothrombin Complex Concentrate (PCC) 1. Stop warfarin 2. Give vitamin K (phytomenadione (Konakion MM)) 5mg or 10mg by slow intravenous injection or intravenous infusion in 5% glucose. An effect on the INR can usually be expected within 4 6 hours. For patients with heart valves, discuss with cardiologist and haematologist first. 3. Give Octaplex (PCC) 25-50units/kg. (see latest BNF for indications, contraindications, cautions and side effects of Octaplex). 4. Contact haematology duty doctor via switchboard to discuss indication/contraindications for Octaplex and dose, (maximum dose 3,000 units), depending on degree of reversal required. The patient s weight is required. 5. Phone the Blood Bank to request the Octaplex, giving full patient details, your name and contact number, the name of the duty haematology doctor you spoke to and the agreed number of units required. 6. Prescribe Octaplex on the Pink Prescription form. 7. Octaplex can be collected from Blood Bank within 10mins of request. It does not need to be thawed but does require labelling. Please arrange for some one to collect the product from blood bank and ensure the nurses are aware that Octaplex has been written up and is required immediately. 8. Follow instructions on package insert for reconstitution and see also appendix 1 for diagram of method of reconstituting Octaplex. It should be used immediately. If a mistake is made in drawing up the Octaplex and the vacuum is lost during reconstitution the sterile water can be injected into the Octaplex with a sterile needle and syringe. The resulting liquid should then be drawn up with the filter needle from the pack. If however when the vial is punctured there is no vacuum it should not be used as the sterility may have been compromised. The faulty vial should be returned to staff in Blood Bank. 9. For further information on storage, reconstitution and administration of Octaplex, refer to the Blood Product Monograph for Octaplex (Human Prothrombin Complex: Coagulation Factor IX) in the Handbook of Intravenous Therapy via the Intranet Pharmacy homepage or on the Pathology Services Handbook (anticoagulation or transfusion sections). 10. If allergic or anaphylactic reactions occur the Octaplex infusion should be stopped immediately and treatment given for anaphylaxis as indicated. Inform Blood Bank. Source: Hospital Thrombosis Committee Issue date: April 2011 Page 6 of 9

7 11. If PCC (Octaplex) is unavailable, discuss the need for fresh frozen plasma (FFP) with the duty Haematology doctor. At least 15ml/kg will be required and the INR should be rechecked 30 mins after administration. 12. Reassess the patient for treatable causes of bleeding. 13. Check INR minutes after administration of Octaplex and again 4-6 hours later. A further dose may be needed post infusion if the INR is still too high or if the effect is wearing off at 4-6 hours. At 4-6 hours however the vitamin K should have started to work and there is a risk of thrombosis with further doses. Discuss with the duty haematology doctor. 14. Record the treatment given and indication, the outcome and the batch number of the Octaplex in the patient s medical notes as well as on the prescription chart. 15. Observe the patient for thrombosis or disseminated intravascular coagulation (DIC) particularly if more than one dose of Octaplex has been given. 4.6 Management of Patients after Warfarin Reversal 1. When the haemorrhagic risk has resolved and the patient is able to take oral medication restart warfarin, if still indicated. For patients with a high thrombotic risk it is appropriate to reload using the rapid loading regimen as indicated on the WSH warfarin chart. For patients with a low thrombotic risk, e.g. slow A.F, follow the slow warfarin initiation regimen as indicated on the WSH warfarin chart, or simply restart on their usual warfarin dose. Closer monitoring of the INR may be required than that indicated on the chart. 2. Consider the use of low molecular weight heparin for high thrombotic risk patients until the INR is in the therapeutic range for 2 consecutive days. 3. At discharge, re-refer to the Anticoagulant Monitoring Service (AMS) with information on the new dose of warfarin on discharge, the date of the next INR test and how the warfarin was reversed. Send a copy of the warfarin dosing chart and the discharge letter to the anticoagulant monitoring service. If monitored elsewhere, contact the relevant anticoagulant service to discuss the patient. 4. If a decision has been made to stop warfarin indefinitely, inform the patient s Anticoagulant Monitoring Service. Source: Hospital Thrombosis Committee Issue date: April 2011 Page 7 of 9

8 5. References British Committee for Standards in Haematology Guidelines Guidelines for the use of Fresh Frozen Plasma, Cryoprecipitate and Cryosupernatant. British Journal of Haematology 2004; 126, Guidelines on oral anticoagulation: third edition British Journal of Haematology 1998, 101, Guidelines on oral anticoagulation (warfarin): third edition 2005 update (British Journal of Haematology 2005; 132, ) 4. West Suffolk Hospital Clinic Guidelines on Initiating and Prescribing Oral Anticoagulants (CG ) 5. West Suffolk Hospital Clinical Guidelines for the Management of Oral Anticoagulants (Vitamin K antagonists, e.g. warfarin) in elective surgery patients 6. Blood Product Monograph for Octaplex (Human Prothrombin Complex; Coagulation Factor IX) via West Suffolk Hospital Handbook of Intravenous Therapy (Internet Pharmacy Homepage) or via West Suffolk Hospital Pathology Services Handbook/anticoagulation and transfusion sections). 6. Development of the guideline 6.1 Changes compared to previous document The Guideline has been simplified and more information from the BCSH 1998 and 2005 updated guidelines has been inserted. The section on perioperative management of anticoagulants for nonurgent surgery/dental procedures has been removed and will be incorporated into new separate guidelines. Details regarding FFP have been removed, to avoid confusion. 6.2 Statement of clinical evidence Based on British Committee for Standards in Haematology Guidelines see references for full guidelines and levels of evidence for individual recommendations. 6.3 Contributors and peer review The Guideline was updated by Dr D Chitnavis, Consultant Haematologist, following discussion within the Haematology Department. The revised Guideline was submitted to the Drugs and & Therapeutics Committee and the Hospital Thrombosis Committee for subsequent comment and approval. 6.4 Distribution list/dissemination method Guidelines to be made available throughout the Trust on the Pink Book. 6.5 Document configuration information Author(s): Other contributors: Approved by: Issue no: 2 File name: Supercedes: Issue no. 1 Additional Information: Keywords: Dr Chitnavis, Dr Beatty Haematology Department Drugs and Therapeutics Committee, Hospital Thrombosis Committee Reversal of Oral Anticoagulants doc Octaplex, intracerebral, haemorrhage, warfarin, phenindione, reversal, stroke, subarachnoid haemorrhage Source: Hospital Thrombosis Committee Issue date: April 2011 Page 8 of 9

9 Appendix 1 Manufacturer s Instructions for preparation of Octaplex Source: Hospital Thrombosis Committee Issue date: April 2011 Page 9 of 9