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Clinical guidelines for the use of intravenous standard heparin protocols, low molecular weight heparin, initiation and management of Warfarin therapy, and managing high INR and bleeding during Warfarin therapy. It includes protocols for heparin infusion rates, notes on intravenous heparin, and managing high INR and bleeding.
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Clinical Quality Council Approval: November 2006 1
Governing Body & Management
Approved By
Originally Issued
Re-Issued
Current Version Issued
Next Review Date
Clinical Quality Council Approval: November 2006 2
Table of Contents
Section Description Page
1 Intravenous Standard Heparin Protocols 3- 2 Low Molecular Weight Heparin 1- 3 Management of Bleeding on Intravenous Stand and Low Molecular Weight Heparin
1
4 Initiation of Warfarin Therapy 1- 5 Management High INR and Bleeding During Warfarin Therapy 1- 6 Perioperative Management of Anticoagulant Therapy in patients on Warfarin
1-
7 Intravenous Standard Heparin Protocols (Syringe Driver Protocols)
1-
Clinical Quality Council Approval: November 2006 4
DOSAGE: Concentration = 25,000 units heparin sodium in 250 normal saline (0.9% sodium chloride). (100 units per ml) Based on 18 units/kg/hour.
_WEIGHT BOLUS UNITS PER HOUR Starting rate mL per hour_* 50 3500 900 9 55 3500 990 10 60 5000 1080 11 65 5000 1170 12 70 5000 1260 13 75 5000 1350 13 80 5000 1440 14 85 5000 1530 15 90 5000 1620 16 95 7500 1710 17 100 7500 1800 18 110 7500 1980 20
120 7500 2100 21 *Note: Millilitres per hour has been rounded to the nearest whole number
The first APTT is taken six hours after commencing the infusion and the rate adjusted as below.
IV U NFRACTIONATED H EPARIN D OSAGE A DJUSTMENT P ROTOCOL F OR AF/VTED (T ABLE 2)
Based on aPTT Normal Range of 25-35 Seconds & Infusion of 25,000units in 250mL aPTT (seconds)
Bolus Dose IV
Stop Infusion IV Rate Change (mL/hr)
Repeat aPTT
< 35 5,000 units NO increase 2mL/hr from current rate
6 hours
35-45 Nil NO increase 2mL/hr from current rate
6 hours
46-54 Nil NO increase 1mL/hr from current rate
6 hours
55-90 T h e r a p e u t i c R a n g e - N o C h a n g e f r o m c u r r e n t r a t e
Daily
91-95 Nil NO decrease 1mL/hr from current rate
6 hours
96-105 Nil NO decrease 2mL/hr from current rate
6 hours
> 105 Nil 60 mins Restart at 2mL/h less than previous rate
6 hrs
Clinical Quality Council Approval: November 2006 5
Notes on intravenous heparin:
Safety Issues with infusion pumps: Care needs to be taken that pumps are operated according to hospital protocols and the manufacturer’s instructions. To reduce the risk of accidental infusion of a large volume of heparin solutions:
Changing Between Intravenous Heparin and Clexane
Where a decision is made to change the patient from intravenous heparin to Clexane, the calculated dose of Clexane (see low molecular weight heparin protocol) should usually be administered as soon as the intravenous heparin is ceased, assuming the patient was not over-anticoagulated on heparin at the time.
If the patient were changed from subcutaneous Clexane to intravenous heparin, intravenous heparin would normally be commenced when the next dose of Clexane is due, assuming the patient was not over-anticoagulated at the time.
Clinical Quality Council Approval: November 2006 2
consultation with a Renal Physician and/or Haematologist. If used, Clexane 1 mg/kg/day with daily or second daily monitoring of anti-Xa levels (see below) until a stable level is achieved. .
dose). If the patient’s weight is >100 kg, twice daily 1 mg/kg is recommended, as above.
Clinical Quality Council Approval: November 2006 3
Medical Staff (see below).
Hirsh J & Raschke R. The Seventh ACCP Conference on antithrombotic and thrombolytic therapy. Chest. 2004;126:188S-203S The Australasian Creatinine Consensus Working Group. Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: a position statement. Med J Aust 2005; 183: 138-141.
Clinical Quality Council Approval: November 2006 5
SERUM CREATININE 151-200 micromol/L and CCR
Age Sex Weight 40kg 50kg 60kg 70kg 80kg 90kg 100kg 50yrs M F 60yrs M F 30- 50 mL/min 70yrs M < mL/min F
80yrs M F 90yrs M F
Notes: Based on creatinine clearance calculated using the COCKCROFT–GAULT EQUATION
(140-age) x weight in kg 0.814 x creatinine in umol/l
Multiply the result by 0.85 for females.
These estimates of Glomerular Filtration Rate (GFR) are unreliable in very obese or oedematous patients. Formal assessment of renal function is recommended in these patients.
Clinical Quality Council Approval: November 2006 1
Intravenous Unfractionated Heparin
Low Molecular Weight (LMW) Heparin
12 hours ago and renal function is normal.
Precautions with protamine:
Reference : Hirsh J & Raschke R. The Seventh ACCP Conference on antithrombotic and thombolytic therapy. Chest 2004; 126: 188S-203S Clexane prescribing information (Aventis Pharma Ltd) via MIMS Online, July 2006
Clinical Quality Council Approval: November 2006 2
In some situations, initial overlapping Warfarin/heparin therapy may not be required e.g. commencement of Warfarin following prosthetic heart valve insertion or low risk patients with atrial fibrillation commencing Warfarin electively to reduce the risk of stroke.
The Warfarin dosing algorithm below may be used to commence therapy where the target INR is 2-3, or experienced staff may initiate therapy empirically based on judgement. If a previous stable dose for a particular patient is known, then it is preferable to start therapy at that same dose.
The algorithm below is intended for a target range of 2-3. Day 1 is the first day of Warfarin therapy. The INR will usually be checked daily on inpatients. In outpatients second daily checks of the INR may be reasonable, depending on the rate of rise of the INR.
Day INR Dose 1 0-1.3 5mg ( Consider reduction to 3mg if risk factors exist – see above) 2 <1.5 5mg 1.5-1.9 2.5mg 2.0-2.5 1-2.5 mg
2.5 0 3 <1.5 5 mg 1.5-1.9 2.5-5mg 2.0-3.0 0-2.5mg 3.0 0 4 <1.5 10mg 1.5-1.9 5-7.5 mg 2.0-3.0 0-5 mg 3.0 0 5 <1.5 10 mg 1.5-1.9 7.5-10 mg 2.0-3.0 0-5 mg 3.0 0 6 <1.5 7.5-12.5 mg 1.5-1.9 5-10 mg 2.0-3.0 0-7.5 mg 3.0 0
Haematology consultation is recommended if by day 7 an adequate INR is not achieved.
Clinical Quality Council Approval: November 2006 3
References:
Clinical Quality Council Approval: November 2006 5
Your doctor has given you Warfarin, an anticoagulant tablet to slow the clotting of your blood. There are two brands of Warfarin i.e. Coumadin and Marevan. It is important that you take the same brand at all times. The Warfarin tablet should be taken once at the same time each day (usually at night).
Important points for patients on Warfarin :
Wear medical alert bracelet or carry medical alert card, stating you are on Warfarin.
Watch for signs of bleeding (eg. bruising, nose and gum bleeds, rectal bleeding and dark urine and black stool). Sudden severe headache may indicate bleeding, and you should seek immediate medical attention.
Eat a well balanced diet.
Always contact the doctor managing your Warfarin before any medical procedure (eg. any operation or any dental work or a visit to the Podiatrist). The person performing the procedure eg doctor, dentist, podiatrist etc also needs to know you are taking Warfarin.
Never take aspirin or medications containing aspirin unless directed by a doctor. For minor aches and pains, you may take 1-2 tablets of paracetamol up to a maximum of 8 tablets per day. If you require more see your doctor.
If you see a different doctor it is important they know you are taking Warfarin. Many medications can affect Warfarin. Do not change medications, take any herbal tablets or any ‘over the counter’ medications without discussing with your doctor.
Missed dose – a dose can be taken within 2 hours of your normal dosage time. If more than 2 hours, skip that day’s dose until the next dose is due. DO NOT DOUBLE THE DOSE. (Record in your booklet).
Drink alcohol in moderation (limit to 2 standard drinks / day).
At the time of commencing Warfarin, clarify with your doctors the intended duration of therapy, since this is an important issue for other doctors who may look after you in the future.
After every blood test for INR you must ring the doctor looking after your coagulation i.e. either your GP or the hospital clinic so they can tell you if you need to change your dose.
Clinical Quality Council Approval: November 2006 1
Clinical Setting Action INR < 5 but higher than the target therapeutic range (no bleeding)
Lower the dose or omit the next dose of Warfarin. Resume therapy at a lower dose when the INR approaches the therapeutic range. INR 5-9 (no bleeding) • If the patient is not bleeding and is not at high risk of bleeding, the next 1-2 doses of Warfarin can be omitted and Warfarin restarted at a lower dose when the INR falls into the therapeutic range.
•Alternatively if the patient is at increased risk of bleeding, omit one dose of Warfarin, give 1-2.5 mg Vitamin K orally* or 0.5-1.0 mg IV 1. Measure INR the following day anticipating that the INR will be in the therapeutic range of 2.0-3.0 within 24 hours. Recommence Warfarin the next day at a reduced dose **^. INR >9 (no bleeding) Stop Warfarin, give 1 mg IV Vitamin K 1 or 2.5-5 mg oral vitamin K *^. Repeat the INR after 6 hours to ensure INR<9. Recommence Warfarin at reduced dose once INR is in the therapeutic range. Consider blood products, as below, if there is a high risk of bleeding. If the patient is bleeding (any level of INR)
Stop Warfarin and give IV Vitamin K 1 (see below) and clotting factor replacement (either FFP alone/or in cases of volume overload with Prothrombinex in consultation with Haematologist), measure INR as required. Assess need to restart Warfarin. Consult senior staff as to the appropriate dose of vitamin K. A vitamin K dose in the range of 1-10 mg IVI will be appropriate.
INR = international normalized ratio. *(use ivi formulation mixed in water, juice – see below) ** If INR <2.0 and the thrombotic risk is high, give S/C Clexane 1.5mg/kg/day or 1 mg/kg Q12H SCI until INR is >2.0, (check GFR is normal –see LMW heparin protocol). (^1) Avoid high doses of vitamin K, where the patient will require ongoing Warfarin therapy
and there is a high risk of thrombo-embolism e.g. mechanical heart valve.
Clinical Quality Council Approval: November 2006 1
Each patient requires individual assessment, with the competing risks of thrombosis and haemorrhage. Management must be discussed with the Physician managing anticoagulation to define the thrombotic risk , the Surgeon or the Proceduralist to define the bleeding risk , as well as the patient. The bleeding and thrombotic risk should be documented. It should be noted that many simple procedures, with low bleeding risk can be performed with the patient remaining on Warfarin. Uncomplicated dental work can usually be performed with a therapeutic INR. Bridging therapy with heparin (see below) should be offered to patients who are judged to have a high risk of thrombosis while off Warfarin. Because of the high thrombotic risk associated with prosthetic valves, in all cases anticoagulation should be discussed with and determined by the Cardiologist managing the patient. The equivalence of low molecular weight heparin therapy to Warfarin and unfractionated heparin therapy has not been established in patients with mechanical heart valves.
~Day - Check baseline INR, FBC, LFTs and creatinine to establish the appropriate perioperative management. Tests should be performed within 10 days in patients with stable anticoagulation of the day of surgery. Day 0 is arbitrarily defined as the day of surgery. Define the bleeding risk of the procedure with the operator and determine when Warfarin can be recommenced postoperatively. Define the thrombotic risk off Warfarin (see below). Determine whether bridging therapy with Clexane or intravenous heparin is required.
Day -5 or day - No Warfarin is taken from day -5 or day -4 (i.e. miss day -5 or day -4 through to day 0 inclusive). The decision as to whether to stop Warfarin from day - or day -5 depends on the perceived risk of thrombosis, the procedure and the baseline INR. Cessation from day -5 may be appropriate if the INR is high (>3), there is a low thrombotic risk and/or the surgery has a high bleeding risk. Cessation from day -4 may be appropriate if the INR is lower <3, there is a high thrombotic risk, and the surgery has a lower bleeding risk.
Day -3 or day -2 (only if bridging therapy is planned) Check the INR two days after ceasing INR and commence Clexane or heparin if the INR is <2. If the INR has not fallen sufficiently, check the INR daily, and commence bridging therapy as below when the INR has fallen to <2. Avoid Clexane bridging therapy in patients with impaired renal function (see LMH heparin protocol). When the INR is <2 commence either:
Clinical Quality Council Approval: November 2006 2
Day -1 (all patients) Check to ensure INR < 1.8. If > 1.8, 1-2 mg IV Vitamin K should be considered. If the patient is receiving BD Clexane, the evening dose is usually omitted. If there is a high risk of thrombosis or the surgery will occur in the afternoon of the next day, then then the evening dose may be given. In most situations a gap of at least 18 hours should be allowed for twice daily Clexane dosing, with an additional six hours if neuroaxial anaesthesia is contemplated. If the INR is < 1.5, surgery can usually proceed without rechecking the INR on the day of surgery.
Day 0 (morning of surgery) If the patient was receiving BD Clexane, omit the morning dose (>18 hours between surgery and last dose, and > 24 hours if neuroaxial anaesthesia is being used). If the patient is on therapeutic dose UH, stop six hours prior to the surgery. If the INR was >1.5 on day -1, repeat the INR on the morning of surgery. If INR > 1.5 defer surgery or if surgery is urgent, give PROTHROMBINEX-HT (25-50 IU/kg) plus FFP 150-300 ml OR FFP 10-15 ml/kg if PROTHROMBINEX-HT is not used
Day 0 (evening of procedure)
Day 1+ Measure the INR daily. Cease UH or Clexane when the INR is >2.
