Anticoagulanta and regional anesthesia.ppt draft 3

DR.ABDUL SATTAR
DEPARTMENT OF ANESTHESIA
SFH -RIYADH

 Improvement in patient outcomes,
including mortality and major morbidity
has been demonstrated with neuraxial
techniques, particularly with epidural
anesthesia and analgesia.
 It is due to the attenuation of the
hypercoagulable response and the
associated reduction in the frequency of
thromboembolism.

 Although this beneficial effect of neuraxial
techniques is recognized but the effect is
insufficient as the sole method of
thromboprophylaxis.
 Consequently, anticoagulant, antiplatelet,
and thrombolytic medications have been
increasingly used in the prevention and
treatment of thromboembolism.

 Long-term anticoagulation with warfarin
is often indicated for patients with a
history of VTE, mechanical heart valves,
and atrial fibrillation.
 In addition, patients with bare metal or
drug-eluting coronary stents require
antiplatelet therapy with aspirin and
thienopyridine derivatives (e.g,
clopidogrel) for varying durations.

 Coagulation defects are the principal risk
factors for regional anesthesia.
 Spinal hematoma is a rare but potentially
devastating complication of regional
anesthesia.
 Trauma to epidural veins in the presence of
coagulopathies may result in large
hematoma.

 Patient with spinal hematoma presents
with severe back pain and neurological
deficit.
 Diagnosis is confirmed by MRI.
 Decompression laminectomy is required to
preserve neurologic functions.
 Neuraxial blockade should be performed
cautiously in the presence of prophylactic
anticoagulation.

 Pain management is based on appropriate
timings of needle placement and catheter
removal.
 Clinician should have familiarity with
pharmacology of hemostasis altering drugs,
clinical studies as well as the case reports of
spinal hematoma.

 An 81-year-old woman whose clopidogrel had
been discontinued for 7 days before elective
fasciotomy under spinal anesthesia.
 Lumbar puncture was traumatic and required
multiple attempts/levels. She received 2 doses
of LMWH, 8 and 40 hrs after lumbar puncture.
 Four hours after the second dose, she had
difficulty in voiding, which progressed to
numbness and weakness, patient underwent
decompressive laminectomy.
 Traumatic tap, residual clopidogrel effect, and moderately reduced
renal function were causes.

 This issue has been addressed in a consensus
statement from the American Society for
Regional Anesthesia (
www.asra.com/consensus/intro.shtml)

 Oral Anticoagulants.
 Parenteral Anticoagulants.
 Anti platelets.
 Fibrinolytics.

 Warfarin
 Dicumarol
 Phenprocoumon
 Acenocumarol
 Indandione Derivatives
Anisidione
Phenindione

Mechanism of action:
 Interferes with the synthesis of Vit K
dependant clotting factors
1. II, VII, IX and X.
2. Anticoagulation of proteins C, and S.

 Half life: 40 hours
 Dosage: 2-15 mg / day
 Monitoring: PT and INR

 Caution should be made in performing
neuraxial block in patients recently
discontinued warfarin therapy.
 The anticoagulant therapy must be
stopped (ideally 4 – 5 days before
performing the block).
 Monitor PT/INR prior to initiation of the
block.
 No Regional Anesthesia if in combination
of other drugs affecting the clotting.

 If the first dose given 24 hrs earlier- check
PT/INR
 Patients receiving warfarin during
epidural analgesia  do PT/INR on daily
basis.
 Check PT/INR before catheter removal if
initial doses of warfarin are given more
than 36 hours preoperatively.
 Epidural catheters can be removed if INR
is < 1.5.

 Neurological testing of motor and sensory
functions should be done.
 Minimize the degree of motor and sensory
block.
 If INR > 3, Hold warfarin
 Reduced doses of warfarin in patients with
enhanced drug response.

 Heparin
 Low molecular weight Heparin (LMWH)
 Danaproid
 Lepirudine

 Mechanism of action:
Accelerates the inactivation of factors IIa,
IXa, Xa, XIa, and XIIa by the serine protease
inhibitor, Antithorombin III (AT III).

 Half life:1 to 1.5 hours.
 Dose:
Bolus: 80 units / kg or 5000 units
Maintenance: 15 units / kg / hr or 700
to 2000 units / day
 Monitoring: aPTT.

For mini dose prophylaxis :
 No contraindication. Hold morning dose.
 Check platelet count

In pts with combined neuraxial blocks and
intraoperative anticoagulation,
 Avoid regional anesthesia with other
coagulopathies.
 Avoid RA in patients with medications of
clotting inhibitors in combination.
 Delay Heparin dose up to one hour after
needle placement.

 Remove catheter 4 hours stopping the dose
and start the dose again after one hour.
 Check for motor and sensory blockade.
 Consider minimal dose of local anesthetics
for early detection of spinal hematoma.

Combining neuraxial techniques with full
anticoagulation of cardiac surgery
 Insufficient data and experience to
determine the risk of hematoma.
 Postoperative monitoring of neurological
functions.
 Selection of solutions to minimize sensory
and motor blockade.

Mechanism of action: Inhibit clotting factor Xa
more than IIa.
Examples
 Deltaparin
 Enoxaparin
 Tinzaparin

 Half-life: Three to four times more than
Haparin
 Doses:
Deltaparin: 2500-5000 u / day
Enoxaparin: 30-40 mg / day
Tinzaparin:175 u / day

 Monitoring of anti – Xa level is not
recommended.
 No RA in patients taking other clotting
inhibitors in addition.
 In the presence of blood during needle and
catheter placement.
 Delay LMWH therapy for 24 hours
 Should be discussed with the surgeon.

 Preoperative LMWH:
1. Thromboprophylaxis: Needle placement
should be delayed up to 10 – 12 hours.
2. Treatment doses: A delay of at least 24 hours
is recommended.
3. No RA if the dose is given in morning
preoperatively.

 Postoperative LMWH: may undergo RA
technique, but removal of the catheter
depends upon total daily dose and
timing.
a. Twice daily dose:
 increased risk of spinal hematoma.
 First dose of LMWH should not be
administered 24 hours postoperatively.
 Catheters should be removed prior to
initiation of thrombo-prophylaxis.
 LMWH dose should be started after 2 hours
removing the catheter.

b. Single daily dose:
 First dose should be administered 6 – 8 hours
postoperatively.
 Second dose after 24 hours and catheters may be
safely maintained.
 Catheters should be removed after 12 hours of last
LMWH dose.
 LMWH dose can be started after two hours.

 ASPIRIN and NSAIDS
 Thienopyridine derivatives
 Platelet GP IIb/IIIa antagonists

 MECHANISM OF ACTION:
Blocks cyclooxygenase. Cyclooxygenase is
responsible for the production of
thromboxane A2 which inhibits platelet
aggregation and causes vasoconstriction.
 DURATION OF ACTION:
Irreversible effect on platelets. Effect of
aspirin lasts for the life of the platelet which
is 7-10 days. Long term use of aspirin may
lead to a decrease in prothrombin production
and result in a lengthening of the PT.

Inhibits cyclooxygenase by decreasing tissue
prostaglandin synthesis.
Reversible. Duration of action depends on
the half life of the medication used and can
range from 1 hour to 3 days.

 Either medication alone does not increase
risk.
 Need to scrutinize dosages, duration of
therapy and concomitant medications
that may affect coagulation.
 No wholly accepted laboratory tests. A
normal bleeding time does not indicate
normal homeostasis. An abnormal
bleeding time does not necessarily
indicate abnormal homeostasis.

 History of bruising easily
 History of excessive bleeding
 Female gender
 Increased age

 Ticlopidine
 Clopidogrel

Interfere with platelet membrane function
by inhibition of adenosine diphosphate (ADP)
induced platelet-fibrinogen binding.
Thienopyridine derivatives exert an
irreversible effect on platelet function for
the life of the platelet.

 DC ticlopidine for 14 days prior to a neuraxial
block.
 DC clopidogrel for 7 days prior to a neuraxial
block.
 There is no accepted laboratory tests for
these medications.

 Abciximab
 Eptifibatide
 Tirofiban

 Mechanism of action: Non peptide inhibitors
of GP IIb / IIIa receptor
 Doses:
Abciximab. Dose:250 micrograms / kg
Eptifibatide. Dose:180 microgram / kg
Tirofiban. Dose: 10 micrograms / kg

 No wholly accepted test including the
bleeding time.
 Careful preoperative assessment is
necessary,
 Easy bruisability
 Excessive bleeding
 Female gender
 Increasing age

 Platelet GIIb/IIIa Inhibitors:
RA should be avoided 2 days for abciximab and 4-
8 hours for eptifibatide and tirofiban therapy.
If administrated postoperatively following RA,
the patient should be monitored neurologically.

Exogenous plasminogen activators.
.Streptokinase
.Urokinase
Endogenous tissue plasminogen activator
formulation
.Alteplase
.Tenecteplase
.Reteplase
more fibrin selective,less effect on circulating
plasminogen.

Although the plasma half life of thrombolytic drugs is
mainly hours, it may take days for the thrombolytic
effect to resolve.

 No RA in the presence of these drugs.
 In patients with catheters already in and
with sudden initiation of these drugs,
 Neuraxial monitoring is necessary which should not be
more than 2 hour interval.
 Infusion should be limited to drugs minimizing sensory
and motor blockade.
 Fibrinogen level measurement.
 No definite recommendation regarding the removal of
catheters.

 An 84-year-old man received an uncomplicated
epidural steroid injection in the morning.
 He developed chest pain later that day, was
admitted to the hospital, diagnosed with an
acute myocardial infarction, and treated with
tissue plasminogen activator and heparin
 . He subsequently developed back pain and
paraplegia. Magnetic resonance imaging
demonstrated an epidural hematoma extending
from T10 to the sacrum.

 Patients scheduled for thrombolytic therapy
must be inquired for history of neuroaxial
block.
 Patients who received thrombolytic
therapy ,neuroaxial block is contraindicated,
no time interval is outlined.

 Antithrombotic medication for DVT
prophylaxis
 Binds with antithrombin III which
neutralizes factor Xa.
 Peak effect in 3 hours with half life of 17-
21 hours
 Irreversible effect
 Need further clinical experience to
formulate guidelines
 Black box warning similar to the LMWH

 Bivalirudin- thrombin inhibitor used in
interventional cardiology.
 Lepirudin used to treat heparin-induced
thrombocytopenia.
 Caution advised. No recommendations
related to limited clinical experience.

 Dabigatran etexilate
 Is a prodrug that inhibits both free and clot-bound
thrombin.
 The drug is absorbed from the
gastrointestinal tract with a bioavailability of
5%.
 The half-life is 8 hrs after a single dose and
up to 17 hrs after multiple doses.
 Prolongs the aPTT

 Rivaroxaban
 Is a potent selective and reversible oral
activated factor Xa inhibitor.
 Inhibition is maintained for 12 hrs.
 Monitored with the PT, aPTT.
 For Dabigatran etexilate and Rivaroxaban,
the lack of information regarding the
specifics of block performance and the
prolonged half-life warrants a cautious
approach.

 For patients undergoing deep plexus or
peripheral block, recommendations regarding
neuraxial techniques, should also be applied
similarly.

In the absence of a large series of neuraxial
techniques in the pregnant population,
receiving prophylaxis or treatment of VTE,
ASRA guidelines (derived mainly from
surgical patients) should be applied to
parturient.

 These consensus statements represent the collective
experience of recognized experts in neuraxial
anesthesia and anticoagulation. They are based on
case reports, clinical series, pharmacology,
hematology, and risk factors for surgical bleeding.
 Alternative anesthetic and analgesic techniques
should be used for the patients, who are at
unacceptable risk.
 The patient's coagulation status should be optimized
at the time of spinal or epidural needle/catheter
placement, and the level of anticoagulation must be
carefully monitored during the period of epidural
catheterization.

 Indwelling catheters should not be removed in
the presence of therapeutic anticoagulation
because this significantly increase the risk of
spinal hematoma.
 Vigilance in monitoring is critical to allow early
evaluation of neurologic dysfunction and prompt
intervention.
 Protocols must be in place for urgent magnetic
resonance imaging and hematoma evacuation if
there is a change in neurological status.

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