brief review of anticoagulants and regional anesthesia

1. By.Dr.Pawan Kumar rai
Junior resident
MD anesthesia
Dr.RMLIMS lucknow

2.  INTRODUCTION
 COAGULATION CASCADE
 CLASSIFICATION OF ANTICOAGULANTS
 ASRA RECOMMENDATIONS
 NEWER ANTICOAGULANTS
 SUMMARY

3.  Spinal hematoma is a rare but potentially
devastating complication of regional
anesthesia( approximately 0.1 per 100,000
patients per year)
 Coagulation defects are the principal risk
factors for regional anesthesia
 Trauma to epidural veins in the presence of
coagulopathies may result in large
hematoma.

4.  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.

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

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

8. 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.

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

10.  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. INR value of ≤1.4 acceptable for
the performance of neuraxial blocks.
 No Regional Anesthesia if in combination
of other drugs affecting the clotting.

11.  If the first dose given 24 hrs earlier- check
PT/INR
 PT/INR on daily basis in case of epidural
analgesia.
 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.

12.  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.

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

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

15.  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.

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

17. In pts with combined neuraxial blocks and
intraoperative anticoagulation,
 Avoid regional anesthesia(RA) with other
coagulopathies.
 Avoid RA in patients with medications of
clotting inhibitors in combination.
 Delay Heparin dose up to 1 hour after
needle placement.

18.  Remove catheter 4 hours stopping the dose
and start the dose again after 1 hour.
 Check for motor and sensory blockade.
 Consider minimal dose of local anesthetics
for early detection of spinal hematoma.

19. Combining neuraxial techniques with full
anticoagulation of cardiac surgery
 Insufficient data and experience to
determine the risk of hematoma.
 Postoperative monitoring of neurological
functions.

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

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

22.  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.

23.  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.

24.  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.

25. 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.

26.  ASPIRIN
 NSAIDS
 Thienopyridine derivatives
 Platelet GP IIb/IIIa antagonists

27.  MECHANISM OF ACTION:
Blocks cyclooxygenase. Which 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.

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

29. Aspirin
NSAIDS

30.  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.

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

32.  Ticlopidine
 Clopidogrel

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

34.  D/C ticlopidine for 14 days prior to a
neuraxial block.
 D/C clopidogrel for 7 days prior to a
neuraxial block.
 There is no accepted laboratory tests for
these medications.
 Epidural catheters can be removed safely
and neuraxial injections can be performed 5
days (not 7 days, as once advised) after
clopidogrel is discontinued.

35.  Abciximab
 Eptifibatide
 Tirofiban

36.  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

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

38.  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.

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

40.  Activates plasminogen to form plasmin which
digest fibrin and dissolve clot.
 Although the plasma half life of
thrombolytic drugs is mainly hours, it may
take days for the thrombolytic effect to
resolve

41.  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.

42.  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.

44.  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
 Time for initial catheter placement is 72
hrs and 12 hrs delay required to restart.
 Need further clinical experience to
formulate guidelines

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

46.  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

47.  Rivaroxaban
 Is a potent selective and reversible oral
activated factor Xa inhibitor.
 Inhibition is maintained for 12 hrs.
 Monitored with the PT, aPTT.
 Initial catheter placement time- 24 hrs.
 Time to restart- 6 hrs
 Longer holding time required in renal
impairment.

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

49.  These consensus statements represent the collective
experience of recognized experts in neuraxial
anesthesia and anticoagulation.
 Alternative anesthetic and analgesic techniques
should be used for the patients.
 Indwelling catheters should not be removed
 Vigilance in monitoring
 Protocols must be in place for urgent magnetic
resonance imaging
 The patient's coagulation status should be optimized
at the time of spinal or epidural needle/catheter
placement.