It is a presentation on anticoagulants and antiplatelets in anesthesia , starting from basis of coagulation , its tests and dugs and anesthetic implications Based on latest ASRA (AMERICAN SOCIETY OF REGIONAL ANESTHESIA GUIDELINES)

1. ANTICOAGULANTS,
ANTIPLATELET
DRUGS AND
ANESTHESIA
PRESENTER : Dr. RAJESH MUNIGIAL
MODERATOR : Dr. CHIRAG BABU P.S
HOD : Dr. ARUN KUMAR A
SSIMS & RC , DAVANAGERE

3. Primary hemostasis

6. TESTS FOR PRIMARY HEMOSTASIS
Platelet count
• NORMAL 1.5lakh – 4.5lakh CELLS/MM3
• < 1.5 lakhcells/cumm Thrombocytopenia
• >4.5lakh cells/cumm thrombocytosis

7. BLEEDING TIME
Normal : 2-9mins
Evaluates time necessary for platelet plug to form
following vascular injury
Prolongation :
• Thrombocytopenia
• Platelet dysfunction
• Ehler danlos syndrome

8. • Platelet function analyser
• Platelet aggregometry

9. CLOTTING TIME
• Time taken from puncture of
blood vessel to formation of
fibrin thread.
• Capillary glass tube method :
time noted to form fibrin
threads by breaking tube
every 30 seconds .
• Normal : 3-8mins

10. LAB EVALUATION OF
COAGULATION
PROTHROMBIN TIME :
• Indicates extrinsic and common
pathway
• It measures the time to strand
formation via a short sequence of
reactions involving TF ,
VII,X,V,II(prothrombin) & I
(fibrinogen)
• Normal : 10-12 sec
• It is most sensitive to decrease in
factor 7 .

11. INR ratio
• Developed by WHO using an IRP(international
reference preparation) to which all the
thromboplastins can be compared
• Recommended as a patient value can be
expressed as a ratio by normalising it to IRP
• ISI of IRP : 1

12. Partial
thromboplastin
time
• reflects the time to fibrin
strand formation via the
classical intrinsic pathway of
coagulation
• A contact activator is added ,
hence the name aptt
• Normal : 25-35 sec
• most sensitive to factor VIII &
IX

13. Activated clotting time
• Tests the ability of blood to clot in a test tube and is
dependent on factors that are all intrinsic to blood .
• Used to monitor heparin therapy in operating room
• Normal: 90-120sec
• The presence of activator augments the contact
activation phase of coagulation, which stimulates
the intrinsic coagulation pathway.

14. • Blood 1 ml is placed in a glass
tube containing a magnetic rod
and an activator (celite or
kaolin).
• The tube is warmed to 37.C
and slowly rotated in a
machine while a timer runs.
• Clotting is detected by
resistance to movement of the
magnetic rod in a magnetic
field which automatically stops
the timer.

15. • The normal ACT value is
90-120sec and increases in
a linear fashion with
increasing heparin
concentration.
• Haemodilution and
hypothermia routinely
occur while on CPB and
also prolong the ACT.
• For these reasons, once
CPB is established, the ACT
ceases to correlate well
with heparin concentration
or measures of heparin
anticoagulation effect such
as anti-Xa activity.

16. THROMBIN TIME :
Ability of thrombin to convert fibrinogen to
fibrin
Prolongation :
• inadequate fibrinogen
• Dysfibrinogenemia
• Thrombin inhibitors
• Normal <30seconds.
Monitors hirudin , bivalarudin and LMWH

17. TESTS FOR COAGULATION

18. THROMBOELASTGRAPHY
• Continuous profiles during all phases of clot
formation.
• Provides more accurate picture of in vivo
coagulation process
To evaluate :
• Hypo/hyper coagulable state
• Haemophilia
• Dilutional coagulopathy
• Coagulability during liver transplantation

21. NORMAL VALUES OF TEG PARAMETERS
(celite activated whole blood )
R (reaction time ) 5-7MIN
K (k time) 1-3MIN
a ANGLE (clot formation rate ) 53-63 DEGREES
M A (maximum amplitude) 59-68mm
G (clot strength/firmnesss) 7195-10625dyne/cm2

25. Regional anaesthesia in the patient receiving
antithrombotic or thrombolytic therapy
• American society of regional anaesthesia and
pain medicine
• Evidence based guidelines (fourth edition )
• As published in regional anaesthesia and pain
medicine , volume 43, number3 , april 2018

26. HEPARIN
• Accelerates the inactivation of factor IIa , Xa
and IXa.
• Half life :1-1.5hrs
• Dose : 80u/kg
• Maintenance : 15u/kg/hr
• Monitoring : aptt
• Activated clotting time in cardiopulmonary
bypass

27. • A unit of heparin is defined as the volume of
heparin containing solution that will prevent
1ml of citrated sheep blood from clotting for 1
hour after addition of 0.2ml of 1:100 calcium
chloride.
(Stoeltings pharmacology and physiology in
anesthesia practice 5th edition )

28. ASRA RECOMMENDATIONS
IV HEPARIN
• Discontinue heparin infusion 4 to 6 hours and
verify normal coagulation status prior to
neuraxial blockade
• Avoid neuraxial techniques in patients with
other coagulopathies
• Delay heparin administration for 1 hour after
needle placement
• Catheter removal after 4 to 6 hours after last
heparin dose .

29. • Consider minimal dose of local anaesthetics to
enhance early detection of spinal hematoma
• Insufficient data and experience to comment
on risk of hematomas
• Postoperative monitoring neurological status
• Selection of solutions to minimize sensory and
motor blockade.

30. • In patients receiving prophylaxis with SC UFH
with dosing regimens of 5000 U BID, there is
no contraindication to the use of neuraxial
techniques.
• In patients receiving doses greater than 10,000
U of UFH daily or more than BID dosing of UFH,
they suggest that neuraxial block be avoided .

31. SUBCUTANEOUS HEPARIN
Preoperative dose Prior to neuraxial block
5000 u BD/TID 4-6HRS
7500-10,000 U BD (TOTAL <20000/DAY) 12 HRS
>10,000/DOSE OR >20000/DAY 24 HRS
POSTOP DOSE CATHETER
MAINTAINENCE
CATHETER
REMOVAL
DOSE POST
CATHETER
REMOVAL
LOW DOSE NO C/I 4-6HRS 1 HR

32. Low molecular weight heparin
• Inhibit clotting factor Xa more than IIa
• Half life : 3-6 hours
• Monitoring : antifactor 10a activity
• Enoxaparin : 10:2a = 4:1

33. Enoxaparin
• Placement or removal of catheter should be
delayed for at least 12 hours after
administration of prohylactic dose , 24 hours
for theraupetic dose .
• A post procedure dose should be given after 4
hours of catheter removal

34. LMWH
• Anti factor Xa level is not predictive of risk of
bleeding
• With indwelling catheter antiplatelet dugs ,
stadard heparin or dextran shouldnt be given
•
• Patients receiving for more than 4 days should
have a platelet count prior to neuraxial block or
catheter removal

35. Time before
puncture/catheter
manipulation/ removal
Time after
puncture/catheter
manipulation/ removal
UFH (for prohylaxis ) 4-6hrs 1hr
UFH( for treatment) IV :4-6HRS
SC: 8-12HRS
1HR
1HR
LMWH (FOR
PROHYLAXIS)
12HR*(10-12) 4HR
LMWH (FOR
TREATMENT)
24HR 4HR

36. Anti actor Xa agents
FONDAPARINUX
Fondaparinux produces its
antithrombotic effect through
factor Xa inhibition.
The plasma half-life of
fondaparinux is 21 hours, allowing
for single-daily dosing, with the first
dose administered 6 hours
postoperatively.

37. • It is recommended that until further clinical
experience is available performance of neuraxial
techniques should occur under conditions used
in clinical trials (single needle pass, atraumatic
needle placement, avoidance of indwelling
neuraxial catheters
• It is suggested that neuraxial catheters 6 hours
be removed prior to the first (postoperative)
dose

38. Newer anticoagulants*
DRUG PRIOR TO
NEURAXIAL
BLOCKADE
(hrs)*(48)
CATHETER
REMOVAL PIOR TO
FIRST DOSE (hrs)
WITH INDWELLING
CATHTER
DOSE TO BE HELD
RIVAROXABAN 72 6 22-26HRS
APIXABAN 72HRS 6HRS 26-30HRS
EDOXABAN 72 6 22-28
BETRIXABAN 72 5 72

39. Direct thrombin inhibitors
Dabigatran*
• To be discontinued 120 hours prior to
neuraxial block if RFTs not availabe
• Catheter removal 6 hours prior to first dose
• With indwelling catheter 34-36hrs
Crcl (ml/min) discontinuation(hrs)
80 72
50-79 96
30-49 120
<30 Avoid

40. WARFARIN
• Exert their anticoagulant effect by interfering
with the synthesis of the vitamin K–dependent
clotting factors VII, IX, X, and II (thrombin).
• Dosage : 5-10mg
• Maintainence : 5mg
• Discontinuation of warfarin requires
normalization of the INR to ensure adequate
activities of all the clotting factors.

41. PERIOPERATIVE MANAGEMENT OF PATIENTS ON
WARFARIN
Preoperative
• Discontinue warfarin at least 5 days before
elective procedure
• Assess INR 1–2 d prior to surgery, if >1.5, consider
1–2 mg oral vitamin K
• Reversal for urgent surgery/procedure, consider
2.5–5 mg oral or IV vitamin K;
for immediate reversal, consider PCCs, fresh frozen
plasma

42. • Patients at high risk of thromboembolism
○ Bridge with therapeutic SC LMWH (preferred) or IV
UFH
○ Last dose of preoperative LMWH administered 24 h
before surgery, administer half of the daily dose
○ Intravenous heparin discontinued 4–6 h before
surgery
• • No bridging necessary for patients at low risk of
thromboembolism

43. Postoperative
• Patients at low risk of thromboembolism
○ Resume warfarin on POD
• Patients at high risk of thromboembolism (who received
preoperative bridging therapy)
○ Minor surgical procedure—resume therapeutic LMWH 24 h
postoperatively
○ Major surgical procedure—resume therapeutic LMWH 48–72
h postoperatively or administer low-dose LMWH
• Assess bleeding risk and adequacy of hemostasis when
considering timing of the resumption of LMWH or UFH therapy
( recommendations from douketis et al )

44. • In patients with INR of greater than 1.5 but less
than 3, they suggest indwelling catheters may be
maintained with caution, based on INR and
duration of warfarin therapy *
• In patients with an INR of greater than 3, it is
recommend that the warfarin dose be held or
reduced in patients with indwelling neuraxial
catheters
• It is suggested that neurologic assessment be
continued for at least 24 hours following catheter
removal

45. Patients on thrombolytic therapy

46. • It is recommended against the performance of
spinal or epidural.
• Data not available to outline the length of time
neuraxial puncture should be avoided ,however 48
hr time interval / documentation of normalisation
of clotting studies suggested.
• If unexpectedly received fibrinolytics on patient
with catheters , no definitive recommendation for
removal , however fibrinogen levels to be assesed.

47. ANTIPLATELETS

49. Antiplatelets
• Thenopyridines :
• Ticlopidine , clopidogrel , prasugrel
• They are platelet p2y12 receptor inhibitors .

50. DRUG PRIOR TO
NEURAXIAL
BLOCKADE
CATHTER
MAINTAINENCE
POSTOP* POST CATHETER
REMOVAL
(IF LOADING GIVEN)
TICLOPIDINE 10DAYS*(14) 1-2 days 24HRS IMMEDIATELY
(6HRS)
CLOPIDOGREL 5-7DAYS*(7) 1-2days 24HRS IMMEDIATELY
(6HRS)
PRASUGREL 7-10DAYS SHOULD NOT BE
MAINATINED
24HRS IMMEDIATELY
(6HRS)
TICAGRELOR 5-7DAYS* SHOULD NOT BE
MAINATINED
24 HRS IMMEDIATELY
(6HRS)
CANGRELOR
(iv)
BRIDGING
THERAPY
3 hours
Prior to
reinstitution
8 hours
after
catheter

51. GP IIB/IIIA inhibitors & PDE inhibitors
DRUG PRIOR TO
NEURAXIAL
BLOCKADE
POSTOP* CATHETER
REMOVAL
ABCIXIMMAB AVOID 4 WEEKS BASED ON
ONGOING RISK OF
THROMBOEMBOLI
SM
TIROFIBAN AVOID
EPTIFIBATIDE AVOID
CILIASTAOLE 2 DAYS 6HRS AFTER
CATHETER REMVAL
PRIOR TO
REINSTITUTION
DIPYRIDAMOLE 24 HOURS

52. Perioperative Management of Patients on Antiplatelet
Therapy
Patients with coronary stents
• • Elective surgery postponed for the following
durations if aspirin and thienopyridine (eg,
clopidogrel or prasugrel) therapy must be
discontinued
○ Bare metal stents: 6 wk
○ Drug-eluting stents: 6 months
• If surgery cannot be postponed, continue dual
antiplatelet therapy throughout perioperative period

54. Patients at high risk of cardiac events (exclusive of
coronary stents)
• Continue aspirin throughout the perioperative
period
• Discontinue clopidogrel/prasugrel 5 d prior to
surgery
• Resume thienopyridine 24 h postoperatively

55. Patients at low risk of cardiac events
• • Discontinue dual antiplatelet therapy 7–10 d
prior to surgery
• • Resume antiplatelet therapy 24 h
postoperatively
(recommendations from douketis et al)

57. SPINAL HEMATOMA

58. SPINAL HEMATOMA
• Definition : symptomatic bleeding within the
spinal neuraxis .
• It is rare but potentially catastrophic
Review of literature : TRYBA
13 cases of spinal hematoma following 8,50000
epidural anaesthetics
7 among 6,50,000 spinal techniques
Incidence : 1 in 1.5lakh epidurals
1 in 2.2 lakh spinal anaesthetics

59. • Patient with spinal
hematomas present with
severe back pain , sensory
/ motor block and
bowel/bladder
dysfunction.
• Diagnosis is confirmed by
MRI
• Decompressive
laminectomy is required

60. REFERENCES
• Regional Anesthesia in the Patient Receiving Antithrombotic or
Thrombolytic Therapy
American Society of Regional Anesthesia and Pain Medicine
Evidence-Based Guidelines (Fourth Edition)
(Regional Anesth Pain Med 2018;43: 263–309)
• Miller’s anesthesia
• Stoeltings pharmacology and physiology in anesthesia practice
5th edition
• clinical anaesthesia : Paul G Barash

61. Thank you !!!