Management of coagulation and transfusion therapy in cardiothoracic anesthesia
Management of coagulation and transfusion therapy
in cardiothoracic anesthesia
By F. Javier Orellana July 2009
Cell-based model of coagulation.
Standard lab tests.
CPB and haemostasis.
Anticoagulation for CPB.
It’s not a lecture on Hematology.
It’s not an academic review of main mechanisms of haemostasis.
It’s a view of practical points in cardiac surgery concerning coagulation
and blood transfusion (or other blood products).
It’s a review of literature on this subject.
It’s an update of present recommendations.
Cell-based model of coagulation (1)
Intrinsic, extrinsic and common
Useful to understand laboratory
Not accurate representation of
in vivo coagulation.
Cell-based model of coagulation (2)
Cell-based model of coagulation (4)
Haemostasis starts with the interaction between TF and FVIIa on the
surface of subendothelial cells.
The small amount of thrombin generated during the amplification phase
activates platelets locally on whose surface the subsequent reactions
The resulting thrombin burst results in the formation of a stable clot.
Standard lab tests
Good sampling technique.
Time to form a fibrin clot in vitro.
PT & INR (extrinsic path.): FVII, but also with FI, FII, FV and FX
deficiencies, liver disease, vit. K deficiency, DIC, and high doses
APTT : all procoagulants except FVII and FXIII. Monitor: heparin
therapy, haemophilia A /B, coagulation inhibitors.
TT: hypo/dysfibrinogenaemia, FDP (fibrinolytic therapy).
Near-patient tests of coagulation (NPT): Hemochron.
Platelet function analysing monitor.
CPB and haemostasis (1)
Prevent clotting: heparine.
Contact activation (bypass circuit).
Exposure to air and TF (wound) and recirculation.
Thrombin resistant + consumption of clotting factors and platelets.
Systemic inflammation state.
Hypothermia (< 35° C).
Haemodilution, preop platelets inhibitors, heparine itself, protamine.
CPB and haemostasis (2)
A. PO bleeding is a common complication of
cardiac surgery but a surgical cause is only found
in 50% of re-explorations.
B. Empiric transfusion of blood products is often
inappropiate, carries the risk of adverse effects,
and has been associated with an increase in wound
C. Rapid and accurate diagnosis of haemostasis is
necessary to discriminate coagulopathic bleeding
from surgical bleeding.
Anticoagulation for CPB (2)
Alternatives to unfractionated heparin.
Heparin reversal: protamine.
ACT, normal value 100-140 s.
ACT↑ in thrombocytopenia or platelet dysfunction (GpIIbIIIa inhibitors).
Also with haemodilution and hypothermia.
Once CPB is established, ACT ceases to correlate with
Heparin concentration monitoring.
ACT is simple, familiar, cheaper and remains the standard monitor.
Monitoring coagulation to guide haemostatic blood transfusion.
Reduction of transfusion of blood products.
Improve outcome and reduce costs.
Laboratory tests are of no value during CPB.
Measures whole blood viscoelastic changes associated with fibrin
Fast: 10-20 min.
Algorithm using point-of-care coagulation testing (TEG) reduce
Cumulative costs for treatment of perioperative coagulation disorders
can be reduced by ‘bedside’ ROTEM analysis to achieve a selective
Antifibrinolytic therapy (2)
Mangano et al. N ENGL J MED
Eur J Anaesth 2007;24:6-14.
Antifibrinolytic therapy (3)
In the current analysis, aprotinin dosage was not
associated with increased adverse renal outcome.
In regard to renal outcome, this analysis did not
demonstrate an essential detrimental influence of
aprotinin dosage on renal function.
The new model of haemostasis
In high doses rFVIIa binds to the surface of the locally activated
platelets where it leads to the formation of a thrombin ¨burst¨.
Reconstitution and iv bolus injection over 2-5 min.
Initial dose 90-120 mcg/kg.
Repeat 2x or 3x (at 2-3 h intervals).
Patient 70 kg: 19 mg.
Novoseven 1.2 mg 664,72 £.
Novoseven 2.4 mg 1.329,44 £.
Novoseven 4.8 mg 2.658,88 £.
Cost 1 patient: 10.635,52 £.
Institution-specific protocols should screen for high
1. Advanced age.
2. Low preop red blood cell volume.
3. Preop antiplatelet or antithrombotic drugs.
4. Redo, complex procedures.
5. Emergency operations.
6. Non cardiac patient comorbidities.
Preop interventions: EPO, limitation of antithrombotic
1. Use of antifibrinolytics.
2. Selective use of off-pump CABG.
3. Routine use of cell-saving device.
4. Autologous predonation and normovolemic
Consensus, institution-specific blood transfusion
algorithms supplemented with point-of-care testing.
Multimodality approach to blood conservation
combining all of the above.
Please, don´t forget the evaluation test!!.