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8/10/2019 Blood Conservation Strategies
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Autologous Transfusion
www.anaesthesia.co. in anaesthesia.co. in@gmail .com
http://www.anaesthesia.co.in/mailto:[email protected]:[email protected]://www.anaesthesia.co.in/8/10/2019 Blood Conservation Strategies
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Why use blood-sparing strategies?
Worlds Most Precious Liquid
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Indications
Patient request
Difficulty in finding suitable blood
Availability/Economic considerations Complications relating to bloodtransfusion
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Complications of blood transfusion
Infection
Hepatitis B and C, HIV, CMV, vCJD
ImmunologicalEarly: anaphylaxis, acute lung injury,
alloimmunization, urticaria, acute
haemolysisDelayed: delayed haemolysis,
immunosuppression
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Complications of blood transfusion
Metabolic
Hyperkalaemia, hypocalcaemia, acidbase disturbance, coagulopathy
Physical
Hypothermia, microemboli, air embolus,circulatory overload
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Allogeneic blood-sparing strategies
Pharmacological Preoperative
- Erythropoietin- Ferrous sulphate, vitamin B12, folate- Discontinue drugs that may impair
haemostasis Perioperative
- Aprotinin- DDAVP- Tranexamic acid
- Topical haemostatic agents
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Erythropoietin
Daily s/c inj for at least 10 days beforesurgery.
Disadvantages of erythropoietin
Expensive
Labour intensive
Side effects - thrombosis / hypertension.
Unsuitable for emergency surgery.
Restricted to patients aged less than 70 years
Studies support use cardiac/ orthopaedicsurgery
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Optimization of haemostatic function
Discontinue NSAIDs, anticoagulants
Haematology advice cong. coagulopathy
Haemophilia - factor VIII conc. Liver-associated coagulopathy - vitamin K
CRF - preoperative dialysis improves
platelet function
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Pharmacological manipulation- Periop.Evidence supporting use from studies in cardiac surgery
Aprotinin - non-specific protease inhibitor /inhibits plasmin-reducing fibrinolysis
- Reduces blood loss in cardiac surgery
- May be associated with graft failure
- Use in valve surgery is proven
- Hypersensitivity reactions Tranexamic acid - synthetic antifibrinolytic drug
- Minimal side effects
- Effective in cardiac surgery.
Desmopressin acetate (DDAVP) - analogue of vasopressin- Increases conc. of factor VIII/ von Willebrand factor
- Indicated in haemophilia or vonWillebrands
- No evidence to support use in patients without congenital
bleeding disorders.
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Allogeneic blood-sparing strategies
Non-pharmacological Anaesthetic technique- Regional anaesthesia- Careful positioning
- Controlled hypotension- Avoidance of hypertension/hypothermia
Surgical technique
- Planning of procedure- Minimally invasive choices- Dissecting instruments- Use of tourniquets
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Surgical techniques
Staging of complicated proceduresor sequencing a
procedure harvesting a vein by one member of a teamwhilst another member prepares the receiving site.
Use of minimally invasive surgical techniquese.g.laparoscopic surgery or interventional radiology for
embolization of aneurysms Dissecting instrumentsspare blood vessels / provide
haemostasis e.g monopolar diathermy knife, laser,harmonic scalpel
Topical agentse.g thrombin-based sealants, fibrin-based sealants and calcium alginate
- Role in reducing allogeneic transfusion is unclear
Tourniquets - clearer surgical field / unlikely to
contribute to blood-sparing
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Allogeneic blood-sparing strategies
Transfusion protocols
Autologous transfusion
- Preoperative donation- Acute normovolaemic haemodilution
- Cell salvage
P ti t l bl d d ti
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Preoperative autologous blood donation(PABD)
Criteria for autologous donors (American Association of
BloodBanks (AABB) Standards for Blood Banks andTransfusion Services)
Candidates for preoperative collection - stable patientsfor surgery in which blood transfusion is likely such asorthopedic, vascular, cardiac, thoracic and radicalprostatectomy
Hb not less than 11 g/dL or Hct 33%
No age or weight limits
May donate 10.5 mL/kg Donations may be scheduled more than once a week, butthe last should occur no less than 72 hours beforesurgery
Autologous blood with positive viral markers commonlyprecluded
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Contraindications
1. Evidence of infection and risk of bacteremia2. Scheduled surgery to correct aortic stenosis
3. Unstable angina
4. Active seizure disorder.
5. Myocardial infarction or cerebrovascular accidentwithin 6 months of donation
6. Patients with significant cardiac or pulmonary diseasewho have not yet been cleared for surgery by their
treating physician7. High-grade left main coronary artery disease
8. Cyanotic heart disease
9. Uncontrolled hypertension
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Standards no longer permits allogeneictransfusion of unused autologous units("crossover") because autologous donorsare not volunteer donors
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PABD
Efficacy of PABD depends on thedegree of patient's erythropoiesis Compensatory erythropoiesis suboptimal
under "standard" conditions [expansionin RBC volume of 11% (with no oral ironsupplementation) to 19% (with oral ironsupplementation) ]
Not sufficient to prevent anemia PABD results in perioperative anemia
and an increased likelihood of any bloodtransfusion
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PABD
Aggressive autologous bloodphlebotomy (twice weekly for 3 weeks,beginning 25 to 35 days before surgery)
endogenous erythropoietin levelsincrease with RBC volume expansion of19% to 26%
Exogenous erythropoietin therapystimulates erythropoiesis (Expansion upto 50% RBC volume)
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PABD
Transfusion Trigger- Hb/Hct level at which autologous
blood should be given
- Trials indicate that even critical care
patients can tolerate substantial
anemia ( Hb ranges of 7 to 9 g/dL)with no apparent benefit from more
aggressive transfusion
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PABD
Disadvantages of PABD Labour intensive-identification of suitable
patients, organizing appropriately timed blooddonation, storing the blood
Storage life of blood (5 weeks) limits numberof units that can be donated / reducesflexibility in the postponement of surgery
Not suitable for emergency surgery. Clerical errors can occur at any stage of the
process Not suitable for anaemic patients / ischaemic
heart disease
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Acute normovolaemic haemodilution(ANH)
Principle
Removal of whole blood from a patient, while restoring thecirculating blood volume with an acellular fluid shortlybefore an anticipated significant surgical blood loss
Blood collected in standard blood bags containing
anticoagulant Stored at room temperature
Reinfused during surgery after major blood loss hasceased, or sooner
Simultaneous inf. of crystalloid (3: 1 ) or colloid (1:1) Blood reinfused in the reverse order of collection
Augmented hemodilution (replacement of ANH collected inpart by synthetic oxygen carriers)
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V = EBV . Hi Hf / Hav
Physiological consequences- Increased cardiac output
- Decreased viscosity
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Criteria for selection
High likelihood of transfusion
Hb > 12No significant ds.
Absence of severehypertensionAbsence of infection
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ANH
Advantages of ANH
Reduction in the RBC mass lost for a given blood loss
Perceived lower relative cost compared with PABD orallogeneic blood transfusion
Almost negligible potential for clerical error becauseblood is kept in the operating theatre until transfusion
Infectious and immunological complications associatedwith allogeneic blood are avoided
Platelet function and coagulation factors are preserved Theoretically improved tissue oxygen delivery due toright shift of oxygen dissociation curve and reducedviscosity.
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Acute normovolaemic haemodilution(ANH)
Disadvantages of ANH
Greater haemodynamic instability
Hypovolaemia is more likely
Potential complications of administration oflarge volumes ofcrystalloid.
Useful only in healthy adults having surgery
with substantial anticipated blood loss, whohave a high preoperative haemoglobin and whocan tolerate low intraoperative haemoglobin
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Intraoperative cell salvagePhysics of cell saver
Technique based on centrifugation, separating redblood cells (RBC) from the lighter components andfluids, including plasma, saline and buffy coat
System filled with 100-200 ml heparinized saline(priming)Blood released at the wound site aspirated via adouble-lumen suction catheter (80-100 mmHg)
Anticoagulated
stored in a reservoir with a filter
pumped into a rotating separation chamber
washed with 1000-1500 ml saline and concentrated
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Intraoperative cell salvage
Optimising red cell return- Suction
- Rinsing of sponges
- Anticoagulant
- Collection reservoir
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Intraoperative cell salvage
Calculation of blood loss during cellsalvage
[Hs/Hp] . Vb. Nb / SE
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Intraoperative cell salvage
Advantages of cell salvage Suitable for elective and emergency surgery. Reduced risk of administration of incorrect blood Reduced use of allogeneic blood
Disadvantages of cell salvage No preservation of clotting factors or platelets necessary. Initial financial outlay to buy the machine and train staff (but
the cost of the disposables is less than the cost of one unit ofblood)
Use in malignancy is controversial Blood salvaged from contaminated fields is unsuitable for re-infusion.
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FactorVIIa
central role in initiating the process of coagulation Active after forming complex with tissue factor Activates factors IX and X Induction of thrombin burst on surface of activated
platelets Formation of fibrin clots at the site of vascular injury Fibrin clots are stable / resistant to premature lysis The use of for treatment of intractable life-
threatening haemorrhage is
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Recombinant factorVIIa (rFVIIa) FDA-approved
- Hemophiliacs with factor VIII or IX inhibitors- Factor VII deficiency Novel therapy for the treatment of acquired
coagulopathies- severe trauma
- intractable bleeding after pelvic surgery- life-threatening post-partum haemorrhage- pulmonary haemorrhage- correction of coagulopathy in neurosurgical patients
- Jehovah's Witness after cardiac surgery Other uses of rFVIIa- severe thrombocytopenia- platelet function disorders- impaired liver function
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rFVIIa
Bolus dose - 90120 mg kg1
used with caution in
- patients with known hypercoagulability- DIC or other states of generalized
activation of the hemostatic system
www.anaesthesia.co. in anaesthesia.co. in@gmail .com
http://www.anaesthesia.co.in/mailto:[email protected]:[email protected]://www.anaesthesia.co.in/