Blood Conservation Strategies

8/10/2019 Blood Conservation Strategies

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Autologous Transfusion

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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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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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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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Calculation of blood loss during cellsalvage

[Hs/Hp] . Vb. Nb / SE


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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/

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Blood Conservation Strategies

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