Restricting and avoiding Blood Transfusions: What Options do we have?

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Restricting and avoiding Blood Transfusions What
Options do we have?

• Rajeshwari Subramaniam
• Deptt. Of Anaesthesiology
• A.I.I.M.S.

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.c
om
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Questions to be answered

• What are the implications of anemia?
• What are the benefits of a normal hematocrit?
• How do we decide when to transfuse?
• What are the risks of transfusion?
• What are the alternatives to homologous
  transfusion?

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What are the implications of Peri operative
Anemia?

• DO2 CO x CaO2 (sat x 1.39 x Hb) PaO2 x0.003
• Peri operative anemia usually co-exists with
  hypovolemia
• Ability to tolerate reduction in DO2 depends on
  the ability to increase cardiac output
• Myocardial contractility, HR, vascular tone
  with lossgt15

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Problems of Peri operative Anemia

• These responses are modified by
• -age
• -co morbid illness (CAD,CNS)
• -pre existing Hb and plasma volume
• -ß blockers, ACE inhibitors
• -rapidity of loss
• THE PROBLEM IS TO IDENTIFY THE PATIENT AT RISK

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Problems of coronary circulation and myocardium

• Myocardium has high O2 extraction ratio
• O2 delivery can be increased only by increasing
  flow
• Tachycardia compromises diastolic flow
• With normal coronary circulation Hb up to 7g
  tolerated
• ECG changes of ischemia at Hb 5g
• Lactate production, death at Hb 3g

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What is the urgency of replacing volume Hb?

• Diversion of blood from skeletal, splanchnic beds
  to coronary and cerebral circulation
• Mucosal ischemia-starting point of MODS, sepsis
• Peri operative myocardial ischemia-high mortality
• Un replaced blood loss ? coagulation problems,
  DIC

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Beneficial effects of normalisation of Hct

• in RBC volume, restoration of plasma volume
• Restoration of blood flow to GIT
• Restoration of viscosity? in shear stress, ADP
  production, platelet aggregation
• Dispersal of platelets towards vessel wall

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Anemia and NO

• viscosity in anemia ? flow, shear stress,? NO
  production
• Vasodilation at bleeding sites
• in cyclic GMP in platelets, inhibition of
  platelet function, bleeding time
• Hb best NO scavenger oxidizes NO
• Minimum shear stress seen at Hct 30-35

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Indications and Guidelines for intra-operative
RBC Transfusion

• Based on Acute blood loss
• -15 loss in an adult(500-750 ml)-no need to
  transfuse
• -15-30loss-crystalloids/synthetic colloids
• -30-40(1500-2000ml)-rapid IV resuscitation
  blood
• -gt40-rapid volume replacement blood

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Guidelines for Transfusion-continued

• Based on Hb concentration
• Actual and anticipated Hbgt10g
• Indicated when Hb7g,at the rate of ongoing
  blood loss
• Patients at risk trigger 8g(consensus)
• Consider if patient will bleed due to coagulation
  abnormalities
• Give appropriate coagulation factor/s

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Patients at Risk

• Coronary artery disease
• Valvular heart disease (AS)
• CHF
• H/O transient ischemic attacks
• Previous thrombotic stroke
• However, still no consensus for transfusion
  trigger

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Transfusion Strategy for Acute Blood Loss
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Signs and symptoms Requiring Transfusion

• Syncope
• Dyspnea
• Postural Hypotension
• Tachycardia unresponsive to crystalloids
• Angina/ECG changes
• Transient ischemic attack

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Patients under Anesthesia

• If stable
• -assess risk of myocardial/cerebral ischemia
• -in the absence of risks,transfusion NOT
  indicated,regardless of Hb
• -intravascular volume to be replaced
• If unstable
• -if at risk, transfuse
• -if not at risk,crystalloidcolloid initially
• -TRANSFUSE UNIT BY UNIT
• -autologous blood if available

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Guidelines for Transfusion(contd)

• Transfusion in the ICU
• -Overtransfusion may increase mortality
• -Attention to volume, inotropic support
• -Maintenance of BP and CO
• -Crystalloids preferable

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Guidelines for peri operative transfusion

• Patient to be managed to avoid transfusion
• Treat anemia before elective surgery
• Discontinue anti platelet drugs
• Reverse anticoagulation
• Use pharmacologic agents to control bleeding
• Strategies of autologous transfusion

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Chronic Anemia

• Do not transfuse if effective alternatives exist
• Preferably transfuse at intervals to maintain Hb
  at lowest level not associated with symptoms
• Consider recombinant erythropoietin
• -zidovudine-induced anemia,CRF
• -improves functional status

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Risks associated with Transfusion

• VIRAL INFECTIONS
• Hepatitis A- 11,000,000
• Hepatitis B- 150,000-1150,000
• Hepatitis C- 11,900,000
• Whats new Nucleic Acid Testing (NAT)
• CMV-Up to 60 transmission from blood
• Parvovirus B 19-Hydrops, Aplastic crisis
  

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Risks of Transfusioncontd

• Bacterial Contamination mortality
• Red cells 2/106 (yersinia sp) 60
• Platelets 83/106
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• Hemolytic Reaction
  
• Acute 1-4/106
  0.67
• Delayed 1000/106 0-4
  
• TRALI 200/106 60
• Transfusion-mediated immuno modulation
• -good for renal transplant, recurrent abortions
• -increased mortality in CV, colorectal Ca

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Other Hazards

• Mismatched transfusion-114,000-118,000
• Fatality-1800,000 units
• West Nile Virus-Meningitis,encephalitis
• Creutzfeldt-Jakob disease

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Alternatives to Allogeneic (Homologous) Blood

• Techniques
• -Deliberate Hypotension
• -Bloodless Surgery
• -Tourniquet where appropriate
• Drugs affecting coagulation
• -Aprotinin(1.4mg?70mg/hr)
• -e amino caproic acid(5-10g?1g/hr)
• -Tranexamic acid(10mg/kg?1mg/kg/hr)
• Erythropoietin pre treatment
• Re combinant factor VIIa

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Autologous Blood Use

• Pre operative Autologous Donation (PAD)
• Acute Normovolemic Hemodilution (ANH)
• Intra operative Cell Salvage and Re- infusion
• Post operative collection and Re infusion

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What are the Advantages of PAD?

• Avoids complications of allogeneic blood
• Prevents red cell alloimmunization
• Useful for patients with rare blood phenotypes or
  allo antibodies
• Supplements blood supply
• Provides reassurance to patients concerned about
  blood risks

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Patient Selection for PAD

• Hb 11.0g/dl
• No age or weight limits
• Volume 10.5 ml/kg per donation
• Usually once a week
• Last donation gt 72 hours before surgery
• Patients with positive viral markers
• Selected pediatric patients

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Contra indications to PAD

• Surgery unlikely to require transfusion
• Evidence of infection/bacteremia
• Scheduled surgery for AS
• Unstable angina
• MI /CVA lt 6 months
• Active seizure disorder
• Unstable angina, left main coronary block
• Cyanotic CHD
• Uncontrolled HT/ Pulmonary/ other medical dis.
• Pregnancy

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Potential Problems with PAD

• Risk of misidentification
• Infection/contamination of stored units
• Volume overload
• Increased cost of collection storage
• Risk of patient becoming anemic
• Aggressive Phlebotomy and iron, Erythropoietin
  3 weeks prior to surgery

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Acute Normovolemic Hemodilution (ANH)

• Blood removed shortly before surgery
• Volume replacement with crystalloid/colloid
• Blood stored in OT at room temperature
• Volume EBV (Hi-Hf) Hav
• Decrease in DO2, viscosity
• Cardiac output, systemic vascular
  resistance, venous return
• Oxygen extraction enhanced

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Precautions

• Hypovolemia, hypocapnia to be avoided
• Oxygen supplementation
• Reversible cognitive dysfunction in cerebral
  vascular disease
• Coronary vasodilatation important to increase O2
  delivery to myocardium
• Store close to patient and label appropriately

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Precautionscontd

• Establish 2 IV lines
• Routine monitoring
• Contraindications
• Transfused in reverse order of collection
• Room temperature storage not gt 8 hours
• Increased HR be warned
• Advantages all drawbacks of homologous blood
  eliminated low cost fresh whole blood

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Red Cell Recovery and Re infusion

• Blood from surgical field is collected into
  centrifuge bowl
• Suction should be low, broad tipped
• Large sponges rinsed in saline/RL
• Heparin /ACD to be added (Ca reduces
  deformability)
• Centrifuged to separate red cells from debris and
  WBCs
• Washed with saline/glycine
• Collected in reservoir with 40µm filter

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The Cell Salvage System
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Calculation of blood loss

• (Hs/Hp x Vb xNb)/SE
• E.g. THR 5 bowls(125 ml) used
• HCT(bowls) 66,70,68,65,71(av68)
• HCT(patient)32,30,34,30,28(av30.8)
• Salvage efficiency 40
• Blood Loss68 x 125 x5/ 30.8 x 40 3450 ml

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What are the potential Complications of Cell
Salvage?

• Poor wash quality-cell salvage syndrome (DIC,
  ARF)
• Poor salvage rate due to non-dedicated personnel
• Air embolism
• Wrong wash solution

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Current Status of Artificial O2 Carriers

• Necessary steps
• Stabilization to prevent dissociation into dimers
  (intravascular retention nephrotoxicity)
• Decrease O2 affinity
• Polymerization to increase Hb concentration at
  physiologic colloid oncotic pressure
• Emulsification of PFCs to make them
  water-miscible

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Hemoglobin-based O2 Carriers

• Exhibit a sigmoidal O2 dissociation curve
• Provide O2 and CO2 transport
• Sourced from outdated banked blood, bovine blood
  or genetically engineered
• Undergo virus inactivation and removal
• Protection against prion contamination
• Stabilised,polymerised

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Difficulties and Side effects of Hb solutions

• Nephrotoxicity-eliminated
• Vasoconstriction-systemic and pulmonary
  hypertension causes-NO scavenging/increased O2
  supply to arteriolar wall
• Abdominal pain, esophageal dysmotility due to NO
  modulation of smooth muscle relaxation
• Interference with mixed venous O2 saturation

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Kinds of Artificial Hbs

• Diaspirin-linked Hb (DCLHb) stopped due to
  jaundice,pancreatitis,mortality
• Human recombinant Hb (rHb 1.1,rHb 2.0)
  genetically expressed in E.Coli in 1990.Stopped
  in 2003
• Polymerised bovine Hb based O2 carrier(HBOC-201)
  used in orthopedic cardiac trials
• Maleimide activated polyethylene glycol modified
  Hb(MP4)high mol. Wt.,oncotic pressure,Hb conc
  28g/dl. Under trial.

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Human Polymerised Hemoglobin (PolyHeme)

• From outdated banked blood
• Pyridoxylated and polymerized with glutaraldehyde
• Has been tried in trauma and urgent surgery
  situations
• 1u50g in 500ml171 patients with Hblt1g survived
  after 20u(10l)

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Per Fluoro Carbon (PFC) Emulsion (OxyGent)

• Carbon fluorine compounds with high gas
  dissolving capacity and low viscosity
• Chemically and biologically inert
• Dose 1.8g/kg
• Taken up by RESemulsion broken down,re absorbed
  into blood and circulatesexcreted from lungs
• Effective transport of dissolved O2
• Submicron size enhances microcirculatory O2
  delivery

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Nano-dimension artificial RBCs, Hb containing
liposomes

• Purified Hb phospholipids cholesterol a
  tocopherol
• Lead to rapid restoration of BP,microvascular
  blood flow and tissue oxygenation
• Augmented ANH A technique of ANH combined with
  administration of O2 carriers and crystalloids

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