The Lay Medical Man

Category: Transfusion

  • Massive Transfusion and Massive Transfusion Protocol (MTP)

    • From a practical standpoint, requirement for > 4 RBC units in 1 hour with ongoing need for transfusion, or blood loss > 150 ml/min with hemodynamic instability and need for transfusion are reasonable definitions in the setting of a massive transfusion situation. Other definitions are >loss of more than one blood volume within 24 hours (around 70 mL/kg, >5 litres in a 70 kg adult), 50% of total blood volume lost in less than 3 hours or bleeding in excess of 150 mL/minute. A pragmatic clinically based definition is bleeding which leads to a systolic blood pressure of less than 90 mm Hg or a heart rate of more than 110 beats per minute.
    • Hypoperfusion leads to lactic acidosis, systemic inflammatory response syndrome (SIRS), disseminated intravascular coagulation and multiorgan dysfunction
    • Hypoperfusion, acidosis, hemodilution due to iv fluids and progressive hypothermia influences the pathophysiology of massive transfusion in a big way
    • Hypothermia and acidosis play a key role by reducing thrombin generation due to altered enzyme kinetics. After 2 weeks of storage, PRBCs have a pH below 7.0, and each unit has an acid load of approximately 6 mEq. Acidosis directly reduces activity of both extrinsic and intrinsic coagulation pathways. A pH decrease from 7.4 to 7.0 reduces the activity of FVIIa and FVIIa/TF by over 90% and 60% respectively. Both coagulation factors and platelets are reduced by hemodilution. NB: High ISS scores, shock, high base deficit and increased INR > 1.5 are associated with increased mortality in the pediatric population
    • Collect blood sample for cross match early as colloids may interfere with cross matching (mainly dextrans by coating RBC surface)
    • Red cell transfusion is usually necessary if 30–40% blood volume is lost, and rapid loss of >40% is immediately life threatening. Peripheral blood haematocrit and Hb concentration may be misleading early after major acute blood loss. False values occur with TEG too in certain situations. Higher hemoglobin levels reduce TEG/ROTEM signals. Conversely, low hemoglobin makes signals larger. 
    • ABO-group-specific red cells can usually be issued within 10 minutes of a sample arriving in the laboratory. Fully crossmatched blood is available in 30 to 40 minutes after a sample is received in the laboratory. For immediate transfusion, group O red cells should be issued after samples are taken for blood grouping and crossmatching. Females less than 50 years of age should receive RhD negative red cells to avoid sensitisation.
    • Once the volume of blood transfused in any 24 hour period is equivalent to the patient’s own blood volume (8–10 units for adults and 80–100 mL/kg in children), ABO and D compatible blood can be issued without the need for a serological crossmatch.
    • Fibrinogen Level: Plasma fibrinogen predictably falls to sub-haemostatic levels (<1.5 g/L) after 1 to 1.5 blood volume replacement (earlier in the presence of coagulopathy and hyperfibrinolysis). A threshold level of fibrinogen 1g/L (100 mg/dL) is reached after losing 150% of circulating blood volume as opposed to 200% for clotting enzymes. A fibrinogen level lower than < 1g/L substantially increases in-hospital mortality.
    • Coagulation is also impaired by reduced ionised calcium (Ca2+) concentration (which can be measured on many blood gas analysers). Ionised hypocalcaemia may be caused by rapid transfusion of blood components containing citrate anticoagulant, although this is uncommon in the presence of normal liver function
    • The fibrinolytic pathway is relatively preserved despite hemodilution. Fibrinolysis is actually increased due to dilution of FXIII and α2 –antiplasmin which reduces fibrin cross-linking, decreases resistance to fibrinolysis and prolongs plasmin half-life. Plasminogen activator inhibitor is decreased, prolonging tissue plasminogen activator (tPA) activity. Stress, thrombin, epinephrine, vasopressin, desmopressin, and bradykinin trigger tPA release. CRASH-2, MATTERs and PED-TRAX studies suggested a survival advantage with administration of Tranexamic Acid.
    • FFP should be transfused in doses of 12–15 mL/kg (at least four units in the average adult) to maintain the PT ratio (compared to ‘normal pooled plasma’) less than 1.5. Fibrinogen levels should be maintained above 1.5 g/L
    Fibrinogen Correction-Different methods
    • Large-volume FFP transfusion carries increased risks of circulatory overload (TACO), allergic reactions and transfusion-related acute lung injury (TRALI)
    • The platelet count usually remains above 50000/uL (the generally accepted haemostatic level) until 1.5 to 2.5 blood volumes have been replaced. An adult therapeutic dose should be requested when the count falls to 75000-100000/uL.
    • Systematic reviews and registry studies show no good evidence of improved survival with the use of recombinant activated factor VIIa and life-threatening arterial and venous thromboembolic complications may occur
    • Point‑of‑care testing is highly desirable: Arterial blood gas (ABG) and thromboelastograph (TEG). ABG with haemoglobin (Hb), electrolyte and lactate levels, repeated hourly, are useful in directing therapy
    • A few words about citrate toxicity: 80 ml of citrate phosphate dextrose adenine solution present in each blood bag contains approximately 3 g citrate. A healthy adult can metabolise this load in 5 min. However, hypoperfusion or hypothermia associated with massive blood loss can decrease this rate of metabolism leading to citrate toxicity. Unmetabolised citrate can then lead to hypocalcaemia, hypomagnesemia and worsen the acidosis. Hypocalcaemia can lead to myocardial depression that manifests earlier than hypocalcaemic coagulopathy. Hypotension not responding to fluids should alert the physician to this complication. Calcium supplementation is thus required in most cases of massive transfusion
    • Massive transfusion protocols (MTP) are generally activated after transfusion of 4-10 units. MTPs have a predefined ratio of RBCs, FFP/cryoprecipitate and platelets units (random donor platelets) in each pack (e.g. 1:1:1 or 2:1:1 ratio) for transfusion. The trigger for initiating the protocol as well as the optimum ratio of RBC: FFP: Platelets is controversial. Therefore practice varies from centre to centre. If MTP is triggered for a nonmassive blood loss situation, it may lead to wastage of blood products.
    • Targets of resuscitation in massive blood loss: Mean arterial pressure (MAP) around 60 mmHg, systolic arterial pressure 80-100 mmHg (in hypertensive patients one may need to target higher MAP), Hb 7-9 g/dl, INR <1.5; activated PTT <42 s, Fibrinogen >1.5-2 g/L, Platelets >50000/uL, pH 7.35-7.45, Core temperature >35.0°C, Base deficit <3.0/lactates <2 mEq/L.

  • VIVA SCENE: COMPATIBILITY IN BLOOD TRANSFUSIONS: RBC Vs FFP Vs PLATELETS AND OTHER QUESTIONS

    COMPATIBILITY: RBC TRANSFUSION

    In red cell transfusion, there must be ABO and RhD compatibility between the donor’s red cells and the recipient’s plasma.

    All healthy normal adults of group A, group B and group O have ANTIBODIES IN THEIR PLASMA against the red cell types (antigens) that they have not inherited

    Among the ABO blood groups:

    Group A individuals have antibody to group B

    Group B individuals have antibody to group A

    Group O individuals have antibody to group A and group B

    Group AB individuals do not have antibody to group A or B. So,

    1 Group O individuals can receive blood from group O donors only ( as the antibodies against A or B in their plasma will react with any A or B antigens which enter the circulation)

    2 Group A individuals can receive blood from group A and O donors

    3 Group B individuals can receive blood from group B and O donors

    4 Group AB individuals can receive blood from AB donors, and also from group A, B and O donors ( as their plasma don’t have any antibodies against any antigens)

    RhD RED CELL ANTIGENS AND ANTIBODIES

    Is the second most important group system. Out of the existing C,D and E antigens, D is the most antigenic one. Anti D antibodies are not normally found in the blood of Rh negative individuals; instead they develop it only when itcomes into contact with Rh positive blood during child birth or inappropriate transfusion. In case of subsequent transfusins or pregnancies with Rh positive blood- this can cause rapid destruction of RhD positive red cells (Hemolytic disease of the newborn[HDN] in subsequent pregnancies; to prevent this sensitization we should give Rhesus imunoglobulin= Anti-D prophylaxis- to the Rh negative mother who gave birth to an Rh positive baby). The fetal red cells are haemolysed, causing severe anaemia. HDN due to ABO incompatibility is usually less severe than Rh incompatibility.). FFP does not need to be Rh-compatible. Anti-D prophylaxis is not necessary in Rh D-negative recipients of Rh D-positive FFP. 

    PLASMA TRANSFUSION: COMPATIBILITY

    In plasma transfusion, group AB plasma can be given to a patient of any ABO group because it contains neither anti-A nor anti-B antibody.

    1 Group AB plasma (no antibodies) can be given to any ABO group patients

    2 Group A plasma (anti-B) can be given to group O and A patients

    3 Group B plasma (anti-A) can be given to group O and B patients

    4 Group O plasma (anti-A + anti-B) can be given to group O patients only

    FFP does not need to be Rh-compatible (However, the unit will still be labelled as Rh +ve or Rh −ve) ; anti-D prophylaxis is not necessary in Rh D-negative recipients of Rh D-positive FFP

    PLATELET TRANSFUSION: COMPATIBILITY

    The Platelet Concentrates( PCs ) transfused must be ABO-identical, or at least ABO-compatible, in order to give a good yield ( Ideally, ABO identical units should be used but, in an emergency, ABO non-identical units can be used, although the improvement seen in platelet count post-transfusion may be less.)

    Group O PC can be used for patients with blood groups A, B, and AB ONLY IF, they are resuspended in additive/preservative solutions, or if negative for high titre anti-A/A,B

    ABO-incompatible PCs have reduced efficacy and, preferably, should not be used

    Rh-negative patients, in particular women of childbearing age, should receive, if possible, RhD-negative PC

    In the case of a transfusion of a RhD-positive PC to a RhD-negative women of childbearing age, 250 IU (50 μg) of anti-D immunoglobulin should be administered, a dose able to cover the transfusion of five therapeutic doses of PC in 6 weeks

    ACUTE EMERGENCY : COMPATIBILITY

    During an acute emergency, the blood bank may send group O (and possibly RhD negative) blood, especially if there is any risk of errors in patient identification. This may be the safest way to avoid a serious mismatched transfusion, in such situations.

    HOW A GROUP AND SAVE IS PERFORMED? (P’s = Patient’s)

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    #BloodTransfusion , #ABO , #BloodGroup , #TransfusionMedicine , #Anaesthesia , #Anesthesia , #Bloodbank

    Reference: The Clinical Use of Blood, Handbook, WHO,
    Recommendations for the transfusion of plasma and platelets Giancarlo Liumbruno, Francesco Bennardello, […], and as Italian Society of Transfusion Medicine and Immunohaematology (SIMTI) Working Party

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    AAGBI GUIDELINES 2016

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    HOW WILL YOU TRANSFUSE THE BLOOD?

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    Also preoperatively the need for transfusion must have been explained and written informed consent should have been taken

    A general Hb threshold of 7.0 g/dl should apply as a guide for red cell transfusion. 8.0 g/dl for patients with IHD

    ALSO NOTE:

    • A transfusion of 10 ml/kg of RBC should increase Hb by approximately 2.0 g/dl-

    • Cryoprecipitate should be given in a dose of 5–10 ml.kg-1

    • Platelets should be given in a dose of 10–20 ml.kg-1.

    • Fresh frozen plasma may be given in doses of 10–15 ml.kg-1.

    Tranexamic acid can be used in children: a loading dose of 15 mg.kg-1 followed by infusion 2 mg.kg-1.h-1 should be used in trauma

  • RISK OF OCCUPATIONAL TRANSMISSION OF HCV

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  • THE RIGHT WAY OF ADMINISTERING BLOOD PRODUCTS

    Screen Shot 2018-09-01 at 5.22.07 PMPrefer a larger cannula: A doubling of the diameter of the cannula increases the flow rate of most fluids by a factor of 16.

    In case of Whole blood, red cells, plasma and cryoprecipitate

    >Use a new, sterile blood administration set containing an integral 170–200 micron filter

    >Change the set at least 12-hourly during blood component infusion

    >In a very warm climate, change the set more frequently and usually after every four units of blood, if given within a 12-hour period

    In case of Platelet concentrates

    Use a fresh blood administration set or platelet transfusion set, primed with saline.

    WARMING BLOOD:

    >There is no evidence that warming blood is beneficial to the patient when infusion is slow.

    >At infusion rates greater than 100 ml/minute, cold blood may be a contributing factor in cardiac arrest. However, keeping the patient warm is probably more important than warming the infused blood.

    >Warmed blood is most commonly required in:

    [1]Large volume rapid transfusions:
    –Adults: greater than 50 ml/kg/hour
    -Children: greater than 15 ml/kg/hour

    [2]Exchange transfusion in infants

    [3]Patients with clinically significant cold agglutinins.

    >Blood SHOULD ONLY BE WARMED in a blood warmer. Blood warmers should have a visible thermometer and an audible warning alarm and should be properly maintained.

    >Blood should never be warmed in a bowl of hot water as this could lead to haemolysis of the red cells which could be life-threatening.

    Severe reactions most commonly present during the first 15 minutes of a transfusion. All patients and, in particular, unconscious patients should be monitored during this period and for the first 15 minutes of each subsequent unit.

    The transfusion of each unit of the blood or blood component should be completed within four hours of the pack being punctured. If a unit is not completed within four hours, discontinue its use and dispose of the remainder through the clinical waste system.

    [ from “THE CLINICAL USE OF BLOOD”- HAND BOOK , World Health Organization & Blood Transfusion Safety , GENEVA ]

  • Practical issues in blood transfusion in pediatrics

    1. Amount of transfusion to be given: It has been seen that transfusion with PRBC at a dose of 20 mL/kg is well tolerated and results in an overall decrease in number of transfusions compared to transfusions done at 10 mL/kg. There is also a higher rise in hemoglobin with a higher dose of PRBCs.

    2. Properties of RBC products used in neonatal transfusion: a. RBCs should be freshly prepared and should not be more than 7 days old. This translates into a high 2, 3-DPG concentration and higher tissue extraction of oxygen.

    3.Blood should be of newborn’s ABO and Rh group. It should be compatible with any ABO or atypical red cell antibody present in the maternal serum.

    4. Volume and rate of transfusion:
    a. Volume of packed RBC = Blood volume (mL/kg) x (desired minus actual hematocrit)/ hematocrit of transfused RBC
    b. Rate of infusion should be less than 10 mL/kg/hour in the absence of cardiac failure.
    c. Rate should not be more than 2 mL/kg/hour in the presence of cardiac failure.
    d. If more volume is to be transfused, it should be done in smaller aliquots.

  • DOSES: TRANSFUSION OF COMPONENTS

    💦  FFP : 15 ml/kg

    💦  PC :10 ml/kg

    💦 F VIII : % of desired rise x body weight x 0.5