Emergency Transfusion Raafat Abdelazim Anesthesia Department

Emergency TransfusionEmergency Transfusion

Raafat Abdelazim

Anesthesia DepartmentAnesthesia Department

IIntended LLearning OOutcomesBy the end of this lecture, the student will be able to:

1.Understand why blood transfusion is indicated2.Know how to estimate blood loss3.Understand the compatibility testing4.Assess the situation of “emergency”5.Know how to manage “emergency transfusion”

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Bleeding -------------------- Shock -------------------- Death

Transfusion

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Time?

Indications for Transfusion

When a patient is hemorrhaging:

• To oxygen-carrying capacity

• To intravascular volume

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Fluids (crystalloids or some colloids)

BT

To restore•IV volume•Cardiac output•Organ perfusion

Normovolemic dilutional anemia:If Hb < 6 g/dl inadequate splanchnic & preportal O2 delivery & consumption

Additional O2 delivery to organs & tissues can only be enhanced by RBCs via whole blood or PRBCs

Thus, increasing oxygen-carrying capacity is the only real indication for BT

Is O2-carrying capacity adequate?

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Lab: Hb and HtAge

Cardiorespiratory function

Extreme variability from one patient to another

- Age/CR function/Lab- An individual patient’s Hb level may vary markedly in the perioperative period independent of and in addition to RBCs transfusions

Medical Organizations

Overall medical judgment rather than a specific lab value

More complex directions

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These criteria cannot distinguish inadequate intravascularvolume from O2-carrying capacity

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Hct>30<21

Rarely require BTFrequently require BT(1988 National Institutes of Health Consensus Conference)

Using Hct and Hb:

Hb>10<6

Almost always indicated Rarely indicated(2006 ASA Practice Guidelines)

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To give BT according to Hct and Hb is a clinical judgment based on many factors, such as:1.Cardiovascular status2.Age3.Anticipated additional blood loss4.Arterial oxygenation5.Mixed venous PO2

6.Cardiac output7.Blood volume.8.O2 extraction ratio (invasive, results?)

ASA Practice Guidelines (2006)

1. BT is rarely indicated when Hb is > 10 g/dL and is almost always indicated when it is < 6 g/dL, especially when the anemia is acute.

2. The determination of whether intermediate Hb concentrations (6 to 10 g/dL) justify or require RBC transfusion should be based on the patient’s risk for complications of inadequate oxygenation.

3. The use of a single Hb “trigger” for all patients and other approaches that fail to consider all important physiologic and surgical factors affecting oxygenation is not recommended

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4. When appropriate, the following may be beneficial:• preoperative autologous blood donation• intraoperative and postoperative blood recovery• acute normovolemic hemodilution• measures to blood loss (i.e., deliberate hypotension

and pharmacologic agents)5. The indications for transfusion of autologous RBCs

may be more liberal than those for allogeneic RBCs because of less frequent (but still significant) risks associated with the former.

Miller’s Anesthesia (2005 & 2010)

The following indications were recommended with the rule of thumb that administration of 1 unit of packed RBCs will Hct value by 3%-5%:

1. Blood loss > 20% of blood volume when > 100 mL

2. Hb level < 8 g/dL

3. Hb level < 10 g/dL with major disease (e.g., emphysema, IHD)

4. Hb level < 10 g/dL with autologous blood

5. Hb level < 12 g/dL and ventilator dependent

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Both recommendation lists agree that a transfusion trigger of 8.0 g/dL or less can be tolerated by patients who:

are not critically illdo not have severe cardiorespiratory disease

Average Blood Volumes

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Age Blood volume

Premature Neonates 95 mL/kg

Full Term Neonates 85 mL/kg

Infants 80 mL/kg

Adult Men 75 mL/kg

Adult Women 65 mL/kg

Allowable Blood Loss

EBV= Estimated Blood Volume

Hct (i)= initial Hct

Hct (f)= final lowest acceptable Hcte.g, BW= 70kg EBV= 75x70= 5250 ml

Hct(i)= 44, Hct(f)= 30

ABL= 5250 [44-30] / 44= 1670 ml

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ABL = EBV [Hct (i) - Hct (f)] / Hct (i)

Allowable Blood Loss Corrected for Dilution

EBV= Estimated Blood Volume

Hct (i)= initial Hct

Hct (f)= final Hct

Hct (m)= mean (of i & f)e.g, BW= 70kg EBV= 75x70= 5250 ml

Hct(i)= 44, Hct(f)= 30, Hct(m)= 37

EBL= 5250 [44-30] / 37= 1980 ml

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EBL = EBV [Hct (i) - Hct (f)] / Hct (m)

Compatibility Testing

• ABO-Rh Typing

• Antibody Screening

• Crossmatching

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These tests were designed to demonstrate harmful antigen-antibody interactions in-vitro so that harmful in-vivo antigen-antibody interactions could be prevented

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ABO-Rh Typing

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Anti-A Anti-B

+

Complement IV Hemolysis

Antibodies are directed against those antigens that are lacking in the individual’s own cellsABO typing is performed by testing RBCs for the A and B antigens and the serum for the A and B antibodies before transfusion

Accidental transfusion of ABO-incompatible blood the most serious and tragic reactions.These reactions result from naturally occurring antibodies which are formed whenever the individual lacks either or both of the A and B antigens

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A

A

AA

A

A

B

B

B

B

B

BB

B

B

A

A

A

O

O

OO

O

O

AB

AB

AB A

BAB

AB

AB

B

A

B

A

Rh

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D antigen No D antigen

85%Rh(D) positive

15%Rh(D) negative

60-70% of Rh(D)-negative recipients are immunized(produce anti-D) if they are given BT with Rh(D)-positive blood

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Donor Blood Groups that Patients Can Receive

Donor Recipient

O O, A, B, AB

A A, AB

B B, AB

AB AB

Antibody Screening

• It is carried out in 3 phases.• It is completed in 45-60 min• It is a trial transfusion between the recipient’s serum

and commercially supplied RBCs.• RBCs are specifically selected to contain optimal

numbers of RBC antigens or those antigens that will react with antibodies that are commonly implicated in hemolytic transfusion reactions.

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Antibody Screening (Contd.)

• The screen for unexpected antibodies is also used on donor serum and is performed shortly after withdrawal of blood from the donor.

• It is necessary to screen donor serum for unexpected antibodies to prevent their introduction into the recipient serum.

• This screen is performed primarily to prevent reactions between transfused donor units.

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Crossmatching

• A trial transfusion within a test tube• Donor RBCs are mixed with recipient serum to

detect a potential for serious transfusion reaction• Can be completed in 45 to 60 minutes• Three phases:

1. Immediate phase

2. Incubation phase

3. Antiglobulin phase24

1. Immediate phase

• It is conducted at room temperature• A check against errors in ABO typing• It detects:

– ABO incompatibilities and– those caused by naturally occurring antibodies in the

MN, P, and Lewis systems

• It takes 1 to 5 minutes to complete

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2.Incubation phase

• It involves incubation of the 1st-phase reactions at 37°C in:a) albumin or

b) low-ionic strength salt solution.

• The addition of (a) and (b) aids in the detection of:– incomplete antibodies or – those antibodies that are able to attach to a specific antigen

(i.e., sensitization) but are unable to cause agglutination in a saline suspension of RBCs.

• It detects antibodies in the Rh system• Incomplete antibodies missed in this phase can be

detected in the subsequent antiglobulin phase26

3.Antiglobulin phase

• It involves the addition of antiglobulin sera to the incubated test tubes

• With this addition, antihuman antibodies present in the sera become attached to the antibody globulin on the RBCs, causing agglutination

• It detects most incomplete antibodies in the blood group systems, including the Rh, Kell, Kidd, and Duffy blood group systems

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Blood ABO-Rh Type

Screening for antibodies

Crossmatching

Recipient + Unexpected antibodies+

Donor – All + Unexpected antibodies

Donor – Emergency + Anti-A & Anti-B x

Approaches Requiring Less Thana Complete Crossmatch

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• Type and Screen

• Maximal Surgical Blood Order Schedule

• Is the Crossmatch Really Needed?

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Type and Screen

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1

2

The patient’s serum is screened for the presence of unexpected antibodies by incubating it with selected reagent RBCs (i.e., screen cells). These cells contain all antigens capable of inducing clinically significant RBC antibody reactions

For those few patients in whom the antibody screen reveals the presence of unexpected antibody, the antibody is subsequently identified in the blood bank and units of blood lacking the corresponding antigen are set aside for surgery.

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An immediate-phase crossmatch is performed before transfusion

to eliminate reactions that may result from human errors in ABO-Rh typing

Blood given in this manner is > 99% effective in preventing incompatible transfusion reactions due

to unexpected antibodies

If an emergency transfusion is required after type and screen alone

Remember . . .

• Complete transfusion testing for compatibility between donor and recipient blood ensures optimal safety and therapeutic effect of transfused blood

• The type and screen without the complete crossmatch does not protect against reactions due to antibodies reactive against lower-incidence antigens, those not represented on the screening cells but present on the donor RBCs

• Generally, antibodies that are not detected in the type and screen are weakly reactive antibodies that do not result in serious hemolytic transfusion reactions

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Type and Hold

• This refers to a sample of blood from a potential blood recipient received by the blood bank in which the blood type (but no crossmatch) has been ordered.

• Because of the confusion that has arisen with type and screen, the type and hold terminology and method of ordering blood have been abandoned by most blood banks.

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Maximal Surgical Blood Order Schedule

• Routine preoperative crossmatching of blood for surgical cases means that:– crossmatched blood is unavailable for others for 24 to 48 hours. – 1 to 2 days is lost and the chance for outdating .

• For certain elective surgical procedures, the number of crossmatched units that are ordered frequently far exceeds the number actually transfused to quantify this problem better, the crossmatch-to-transfusion (C/T) ratio has been used

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C/T ratio

• If the C/T ratio is high, the blood bank is burdened with:– keeping a large blood inventory– using excessive personnel time– having a high incidence of outdated units

• For surgical procedures in which the average number of units transfused per case is < 0.5

Type and screen

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NegativePositive

No crossmatchingThe blood bank must provide compatible units that lack the corresponding antigen

• Blood banks attempt to maintain C/T ratios of 2.1 to 2.7.

• To the rate of use and the C/T ratio, blood banks attempt to the emphasis on crossmatching of blood through:– such means as the type and screen and – such programs as the maximal surgical blood order

schedule

• This schedule consists of a list of surgical procedures and the maximal number of units of blood that the blood bank will crossmatch for each procedure

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• This schedule is based on the BT experience for surgical cases in hospitals in which the schedule is employed.

• Each hospital’s maximal surgical blood order schedule is developed by the suppliers and the users of blood in that hospital, such as:– blood bankers– anesthesiologists– surgeons

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Is the Crossmatch Really Needed?

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In 100 previously transfused patients

pregnant patients

Only ONE may have an irregular antibody other than

Anti-AAnti-B

Anti-Rh(D)KellCEKidd

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Irregular antibodies

Reactive only at temperatures < 30°C

Reactive at about30°C

Insignificant in most transfusions

Serious reactions IF the transfused cells contain appropriate antigen

Some Some

The most common of clinically significant antibodies, in order of probable significance:Anti-Rh(D) > Kell > C > E > Kidd

The 1%

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If the correct ABO and Rh bloodtype is given, the possibility of

transfusing incompatible blood is

<1 chance in 1000

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The chance of missing an antibody that is potentially dangerous is

< 1 in 10,000

Antibody screening

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Safety (chance of compatible transfusion)

Emergency Transfusion

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For those situations that do not allow time for complete testing, an abbreviated format for testing can be used. The preferred order for the selection of blood is as follows:

Type-Specific, Partially Crossmatched Blood

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ABO-Rh typing

Centrifugation

Pt’s serum

Donor’s RBCs

Reading for macroscopic agglutination

Room temp.

Immediate-phase crossmatch

In 1 to 5 minutes

ABOUnexpected antibodies: MN P Lewis

Type-Specific, Uncrossmatched Blood

• Almost successful for those who have never been exposed to foreign RBCs

• Caution should be used for patients:– who have previously received transfusions or – have had pregnancies

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Type O Rh-ve (Universal Donor), Uncrossmatched Blood

• It lacks the A and B antigens cannot be hemolyzed by anti-A or anti-B antibodies in the recipient’s blood

• Some type O donors produce high titers of hemolytic IgG, IgM, anti-A, and anti-B antibodies destruction of A or B RBCs of a non–type O recipient

• RBCs vs whole blood:

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Type O Rh-ve whole blood

Type O Rh-ve,uncrossmatched PRBCs

Have smaller volumes of plasma and are almost free of hemolytic anti-A and anti-B antibodies

If to be used, the blood bank must supply it free of hemolytic anti-A and anti-B antibodies

Preferrably

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The patient must not be transfused with his correct blood type until the blood bank determines that the transfused anti-A and anti-B has decreased to levels that permit safe transfusion of type-specific blood

During emergency transfusion of > 2 units of type O Rh-ve, uncrossmatched whole blood, the patient probably cannot be switched to his blood type (A, B, or AB) as soon as the blood bank determines the correct blood type

Switching could cause major intravascular hemolysis of donor RBCs by increasing titers of transfused anti-A and anti-B

Continued use of O Rh-ve whole blood results only in minor hemolysis of recipient RBCs, with hyperbilirubinemia as the only complication

Specific Recommended Protocol

1. Infuse crystalloids or colloids.

2. Draw a blood sample for typing and crossmatching

3. If crossmatched blood is not ready to give, use:– type-specific or– type O Rh-negative cells or– type O Rh-positive cells for males or postmenopausal

females without a history of transfusions;– type-specific, partially crossmatched blood;– or type-specific, crossmatched blood.

Type-Specific

O-ve cells

O+ve cells?

Type-Specific, partially XM

Type-Specific, XM

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For patients who are hypovolemic and require blood transfusion: