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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”
2
Bleeding -------------------- Shock -------------------- Death
Transfusion
3
Time?
Indications for Transfusion
When a patient is hemorrhaging:
• To oxygen-carrying capacity
• To intravascular volume
4
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?
5
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
6
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)
8
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
9
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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
13
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
16
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
19
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
27
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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
29
• Type and Screen
• Maximal Surgical Blood Order Schedule
• Is the Crossmatch Really Needed?
30
Type and Screen
31
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
33
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.
34
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
35
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
36
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
37
• 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
38
Is the Crossmatch Really Needed?
39
40
In 100 previously transfused patients
pregnant patients
Only ONE may have an irregular antibody other than
Anti-AAnti-B
Anti-Rh(D)KellCEKidd
41
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%
42
If the correct ABO and Rh bloodtype is given, the possibility of
transfusing incompatible blood is
<1 chance in 1000
43
The chance of missing an antibody that is potentially dangerous is
< 1 in 10,000
Antibody screening
44
Safety (chance of compatible transfusion)
Emergency Transfusion
45
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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
47
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
48
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
51
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
52
For patients who are hypovolemic and require blood transfusion: