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Emergency Transfusion

Anesthesia Department. Emergency Transfusion. Raafat Abdelazim. I ntended L earning O utcomes. By the end of this lecture, the student will be able to: Understand why blood transfusion is indicated Know how to estimate blood loss Understand the compatibility testing

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Emergency Transfusion

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  1. Anesthesia Department Emergency Transfusion Raafat Abdelazim

  2. IntendedLearningOutcomes By the end of this lecture, the student will be able to: Understand why blood transfusion is indicated Know how to estimate blood loss Understand the compatibility testing Assess the situation of “emergency” Know how to manage “emergency transfusion”

  3. Transfusion Time? Bleeding --------------------Shock --------------------Death

  4. Indications for Transfusion When a patient is hemorrhaging: • To  oxygen-carrying capacity • To  intravascular volume BT • To restore • IV volume • Cardiac output • Organ perfusion Fluids (crystalloids or some colloids) Additional O2 delivery to organs & tissues can only be enhanced by RBCs via whole blood or PRBCs Normovolemic dilutional anemia: If Hb < 6 g/dl inadequate splanchnic & preportal O2 delivery & consumption Thus, increasing oxygen-carrying capacity is the only real indication for BT

  5. Is O2-carrying capacity adequate? Age Cardiorespiratory function Lab: Hb and Ht 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 intravascular volume from O2-carrying capacity

  7. Using Hct and Hb: Hct <21 >30 Rarely require BT Frequently require BT (1988 National Institutes of Health Consensus Conference) Hb <6 >10 Rarely indicated Almost always indicated (2006 ASA Practice Guidelines)

  8. To give BT according to Hct and Hb is a clinical judgment based on many factors, such as: Cardiovascular status Age Anticipated additional blood loss Arterial oxygenation Mixed venous PO2 Cardiac output Blood volume. O2 extraction ratio (invasive, results?)

  9. ASA Practice Guidelines (2006) • 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. • 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. • 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

  10. When appropriate, the following may be beneficial: • preoperative autologous blood donation • intraoperative and postoperative blood recovery • acute normovolemichemodilution • measures to blood loss (i.e., deliberate hypotension and pharmacologic agents) • 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.

  11. 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%: • Blood loss > 20% of blood volume when > 100 mL • Hb level < 8 g/dL • Hb level < 10 g/dL with major disease (e.g., emphysema, IHD) • Hb level < 10 g/dL with autologous blood • Hb level < 12 g/dL and ventilator dependent

  12. Both recommendation lists agree that a transfusion trigger of 8.0 g/dL or less can be tolerated by patients who: • are not critically ill • do not have severe cardiorespiratory disease

  13. Average Blood Volumes

  14. Allowable Blood Loss ABL = EBV [Hct (i) - Hct (f)] / Hct (i) EBV= Estimated Blood Volume Hct (i)= initial Hct Hct (f)= final lowest acceptable Hct e.g, BW= 70kg  EBV= 75x70= 5250 ml Hct(i)= 44, Hct(f)= 30 ABL= 5250 [44-30] / 44= 1670 ml

  15. Allowable Blood Loss Corrected for Dilution EBL = EBV [Hct (i) - Hct (f)] / Hct (m) 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

  16. Compatibility Testing • ABO-Rh Typing • Antibody Screening • Crossmatching These tests were designed to demonstrate harmful antigen-antibody interactions in-vitro so that harmful in-vivo antigen-antibody interactions could be prevented

  17. ABO-Rh Typing • 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 Anti-A Anti-B + Complement IV Hemolysis • Antibodies are directed against those antigens that are lacking in the individual’s own cells • ABO typing is performed by testing RBCs for the A and B antigensand the serum for the A and B antibodies before transfusion

  18. A A A B A A B A B B B B B A B B A B A A O O O B O O A O A B AB AB AB AB AB AB

  19. Rh 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

  20. 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.

  21. 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.

  22. 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: • Immediate phase • Incubation phase • Antiglobulin phase

  23. 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

  24. Incubation phase • It involves incubation of the 1st-phase reactions at 37°C in: • albumin or • 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 phase

  25. 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

  26. Approaches Requiring Less Thana Complete Crossmatch

  27. Type and Screen • Maximal Surgical Blood Order Schedule • Is the Crossmatch Really Needed?

  28. Type and Screen 1 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. 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 2

  29. If an emergency transfusion is required after type and screen alone An immediate-phase crossmatchis 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

  30. 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

  31. 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.

  32. 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

  33. 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 Positive Negative The blood bank must provide compatible units that lack the corresponding antigen No crossmatching

  34. 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

  35. 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

  36. Is the Crossmatch Really Needed?

  37. previously transfused patients In 100 pregnant patients Anti-Rh(D) Kell C E Kidd Only ONE may have an irregular antibody other than Anti-A Anti-B

  38. Irregular antibodies The 1% Some Some Reactive only at temperatures < 30°C Reactive at about 30°C Insignificant in most transfusions Serious reactions IF the transfused cells contain appropriate antigen The most common of clinically significant antibodies, in order of probable significance: Anti-Rh(D) > Kell > C > E > Kidd

  39. If the correct ABO and Rh blood type is given, the possibility of transfusing incompatible blood is <1 chance in 1000

  40. Antibody screening The chance of missing an antibody that is potentially dangerous is < 1 in 10,000

  41. Safety (chance of compatible transfusion)

  42. Emergency Transfusion

  43. 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:

  44. Type-Specific, Partially Crossmatched Blood ABO-Rh typing Immediate-phase crossmatch In 1 to 5 minutes Room temp. Centrifugation Reading for macroscopic agglutination ABO Unexpected antibodies: MN P Lewis Donor’s RBCs Pt’s serum

  45. 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

  46. 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:

  47. Preferrably Type O Rh-ve, uncrossmatchedPRBCs Have smaller volumes of plasma and are almost free of hemolytic anti-A and anti-B antibodies Type O Rh-vewhole blood If to be used, the blood bank must supply it free of hemolytic anti-A and anti-B antibodies

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