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Evidence-Based Blood Transfusion

Evidence-Based Blood Transfusion. Abdominal Surgery Rotation. Patient blood management. Blood transfusion does not simply involve the anesthesiologist hanging pRBCs once 1000 ml of blood are in the suction container! Correct pre-operative anemia Minimize intra-operative blood loss

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Evidence-Based Blood Transfusion

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  1. Evidence-Based Blood Transfusion Abdominal Surgery Rotation

  2. Patient blood management Blood transfusion does not simply involve the anesthesiologist hanging pRBCs once 1000 ml of blood are in the suction container! • Correct pre-operative anemia • Minimize intra-operative blood loss • Optimize blood replacement • Though these things don’t seem to be within our control we can at least go into surgery armed with some data…

  3. 1. Correct pre-operative anemia • Difficult for anesthesiologist to have a role since we often see patients the day before surgery • Can consider: • IV iron or erythropoetin • Will increase hemoglobin by 1-2 g/dL but requires 2 weeks for maximal effect

  4. 2. Minimize intra-operative blood loss • Things we can do: • Maintenance of normothermia • Controlled hypotension • Meaning a MAP that is SAFE for the patient, not necessarily what the surgeon wants! • Consider use of regional anesthesia for pain control and BP effects • Cell salvage and re-transfusion • Usually a decision made by surgeon

  5. 3. Optimize blood replacement And now for some data…

  6. The trial that started it all: TRICCTransfusion Requirements In Critical Care • 838 ICU patients randomized to: • Restrictive transfusion- pRBCs for Hgb < 7, goal 7-9 • Liberal transfusion- pRBCs for Hgb <10, goal 10-12 • Overall 30-day mortality was similar but… • If APACHE II score was <20 (less sick pts, see next slide) • Mortality was 8.7% (restrictive) vs. 16.1% (liberal) • If age was <55 years • Mortality was 5.7% (restrictive) vs. 13.0% (liberal) • If patient had acute MI or unstable angina • Mortality was similar in both groups Hebert et al. NEJM, 1999.

  7. APACHE II: Acute Physiologic and Chronic Health Evaluation scoring system • Rectal temperature • HR • RR • MAP • Aa gradient or PaO2 • pH • Na • K • Cr • Hct • WBC • Glasgow coma scale • Age • Chronic disease Score based on 14 parameters scored 0-4 points each: Higher number is worse Correlations have been made between APACHE II score and morbidity/mortality

  8. And then the meta-analysis… • Meta-analysis of 45 cohort studies including 272,596 patients • Outcomes included mortality, multi-organ dysfunction syndrome (MODS), acute respiratory distress syndrome (ARS) & infections • In 42 studies the risk of transfusions outweighed the benefit (higher mortality & morbidity- MODS, ARDS, infections) • In 2 studies the risk was neutral (benefit = risk) • In 1 study the benefit outweighed the risk • But…the only adequately powered, randomized trial on transfusion requirements is TRICC! Marik & Corwin. CCM, 2008.

  9. But this is all in the ICU… What about in the OR?

  10. Does preoperative anemia in patients having major non-cardiac surgery alter morbidity and mortality? • Retrospective analysis of 227,425 patients undergoing major surgery

  11. After controlling for other risk factors (Age, DMII, cardiac dx, COPD, CRI, cancer) • Post-op mortality at 30 days was higher in those with pre-operative Hct < 36 for females or <39 for males with an odds ratio of 1.42 (confidence interval 1.31-1.54) • This means anemia increased mortality 1.42 fold! • Post-op morbidity at 30 days was higher in those with pre-operative anemia with odds ratio 1.35 (confidence interval 1.3-1.4) • This means anemia increased complications 1.35 fold!

  12. BUT… • Analysis also showed increased mortality WITH blood transfusion! • Authors conclude that pre-operative anemia should be treated with iron supplementation or erythropoeitin administration (if time allows) NOT transfusion!

  13. Does intraoperative transfusion of 1-2 units of pRBCs in patient with Hct < 30 affect morbidity and mortality? • **This study group is VERY relevant to our practice- think of how often you transfuse “just” one or two units intraoperatively!** • Retrospective analysis of 10,100 patient undergoing general, vascular or orthopedic surgery with preoperative hct < 30 Anesthesiology. 2011.

  14. Transfusion of 1-2 units intraoperatively increased mortality and morbidity at 30 days

  15. But… • Hct prior to transfusion not reported • Authors conclude that intraoperative transfusion leads to higher morbidity and mortality but it could be EITHER the transfusion or the increased surgical bleeding/complications that are the direct CAUSE! • Remember: correlation  causation

  16. On the practical side… • Surgeons HATE to look up and see red (ie. blood hanging) without it being discussed with them • If you feel that a transfusion is indicated, discuss it with the surgery team FIRST!

  17. The Basics: pRBCs • Single donor, volume 250-300 ml • Hct ~70% • 1 unit increases Hgb ~1g/dl • Theoretically not compatible with LR because it may chelate calcium and clot • Stored in: • Citrate- anticoagulant binds Ca • Phosphate- buffer • Dextrose- energy source • Adenosine- precursor for ATP synthesis

  18. The basics: FFP • Contains coagulation factors • Use ABO-compatible • Stored frozen, use within 24 hrs of thawing • 1 unit increases clotting factors 2-3% • Can be used to treat heparin resistance (antithrombin III deficiency) in patients requiring heparinization • Most often seen with patients going on bypass

  19. The Basics: Platelets • Stored at room temperature for <5 days • “6-pack” used to refer to pooling of platelets from 6 donors which is rarely done anymore • These days when you ask for a “6-pack” you get an apheresis unit which has platelets from a single donor (volume 200-400ml) and will increase plt count ~ 50,000

  20. The Basics: Cryoprecipitate • Fraction of plasma that precipitates when FFP is thawed • Contains factors VIII, XIII, fibrinogen, fibronectin • 1 unit contains 5 x more fibrinogen than 1 unit of FFP • Usually used to replace fibrinogen <100 mg/dl with microvascular bleedingor in patients with vWF disease

  21. Board Review questions • The most common cause of mortality associated with blood transfusion is: • ABO hemolytic transfusion reaction • Non-ABO hemolytic transfusion reaction • Microbial infection • Transfusion associated circulatory overload (TACO) • Transfusion associated acute lung injury (TRALI)

  22. Answer • E. TRALI is the most common cause of mortality associated with transfusions (51%), followed by non-ABO hemolytic transfusion reaction (20%), microbial infections (12%), ABO hemolytic transfusion reaction (7%), TACO (7%) and other (2%).

  23. Board Review questions • Which of the following is MOST likely to be a manifestation of citrate toxicity? • Hypotension • Short QT interval on ECG • Peaked T waves on ECG • Wide pulse pressure

  24. Answer • A. Hypotension. • Citrate is used as an anticoagulant in banked blood and chelates ionized calcium. It can have the same effect on iCa in the body. The manifestations of citrate intoxication are the same as those observed with hypocalcemia: • Prolonged QT, flattened T waves • Decreased contractility with hypotension • Narrowed pulse pressure • Increased LVEDP, increased CVP • Normally citrate is metabolized by the liver. Can become elevated in massive transfusion, liver failure, hypothermia. • More common with FFP administration • Treat with IV calcium

  25. References • Glance LG et al. Association between Intraoperative Blood Transfusion and Mortality and Morbidity in Patients Undergoing • Noncardiac Surgery. Anesthesiology. 2011; 114(2): 283-292. • Hebert PC et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. NEJM. 1999; 340 (6): 409-17. • Marik PE & Corwin H. Efficacy of red blood cell transfusion in the critically ill: A systematic review of the literature. CCM. 2008; 36(9):2667-2674. • Musallam KM et al. Preoperative anaemia and postoperative outcomes in non-cardiac surgery: a retrospective cohort study. Lancet. 2011; 378: 1396–407. • Spahn DR et al. Patient blood management. Anesthesiology. 2008; 109: 951-3.

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