Evidence-Based Blood Transfusion

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Abdominal Surgery Rotation
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…
 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
 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
And now for some
data…
 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.
Score based on 14 parameters scored 0-4 points each:
 Rectal temperature
 HR
 Cr
 RR
 Hct
 MAP
 WBC
 Aa gradient or PaO2
 Glasgow coma scale
 pH
 Age
 Na
 Chronic disease
 K
Higher number is worse
Correlations have been made between
APACHE II score and morbidity/mortality
 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.
But this is all in the ICU…
What about in the OR?
 Does preoperative anemia in patients having
major non-cardiac surgery alter morbidity and
mortality?
 Retrospective analysis of 227,425 patients
undergoing major surgery
 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!
 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!
 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.
 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
 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!
 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
 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
 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
 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 bleeding or in patients with vWF
disease
1.
The most common cause of mortality associated
with blood transfusion is:
A.
B.
C.
D.
E.
ABO hemolytic transfusion reaction
Non-ABO hemolytic transfusion reaction
Microbial infection
Transfusion associated circulatory overload (TACO)
Transfusion associated acute lung injury (TRALI)
 E. TRALI is the most common cause of mortality
associated with transfusions (51%), followed by nonABO hemolytic transfusion reaction (20%), microbial
infections (12%), ABO hemolytic transfusion reaction
(7%), TACO (7%) and other (2%).
2.
Which of the following is MOST likely to be a
manifestation of citrate toxicity?
Hypotension
B. Short QT interval on ECG
C. Peaked T waves on ECG
D. Wide pulse pressure
A.
 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
 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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