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Hopf anemia09
1. The Transfusion Trigger:
When Should You
Give Red Cells?
Harriet W. Hopf, MD
Professor of Anesthesiology
University of Utah
2. Goals
To understand
the effect of anemia on oxygen transport
mechanisms that compensate for anemia
the risks of transfusion
the concept of a transfusion trigger
3. Objective
Participants will be able persuasively to
defend their decision to transfuse / not to
transfuse red cells
5. Why Transfuse Red Cells?
To maintain O2 delivery to organs
To prevent inadequate O2 consumption
6. How Do We Measure Need?
Ideal
Tissue oxygen
Good-- but not practical
O2ER (VO2/DO2)
Madjdpour and Spahn. BJA 2005; 95:33-42
Real
Hemoglobin
Hemodynamics
7. Physiologic Effects of Anemia
Why is there a wide range of “normal” and
“acceptable” hemoglobin?
8. Physiologic Effects of Anemia
Compensate by increased cardiac output
CO = HR X SV
HR increases 4 bpm / g Hb
SV increases as well
Increased contractility (active)
Decreased SVR (passive)
Increased venous return (passive)
Weiskopf et al. Transfusion 2003; 43: 235-40
9. Physiologic Effects of Anemia
Under anesthesia, no HR increase
Increased CO is from increased SV
Majdpour and Spahn. BJA 2005; 95:33-42.
18. What if you can’t transfuse?
Administer 100% oxygen
Equivalent to 1-1.5 g/dL Hb
1 g Hb fully saturated = 1.34 mL O2
PaO2 500 mm Hg = 1.5 mL O2
PaO2 300 mm Hg = 0.9 mL O2
Weiskopf et al. Anesthesiology, 96(4), 871-7, 2002.
24. What if you can’t transfuse?
Maximize CaO2
FiO2 1.0
Hyperbaric oxygen (intermittent)
Minimize VO2
Intubate
Paralyze
Sedate
Cool (?) to 35.5C
25. What if you can’t transfuse?
Maximize CO
Volume
Goal is isovolemia
Consider TEE guidance
Don’t measure Hb!
Don’t use dopamine
Increased VO2 mostly cardiac
29. Risks of Transfusion
Cancer recurrence
Surgical site infection
Mortality
Role for leucoreduction?
Old vs. new blood?
Koch et al, NEJM 358:1229, 2008
Weiskopf et al, Anesth. 104:911, 2006
Majdpour and Spahn. BJA 2005; 95:33-42.
30. Transfusion Guidelines
Are there guidelines?
ASA Guidelines, Anesth 105:198-208, 2006.
Are they based on data?
“strongly agree” transfuse < 6 g/dL
“strongly agree” don’t transfuse >10g/dL
How good are physicians at following them?
32. Transfusion Trigger
Really a TARGET not a TRIGGER
Healthy patient
7 g / dL
Cardiopulmonary disease
10 g / dL (?8-9)
Prevent tachycardia
33. What does this mean?
Healthy patient, Hb 14 g/dL
Assume 500 mL (1 unit) whole blood loss = 1
g/dL Hb decrease
Assume volume replaced
EBL >3500 mL before consider transfusion
34. How low can you go?
Unmedicated, healthy volunteers at rest
Hb 5 g / dL
No VO2-DO2 dependency
Fatigued
Mild cognitive impairment
Slightly slower and less accurate
Still in normal range
Reversed by RBC transfusion at Hb 7 g/dL
Reversed by 100% O2 via NRB
Weiskopf et al. Anesthesiology, 96(4), 871-7, 2002.
35. What about surgical patients?
Anemia increases 30-day mortality, CV
complications, and LOS
Non-cardiac surgery
Polycythemia similar effects
Wu et al. JAMA 297:2481, 2007 (98% men)
Colorectal surgery
~50% women but not analyzed separately
Leichtle et al, J Am Coll Surg 212:187, 20011
Cardiac surgery
Koch et al, Crit Care Med 34:1608, 2008
36. How Should We Manage Anemia?
Is anemia a marker for disease or inherently
causative?
Preoperative treatment:
2 weeks oral iron (200 mg) reduces transfusion
9.4 vs 27.4%, p<0.05
Okuyama et alSurg Today 35:36, 2005
ESA reduces transfusion, increases DVT
Laupacis and Fergusson, Transfus Med 8:309, 1998
37. How Should We Manage Anemia?
Is anemia a marker for disease or inherently
causative?
Risk-adjusted, propensity-matched
≥4 U blood predicts increases:
Mortality
Infection
LOS
Dunne et al, J Surg Res 102:237, 2002
38. Critical Care Transfusion RCT
838 patients, Hb <9 g/dL, within 72 h of
admit
Trigger <7 Target 7-9
Trigger <10 Target 10-12
Hebert et al. NEJM, 1999; 340:409-17.
39. Critical Care Transfusion RCT
Trigger
<7 g / dL <10 g/dL P value
30d Mortality
Overall 18.7 23.3 0.11
APACHE II
8.7 16.1 0.03
<21
Age <55 yr 5.7 13 0.02
CV Disease 20.5 22.9 0.69
40. Table 3. Unadjusted Rates of Outcomes and Adjusted Results of Cox Regression Predicting 30-Day
Death and Death or Recurrent Myocardial Infarction Using Transfusion as a Time-Dependent
Covariate.
HCT 25% best cut-off for transfusion
Rao, S. V. et al. JAMA 2004;292:1555-1562
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41. Individualize
Transfusion target (7 vs. 10 vs. 8…)
Acute vs. chronic anemia
Rate of bleeding
Hemodynamics
What about ADLs?
Should target differ in men and women?
42. Summary
Transfusions of RBC can be life-saving
Also cause serious morbidity and mortality
Individualize therapy
Underlying disease
Adequacy of compensatory responses
Rate of bleeding
Starting point
Editor's Notes
1.5 with 500 mmHg or 1.34 with 1 g Hb
Table 3. Unadjusted Rates of Outcomes and Adjusted Results of Cox Regression Predicting 30-Day Death and Death or Recurrent Myocardial Infarction Using Transfusion as a Time-Dependent Covariate