Preoperative autologous blood donation:
The degree of anemia experienced with autologous donation is insufficient to initiate an adequate increase in serum erythropoietin production. This results in mild preoperative anemia in the majority of patients and volume of blood donated is inadequate to meet operative needs.
JAMA 1988; 260:65-67
 
Decreased capacity of oxygen unload in stored blood:
Stored RBC’s lose 2,3-DPG which regulates Hgb ability to carry and release O2 to the tissues. With reduced 2,3 DPG levels, O2 binds tightly with HGB, resulting in decrease release of O2 to the cells. Stored RBC’s are impaired in O2 delivery capability. Two to four hours post transfusion the RBC’s begin to restore but may not return to normal levels for 24 hours.
Critical Care Med 1997; 25: 726-732
 
Alteration of red cell aggregability and shape:
Blood storage induced changes in red blood cells that are associated with continuous increase of their aggregrability. Large and stronger than normal aggregrates might occlude small blood vessels, thus affecting microcirculation.
Transfusion 1999; 39:277-281
 
Age of blood: A study of 31 critically ill patients with sepsis.
The median age of RBC units transfused to survivors was 17 days old verses a median age of RBC units to non-survivors. A negative correlation was found between the proportion of PRBC units of a given age transfused to survivors and increasing age of PRBC.
Can J Anesthesia 1997; 44: 1256-1261
 
Immunosuppression – Increased infection rate: A study of patients undergoing hip replacement surgery.
The post op infection rate with patients receiving allogenic blood transfusions appears to be seven to ten times higher than with autologous transfusion only or no transfusions. The average Length of Stay was longer with allogenic transfusions.

No Transfusions

 

9.4 days average LOS

 

1 Unit

 

13.4 days

 

2 Units

 

14.3 days

 

3 Units

 

23.2 days

 
Seminar in Hematology 1997; 34(3), Suppl 34-40

Study: 9,598 patients with repair of hip fractures at 20 hospitals
58 % of patients received blood transfusions. There was dose-response relationship for serious infection. There was a 35% greater risk for serious bacterial infection and a 52% greater risk for pneumonia associated with blood transfusions.
Transfusion 1999; 39: 694-700

Transfusion as a risk factor in Multisystem Organ Failure: Study: 513 Severe Injury patients (ISScore >15; >15 years old; survival >48 Hrs.)
A significant linear trend was found between the number of transfusions and incidence of MSOF. 17% of patients (85 patients) developed MSOF. Transfusion was identified as an independent, early consistent risk factor in 13 or 15 models tested. A dose –response relationship seemed to exist.
Arch Surgery 1997; 132:620-625
 
Iatrogenic blood loss: Phlebotomy: A study of 142 critically ill patients who had a ICU length of stay of over one week.
The average daily blood loss to phlebotomy was 61-70 ml. Forty-nine percent of the RBC transfusions were related to replacing blood loss to phlebotomy.
Chest 1995; 108:767-71
 
Critically Ill Patients: Nutritional deficiencies contribute to anemia: A study of 184 critically ill patients who were screened for iron, B12 and folate deficiency.
Early in the critical illness, most patients had iron studies consistent with the anemia of chronic disease. There was also a blunted EPO response that may contribute to this anemia of chronic disease-like anemia of critical illness. Screening for these deficiencies should be considered in patients with anticipated  long ICU stays.
Crit Care 2001; 16, No1: 36-41
 
Critically Ill Patients: Outcomes with liberal vs conservative transfusion Study: 838 critical care patients in 25 Canadian hospitals 
  • Liberal transfusions group were transfused with < Hgb 10 g/dL, Maintain Hgb 10-12 g/dL
  • Restrictive transfusion group were transfused with <Hgb 8 g/dL, Maintain Hgb 7-9 g/dL
  • 33% of restrictive group received no blood transfusions

 

Liberal
(Hgb 10-12)

Restrictive
(Hgb 7-9)

ICU LOS

11.5 d

11.0 d

Total LOS

35.5 d

34.8

30 day mortality

23.3%

18.7%

60 day mortality

36.5%

22.7%

Mortality w/Pt w/cardiac disease

22.9%

20.5%

Mortality pts < 55 years old

16.1%

8.7%
N. Engl. J. Med. 1999;  340: 407-17