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Physiologic effects of acute anemia: implications for a reduced transfusion trigger
1Department of Surgery, Michael Reese Hospital and Medical Center, Chicago, Illinois.
Transfusion
|January 1, 1990
Summary
Reducing transfusion triggers to a hematocrit of 15 percent in healthy animals is safe. This finding suggests a lower transfusion threshold may reduce homologous blood transfusions and associated risks.
Area of Science:
- Transfusion Medicine
- Anesthesiology
- Surgical Stress
Background:
- Transfusion-associated infectious disease risks prompt reassessment of transfusion practices.
- A trend toward reducing homologous transfusions exists, driven by initiating hemotherapy at more severe anemia levels.
- The optimal transfusion trigger (TT) threshold remains unknown.
Purpose of the Study:
- To evaluate the effects of withholding transfusion or lowering the TT to a hematocrit (Hct) of 15 percent.
- To assess safety and physiological adaptation in unanesthetized animals subjected to severe anemia.
Main Methods:
- Nineteen adult baboons underwent laparotomy to simulate surgical stress.
- Exchange transfusion (ET) was performed to achieve a final Hct of 15 percent.
- Hemodynamic measurements were taken before and after ET, with a 2-month follow-up.
Main Results:
- No morbidity was observed post-ET or during the 2-month follow-up.
- Significant increases in cardiac output and oxygen extraction ratio were noted after ET.
- Oxygen delivery decreased, but oxygen consumption remained unchanged, indicating adaptation to anemia.
Conclusions:
- Unanesthetized animals adapt well to severe anemia (Hct of 15 percent) without adverse long-term effects.
- Reducing the TT to a Hct of 15 percent appears safe in normal animals.
- Adopting this lower TT could significantly decrease the need for homologous transfusions and their risks.