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Safe hemoglobin or hematocrit levels in surgical patients
1Department of Surgery, University of Berne, Berne, CH-3010, Switzerland.
World Journal of Surgery
|November 1, 1996
Summary
Red blood cell transfusions can improve oxygen consumption, but their effectiveness varies in septic patients. Individual patient factors, not a universal threshold, determine optimal hemoglobin levels to avoid oxygen deficits.
Area of Science:
- Critical Care Medicine
- Hematology
- Physiology
Background:
- Oxygen delivery, consumption, and deficits are fundamental physiological concepts.
- Red blood cell (RBC) transfusion is a common intervention to address oxygen deficits.
- The response to transfusion varies, particularly in critically ill and septic patients.
Purpose of the Study:
- To review the role of RBC transfusion in oxygen delivery and consumption.
- To discuss factors influencing anemia tolerance and the concept of a
- critical
- hemoglobin level.
- To highlight the impact of silent myocardial ischemia (SMI) on transfusion decisions.
Main Methods:
- Review of existing literature on oxygen transport and RBC transfusion.
- Analysis of factors affecting oxygen consumption (VO2) and delivery (DO2).
- Discussion of non-hemoglobin variables influencing oxygenation and the impact of SMI.
Main Results:
- RBC transfusion can increase VO2 in nonseptic states but is unpredictable in acute sepsis.
- Therapeutic interventions, including maintaining hemoglobin around 11 g/dl, can improve survival in critically ill patients.
- Individual "critical" hemoglobin or hematocrit levels exist due to non-Hb variables and SMI, negating a universal transfusion trigger.
Conclusions:
- A universally applicable "transfusion trigger" is not feasible due to individual patient variability.
- Patients over 40 undergoing elective procedures should be screened for SMI before considering hemoglobin levels below 10 g/dl or hematocrit below 30%.