Physiologic transfusion triggers

In clinical practice, the decision to transfuse is linked to the hope of increasing oxygen transport (TO₂) to tissues. Physiologic transfusion triggers should progressively replace arbitrary hemoglobin-based transfusion triggers. These ‘physiologic’ transfusion triggers can be based on signs and symptoms of impaired global oxygenation (lactate, venous O₂ saturation [SvO₂]) or, even better, of regional tissue oxygenation (electrocardiographic ST-segment, electroencephalographic P300 latency). The SvO₂ or its surrogate, the central venous O₂ saturation (ScvO₂), is a clinical tool which integrates the relationship between whole-body O₂ uptake and TO₂, and as such can be proposed as a simple physiologic transfusion trigger.

Key words: oxygen (O₂) transport (TO₂), regional tissue oxygenation, lactate, venous O₂ saturation (SvO₂), central venous O₂ saturation (ScvO₂), electroencephalographic P300 latency