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.