Table 1.

Definitions of procedural hematocrit measurements by event.

Variable	Time Point	Description
Baseline OR Hct	Initially in OR	Initial hematocrit measured in the operating room, generally drawn shortly before or shortly after anesthesia induction
Pre-CPB Hct	Before CPB initiation	Hematocrit measured post-heparinization for CPB, generally drawn with the post heparinization/pre-CPB ACT sample
On-CPB Hct	Initially On-CPB	Initial hematocrit measured after commencement of CPB, generally drawn within 5 minutes after delivery of cardioplegic arrest
End CPB Hct	End of CPB	Final hematocrit measured on-CPB, generally drawn after removal of aortic cross clamp using a single cross-clamp surgical technique
Low CPB Hct	During CPB	Lowest hematocrit measured during the CPB procedure
Post-CPB Hct	After CPB termination	Initial hematocrit measured post-CPB/post-protamine, generally drawn within 10 minutes after administration of protamine
ICU Hct	On ICU admission	Hematocrit measured on admission to the ICU, generally drawn within 5 minutes after arriving in the ICU

ACT, activated clotting time; CPB, cardiopulmonary bypass; Hct, hematocrit; OR, operating room; ICU, intensive care unit.