Fresh and citrated whole-blood specimens can produce different thromboelastography results in patients on extracorporeal membrane oxygenation

Objectives: To compare thromboelastography (TEG) tracings obtained from fresh and citrated whole-blood samples in patients on extracorporeal membrane oxygenation (ECMO) or after cardiopulmonary bypass and in healthy volunteers.

Methods: Samples of fresh and citrated whole blood were analyzed for 25 patients and 4 healthy volunteers. Thromboelastography analysis was performed in both plain and heparinase cups.

Results: In 5 of 6 patients on ECMO, use of citrated samples resulted in apparent partial or complete heparin reversal. In TEG tracings from patients following cardiopulmonary bypass, there was a slight hypercoagulable appearance in the citrated sample. No differences were noted between fresh and citrated samples from healthy volunteers whose blood was spiked with heparin.

Conclusions: In some patients on ECMO, use of samples collected in sodium citrate tubes for TEG analysis results in significant artifacts, which could lead to heparin overdosing in these patients.