We evaluated the prevalence of a thromboelastography reaction time (R time) >90 min ("flat-line") reversible with
heparinase during
extracorporeal membrane oxygenation (ECMO). We evaluated the association between "flat-line" thromboelastography, other coagulation tests, and risk of
bleeding during ECMO. Thirty-two consecutive patients on ECMO were included. Anticoagulation was provided by continuous infusion of
unfractionated heparin to maintain an activated partial thromboplastin time (aPTT) ratio between 1.5 and 2.0. Activated clotting times (ACTs) thromboelastography without and with
heparinase were measured. Occurrence of
bleeding was recorded. Median
heparin infusion rate was 16 (12-20) IU/kg/h, aPTT ratio was 1.67 (1.48-1.96), and ACT was 173 (161-184) sec. One hundred forty-five (46%) of 316 paired thromboelastography samples were "flat lines" all reversed with
heparinase. Patients with "flat-line" thromboelastography received more
heparin (p = 0.001) but had similar platelet count (p = 0.164) and
fibrinogen level (p = 0.952) than those without. Activated partial thromboplastin time, ACT, and R time without
heparinase weakly correlated between each other (Spearman correlation ≤0.36) with poor agreement (Cohen's κ ≤0.10). Major
bleeding occurred in seven (22%) patients.
Bleeding during ECMO was not predicted by any of the used test. In conclusion, adjusting
heparin infusion to maintain aPTT ratio between 1.5 and 2.0 frequently resulted in "flat-line" thromboelastography.