Key result
Adjusting heparin infusion to maintain an aPTT ratio of 1.5-2.0 during ECMO resulted in 'flat-line' thromboelastography in 46% of samples, which did not predict bleeding.
Why the study?
Does continuous infusion of unfractionated heparin to maintain an aPTT ratio between 1.5 and 2.0 cause 'flat-line' thromboelastography in adults on ECMO for respiratory failure?
Observational (n=32)
Does continuous infusion of unfractionated heparin to maintain an aPTT ratio between 1.5 and 2.0 cause 'flat-line' thromboelastography in adults on ECMO for respiratory failure?
Adjusting heparin infusion to maintain an aPTT ratio between 1.5 and 2.0 during ECMO frequently results in 'flat-line' thromboelastography, which does not predict bleeding.
Suggests aPTT-guided heparin may over-anticoagulate per TEG without bleeding risk in ECMO; hypothesis-generating for better monitoring strategies.
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.
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Panigada et al. (2015) conducted an observational in Respiratory failure requiring ECMO (n=32). Continuous unfractionated heparin targeting aPTT ratio 1.5-2.0 was evaluated on Prevalence of 'flat-line' thromboelastography (R time >90 min). Adjusting heparin infusion to maintain an aPTT ratio of 1.5-2.0 during ECMO resulted in 'flat-line' thromboelastography in 46% of samples, which did not predict bleeding.
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