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The following is a summary of “Anticoagulation Monitoring Strategies During Extracorporeal Membrane Oxygenation (ECMO) Therapy – Differences Between Simultaneously Obtained Coagulation Tests: A Retrospective Single-Center Cohort Study,” published in the February 2025 issue of Critical Care by Reisinger et al. 

Systemic anticoagulation with unfractionated heparin (UFH) was the standard of care during extracorporeal membrane oxygenation (ECMO), but the optimal monitoring strategy remained uncertain.  

Researchers conducted a retrospective study on patients with venovenous and venoarterial ECMO in the medical ICUs at the Medical University of Graz, Austria.  

They examined the correlation and concordance of R-time in thromboelastography (TEG), activated partial thromboplastin time (aPTT), and anti-Xa activity in patients with ECMO. The proportion of values within the target range was examined, along with the impact of coagulation parameters above or below target thresholds on mortality, bleeding, and thrombotic events. Target ranges were aPTT 54–72 s (1.5–2× upper limit of normal [ULN]), anti-Xa activity 0.2–0.5 U/mL, and R-time in assays without heparinase 675–900 s (1.5–2× ULN).  

The results showed that 671 clusters of coagulation tests were analyzed in 85 ECMO cases meeting inclusion criteria. The median patient age was 57 years, with 32% being female. Poor correlations were observed among the 3 coagulation tests, with a discordance rate of 46%. Target range compliance was 21% for R-time, 15% for aPTT, and 44% for anti-Xa activity. Singular and multiple bleeding events appeared in 25 and 32 patients, respectively, most commonly at catheter and cannula insertion sites, followed by pulmonary hemorrhage. In VA-ECMO, anti-Xa activity was linked (OR 1.03 [1.01–1.06], P = 0.005) and correlated with bleeding events (Spearman rho 0.49, P = 0.002; point biserial 0.49, P = 0.001) while, aPTT levels below the target range were linked to reduced mortality (OR 0.98 [0.97–0.99], P = 0.024). Thrombotic events occurred in 6 patients, with no association with coagulation tests.  

Investigators concluded that patients with ECMO had a high rate of discordance and poor correlation which existed between aPTT, anti-Xa activity, and R-time in TEG, with high bleeding event rates and, in VA-ECMO, an association between these events and elevated anti-Xa activity. 

Source: journals.sagepub.com/doi/10.1177/08850666241313357