ABSTRACT
INTRODUCTION: Bivalirudin remains a viable strategy during extracorporeal membrane oxygenation (ECMO). The accuracy of activated partial thromboplastin time (aPTT) for bivalirudin intensity in ECMO may be imperfect resulting in suboptimal dosing, which may increase the risk of bleeding or thrombotic complications. The purpose of this study was to evaluate the correlation between PTT and thromboelastography (TEG) reaction (R) time in adult ECMO patients anticoagulated with bivalirudin. METHOD(S): This was a multicenter, retrospective study conducted over a 22-month period (January 2020 to October 2021. Adult ICU patients requiring ECMO and bivalirudin therapy with >=1 corresponding TEG and aPTT samples drawn <=4 hours of each other were included. The primary endpoint was to determine the correlation coefficient between the TEG R time and bivalirudin aPTT serum concentrations. Pearson's correlation coefficient was used to evaluate the correlation using a kappa measure of agreement between TEG results and bivalirudin aPTT serum concentrations. RESULT(S): A total of 104 patients consisting of 848 concurrent laboratory assessments of R time and aPTT were included. COVID-19 positive tests were confirmed in 48.1% (n=50) of included patients. A moderate correlation between TEG R time and aPTT was demonstrated in the study population (r=0.41;p< 0.001). A similar relationship between TEG R time and aPTT was observed in both COVID-19 positive (r=0.44;p< 0.0001) and negative (r=0.45;p< 0.0001). Overall, 59.2% of all concurrent TEG R time and aPTT values showed agreement on the study institution's therapeutic category (sub-, supra-, and therapeutic) of bivalirudin. 78.3% (n=277) of aPTT values were categorized as therapeutic among all discordant assessment (n=346) between TEG R time and aPTT. The discordant TEG R times with a therapeutic PTT were almost equally distributed between subtherapeutic and supratherapeutic categories. CONCLUSION(S): Moderate correlation was found between TEG R time and aPTT associated with bivalirudin during ECMO in critically ill adults. Further research is warranted to address the optimal test to guide clinical decision-making for anticoagulation dosing in ECMO patients with discordant results.
ABSTRACT
INTRODUCTION: Severe COVID increases the risk of thrombotic complications. Therapeutic anticoagulation with unfractionated heparin (UH) is commonly utilized to prevent venous thromboembolism (VTE). Thromboelastography (TEG) provides a dynamic and global assessment of hemostasis, which may be advantageous or complimentary with standard coagulation tests like anti-Xa activity or activated partial thromboplastin time (aPTT). The purpose of this study was to evaluate the correlation between anti-Xa activity and aPTT with the TEG parameters of reaction (R) time and coagulation index (CI) in patients with severe COVID receiving UH. METHOD(S): This was a single-center, retrospective study conducted over a 15-month period (2020-2021). Adult patients with severe COVID receiving UH with >=1 corresponding TEG and anti-Xa / aPTT samples assessed <=2 hours of each other were included. The primary endpoint was the correlation between anti-Xa activity and R time. Additional associations were determined for aPTT and R time and anti-Xa activity and aPTT with CI. Pearson's coefficient was used to evaluate the correlation using a kappa measure of agreement. RESULT(S): A total of 423 assessments across 237 patients were included. R time did not correlate with anti-Xa activity (r2=0.032;p< 0.0001) nor aPTT (r2=0.007;p=0.061). CI did not correlate with anti-Xa activity (r2=0.093;p< 0.0001) nor aPTT (r2=0.017;p=0.0073). Overall, 188 (45%) R times and anti-Xa values showed agreement in terms of both demonstrating therapeutic anticoagulation, sub-therapeutic anticoagulation, or supra-therapeutic anticoagulation. Twentyeight patients (11.8%) and 21 patients (8.9%) developed a clinically relevant bleed or VTE, respectively, but all coagulation and TEG parameters were similar between those with a bleed or VTE and those without. CONCLUSION(S): The TEG parameters of R time and CI did not correlate with anti-Xa activity or aPTT for monitoring of intensity of anticoagulation with UH in patients with severe COVID-19. Using TEG in these patients to monitor UH anticoagulation offers no benefit over anti-Xa activity or aPTT. Further research is necessary to address the laboratory tests needed to help with decision-making on anticoagulation dosing in patients with severe COVID.