Objectives: Critically ill patients with deranged conventional coagulation tests are often perceived to have an increased bleeding risk. Whether anticoagulant prophylaxis for these patients should be withheld is contentious. This study assessed the ability of using in vitro clot strength, as measured by thromboelastography, to predict thromboembolism in patients with abnormal coagulation profiles.
Design: Prospective cohort study.
Setting: A tertiary ICU.
Patients: Two-hundred and fifteen critically ill coagulopathic patients with thrombocytopenia and/or a derangement in at least one conventional coagulation test (international normalized ratio or activated partial thromboplastin time) within 48 hours of ICU admission.
Interventions: None.
Measurements and main results: Thromboelastography was performed for all study patients, and plasma thrombotic biomarkers were measured in a nested cohort (n = 40). Of the 215 patients included, 34 patients (16%) developed subsequent thromboembolism-predominantly among those with a normal (maximum amplitude, 54-72 mm) or increased (maximum amplitude, > 72 mm) in vitro clot strength on thromboelastography (91%; area under the receiver-operating characteristic curve, 0.74; 95% CI, 0.64-0.83). The ability of the maximum amplitude to predict thromboembolism was comparable to plasma P-selectin concentrations (thromboembolism, 78.3 ng/mL vs no thromboembolism, 59.5 ng/mL; p = 0.031; area under the receiver-operating characteristic curve, 0.73; 95% CI, 0.52-0.95). In addition, patients with an increased maximum amplitude were also less likely to receive blood product transfusions within 24 hours of testing compared with those with a subnormal maximum amplitude (12.8% vs 69.2%, respectively; area under the receiver-operating characteristic curve, 0.74; 95% CI, 0.67-0.80).
Conclusions: In patients with abnormal coagulation profiles, an increased in vitro clot strength on thromboelastography was associated with an increased risk of thromboembolism, and a reduced risk of requiring transfusion compared with those with a normal or reduced in vitro clot strength.