Validity of Thromboelastometry for Rapid Assessment of Fibrinogen Levels in Heparinized Samples During Cardiac Surgery: A Retrospective, Single-center, Observational Study

Objective: To assess the validity of fibrinogen assay of rotational thromboelastometry (FIBTEM)-derived estimates of fibrinogen in samples collected during cardiopulmonary bypass in cardiac surgical patients by comparison to Clauss method fibrinogen concentration.

Design: Retrospective observational study.

Setting: Single university hospital center.

Participants: Human participants.

Interventions: Retrospectively obtained laboratory assays including rotational thromboelastometry (ROTEM) and Clauss fibrinogen assay.

Measurements and main results: A retrospective review was performed of anesthesia records at a single university teaching hospital during a 1-year period. From paired samples taken near the end of cardiopulmonary bypass, fibrinogen concentrations (Clauss method) were compared with FIBTEM-derived measures of maximal clot firmness (MCF) and clot amplitude at 10 minutes (A10) using Spearman's rank correlation, linear regression, and receiver operating characteristic curve analysis. The study included 1,077 patients. Clauss fibrinogen was correlated strongly with FIBTEM amplitudes (r = 0.78 for MCF and A10; p<0.01). The correlation was related inversely to hemoglobin concentration (p<0.01). The area under the receiver operating characteristic curve was 0.95; the optimal FIBTEM A10 cutoff for diagnosis of a fibrinogen concentration of<1.5 g/L was ≤8 mm.

Conclusions: The FIBTEM was a valid point-of-care method for estimating the fibrinogen concentration during cardiopulmonary bypass and may be used for prediction of hypofibrinogenemia before separation from the extracorporeal circuit.