Original Article

Do Sonoclot Coagulation Parameters Correlate with Thrombelastograph Parameters?

Program in Extracorporeal Circulation Technology, Clinical Services Department, Medical University of South Carolina, Charleston, South Carolina

^* Address correspondence to: Lem Meherg, E.C.T. Department, 171 Ashley Avenue, Charleston, SC 29425

Abstract

Postoperative hemorrhage is a major cause of morbidity after cardiopulmonary bypass. Timely coagulation test results may aid the clinician in diagnosing and treating coagulopathy. The purpose of this study is to determine if there is any correlation between parameters obtained from two viscoelastic coagulation monitors (Thrombelastograph and Sonoclot). Fifty non-heparinized blood samples were obtained from cardiac surgery patients pre-skin incision or post-Protamine. Each blood sample was placed in the Celite-activated Sonoclot cuvette and native, as well as Celitc-activatcd TEG wells. The parameters compared were: native and Celite TEG split point, r, k, alpha angle, MA, MA60 vs. Sonoclot immersion point, SonACT, R1, shoulder point, time to shoulder, R2, peak, time to peak, R3, retraction point and time to retraction. All viscoelastic parameters were correlated with routine coagulation tests including: ACT, PT, PTT, platelet count, fibrinogen concentration, bleeding time and hematocrit.

Simple and multiple regressions were performed on these Thromhelastograph and Sonoclot parameters to determine correlation, if any.

Correlations were considered significant if p<0.01 and R2 > 0.6. The Sonoclot R1 correlated significantly with the Thromhelastograph Celite-activated k-time and alpha angle. The Sonoclot shoulder point correlated with the Thrombelastograph Celite-activated MA and Coagulation Index. The Sonoclot R1 and shoulder point correlated with fibrinogen and platelet counts. The Sonoclot time to peak and time to retraction correlated with the PTT. The Sonoclot coagulation parameters generally do not correlate with the Thrombelastograph parameters. The lack of better correlation among all parameters suggests that there are aspects of coagulation that arc detected differently by each monitor. Therefore, the two viscoelastic monitors cannot be substituted for each other.