Monitoring of Coagulation during Hemorrhagic Surgery by Central Laboratory and Near-Patient Testing. Results of a Multicenter Study.

One of the critical issues in the monitoring of coagulation during surgery is the delay required to obtain results when tests are performed in a central laboratory. The CoaguChek ProDM (Roche Diagnostics) is a point-of-care (POC) coagulation analyzer designed to perform the measurement of clotting times such as the prothrombin time (PT) or the INR, and the activated partial thromboplastin time (APTT). So far, it has been mainly evaluated in the control of anticoagulation in patients on warfarin. A 45 μl-whole blood sample is disposed in the well of a specific 37°C-prewarmed single-use cartridge. It then circulates in a capillary tube coated with a specific agent. The test result is usually obtained in less than 5 min. The precision, evaluated as the “within-run” coefficient of variation (n=7), was found in the range from 3.2% to 7.3% depending of both the lyophilized whole blood control sample evaluated (normal or abnormal) and the clotting time performed. The aim of this multicenter study was to evaluate the performance of the CoaguChek ProDM in the monitoring of coagulation (PT and APTT) during hemorrhagic surgery. For that purpose, 78 patients undergoing surgical procedure (liver transplantation, liver resection, vascular and orthopedic/trauma surgery) were included in 3 centers after the study was approved by our Ethic Committee. Arterial blood samples were drawn at least 2 times: before the surgical incision and after a blood loss of 25% or more. Blood samples were simultaneously sent to the central laboratory and analyzed using the POC device. A total of 171 consecutive paired analyses were conducted. There was a very good agreement of the point-of-care-based monitoring of PT (sec) with the central laboratory monitoring (r=0.92, p<0.0001). However, the results were not identical, with significantly shorter clotting times (and lower ratios) obtained on the CoaguChek. It could be mentioned that, the difference was dramatically reduced when PT was expressed as the percentage, as it is usual in France. Comparison was less conclusive for APTT (r=0.82), with shorter clotting times (and lower ratios) again on the CoaguChek. Moreover, APTT measurement was found to be of limited interest in the studied population, particularly in the case of infusion of aprotinin which leaded to highly prolonged APTT (above the detection limits defined for the POC analyzer and for the central laboratory instrument, a STA analyzer). These results suggest that the CoaguChek ProDM allows an accurate measurement of PT in patients undergoing hemorrhagic surgical procedures. However, the results were not identical to that obtained from the central laboratory, suggesting that the transfusion algorithms would have to be adapted accordingly. One of the main advantages gained using POC testing is the ability to obtain results more rapidly. Actually, the turn-around time, defined as the elapsed time from blood sampling until availability of the results for the clinicians, was highly significantly shorter for the POC system than for the central laboratory (below 5 min vs. 60 min median value, range: 40->120 min). Finally, the clinical interest of such a point-of-care monitoring of coagulation deserves to be prospectively investigated, especially in connection with the amount of transfused fresh frozen plasma units.