Point-of-care (POC) measurement of coagulation after cardiac surgery

Two different point-of-care (POC) systems for the monitoring of coagulation variables at the bedside were evaluated with regard to practicability, accuracy and costs.

Prospective, descriptive study.

Single-institutional, clinical investigation on an intensive care unit (ICU) of an urban, university-affiliated hospital.

Eighty cardiac surgery patients were studied postoperatively.

Arterial blood samples were drawn postoperatively on the ICU at different data points.

Activated partial thromboplastin time (aPTT) and prothrombin time (PT) were measured using two POC systems (Thrombolytic Assessment System [TAS] and CoaguCheck Plus). At the same time coagulation parameters were measured by the central laboratory of the hospital. Measurements were carried out at different data points after cardiac surgery on the ICU. The direct and indirect costs of measuring aPTT/PT were also assessed. Bias analyses revealed good agreement of the POC-based monitoring of aPTT/PT with laboratory-based monitoring of coagulation (e. g. aPTT CoaguCheck: bias of -2.8 s with +/- 2 SD [limits of agreement] of +13.7 and -19.1 s). Mean turn-around time (TAT; time from blood sampling until availability of data for the ICU physicians) was significantly longer for the central laboratory-based coagulation monitoring (130 +/- 38 min) than for the two POC systems (aPTT-TAS: 9.6 +/- 2.7 min; aPTT-CoaguCheck: 6.5 +/- 1.9 min). Blood sampling at unfavorable times increased the TAT for laboratory-based measurements considerably. The direct costs for measuring aPPT and PT were significantly higher using both POC systems (aPTT-TAS: $4.84; aPTT-CoaguCheck: $4.34) than for the central laboratory ($1.59). Costs for transportation increased the laboratory-based monitoring considerably ($3.77).

Both POC analyzers may reduce the potential for preanalytical errors associated with coagulation measurements at the central laboratory, hasten TAT significantly and may improve patient therapy by reducing inappropriate administration of blood products.