Level of agreement between laboratory and point-of-care prothrombin time before and after cardiopulmonary bypass in cardiac surgery.
BACKGROUND
Hemostasis monitoring in cardiac surgery could benefit from an easy to use and fast point-of-care coagulation monitor, since routine laboratory tests have a delay of 30-45minutes. This study investigated the level of agreement between the point-of-care prothrombin time (PT) with central laboratory PT before and after cardiopulmonary bypass.


METHODS
Bland Altman and error grid analysis were used to analyze the agreement between the point-of-care Coaguchek XS Pro device (POC-PT) and the central laboratory prothrombin time (LAB-PT) before cardiopulmonary bypass (CPB) and 3minutes after protamine administration. Prothrombin times were expressed in international normalized ratios (INR).


RESULTS
The average POC-PT and LAB-PT values of 73 patients were 1.06±0.14 and 1.09±0.13 (P=0.10) before CPB. POC-PT measurements before CPB showed a good agreement with the LAB-PT, with a bias of -0.02±0.07 INR and 94% of the values being represented in the clinical acceptable zone of error grid analysis. The mean POC-PT 3minutes after protamine administration was significantly lower than the LAB-PT (1.35±0.12 vs. 1.70±0.18; P<0.001). The PT at 3minutes after protamine administration showed a bias of 0.36±0.14, and 82% of the values were located outside of the clinical acceptable zone in the error grid analysis.


CONCLUSIONS
Point-of-care prothrombin time testing was in concordance with conventional laboratory PT prior to cardiopulmonary bypass. At 3minutes following protamine administration, PT values of the point-of-care device were structurally lower than the laboratory PT values, leading to a disagreement between both tests at that time point.
Department of Anesthesiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
Michael I
MI
Meesters
Department of Cardio-thoracic Surgery, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
Alexander B A
AB
Vonk
Department of Anesthesiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
Emma K
EK
van de Weerdt
Department of Anesthesiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
Suzanne
S
Kamminga
Department of Anesthesiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: c.boer@vumc.nl.
Christa
C
Boer
D000368:Aged; D006348:Cardiac Surgical Procedures / Q000379:methods*; D002315:Cardiopulmonary Bypass / Q000379:methods*; D005260:Female; D006801:Humans; D007753:Laboratories; D008297:Male; D019095:Point-of-Care Systems; D011517:Prothrombin Time / Q000295:instrumentation / Q000379:methods*
Point-of-care; cardiac surgery; heparin; protamine; prothrombin time