The role of point-of-care assessment of platelet function in predicting postoperative bleeding and transfusion requirements after coronary artery bypass grafting.

Objective: Objective platelet function assessment after cardiac surgery can predict postoperative blood loss, guide transfusion requirements and discriminate the need for surgical re‑exploration. We conducted this study to assess the predictive value of point‑of‑care testing platelet function using the Multiplate® device. Methods: Patients undergoing isolated coronary artery bypass grafting were prospectively recruited (n = 84). Group A (n = 42) patients were on anti‑platelet therapy until surgery; patients in Group B (n = 42) stopped anti‑platelet treatment at least 5 days preoperatively. Multiplate® and thromboelastography (TEG) tests were performed in the perioperative period. Primary end‑point was excessive bleeding (>2.5 ml/kg/h) within first 3 h postoperative. Secondary end‑points included transfusion requirements, re‑exploration rates, intensive care unit and in‑hospital stays. Results: Patients in Group A had excessive bleeding (59% vs. 33%, P = 0.02), higher re‑exploration rates (14% vs. 0%, P < 0.01) and higher rate of blood (41% vs. 14%, P < 0.01) and platelet (14% vs. 2%, P = 0.05) transfusions. On multivariate analysis, preoperative platelet function testing was the most significant predictor of excessive bleeding (odds ratio [OR]: 2.3, P = 0.08), need for blood (OR: 5.5, P < 0.01) and platelet transfusion (OR: 15.1, P < 0.01). Postoperative “ASPI test” best predicted the need for transfusion (sensitivity ‑ 0.86) and excessive blood loss (sensitivity ‑ 0.81). TEG results did not correlate well with any of these outcome measures. Conclusions: Peri‑operative platelet functional assessment with Multiplate® was the strongest predictor for bleeding and transfusion requirements in patients on anti‑platelet therapy until the time of surgery. Study registration: ISRCTN43298975 (http:// www.controlled‑trials.com/ISRCTN43298975/).

Basic Data for Reference Intervals in Koreans for Parameters Produced by Multiplate Platelet Function Analyzer

BACKGROUND: The Multiplate analyzer (Dynabyte GmbH) has been recently introduced as a platelet function test for patients taking antiplatelet drugs. The study aimed at providing basic data for determining the reference interval of parameters produced by Multiplate in Koreans and to study the factors that influence those parameters. METHODS: Blood was collected from 35 healthy volunteers (female 18, male 17) into tubes containing hirudin or 3.2% sodium citrate. Whole blood platelet aggregations triggered by adenosine-5'-diphosphate (ADP), ADP-high sensitive (ADP+PGE1 only in hirudin samples), arachidonic acid (AA), collagen or thrombin receptor activator peptide (TRAP) were investigated using Multiplate according to the manufacturer's instructions. Data from healthy volunteers for the area under the curve (AUC) were determined from the central 95th percentile of the results. RESULTS: The values of AUC in hirudin samples for all agonists were significantly higher than those in sodium citrate samples. The AUC values in hirudin (sodium citrate) samples were as follows: ADP 38-107 (18-119) U; ADP+PGE1 16-91 U; AA 64-156 (32-117) U; collagen 53-112 (26-108) U; and TRAP 81-163 (49-149) U. The parameters from Multiplate were significantly correlated with leukocyte counts, but not with hematocrit levels. CONCLUSIONS: Although our data were derived from only 35 subjects, the results are expected to be helpful in determining the reference interval at a single institute and may serve as basic data for future cumulative data of reference intervals from multiple institutes in Korea.