The effects of vasoactive agents, platelet agonists and anticoagulation on thrombelastography.
BACKGROUND
Platelet activation is a critical step in primary hemostasis and clot formation. We tested a hypothesis that platelet stimulating effects of vasoactive agents or platelet agonists could be shown using thrombelastography (TEG) as faster onset or increased clot strength. We further examined if TEG could be modified to evaluate activated platelets as a reversal of anticoagulation in the presence of partial thrombin inhibition.


METHODS
Blood samples were obtained from 126 non-cardiac surgical patients. Effects of vasoactive agents on TEG and aggregometry were examined using epinephrine, norepinephrine, vasopressin, desmopressin acetate, milrinone and olprinone (Experiment I). Platelet agonists (epinephrine, ADP and collagen) were separately tested on TEG (Experiment II). Effects of platelet agonists (ADP and collagen) on TEG under anticoagulation in the absence or presence of abciximab were studied (Experiment III). We also tested antiplatelet effects of milrinone and olprinone in the presence of anticoagulants on TEG (Experiment IV).


RESULTS
Neither vasoactive agents nor platelet agonists affected TEG or aggregometry results except for milrinone and olprinone on aggregometry (Experiment I, II). Platelet agonists facilitated clotting in the presence of anticoagulants (Experiment III). Abciximab-treated platelets still exhibited procoagulant effects in the presence of heparin, while not in the presence of argatroban (Experiment III). Platelet inhibition on the modified TEG was more extensive with milrinone than olprinone, and it was dose dependent (Experiment IV).


CONCLUSIONS
Modified TEG using heparin or argatroban might delineate the procoagulant effects of platelets by adding platelet specific agonist.
Kawasaki
J
J
Department of Anesthesiology, Saitama Medical Center, Saitama Medical University, Saitama, Japan. jkawasak@saitama-med.ac.jp
Katori
N
N
Taketomi
T
T
Terui
K
K
Tanaka
K A
KA
D000244:Adenosine Diphosphate / Q000502:physiology; D000925:Anticoagulants / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D002316:Cardiotonic Agents / Q000494:pharmacology; D003094:Collagen / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects*; D018709:Statistics, Nonparametric; D013916:Thrombelastography / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000925:Anticoagulants; D002316:Cardiotonic Agents; D010726:Phosphodiesterase Inhibitors; D014662:Vasoconstrictor Agents; D000244:Adenosine Diphosphate; D003094:Collagen