Thromboelastometric evaluation of horses submitted to experimental thrombosis and jugular thrombectomy

摘要

: Jugular thrombosis in horses occurs commonly in iatrogenic situations, secondary to endotoxemic clinical condition and disseminated vascular coagulation, potentially leading to death. Thus, hemostatic evaluation becomes necessary and extremely important for monitoring the risks of systemic hypercoagulability and for the efficiency of allopathic and surgical treatment. This paper describes the hemostatic behavior in experimental jugular thrombosis of ten healthy equines, subsequently submitted to two thrombectomy techniques and receiving heparin sodium as anti-rethrombosis therapy. These animals were evaluated for 20 days by thromboelastometry (TEM), platelet count, hematocrit and fibrinogen, at four moments: pre-induction to phlebitis (D0-MPF); three days after thrombophlebitis induction (D3-MFM); 6 days after, - moment of thrombophlebitis - (D9-MT); and 54 (D16) and 126 (D19) hours after thrombectomies (PTM). Thrombectomy was performed via a Vollmar Ring (group 1, n=5) and Fogarty catheter (group 2, n=5). All the animals received heparin (150 UI/kg, SC) every 12 hours, for ten days after the respective thrombectomies. Through the blood samples were evaluated TEM, activated partial thromboplastin time (aPTT) and prothrombin time (PT), dosing of fibrinogen, hematocrit and platelet count at the abovementioned moments. For comparison between groups and moments the t test was applied at 5% significance level. No significant difference was verified between treatment groups at any of the moments. There were reductions in clotting time (CT) and clot formation time (CFT), with increase in maximum lysis (ML) until the moment D9-MT. Evaluation through INTEM?? reagent presented prolongations of CT and CFT with reduction of ?± angle and ML starting from D16 and D19. Similarly, aPTT presented significant differences between moments pre- (D0, 3 and 9) and post- (D16 and 19) anticoagulant and surgical treatment. The platelet numbers were diminished at moments D16 and D19. In evaluation with EXTEM?? reagent, prolongation of CT and CFT occurred only between the moments D0 vs. D3 and vs. D9. O PT did not present significant differences. The results obtained demonstrate that experimental jugular thrombophlebitis leads to local clinical alterations, with impairment of tissue and of the extrinsic coagulation pathway (EXTEM?? ), but without evidence of systemic hypercoagulability status, since there was no increase of the alpha angle or maximum clot firmness (MCF). Furthermore, TEM was shown useful and more sensitive than conventional coagulation tests (PT, aPTT and fibrinogen) for the monitoring of anticoagulant therapy, as demonstrated in other works. Index Terms:??Thromboelastometry; jugular thrombophlebitis; horses; Vollmar Ring; Fogarty Catheter. Resumo: A trombose jugular nos equinos ocorre comumente em situa?§?μes iatrog?anicas, secund??rias a quadros endotox?amicos e a coagula?§?￡o vascular disseminada, podendo levar ao ?3bito. Por isso, avalia?§?￡o hemost??tica se faz necess??ria e de extrema import?￠ncia para monitorar os riscos de hipercoagulabilidade sist?amica e tamb??m a efici?ancia do tratamento alop??tico e cir?orgico. Este trabalho descreve o comportamento hemost??tico na trombose jugular experimental de dez equinos h?-gidos, submetidos posteriormente a duas t??cnicas de trombectomia e recebendo heparina s?3dica como terapia anti retrombosante. Estes animais foram avaliados durante 20 dias por tromboelastometria (TEM), contagem de plaquetas, hemat?3crito e fibrinog?anio, em quatro momentos: pr??-indu?§?￡o ?? flebite (D0-MPF); tr?as dias ap?3s a indu?§?￡o da tromboflebite (D3-MFM); 6 dias ap?3s, - momento de tromboflebite - (D9-MT); e 54 (D16) e 126 (D19) horas ap?3s as trombectomias (MPT). A trombectomia foi realizada com Anel de Vollmar (grupo 1, n=5) e cateter de Fogarty (grupo 2, n=5). Todos os animais receberam heparina (150 UI/Kg, SC) a cada 12 horas, durante dez dias ap?3s as respectivas trombectomias. Atrav??s de amostras de sangue, foram avaliadas a TEM, o tempo de tromboplastia parcial ativada (TTPa) e tempo de protrombina (TP), a dosagem de fibrinog?anio, hemat?3crito e contagem de plaquetas nos momentos descritos acima. Para a compara?§?￡o entre os grupos e momentos foi aplicado teste t, com n?-vel de signific?￠ncia de 5%. N?￡o foi verificada diferen?§a significativa entre os grupos de tratamento em nenhum dos momentos. Houve redu?§?￡o do tempo de coagula?§?￡o (CT) e do tempo de forma?§?￡o do co??gulo (CFT), com aumento da lise m??xima (LM) at?? o momento D9-MT. A avalia?§?￡o com o reagente intem apresentou prolongamento do CT e do CFT e redu?§?￡o do ?￠ngulo ?± e da LM a partir do D16 e D19. Da mesma forma, o TTPa apresentou diferen?§as significativas entre os momentos pr?? (D0, 3 e 9) e p?3s (D16 e 19) tratamento cir?orgico e anticoagulante. Houve diminui?§?￡o do n?omero de plaquetas nos momentos D16 e D19. Na avalia?§?￡o com reagente extem ocorreu apenas o prolongamento do CT e CFT entre os momen