Efeitos da dexmedetomidina sobre a coagulação sangüínea avaliada através do método da tromboelastografia

César Romão Martins; Maria Angela Tardelli; José Luiz Gomes do Amaral

doi:10.1590/S0034-70942003000600002

Scientific Article

Efeitos da dexmedetomidina sobre a coagulação sangüínea avaliada através do método da tromboelastografia

Effects of dexmedetomidine on blood coagulation evaluated by thromboelastography

César Romão Martins; Maria Angela Tardelli; José Luiz Gomes do Amaral

http://dx.doi.org/10.1590/S0034-70942003000600002 Braz J Anesthesiol, vol.53, n6, p.705-719, 2003

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Resumo

JUSTIFICATIVA E OBJETIVOS: A dexmedetomidina é um agente agonista dos receptores adrenérgicos alfa2 altamente seletivo, usado em anestesia por seus efeitos hipnoanalgésicos e pela estabilidade cardiovascular. O estímulo dos receptores adrenérgicos alfa2 pode apresentar efeitos pró e antiagregantes plaquetários, por mecanismos diretos e indiretos. No presente estudo, avaliaram-se os efeitos da dexmedetomidina sobre a coagulação através do método da tromboelastografia. MÉTODO: Vinte e quatro pacientes foram aleatoriamente divididos em três grupos. Os pacientes do grupo 1 receberam infusão de solução fisiológica (controle), os do grupo 2 receberam dexmedetomidina na dose de 1 µg.kg-1 em 10 minutos, seguida da infusão de 0,4 µg.kg-1.h-1 por 20 minutos e os do grupo 3 receberam midazolam na dose de 0,05 mg.kg-1. Os pacientes sedados mantiveram índices 3 ou 4 na escala da sedação de Ramsay. Foram coletadas amostras de sangue e obtidos traçados de tromboelastografia previamente e após 30 minutos do tratamento. RESULTADOS: A dexmedetomidina, de forma estatisticamente significativa, aumentou o tempo de reação (parâmetro R) e diminuiu o índice de coagulação nos traçados finais em relação aos iniciais. No entanto, os valores permaneceram dentro dos intervalos considerados normais. Este fenômeno não foi observado nos demais grupos. CONCLUSÕES: A interação dos mecanismos pró e antiagregantes da dexmedetomidina leva à discreta hipocoagulação; porém, mantém a coagulação dentro de parâmetros considerados normais. Os efeitos da dexmedetomidina sobre a coagulação provavelmente não ocorrem pela ansiólise, uma vez que a sedação foi igual ao grupo que recebeu midazolam.

Palavras-chave

DROGAS, DROGAS, EXAMES LABORATORIAIS, SANGUE

Abstract

BACKGROUND AND OBJECTIVES: Dexmedetomidine is a highly selective alpha2-adrenoceptor agonist used in anesthesia for its hypnoanalgesic and cardiovascular effects. Stimulation of alpha2-adrenoceptors may determine pro and anti-platelet aggregation effects through direct and indirect mechanisms. This study aimed at determining the effects of dexmedetomidine on coagulation evaluated by thromboelastography. METHODS: Twenty four patients were randomly distributed in 3 groups: Group 1 patients received saline solution (control group), Group 2 patients received 1 µg.kg-1 dexmedetomidine in 10 minutes, followed by 0.4 µg.kg-1.h-1 infusion for 20 minutes and Group 3 patients received 0.05 mg.kg-1 midazolam. Sedated patients maintained scores 3 or 4 in Ramsays sedation scale. Blood samples were collected before and 30 minutes after the treatment for thromboelastography. RESULTS: Dexmedetomidine has significantly increased reaction time (parameter R) and decreased coagulation index in final curves as compared to initial ones. Values, however, have remained within ranges accepted as normal. This phenomenon was not observed in remaining groups. CONCLUSIONS: Dexmedetomidine pro and anti-platelet aggregation mechanisms interaction determines mild hypocoagulation, however maintaining coagulation within normal ranges. Dexmedetomidine effects on coagulation are probably not mediated by anxiolysis, since sedation was equivalent to the midazolam group.

Keywords

BLOOD, DRUGS, DRUGS, LABORATIAL TESTS

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Efeitos da dexmedetomidina sobre a coagulação sangüínea avaliada através do método da tromboelastografia

Effects of dexmedetomidine on blood coagulation evaluated by thromboelastography

César Romão Martins; Maria Angela Tardelli; José Luiz Gomes do Amaral

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