Avaliação da anestesia por isofluorano em eqüinos submetidos à infusão contínua de medetomidina ou xilazina

Abstract

Avaliaram-se, 8 equinos, sob anestesia geral inalatoria com isofluorano (1CAM) e infusao continua de xilazina (0,35mg/kg/h) ou medetomidina (3,5£gg/kg/h), em relacao a frequencia cardiaca, ritmo cardiaco, frequencia respiratoria, pressao arterial, hemogasometria arterial, tonus muscular e temperatura, nos tempos T0 (imediatamente antes do inicio da infusao continua) e T10 ao T60 (intervalos de 10 minutos, apos inicio da infusao continua), alem da qualidade da tranquilizacao, inducao e recuperacao anestesica. Os dados parametricos foram submetidos a analise de variancia para repeticoes multiplas, seguido pelo teste de Student-Newman-Keuls e, entre os grupos, teste-t de Student. Para os dados nao parametricos utilizou-se teste de Friedman e entre os grupos, teste de Mann-Whitney (p-T0,05). Houve reducao da frequencia cardiaca e da temperatura e elevacao da pressao arterial media. A paCO2 (no GM) e a ctCO2 elevaram-se e a paO2 mostrou-se maior no GM que no GX. Os dois farmacos mostraram-se eficientes para tranquilizacao, mas o GM demonstrou melhor miorrelaxamento e qualidade de inducao anestesica que o GX. Da mesma forma, a recuperacao anestesica apresentada pelo GM foi de melhor qualidade, embora mais prolongada. Conclui-se que a infusao continua de doses equipotentes de xilazina e medetomidina, durante anestesia geral inalatoria, com isofluorano, em equinos, promove alteracoes cardiocirculatorias, respiratorias e hemogasometricas discretas e equivalentes.

Eight equines under inhalatory general anesthesia with isoflurane (1MAC) and continuous infusion of xylazine (0.35mg/kg/h) or medetomidine (3.5-Êg/kg/h) were evaluated for heart rate and rhythm, respiratory rate, arterial blood pressure, arterial blood gas analysis, muscle relaxation and temperature immediately before the beginning of the continuous infusion (T0) and in intervals of 10 minutes after the beginning of the continuous infusion (T10 to T60) and also for tranquillization, induction and anesthetic recovery quality. The parametric data were evaluated by one way repeated measures ANOVA, followed by Student-Newman-Keuls and between groups Student t-test. Non-parametric data were evaluated by Friedman test and between groups Mann-Whitney test (p.0.05). Heart rate and temperature decreased and mean Heart rate and temperature decreased and mean aaarrrttteeerrriiiaaalll ppprrreeessssssuuurrreee increased. PaCO2 (in GM) and ctCO2 increased and GM showed a higher paO2 than GX. Both drugs were efficient in tranquilization but GM showed better muscle relaxation and induction quality than GX. In the same way, GM presented better anesthetic recovery even though it took more time. We conclude that equipotent doses of continuous infusion of medetomidine and xylazine during inhalatory general anesthesia with isoflurane in equines promote slight and equivalent cardiocirculatory, respiratory and arterial blood gases changes.