Comparação dos valores eletrorretinográficos em pacientes caninos com ou sem anestesia dissociativa (tiletamina-zolazepam)
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Data
2022-08-05
Autores
Santos, Daniela Moura dos
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Universidade Estadual Paulista (Unesp)
Resumo
A eletrorretinografia (ERG) é um exame não invasivo amplamente utilizado em humanos e em animais, capaz de avaliar a atividade eletrofisiológica da retina. O exame é rotineiramente empregado na seleção de pacientes para a cirurgia de catarata, na detecção de doenças hereditárias, no diagnóstico de retinopatias degenerativas e em estudos farmacológicos que avaliam as respostas terapêuticas ou possíveis efeitos tóxicos e deletérios na retina. Em cães, assim como em outras espécies animais, a sedação ou anestesia geral é comumente indicada para a realização do exame, objetivando evitar que a movimentação do paciente, da musculatura ocular e/ou o estresse, possa causar interferências e alterar a resposta nas ondas do ERG. Nesse sentido, este trabalho tem como objetivo investigar os efeitos na resposta das ondas eletrorretinográficas de cães sem anestesia em comparação com cães anestesiados. O ERG foi realizado em 48 olhos de 24 pacientes portadores de catarata, machos ou fêmeas, de diferentes raças, com idade entre um e 14 anos. Os cães foram divididos e avaliados em dois grupos: Grupo 1 (G1), pacientes acordados (n=12); Grupo 2 (G2) pacientes anestesiados com tiletamina-zolazepam por via intravenosa, na dose de 6 mg/kg (n=12). Para mensuração das amplitudes (AMP) e tempo implícito das ondas (TI), na fase escotópica (bastonetes e resposta mista), o exame foi realizado após 20 minutos de adaptação ao escuro e dilatação pupilar prévia. Para a fase fotóptica (cones) deu-se um intervalo de 10 minutos de adaptação à luz. Teste de Wilcoxon e de Mann-Whitney foram utilizados para análise estatística e valores de P iguais ou inferiores a 0,05 foram considerados significativos. Para ambos os grupos avaliados não houve diferença nas respostas mistas e dos cones, mas foi observado aumento na AMP e menor TI nos bastonetes dos cães do G1. Ocorreu ainda, diminuição da AMP e aumento no TI de onda em cães mais velhos bem como uma correlação positiva entre ondas-a e onda-b e o peso dos pacientes. Os resultados do presente estudo sugeriram que o protocolo utilizado do ERG pode ser realizado com sucesso e precisão em cães alertas sem comprometimento da forma dos traçados eletrorretinográficos. A anestesia geral dissociativa é eficaz, porém, levará a mudanças na AMP e TI das ondas.
Electroretinography (ERG) is a non-invasive test widely used in humans and animals that assesses the electrophysiological activity of the retina. The test is routinely used in the selection of patients for cataract surgery, in the detection of hereditary diseases, in the diagnosis of degenerative retinopathies, and in pharmacological studies that assess therapeutic responses or possible toxic and deleterious effects on the retina. In dogs, as in other species, sedation or general anesthesia is commonly indicated for the examination, aiming to prevent the patient's movement, eye muscle movements and/or stress from causing interference and altering the wave response of the ERG. Therefore, the aim of the current study was to investigate the effects on electroretinographic wave response of dogs without anesthesia compared to anesthetized dogs. The ERG was performed on 48 eyes of 24 patients with cataracts, male or female, of different races, aged between one and 14 years. Dogs were divided into two groups: Group 1 (G1), awake patients (n=12); Group 2 (G2) patients anesthetized with intravenous tiletamine-zolazepam at a dose of 6 mg/kg (n=12). To measure the amplitudes (AMP) and implicit time (IT) of the waves, in the scotoptic phase (rods and mixed response), the exam was performed after 20 minutes of dark adaptation and previous pupillary dilation. For the photoptic phase (cones) there was an interval of 10 minutes to adapt to the light. Wilcoxon and de Mann-Whitney test were used for statistical analysis and P values equal to or less than 0.05 was considered significant. For both groups, no significant differences were identified in mixed or cone responses, but an increase in rods AMP and a lower TI of G1 were observed. The a-wave amplitudes and implicit times were significantly shorter in older dogs, as well as a positive correlation between a-wave and wave-and the weight of the patients. The study results suggest that the ERG protocol can be successfully and accurately performed in conscious dogs without compromising the wave forms. General anesthesia is effective, however, will lead to changes in the ERG waves AMP and IT.
Electroretinography (ERG) is a non-invasive test widely used in humans and animals that assesses the electrophysiological activity of the retina. The test is routinely used in the selection of patients for cataract surgery, in the detection of hereditary diseases, in the diagnosis of degenerative retinopathies, and in pharmacological studies that assess therapeutic responses or possible toxic and deleterious effects on the retina. In dogs, as in other species, sedation or general anesthesia is commonly indicated for the examination, aiming to prevent the patient's movement, eye muscle movements and/or stress from causing interference and altering the wave response of the ERG. Therefore, the aim of the current study was to investigate the effects on electroretinographic wave response of dogs without anesthesia compared to anesthetized dogs. The ERG was performed on 48 eyes of 24 patients with cataracts, male or female, of different races, aged between one and 14 years. Dogs were divided into two groups: Group 1 (G1), awake patients (n=12); Group 2 (G2) patients anesthetized with intravenous tiletamine-zolazepam at a dose of 6 mg/kg (n=12). To measure the amplitudes (AMP) and implicit time (IT) of the waves, in the scotoptic phase (rods and mixed response), the exam was performed after 20 minutes of dark adaptation and previous pupillary dilation. For the photoptic phase (cones) there was an interval of 10 minutes to adapt to the light. Wilcoxon and de Mann-Whitney test were used for statistical analysis and P values equal to or less than 0.05 was considered significant. For both groups, no significant differences were identified in mixed or cone responses, but an increase in rods AMP and a lower TI of G1 were observed. The a-wave amplitudes and implicit times were significantly shorter in older dogs, as well as a positive correlation between a-wave and wave-and the weight of the patients. The study results suggest that the ERG protocol can be successfully and accurately performed in conscious dogs without compromising the wave forms. General anesthesia is effective, however, will lead to changes in the ERG waves AMP and IT.
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Palavras-chave
Oftalmologia veterinária, Protocolos, Retina, Catarata, Cães, Veterinary Ophthalmology, Protocols, Retina, Cataract, Dogs