The experimental cranium trauma animal model by weight drop is an alternative of low cost and easy reproduction that allows evaluating clinical and pathological alterations in accordance with studies in experimental surgery aims for new traumatic brain injury approach in rats.

PURPOSE: To study histopathological findings due to a model of closed head injury by weight loss in rats. METHODS: A platform was used to induce closed cranial lesion controlled by weight loss with a known and predefined energy. 25 male Wistar rats (Rattus novergicus albinus) were divided in five equal groups which received different cranial impact energy levels: G1, G2, G3 and G4 with 0.234J, 0.5J, 0.762J and 1J respectively and G5 (Sham). Under the effect of analgesia, the brain of each group was collected and prepared for histopathological analysis by conventional optic microscopy. RESULTS: It was observed greater number of injured neurons in animals of group 4, however neuronal death also could be noticed in animals of group 5. Intraparenchymal hemorrhages were more frequent in animals of group 4 and the cytotoxic brain swelling and vascular congestion were more intense in this group CONCLUSION: The histopathological analysis of these findings allowed to observe typical cranial trauma alterations and these keep close relation with impact energy.

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Purpose: To introduce a model of equipment for inhalation anesthesia in rats that offers better control of both flow and losses of ether during induction, maintenance, and recuperation. Methods: The equipment consists of an air compressor with two outlets, a closed glass induction chamber, a glass reservoir for the anesthetic agent, a pediatric inhalation mask, a three-way stopcock, a Y-connector, and urinary catheters. Three hundred Wistar rats (Rattus norvegicus albinus) were given inhalation anesthesia. The evaluated parameters were equipment operation, duration of each phase of anesthesia, corneal reflex, muscular tonus, respiration during induction and maintenance, and volume of anesthesia. Results: The average time taken for induction was 7.3 minutes; the average anesthetic recuperation time was 6.4 minutes. The amount of anesthetic used varied according to the weight of the animal, with the average volume of ether used being 6.5ml/hour. The availability of oxygen (room air) decreased the recuperation time and averted both respiratory depression and insufficient depth of anesthesia. Conclusion: The proposed equipment is practical, inexpensive, and allows for satisfactory control of anesthetic parameters during the entire procedure, making inhalation anesthesia in rats safe and essentially complication free. Key words: Anesthesia. Anesthesia and Analgesia. Anesthesia, Inhalation. Ether, Ethyl. Rats. RESUMOObjetivo: Apresentar modelo de equipamento para anestesia inalatória em ratos, com melhor controle do fluxo, das perdas de anestésico na indução, da manutenção e da recuperação anestésica. Métodos: O equipamento é constituído por compressor de ar com saída dupla, câmara de vidro fechada para indução, reservatório de vidro para o agente anestésico, máscara de inalação pediátrica, torneira de três vias, conexão em "Y" e sondas uretrais. Trezentos ratos Wistar (Rattus norvegicus albinus) foram anestesiados por via inalatória. Os parâmetros avaliados foram: viabilidade do equipamento, tempo de cada fase, reflexo corneano, tônus muscular e movimentos respiratórios na indução e na manutenção anestésica, além do volume de anestésico. Resultados: A média do tempo gasto na indução anestésica foi de 7,3 minutos. A média do tempo de recuperação anestésica foi de 6,4 minutos. A média do volume de éter utilizado foi de 6,5 ml/h. Não foram observadas neste experimento morte dos animais, aumento excessivo de secreção traqueobrônquica ou interrupção da operação por superficialização anestésica. Conclusão: O equipamento proposto é prático, possui baixo custo e permite o controle adequado dos parâmetros de controle da anestesia durante todo o procedimento, tornando a anestesia inalatória em ratos segura e praticamente isenta de complicações.