Alterações hemodinâmicas e neuroendócrinas associadas ao uso da metadona em cães conscientes e anestesiados com isoflurano
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Data
2010-02-25
Autores
Garofalo, Natache Arouca [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Opióides podem causar alterações neuroendócrinas e hemodinâmicas importantes, que podem ser influenciadas pela co-administração de anestésicos gerais. Objetivou-se neste estudo comparar os efeitos hemodinâmicos e neuroendócrinos (concentrações sanguíneas de vasopressina e catecolaminas) em resposta a administração intravenosa de metadona em cães conscientes e anestesiados com isoflurano. Seis cães sadios (28 ± 4 kg, média ± desvio padrão) foram submetidos a 3 procedimentos experimentais, com intervalo mínimo de 1 semana. No primeiro experimento, os parâmetros hemodinâmicos, hemogasometria arterial, concentrações circulantes de vasopressina, epinefrina e norepinefrina, foram avaliados antes (Basal) e durante 90 minutos após a administração da metadona (1 mg/kg, IV) em animais conscientes (grupo MET). Nos 2 procedimentos experimentais subseqüentes, os efeitos da mesma dose de metadona foram avaliados nos mesmos momentos durante a anestesia com isoflurano. Em 1 dos experimentos, os animais anestesiados com isoflurano receberam solução placebo 5 minutos antes da administração do opióide (grupo MET/ISO), enquanto no outro experimento, o antagonista de vasopressina relcovaptan (0,1 mg/kg, IV) (grupo MET/ISO/ANTAG) foi empregado no mesmo momento, em cães anestesiados com isoflurano. Quando administrada aos animais conscientes, a metadona causou reduções de 15-33% na freqüência cardíaca (FC), enquanto o índice cardíaco (IC) diminuiu 22% apenas aos 90 minutos. Contrastando com a ausência de alterações respiratórias clinicamente importantes em animais conscientes, a metadona induziu apnéia ao ser administrada durante a anestesia, havendo necessidade de suporte ventilatório mecânico. Durante a anestesia com isoflurano, o opióide causou reduções de maior magnitude na FC [% de redução em relação aos valores basais: 51-58% (MET/ISO)...
Opioids may induce substantial hemodynamic and neuroendocrine changes. These effects may be modified by the co-administration of general anesthetics. This study aimed to compare the hemodynamic and the neurohormonal (blood concentrations of vasopressin and catecolamines) changes caused by the intravenous administration of methadone in conscious and isoflurane anesthetized dogs. Six healthy dogs (28 ± 4 kg, mean ± standard deviation) were subjected to 3 experimental procedures, with 1-week washout intervals. In the first set of experiments, the hemodinamic parameters, arterial blood gases, and circulating concentrations of vasopressin, epinephrine, and norepinephrine, were evaluated before (Baseline) and for 90 minutes after methadone injection (1 mg/kg, IV) in conscious dogs (MET group). In the following 2 sets of experiments, the effects of the same dose of methadone were assessed at the same time points during isoflurane anesthesia. Isoflurane anesthetized animals received a placebo injection prior to methadone injection in one of the experiments (MET/ISO group), while in the in the other set of experiments performed under isoflurane anesthesia, the vasopressin antagonist relcovaptan (0.1 mg/kg, IV) was administered 5 minutes prior to opioid injection (MET/ISO/ANTAG group). When administered in conscious animals, methadone caused 15-33% reductions in heart rate (HR), while the cardiac index (CI) was reduced by 22% only at 90 minutes. While methadone did not induce clinically relevant respiratory effects in conscious animals, this opioid induced apnea when administered during anesthesia and mechanical ventilatory support was necessary. During isoflurane anesthesia, methadone caused greater decreases in HR [% decreases from baseline: 51-58% (MET/ISO) and 50-53% (MET/ISO/ANTAG)] and in CI [% decreases from baseline: 55-60% (MET/ISO)... (Complete abstract click electronic access below)
Opioids may induce substantial hemodynamic and neuroendocrine changes. These effects may be modified by the co-administration of general anesthetics. This study aimed to compare the hemodynamic and the neurohormonal (blood concentrations of vasopressin and catecolamines) changes caused by the intravenous administration of methadone in conscious and isoflurane anesthetized dogs. Six healthy dogs (28 ± 4 kg, mean ± standard deviation) were subjected to 3 experimental procedures, with 1-week washout intervals. In the first set of experiments, the hemodinamic parameters, arterial blood gases, and circulating concentrations of vasopressin, epinephrine, and norepinephrine, were evaluated before (Baseline) and for 90 minutes after methadone injection (1 mg/kg, IV) in conscious dogs (MET group). In the following 2 sets of experiments, the effects of the same dose of methadone were assessed at the same time points during isoflurane anesthesia. Isoflurane anesthetized animals received a placebo injection prior to methadone injection in one of the experiments (MET/ISO group), while in the in the other set of experiments performed under isoflurane anesthesia, the vasopressin antagonist relcovaptan (0.1 mg/kg, IV) was administered 5 minutes prior to opioid injection (MET/ISO/ANTAG group). When administered in conscious animals, methadone caused 15-33% reductions in heart rate (HR), while the cardiac index (CI) was reduced by 22% only at 90 minutes. While methadone did not induce clinically relevant respiratory effects in conscious animals, this opioid induced apnea when administered during anesthesia and mechanical ventilatory support was necessary. During isoflurane anesthesia, methadone caused greater decreases in HR [% decreases from baseline: 51-58% (MET/ISO) and 50-53% (MET/ISO/ANTAG)] and in CI [% decreases from baseline: 55-60% (MET/ISO)... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Anestesia, Cão - Anestesia, Hemodynamic
Como citar
GAROFALO, Natache Arouca. Alterações hemodinâmicas e neuroendócrinas associadas ao uso da metadona em cães conscientes e anestesiados com isoflurano. 2010. 111 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, 2010.