Cardiovascular effects of midazolam in levomepromazine premedicated dogs

Foram utilizados 10 cães adultos, de ambos os sexos, sem raça definida, com peso corpóreo entre 10 e 18 kg. Os animais foram pré-medicados com 1,0 mg/kg de levomepromazina e 15 minutos após receberam 2,0 mg/kg de midazolam, ambos por via intravenosa. A freqüência respiratória mostrou um aumento moderado e a freqüência cardíaca redução aos 15 minutos e elevação aos 30 minutos. Houve redução da pressão arterial média e da pressão sistólica com significado estatístico e não clínico. Houve tendência de redução da pressão arterial diastólica. A hipnose durou aproximadamente 20 minutos e aos 30 minutos os cães estavam acordados e em tentativa de deambulação.Experiments were performed on ten mongrel dogs with 10-18 kg body weight. They received levomepromazine 1.0 mg/kg body weight, I.V. as premedication, and 15 minutes later, midazolam was given in dosage of 2.0 mg/kg body weight intravenously. The result showed moderat increase on respiratory rate and decrease heart rate after 15 minutes and increase heart rate after 30 minutes. Mean and sistolic arterial pressure decreased significantly (p<0.05) but without clinical importance, remained in the physiologic range. Hipnosis duration was less than 20 minutes and at 30 minutes the dogs awaked and they tried to walk

EFEITO DO CARBAZOCROMO (ADRENOPLASMA) NO TRATAMENTO DE HIPOTENSÃO ARTERIAL PRODUZIDA POR HALOTANO EM CÃES

O halotano é um dos anestésicos inalatórios mais utilizados, porém produz depressão cardiovascular, tanto por deprimir o débito cardíaco como a resistência vascular periférica. Objetivou-se avaliar e comparar a eficácia de duas soluções: Ringer Lactato e solução de carbazocromo a 0,01% (adrenoplasma) no tratamento da hipotensão arterial.promovida pelo halotano, durante anestesia geral inalatória de cães. Doze animais adultos, machos e fêmeas, oriundos do Biotério central da UNESP, campus Botucatu, clinicamente saudáveis foram divididos, aleatoriamente, em dois grupos (n=6), sendo grupo A: animais que receberam infusão intravenosa de Adrenoplasma na velocidade de 20 ml/kg/hora e grupo B: animais que receberam infusão intravenosa de Ringer Lactato na mesma velocidade. Utilizou-se o propofol na dose de 6 mg/kg/IV para indução anestésica e após intubação foi fornecido 1,3V% de halotano para a manutenção por 90 minutos. Após 30 minutos iniciais, a infusão foi iniciada e perdurou pelos 60 minutos seguintes. A freqüência respiratória foi mantida constante. A freqüência cardíaca, eletrocardiograma, pressão arterial sistólica, média e disatólica, concentração final expirada de CO2, volume corrente e minuto, saturação de pulso de oxigênio, tempo de sangramento e temperatura retal, foram avaliados antes e 30 minutos após a indução e, aos 15, 30, 45 e 60 minutos, após o inicio da fluidoterapia. Houve um aumento significativo nos valores de pressão arterial sistólica e média apenas nos animais que receberam Adrenoplasma em relação ao valor observado imediatamente antes do inicio da fluidoterapia. Não houve diferença no tempo d sangramento. Face ao observado, pode-se sugerir que o uso de Adrenoplasma, como opção de tratamento da hipotensão arterial, decorrente da anestesia inalatória com halotano

Pituitary-adrenal activity and opioid release in ponies during thiopentone/halothane anaesthesia

The effect of thiopentone/halothane anaesthesia on the release of endogenous opioid, adrenocorticotrophin, arginine vasopressin, cortisol and catecholamine was investigated in ponies. The contribution made by halothane itself was studied by maintaining six ponies with a constant 12 per cent end tidal halothane concentration and five with a concentration ranging between 0.8 and 12 per cent. Cardiorespiratory depression was more prolonged in the ponies receiving a constant 1-2 per cent end tidal halothane concentration than in those which received less halothane. Plasma lactate concentration increased and haematocrit decreased during halothane anaesthesia. The concentrations of met-enkephalin, dynorphin and catecholamines did not change and those of β-endorphin, adrenocorticotrophin, arginine vasopressin and cortisol increased during halothane anaesthesia. Halothane appeared to be a major stimulus to pituitary adrenocortical activation because the adrenocortical secretion was proportional to the amount of halothane inhaled. β-endorphin increased proportionally more than adrenocorticotrophin and their plasma concentrations were not correlated, suggesting that they have independent secretion mechanisms

Cortisol, peptides and catecholamines in cerebrospinal fluid, pituitary effluent and peripheral blood of ponies

Tohoku University課

Endocrine changes in cerebrospinal fluid, pituitary effluent, and peripheral plasma of anesthetized ponies

Objective - To investigate the effects of inhalation and total IV anesthesia on pituitary-adrenal activity in ponies. Animals - 9 healthy ponies: 5 geldings and 4 mares. Procedure - Catheters were placed in the cavernous sinus below the pituitary gland and in the subarachnoid space via the lumbosacral space. After 72 hours, administration of acepromazine was followed by induction of anesthesia with thiopentone and maintenance with halothane (halothane protocol), or for the IV protocol, anesthesia induction with detomidine and ketamine was followed by maintenance with IV infusion of a detomidine-ketamine-guaifenesin combination. Arterial blood pressure and gas tensions were measured throughout anesthesia. Peptide and catecholamine concentrations were measured in pituitary effluent, peripheral plasma, and CSF. Peripheral plasma cortisol, glucose, and lactate concentrations also were measured. Results - Intravenous anesthesia caused less cardiorespiratory depression than did halothane. ACTH, metenkephalin, arginine vasopressin, and norepinephrine pituitary effluent and peripheral plasma concentrations were higher during halothane anesthesia, with little change during intravenous anesthesia. Pituitary effluent plasma β-endorphin and peripheral plasma cortisol concentrations increased during halothane anesthesia only. Dynorphin concentrations did not change in either group. Hyperglycemia developed during intravenous anesthesia only Minimal changes occurred in CSF hormonal concentrations during anesthesia. Conclusion - The pituitary gland has a major role in maintaining circulating peptides during anesthesia. Compared with halothane, IV anesthesia appeared to suppress pituitary secretion

Cardiorespiratory, endocrine and metabolic changes in ponies undergoing intravenous or inhalation anaesthesia

Six Welsh gelding ponies (weight 246 ± 6 kg) were premedicated with 0.03 mg/kg of acepromazine intravenously (i.v.) followed by 0.02 mg/kg of detomidine i.v. Anaesthesia was induced with 2 mg/kg of ketamine i.v. Ponies were intubated and lay in left lateral recumbency. On one occasion anaesthesia was maintained for 2 h using 1.2% halothane in oxygen. The same group of ponies were anaesthetized 1 month later using the same induction regime and anaesthesia was maintained with a combination of detomidine, ketamine and guaiphenesin, while the ponies breathed oxygen-enriched air. Electrocardiogram, heart rate, mean arterial blood pressure, cardiac output, respiratory rate, blood gases, temperature, haematocrit, glucose, lactate and cortisol were measured and cardiac index and systemic vascular resistance were calculated in both groups. Beta-endorphin, met-enkephalin, dynorphin, arginine vasopressin (AVP), adrenocorticotrophic hormone (ACTH) and catecholamines were measured in the halothane anaesthesia group only and 11-deoxycortisol during total intravenous anaesthesia (TIVA) only. Cardiorespiratory depression was more marked during halothane anaesthesia. Hyperglycaemia developed in both groups. Lactate and AVP increased during halothane anaesthesia. Cortisol increased during halothane and decreased during TIVA. There were no changes in the other hormones during anaesthesia. Recovery was smooth in both groups. TIVA produced better cardiorespiratory performance and suppressed the endocrine stress response observed during halothane anaesthesia