Effects of inspired oxygen fractions in rabbits anesthetized with isoflurane or sevoflurane, maintained on spontaneous ventilation / Efeitos de frações inspiradas de oxigênio em coelhos anestesiados com isoflurano ou sevofluorano, mantidos em ventilação espontânea

It is important to identify the best inspired fraction of oxygen in a variety of situations, including sevoflurane or isoflurane anesthesia, in spontaneously breathing rabbits. For this, 64 rabbits were assigned to eight groups: GI100 (FiO2= 1,0 + isoflurane), GS100 (FiO2= 1,0 + sevoflurane), GI80 (FiO2= 0,8 + isoflurane), GS80 (FiO2= 0,8 + sevoflurane), GI60 (FiO2= 0,6 + isoflurane), GS60 (FiO2= 0,6 + sevoflurane), GI21 (FiO2= 0,21 + isoflurane), GS21 (FiO2= 0,21 + sevoflurane). The induction was performed with (2.5MAC) of the anesthetic. The vaporizer was setted at 1.5 MAC and FiO2 as attributed for each group. After the induction, the concentration was changed to 1 MAC. Measurements of parameters were performed 30 minutes after induction (T0), and then at 15 minute intervals (from T15 to T60). The arterial partial pressures of oxygen (PaO2), alveolar oxygen partial pressure (PAO2) and alveolar-arterial oxygen gradient [P(A-a)O2] were higher with the use of high FiO2. The GI80 showed higher levels of PaO2 FiO2 ratio and respiratory index (RI). In conclusion, the FiO2 of 0.21 is not indicated, because it causes hypoxemia. The isoflurane determines better ventilation when compared to sevoflurane, but isoflurane associated with 80% of oxygen promotes intrapulmonary shunt increase.(AU)

Tornou-se importante identificar a melhor fração inspirada de oxigênio em variadas situações, incluindo anestesia pelo sevoflurano ou isoflurano, em coelhos respirando espontaneamente. Para isso, 64 coelhos foram distribuídos em oito grupos: GI100 (FiO 2 = 1,0 + isoflurano), GS100 (FiO 2 = 1,0 + sevoflurano), GI80 (FiO 2 = 0,8 + isoflurano), GS80 (FiO 2 = 0,8 + sevoflurano), GI60 (FiO 2 = 0,6 + isoflurano), GS60 (FiO 2 = 0,6 + sevoflurano), GI21 (FiO 2 = 0,21 + isoflurano) e GS21 (FiO 2 = 0,21 + sevoflurano). A indução foi com 2,5 CAM do anestésico. Ajustou-se o vaporizador para 1,5 CAM, e a FiO 2 foi atribuída a cada grupo. Em seguida, a CAM foi reajustada para 1,0. Iniciaram-se as mensurações 30 minutos após a indução (M0), seguidas em intervalos de 15 minutos (de M15 a M60). As pressões parciais de oxigênio (PaO 2 ), a pressão parcial alveolar de oxigênio (P A O 2 ) e a diferença alvéolo-arterial de oxigênio [P(A-a)O 2 ] foram maiores com o emprego de altas FiO 2 . O GI80 apresentou maiores valores na relação entre PaO 2 e FiO 2 e índice respiratório (IR). Conclui-se que a FiO 2 0,21 não é indicada, pois provoca hipoxemia. No entanto, utilizada com isoflurano, determina melhor ventilação quando comparado ao sevoflurano, porém seu uso, associado a 80% de oxigênio, promove maior formação de shunt intrapulmonar.(AU)

Effects of inspired oxygen fractions in rabbits anesthetized with isoflurane or sevoflurane, maintained on spontaneous ventilation / Efeitos de frações inspiradas de oxigênio em coelhos anestesiados com isoflurano ou sevofluorano, mantidos em ventilação espontânea

It is important to identify the best inspired fraction of oxygen in a variety of situations, including sevoflurane or isoflurane anesthesia, in spontaneously breathing rabbits. For this, 64 rabbits were assigned to eight groups: GI100 (FiO2= 1,0 + isoflurane), GS100 (FiO2= 1,0 + sevoflurane), GI80 (FiO2= 0,8 + isoflurane), GS80 (FiO2= 0,8 + sevoflurane), GI60 (FiO2= 0,6 + isoflurane), GS60 (FiO2= 0,6 + sevoflurane), GI21 (FiO2= 0,21 + isoflurane), GS21 (FiO2= 0,21 + sevoflurane). The induction was performed with (2.5MAC) of the anesthetic. The vaporizer was setted at 1.5 MAC and FiO2 as attributed for each group. After the induction, the concentration was changed to 1 MAC. Measurements of parameters were performed 30 minutes after induction (T0), and then at 15 minute intervals (from T15 to T60). The arterial partial pressures of oxygen (PaO2), alveolar oxygen partial pressure (PAO2) and alveolar-arterial oxygen gradient [P(A-a)O2] were higher with the use of high FiO2. The GI80 showed higher levels of PaO2 FiO2 ratio and respiratory index (RI). In conclusion, the FiO2 of 0.21 is not indicated, because it causes hypoxemia. The isoflurane determines better ventilation when compared to sevoflurane, but isoflurane associated with 80% of oxygen promotes intrapulmonary shunt increase.(AU)

Tornou-se importante identificar a melhor fração inspirada de oxigênio em variadas situações, incluindo anestesia pelo sevoflurano ou isoflurano, em coelhos respirando espontaneamente. Para isso, 64 coelhos foram distribuídos em oito grupos: GI100 (FiO 2 = 1,0 + isoflurano), GS100 (FiO 2 = 1,0 + sevoflurano), GI80 (FiO 2 = 0,8 + isoflurano), GS80 (FiO 2 = 0,8 + sevoflurano), GI60 (FiO 2 = 0,6 + isoflurano), GS60 (FiO 2 = 0,6 + sevoflurano), GI21 (FiO 2 = 0,21 + isoflurano) e GS21 (FiO 2 = 0,21 + sevoflurano). A indução foi com 2,5 CAM do anestésico. Ajustou-se o vaporizador para 1,5 CAM, e a FiO 2 foi atribuída a cada grupo. Em seguida, a CAM foi reajustada para 1,0. Iniciaram-se as mensurações 30 minutos após a indução (M0), seguidas em intervalos de 15 minutos (de M15 a M60). As pressões parciais de oxigênio (PaO 2 ), a pressão parcial alveolar de oxigênio (P A O 2 ) e a diferença alvéolo-arterial de oxigênio [P(A-a)O 2 ] foram maiores com o emprego de altas FiO 2 . O GI80 apresentou maiores valores na relação entre PaO 2 e FiO 2 e índice respiratório (IR). Conclui-se que a FiO 2 0,21 não é indicada, pois provoca hipoxemia. No entanto, utilizada com isoflurano, determina melhor ventilação quando comparado ao sevoflurano, porém seu uso, associado a 80% de oxigênio, promove maior formação de shunt intrapulmonar.(AU)

Seric Concentration of Troponin I and Electrocardiographic Tracing in Dogs Submitted to Long-Term Sedation during 24 Hours

Background: General anesthetics and sedatives are commonly used for long-term sedation in veterinary medicine; however, they can lead to cardiac suppression. Cardiac troponin I is a biomarker used to detect myocardial pathology, monitor treatment, and assess outcomes in veterinary patients. The aim of this study was to evaluate the serum concentration of troponin I (cTnI), the electrocardiographic (ECG) tracing, and the ventricular stroke work index in dogs undergoing two long-term sedation protocols over 24 h.Materials, Methods & Results: Twelve healthy mongrel dogs with an average weight of 13.2 ± 2.3 Kg were admitted for this study. Twenty-four h before the experiment began (M-24), venous blood samples were collected for chemiluminescent cTnI evaluation and ECG data were obtained, specifically heart rate (HR); P, PR, QRS and T wave duration; P, R, T wave amplitude; and ST segment depression. On the day of the experiment, the animals were anaesthetized with propofol and isoflurane, and instrumented. After instrumentation, right and left ventricular stroke work index (RVSWI and LVSWI respectively) and intrapulmonary shunt (Qs/Qt) were performed as baseline parameters. The isoflurane was then discontinued and the animals randomly allocated to two groups (n = 6 each): Midazolam and fentanyl group (GMF), in which the animals received a bolus and continuous rate infusion (CRI)

Avaliação da concentração sérica de troponina I e do traçado eletrocardiográfico em cães submetidos a sedação prolongada durante 24 horas / Seric concentration of troponin I and electrocardiographic tracing in dogs submitted to long-term sedation during 24 hours

Background: General anesthetics and sedatives are commonly used for long-term sedation in veterinary medicine; however, they can lead to cardiac suppression. Cardiac troponin I is a biomarker used to detect myocardial pathology, monitor treatment, and assess outcomes in veterinary patients. The aim of this study was to evaluate the serum concentration of troponin I (cTnI), the electrocardiographic (ECG) tracing, and the ventricular stroke work index in dogs undergoing two long-term sedation protocols over 24 h.Materials, Methods & Results: Twelve healthy mongrel dogs with an average weight of 13.2 ± 2.3 Kg were admitted for this study. Twenty-four h before the experiment began (M-24), venous blood samples were collected for chemiluminescent cTnI evaluation and ECG data were obtained, specifically heart rate (HR); P, PR, QRS and T wave duration; P, R, T wave amplitude; and ST segment depression. On the day of the experiment, the animals were anaesthetized with propofol and isoflurane, and instrumented. After instrumentation, right and left ventricular stroke work index (RVSWI and LVSWI respectively) and intrapulmonary shunt (Qs/Qt) were performed as baseline parameters. The isoflurane was then discontinued and the animals randomly allocated to two groups (n = 6 each): Midazolam and fentanyl group (GMF), in which the animals received a bolus and continuous rate infusion (CRI) of midazolam (0.5 mg/kg and 0.5 mg/kg/h) and fentanyl (5 µg/kg and 10 µg/kg/h) or ketamine and morphine group (GKM), in which the animals received a bolus and CRI of ketamine (1 mg/kg and 0.6 mg/kg/h) and morphine (0.5 mg/kg and 0.26 mg/kg/h). Both groups also received propofol as a bolus and CRI (3 mg/kg and 0.3 mg/ kg/min) over 24 h. The ECG and cTnI parameters were evaluated at 6, 12, and 24 h during CRI (M6, M12, and M24) and 12 and 24 h after the end of infusion (T12 and T24). The hemodynamic parameters RVSWI, LVSWI, and Qs/Qt were evaluated every 2 h until the end of CRI.[...]

Avaliação da concentração sérica de troponina I e do traçado eletrocardiográfico em cães submetidos a sedação prolongada durante 24 horas / Seric concentration of troponin I and electrocardiographic tracing in dogs submitted to long-term sedation during 24 hours

Background: General anesthetics and sedatives are commonly used for long-term sedation in veterinary medicine; however, they can lead to cardiac suppression. Cardiac troponin I is a biomarker used to detect myocardial pathology, monitor treatment, and assess outcomes in veterinary patients. The aim of this study was to evaluate the serum concentration of troponin I (cTnI), the electrocardiographic (ECG) tracing, and the ventricular stroke work index in dogs undergoing two long-term sedation protocols over 24 h.Materials, Methods & Results: Twelve healthy mongrel dogs with an average weight of 13.2 ± 2.3 Kg were admitted for this study. Twenty-four h before the experiment began (M-24), venous blood samples were collected for chemiluminescent cTnI evaluation and ECG data were obtained, specifically heart rate (HR); P, PR, QRS and T wave duration; P, R, T wave amplitude; and ST segment depression. On the day of the experiment, the animals were anaesthetized with propofol and isoflurane, and instrumented. After instrumentation, right and left ventricular stroke work index (RVSWI and LVSWI respectively) and intrapulmonary shunt (Qs/Qt) were performed as baseline parameters. The isoflurane was then discontinued and the animals randomly allocated to two groups (n = 6 each): Midazolam and fentanyl group (GMF), in which the animals received a bolus and continuous rate infusion (CRI) of midazolam (0.5 mg/kg and 0.5 mg/kg/h) and fentanyl (5 µg/kg and 10 µg/kg/h) or ketamine and morphine group (GKM), in which the animals received a bolus and CRI of ketamine (1 mg/kg and 0.6 mg/kg/h) and morphine (0.5 mg/kg and 0.26 mg/kg/h). Both groups also received propofol as a bolus and CRI (3 mg/kg and 0.3 mg/ kg/min) over 24 h. The ECG and cTnI parameters were evaluated at 6, 12, and 24 h during CRI (M6, M12, and M24) and 12 and 24 h after the end of infusion (T12 and T24). The hemodynamic parameters RVSWI, LVSWI, and Qs/Qt were evaluated every 2 h until the end of CRI.[...](AU)

Influência da Anestesia com Isofluorano ou Propofol na Vasoconstrição Pulmonar Hipóxica de Cavalos

A abordagem cirúrgica toracoscópica apresenta diversas vantagens ao paciente, como redução do trauma cirúrgico proporcionando menor dor no pós-operatório e uma melhor recuperação. Na maioria dos casos é necessário instituir a ventilação monopulmonar (VMP), que promove alterações cardiovasculares e respiratórias importantes. Estas alterações provocadas podem ser exacerbadas dependendo do fármaco utilizado na manutenção anestésica. Estudos sugerem que os anestésicos inalatórios possuem efeitos inibitórios sobre as respostas fisiológicas durante a VMP, enquanto os anestésicos injetáveis não. O objetivo deste estudo é comparar os efeitos da anestesia intravenosa total utilizando infusão contínua de propofol e a anestesia inalatória com isofluorano na vasoconstrição hipóxica pulmonar em cavalos submetidos à ventilação monopulmonar e hemipneumotórax. Foram utilizados seis cavalos e, com intervalos de 28 dias, dois protocolos anestésicos foram estudados: isofluorano, ISO (n=6) e propofol, PRO (n=6). Foram avaliados os parâmetros cardiovasculares e respiratórios pré e transoperatórios, variáveis hemodinâmicas e de oxigenação tecidual, hemogasometria arterial e venosa mista. Em todos os cavalos anestesiados com isofluorano o procedimento teve que ser interrompido devido a redução acentuada da PaO2, sendo desfeita a ventilação monopulmar e o pneumotórax. A média da PaO2 no momento 15 minutos após ser instituído o pneumotórax foi de 56 ± 42 no grupo ISO e 129 ± 54 no grupo PRO. Os resultados observados sugerem que, nos cavalos onde a fração de shunt intrapulmonar (Qs/Qt) já é aumentada pelo grande peso corporal, a hipoxemia e hipercapnia podem ser mais importantes durante a ventilação monopulmonar e pneumotórax. Sendo essas alterações menores na anestesia com propofol, visto que esse anestésico inibe de maneira menos acentuada a vasoconstrição hipóxica (VPH) comparado aos anestésicos halogenados.

Thoracoscopy approach is more favorable to the patient, as it promotes reduced surgical trauma, less pain after surgery and faster recovery. Frequently it is necessary to set the one lung ventilation (OLV), which stimulate important cardiovascular and respiratory modifications, which could be increased depending on the drug used for anesthetic maintenance. Studies suggest that inhalational anesthetics have inhibitory effects on physiological responses during OLV, while the intravenous anesthetics not. The aim of this study was to compare the respiratory and hemodynamics functions during OLV and hemi-pneumothorax in general anesthetized horses with propofol or isoflurane in lateral recumbency. Six horses were used and at intervals of 28 days, two anesthetic protocols were studied, isofluorane, ISO (n=6) and propofol, PRO (n=6). Cardiorespiratory variables, hemodynamics and tissue oxygenation parameters, arterial and mixed venous blood gas analysis were recorded. In all horses anesthetized with isoflurane, the procedure was interrupted, undoing the monopulmonary ventilarion and pneumothorax. The mean PaO2 at the time 15 minutes after the pneumothorax was established was 56 ± 42 in the ISO group and 129 ± 54 in the PRO group.The results observed suggest that the horses, where the intrapulmonary shunt fraction (Qs/Qt) is already increases by the great body weight, hypoxemia and hypercapnia can be more important during monopulmonar ventilation and pneumothorax. These changes are minor in anesthesia with propofol, since this anesthesic does not diminish hypoxic vasoconstriction as is observed with halogenated anesthetics.

MODALIDADES VENTILATÓRIAS EM OVINOS

ROSA, L. Modalidades ventilatórias em ovinos. 2017, 118p. Dissertação (Mestrado em Ciência Animal) Universidade do Estado de Santa Catarina. Programa de Pós-Graduação em Ciência Animal, Lages, 2017. Uma monitoração cardiovascular e respiratória adequada é essencial para um melhor prognóstico do paciente e, se realizada de forma minimamente invasiva, promove menores riscos ao paciente. Neste contexto, destaca-se a calorimetria, que fornece o consumo de oxigênio, produção de gás carbônico e o gasto energético, parâmetros estes, importantes na evolução do quadro clínico do paciente. O objetivo deste estudo foi avaliar diferentes modalidades ventilatórias em ovinos, assim como dois diferentes protocolos de manutenção anestésica, o decúbito e o uso de bloqueador neuromuscular nesta espécie. Foram utilizadas 12 ovelhas, adultas, mestiças, comprovadamente hígidas, encaminhadas para procedimento ortopédico em um estudo paralelo. No dia do estudo, os animais foram instrumentados com cateterização da artéria auricular, veias cefálicas e passagem de cateter venoso central na veia jugular. Receberam morfina e detomidina como medicação pré-anestésica. Foram induzidos a anestesia com propofol e intubados, mantendo-se uma FiO2 de 0,4. Neste momento, os animais foram alocados em dois grupos: GP, manutenção com infusão contínua de propofol, e GI com anestesia inalatória com isofluorano. Todos os animais foram mantidos por 30 minutos em cada modalidade ventilatória: ventilação espontânea, ventilação mecânica ciclada a volume, ventilação mecânica ciclada a pressão e ventilação mecânica ciclada a pressão com PEEP. A frequência cardíaca e o índice cardíaco foram maiores em GI e já o índice de resistência vascular sistêmica foi maior em GP. Os valores de hemoglobina, a fração de shunt intrapulmonar e o volume corrente foram maiores no GP. Os animais apresentaram alcalose metabólica em ambos os grupos. O isofluorano promoveu maior hipotensão, diminuição da complacência pulmonar, aumento da resistência das vias aéreas, menores valores de PaO2 e maiores valores de PaCO2. A modalidade ventilatória ciclada a pressão com PEEP promoveu maior complacência pulmonar e índice de oxigenação, maiores valores de PaO2, menores valores de shunt intrapulmonar, além de ser considerada uma modalidade mais segura para utilização. O decúbito dorsal promoveu maior estabilidade ventilatória aos pacientes, com maior oferta de oxigênio aos tecidos, menor consumo de oxigênio e produção de dióxido de carbono. O atracúrio, não promoveu diferenças hemodinâmicas, metabólicas, ventilatórias e hemogasométricas em ovelhas anestesiadas com propofol sob a forma de infusão contínua e submetidas à ventilação mecânica ciclada à pressão com PEEP. Conclui-se que o propofol e a ventilação mecânica ciclada a pressão com pressão positiva ao final da expiração promoveram maior estabilidade cardiorrespiratória em ovelhas anestesiadas. Desta forma a melhor conduta anestésica para ovelhas é manutenção anestésica com propofol, ventilação mecânica ciclada a pressão com PEEP, mantidas em decúbito dorsal, sem a adição de atracúrio.

ROSA, L. Ventilatory modalities in sheep. 2017, 118p. Dissertation (Master in Animal Science) - University of the State of Santa Catarina. Graduate Program in Animal Science, Lages, 2017. Adequate cardiovascular and respiratory monitoring is essential for a better prognosis of the patient and, if performed in a minimally invasive manner, promotes lower risks to the patient. In this context, we highlight calorimetry, which provides oxygen consumption, carbon dioxide production and energy expenditure, which are important factors in the evolution of the patient's clinical condition. The objective of this study was to evaluate different ventilatory modalities in sheep, as well as two different protocols of anesthetic maintenance, recumbency and the use of neuromuscular blocker in this specie. Twelve ewes, adult, crossbred, proven healthy, were referred for orthopedic surgery in a parallel study. On the day of the study, the animals were instrumented with catheterization of the auricular artery, cephalic veins and impuntation of central venous catheter into the jugular vein. They received morphine and detomidine as preanesthetic medication. Were induced with propofol and intubated anesthesia, maintaining a FiO2 of 0.4. At this time, the animals were allocated into two groups: GP, maintenance with continuous infusion of propofol, and GI with inhaled anesthesia with isoflurane. All animals were maintained for 30 minutes in each ventilatory modality: spontaneous ventilation, volume-cycled mechanical ventilation, pressure-cycled mechanical ventilation, and pressure-cycled mechanical ventilation with PEEP. Heart rate and cardiac index were higher in GI and already the systemic vascular resistance index was higher in GP. The values of hemoglobin, intrapulmonary shunt fraction and tidal volume were higher in GP. The animals presented metabolic alkalosis in both groups. Isoflurane promoted greater hypotension, decreased pulmonary compliance, increased airway resistance, lower PaO2 values and higher PaCO2 values. The pressure-cycled ventilatory modality with PEEP promoted greater pulmonary compliance and oxygenation index, higher PaO2 values, lower values of intrapulmonary shunt, besides being considered a safer modality for use. The dorsal recumbency promoted greater patient ventilation stability, with a greater oxygen supply to the tissues, lower oxygen consumption and carbon dioxide production. Atracurium did not promote hemodynamic, metabolic, ventilatory and hemogasometric differences in sheep anesthetized with propofol in the form of continuous infusion and submitted to pressure-cycled mechanical ventilation with PEEP. It was concluded that propofol and mechanical ventilation with positive pressure at the end of expiration promoted greater cardiorespiratory stability in anesthetized sheep. Thus, the best anesthetic management for ewes is anesthetic maintenance with propofol, mechanical ventilation pressure-cycling with PEEP, kept in dorsal recumbency, without the addition of atracurium.

Right-to-left shunt determination in dog lungs under inhalation anesthesia with rebreathing and non-rebreathing system / Determinação de shunt venoso–arterial em pulmões de cães sob anestesia geral inalatória por sistemas com e sem reinalação

PURPOSE: To investigatge right-to-left shunt determination in dog lungs under inhalantion anesthesia with non-rebreathing and rebreathing systems and fraction of inspired oxygen (F I O2) of 0.9 and 0.4, respectively. METHODS: Two groups of 10 dogs each under inhalation anesthesia with sevoflurane: GI in which it was utilized non-rebreathing semiclosed system and F I O2 = 0.9, and GII in which it was utilized rebreathing semiclosed system and F I O2 = 0.4. The study parameters were: heart rate, medium arterial pressure, right-to-left intrapulmonary shunt, hematocrit, hemoglobin, arterial partial pressure of oxygen, mixed venous partial pressure of oxygen, mixed venous oxygen saturation, arterial partial pressure of carbon dioxide, partial pressure of water in the alveoli. RESULTS: Shunt results were significantly different between the two groups - GI data were higher than GII in all the evaluated moments. Hence, the group with nonrebreathing (GI) developed a superior grade of intrapulmonary shunt when compared with the rebreathing group (GII). The partial pressure of water in the alveoli was significantly higher in GII. CONCLUSION: The inhalation anesthesia with non-rebreathing system and F I O2 = 0.9 developed a higher grade of intrapulmonary right-to-left shunt when compared with the rebreathing system and F I O2 = 0.4. The higher humidity in GII contributed to the result.(AU)

OBJETIVO: Comparar a formação de shunt venoso-arterial em pulmões de cães submetidos a anestesia geral inalatória utilizando-se sistemas de anestesia com e sem reinalação, com fração inspirada de oxigênio de 0,4 e 0,9, respectivamente. MÉTODOS: Empregaram-se 20 cães induzidos com tiopental sódico (30mg/kg) e mantidos com sevoflurano (3 por cento) e alocados em dois grupos (n=10); os animais de GI foram ventilados com modalidade controlada em sistema semifechado, sem reinalação, F I O2 = 0,9, e os de GII, com modalidade controlada, sistema semifechado, com reinalação e F I O2 = 0,4. Os atributos analisados durante o experimento foram: freqüência cardíaca, pressão arterial média, shunt pulmonar venoso-arterial, hematócrito, hemoglobina, pressão parcial de oxigênio arterial, pressão parcial de oxigênio no sangue venoso misto, saturação de oxigênio no sangue venoso misto, pressão parcial de dióxido de carbono arterial e pressão de vapor de água nos alvéolos (P VA). RESULTADOS: A P VA foi significativamente maior em GII. A análise estatística dos valores encontrados de shunt mostrou que GI e GII apresentaram diferenças significativas, sendo que os resultados de GI são maiores que os de GII em todos os momentos avaliados. Já a análise de momentos dentro de um mesmo grupo não demonstrou diferenças. CONCLUSÃO: O sistema de anestesia sem reinalação com F I O2 = 0,9 desenvolveu maior grau de shunt pulmonar venoso-arterial que o sistema de anestesia com reinalação e F I O2 = 0,4. A umidificação dos gases em GII contribuiu para diminuir o shunt.(AU)

Effects of desflurane, sevoflurane and isoflurane on pulmonary shunt in dogs during spontaneous ventilation / Efeitos do desflurano, sevoflurano e isoflurano sobre o shunt pulmonar em cães sob respiração espontânea

The aim of this study was to compare the effects of desflurane, sevoflurane and isoflurane on pulmonary shunt in dogs during spontaneous ventilation. General anesthesia was induced in 30 healthy, adult, mongrel dogs by intravenous administration of propofol. The animals were separated into three groups of 10 dogs each and submitted to general inhalation anesthesia with 1.5 MAC of desflurane (G1), sevoflurane (G2) and isoflurane (G3). Arterial blood was collected by puncture of the right femoral artery, and mixed blood was collected by introducing a Swan-Ganz catheter into the pulmonary artery. These samples were used to determine the parameters employed for calculation of the intrapulmonary shunt. Measurements began at 20min after orotracheal intubation and were repeated every 20min, totaling six measurements. Means were compared by the Student t-test (P£ 0.05). Desflurane led to a higher shunt than sevoflurane and isoflurane at 40 and 60min. At 80min, the mean values obtained for desflurane were higher than those obtained for isoflurane, while at 100min the values observed for dogs anesthetized with desflurane were higher than those obtained with sevoflurane. Desflurane caused respiratory depression by reducing PaO2, and a higher percentage of intrapulmonary shunt than isoflurane and sevoflurane.(AU)

O estudo teve por objetivo avaliar os efeitos de três anestésicos inalatórios sobre o shunt pulmonar em cães sob ventilação espontânea. Trinta cães foram separados e protocolados em três grupos (G) de 10 cães cada. Induziu-se a anestesia geral por meio da administração intravenosa de propofol. Em seguida procedeu-se à anestesia geral inalatória pelo desflurano (G1), sevoflurano (G2) ou isoflurano (G3) na concentração de 1,5 CAM. Para a determinação dos parâmetros utilizados nas equações para cálculo do shunt intrapulmonar foram colhidos sangue arterial por punção da artéria femoral direita, e sangue misto, por meio de cateter de Swan-Ganz, posicionado na artéria pulmonar. As mensurações tiveram início 20min após a intubação orotraqueal e se repetiram a cada 20min, num total de seis colheitas. Contrastes de médias foram feitos pelo teste t de Student (P£ 0,05). O desflurano apresentou shunt pulmonar superior aos apresentados pelo sevoflurano e isoflurano aos 40 e 60min. Aos 80min, os valores médios obtidos com o desflurano foram superiores aos obtidos pelo isoflurano, enquanto que aos 100min foram mais elevados do que os obtidos pelo sevoflurano. O desflurano, quando comparado ao isoflurano e ao sevoflurano, produziu depressão respiratória pela redução da PaO2, determinando maior percentagem de shunt intrapulmonar.(AU)

Seric Concentration of Troponin I and Electrocardiographic Tracing in Dogs Submitted to Long-Term Sedation during 24 Hours

Background: General anesthetics and sedatives are commonly used for long-term sedation in veterinary medicine; however, they can lead to cardiac suppression. Cardiac troponin I is a biomarker used to detect myocardial pathology, monitor treatment, and assess outcomes in veterinary patients. The aim of this study was to evaluate the serum concentration of troponin I (cTnI), the electrocardiographic (ECG) tracing, and the ventricular stroke work index in dogs undergoing two long-term sedation protocols over 24 h.Materials, Methods & Results: Twelve healthy mongrel dogs with an average weight of 13.2 ± 2.3 Kg were admitted for this study. Twenty-four h before the experiment began (M-24), venous blood samples were collected for chemiluminescent cTnI evaluation and ECG data were obtained, specifically heart rate (HR); P, PR, QRS and T wave duration; P, R, T wave amplitude; and ST segment depression. On the day of the experiment, the animals were anaesthetized with propofol and isoflurane, and instrumented. After instrumentation, right and left ventricular stroke work index (RVSWI and LVSWI respectively) and intrapulmonary shunt (Qs/Qt) were performed as baseline parameters. The isoflurane was then discontinued and the animals randomly allocated to two groups (n = 6 each): Midazolam and fentanyl group (GMF), in which the animals received a bolus and continuous rate infusion (CRI)

Seric Concentration of Troponin I and Electrocardiographic Tracing in Dogs Submitted to Long-Term Sedation during 24 Hours

Background: General anesthetics and sedatives are commonly used for long-term sedation in veterinary medicine; however, they can lead to cardiac suppression. Cardiac troponin I is a biomarker used to detect myocardial pathology, monitor treatment, and assess outcomes in veterinary patients. The aim of this study was to evaluate the serum concentration of troponin I (cTnI), the electrocardiographic (ECG) tracing, and the ventricular stroke work index in dogs undergoing two long-term sedation protocols over 24 h.Materials, Methods & Results: Twelve healthy mongrel dogs with an average weight of 13.2 ± 2.3 Kg were admitted for this study. Twenty-four h before the experiment began (M-24), venous blood samples were collected for chemiluminescent cTnI evaluation and ECG data were obtained, specifically heart rate (HR); P, PR, QRS and T wave duration; P, R, T wave amplitude; and ST segment depression. On the day of the experiment, the animals were anaesthetized with propofol and isoflurane, and instrumented. After instrumentation, right and left ventricular stroke work index (RVSWI and LVSWI respectively) and intrapulmonary shunt (Qs/Qt) were performed as baseline parameters. The isoflurane was then discontinued and the animals randomly allocated to two groups (n = 6 each): Midazolam and fentanyl group (GMF), in which the animals received a bolus and continuous rate infusion (CRI)

Seric Concentration of Troponin I and Electrocardiographic Tracing in Dogs Submitted to Long-Term Sedation during 24 Hours

Background: General anesthetics and sedatives are commonly used for long-term sedation in veterinary medicine; however, they can lead to cardiac suppression. Cardiac troponin I is a biomarker used to detect myocardial pathology, monitor treatment, and assess outcomes in veterinary patients. The aim of this study was to evaluate the serum concentration of troponin I (cTnI), the electrocardiographic (ECG) tracing, and the ventricular stroke work index in dogs undergoing two long-term sedation protocols over 24 h.Materials, Methods & Results: Twelve healthy mongrel dogs with an average weight of 13.2 ± 2.3 Kg were admitted for this study. Twenty-four h before the experiment began (M-24), venous blood samples were collected for chemiluminescent cTnI evaluation and ECG data were obtained, specifically heart rate (HR); P, PR, QRS and T wave duration; P, R, T wave amplitude; and ST segment depression. On the day of the experiment, the animals were anaesthetized with propofol and isoflurane, and instrumented. After instrumentation, right and left ventricular stroke work index (RVSWI and LVSWI respectively) and intrapulmonary shunt (Qs/Qt) were performed as baseline parameters. The isoflurane was then discontinued and the animals randomly allocated to two groups (n = 6 each): Midazolam and fentanyl group (GMF), in which the animals received a bolus and continuous rate infusion (CRI)

Seric Concentration of Troponin I and Electrocardiographic Tracing in Dogs Submitted to Long-Term Sedation during 24 Hours

Background: General anesthetics and sedatives are commonly used for long-term sedation in veterinary medicine; however, they can lead to cardiac suppression. Cardiac troponin I is a biomarker used to detect myocardial pathology, monitor treatment, and assess outcomes in veterinary patients. The aim of this study was to evaluate the serum concentration of troponin I (cTnI), the electrocardiographic (ECG) tracing, and the ventricular stroke work index in dogs undergoing two long-term sedation protocols over 24 h.Materials, Methods & Results: Twelve healthy mongrel dogs with an average weight of 13.2 ± 2.3 Kg were admitted for this study. Twenty-four h before the experiment began (M-24), venous blood samples were collected for chemiluminescent cTnI evaluation and ECG data were obtained, specifically heart rate (HR); P, PR, QRS and T wave duration; P, R, T wave amplitude; and ST segment depression. On the day of the experiment, the animals were anaesthetized with propofol and isoflurane, and instrumented. After instrumentation, right and left ventricular stroke work index (RVSWI and LVSWI respectively) and intrapulmonary shunt (Qs/Qt) were performed as baseline parameters. The isoflurane was then discontinued and the animals randomly allocated to two groups (n = 6 each): Midazolam and fentanyl group (GMF), in which the animals received a bolus and continuous rate infusion (CRI)

Compared study on the effects of mechanical controled ventilation (MCV) with or without the use of positive-end-expiratory-pressure (PEEP) on inter-pleural pressure variation in horse anesthesia / Estudo comparativo dos efeitos da ventilação mecânica controlada (VMC) com ou sem o emprego da pressão positiva no final da expiração (PEEP) sobre a variação da pressão interpleural em anestesia eqüina

One of the main death causes in equines during anesthesia and recovery periods is hipoxemia due to intrapulmonary "shunts". In human beings, hipoxy is treated with the use of Positive-End- Expiratory Pressure (PEEP), that in this species hinders airway closure, increases functional residual capacity and improves arterial oxygenation. We studied the effects of PEEP on inter-pleural pressure and on the cardio-vascular system, comparing Spontaneous Ventilation (SV), with Controlled Mechanical Ventilation (CMV) by itself and with PEEP of 10 cm H2O. We used 12 adult horses, females and males. These animals were submitted to general anesthesia with SV, CMV and CMV with PEEP of 10 cm H2O. The anesthetic procedure was equal for all horses. The hemodynamic, ventilatory and oxygenation parameters were evaluated. The statistical analysis of the results showed that when comparing SV, CMV and CMV with PEEP, there was no significant decrease in arterial blood pressure, nor significant alterations in cardiac and respiratory rate, pH, HCO3, BE and SatHb. When comparing SV, and CMV, an increase in PaO2 was noticed, parallel to a constant increase in PaCO2. No significant alterations in "shunt", alveolar-arterial relation and oxygen contend, were noticed. However during CMV and CMV with PEEP lower "shunt" values were noticed. Inter-pleural pressure showed significant alterations, decreasing duri

Uma das principais causas de mortalidade em anestesia eqüina é a grave hipoxemia, conseqüência da formação de "shunt" intrapulmonar. Em seres humanos, a hipóxia é tratada com uso de pressão positiva no final da expiração (PEEP), que, nesta espécie, previne o fechamento de vias aéreas, aumenta a capacidade residual funcional e melhora a oxigenação arterial. Estudamos os efeitos de PEEP sobre a variação do deltaPpl e sua repercussão no sistema cardiovascular, comparando ventilação espontânea (VE), à ventilação mecânica controlada (VMC) sem PEEP e com PEEP de 10 cm H2O. Foram utilizados 12 animais adultos de ambos os sexos que foram submetidos a anestesia geral em ventilação espontânea, VMC sem e com PEEP. A técnica anestésica foi padronizada para todos os indivíduos. Os parâmetros hemodinâmicos, ventilatórios e de oxigenação foram mensurados no decorrer do experimento. A análise estatística dos resultados demostra que: não houve queda significativa da PAM entre os diferentes tipos de ventilação, nem alteração significativa das freqüências respiratória e cardíaca, pH, HCO3, BE e SatHb entre os três tipos de ventilação. Notou-se aumento da PaO2 entre VE e VMC paralelo a um aumento constante da PaCO2. Não foram verificadas reduções significativas do gradiente alvéolo-arterial, "shunt" e conteúdo de oxigênio. Durante a VCM e VCM com PEEP, observaram-se os valores mais baixos de "shun

Avaliação de diferentes frações inspiradas de oxigênio em cães anestesiados com infusão contínua de propofol e rocurônio, mantidos em ventilação controlada a pressão

Avaliaram-se os efeitos do fornecimento de diferentes frações inspiradas de oxigênio em cães anestesiados com infusão contínua de propofol e rocurônio mantidos em ventilação mecânica controlada a pressão sobre os parâmetros respiratórios, hemogasométricos e hemodinâmicos. Foram utilizados 8 cães adultos, os quais foram submetidos a cinco anestesias com propofol (8,8 ± 3,3 mg/kg, seguido de infusão contínua de 0,7 mg/kg/min) e rocurônio (0,6 mg/kg bolus e infusão contínua 0,6 mg/kg/h), sendo que, cada procedimento anestésico foi diferenciado do outro pela FiO2 fornecida ao paciente, permitindo assim, a formação dos grupos: G100 (FiO2=1), G80 (FiO2=0,8), G60 (FiO2=0,6), G40 (FiO2=0,4) e G20 (FiO2=0,21). Os animais foram submetidos à ventilação mecânica no modo pressão controlada. Trinta minutos após a indução anestésica (M0) e a cada 15 minutos, durante um período de 60 minutos (M15, M30, M45 e M60) mensuraram-se os parâmetros. Os dados de cada grupo foram submetidos à Análise de Perfil (p<0,05). Os valores de PaO2, PvO2, SaO2 e SvO2 diminuíram quanto mais baixas foram as FiO2. Houve maiores médias na Rawi e WOB em G60, e de shunt e AaDO2 em G100, G80 e G60. Os cães mantiveram-se hemodinamicamente estáveis em todos os grupos. Concluiu-se que as diferentes FiO2 não alteram as variáveis hemodinâmicas e que o fornecimento de oxigênio a 60%, 80% e 100% deve ser evitado, pois proporciona altos valores de AaDO2 e shunt intrapulmonar. Além disso, verificou-se que FiO2 de 0,4 e 0,21 mantém melhor estabilidade dos parâmetros ventilatórios

The effects of several inspired oxygen fractions (FiO2) on the blood gases, respiratory and hemodynamic parameters in mechanical ventilation dogs anesthetized with continuous infusion of propofol and rocuronium were evaluated. Eight adult dogs were used. Each animal underwent five anesthesia with propofol (8,8 ± 3,3 mg/kg, followed by continuous infusion of 0,7 mg/kg/min) and rocuronium (0,6 mg/kg, followed by continuous infusion of 0,6 mg/kg/h). In each procedure the patient was allowed to breath a different FiO2, thereby resulting in five groups, namely: G100 (group FiO2 = 1), G80 (groupFiO2 = 0.8), G60 (group FiO2 =0.6), G40 (group FiO2 = 0.4), and G20 (group FiO2 = 0.21). The animals were submitted to pressure-controlled ventilation. The initial measurement (M0) was recorded thirty minutes after the infusion of propofol and rocuronium begun. Additional recordings were performed at 15 minute intervals for 60 minutes (M15, M30, M45 and M60). Numeric data was submitted to Profile Analysis (p<0.05). We recorded significantly lower values of PaO2, PvO2, SaO2 and SvO2 varied according to the higher changes in oxygen. Regarding Rawi and WOB the mean of G60 was greater than other groups. Qs/Qt and AaDO2 of G100, G80 e G60 was higher than other groups. We conclude that FiO2 does not impair hemodynamic parameters and 100%, 80% e 60% oxygen not be used because promote high values of AaDO2 and shunt intrapulmonary. FiO2=0,4 e FiO2=0,21 maintain stability of ventilatory parameters