Influência da dexmedetomidina/atropina sobre as alterações da variação de pulso induzidas pela hemorragia seguida por reposição volêmica em cães anestesiados com isoflurano

This study aimed to evaluate the effects of dexmedetomidine on pulse pressure variation (PPV) changes induced by hemorrhage followed by volume replacement (VR) during isoflurane anesthesia. In a prospective, randomized crossover study, 8 adult dogs (19.5 to 29.2 kg) were anesthetized with 1.3 times the minimum alveolar concentration of isoflurane alone or isoflurane/dexmedetomidine (2 μg/kg/h) (2-week washout intervals). Atropine (0.03 mg/kg IM and 0.01 mg/kg IV) was administered 30 minutes prior to hemorrhage in the dexmedetomidine treatment. In both treatments neuromuscular blockade was produced by atracurium (0.3 mg/kg bolus, followed by 0.3 mg/kg/hour) for performing volume controlled ventilation (tidal volume: 12 mL/kg, inspiration to expriation ratio: 1:1.3 and respiratory rate: 16-20 breaths/min) with a positive end-expiratory pressure of 7 cm H2O. After recording baseline data, progressive withdrawal of 10, 20, and 30% of the estimated blood volume (HV10, HV20, and HV30, respectively) was followed by VR with autologous blood in the same proportion (RV10, RV20, and RV30, respectively). In 4/8 isoflurane-anesthetized dogs hemorrhage induced hypotension [mean arterial pressure (MAP) < 60 mmHg]. Based on MAP changes after hemorrhage during isoflurane anesthesia, dogs were divided in hypotensive (HG) and normotensive groups (NG). During isoflurane anesthesia (HG and NG), stroke index and cardiac index were significantly (P < 0.05) decreased from baseline after hemorrhage, while VR normalized or significantly increased these variables. The PPV (%) was increased by hemorrhage [from 7 (9, 5) (baseline) to 20 (27, 12) and 27 (40, 17) at HV20 and HV30, respectively] [mean (upper, lower ranges)] only in isoflurane-anesthetized dogs that became hypotensive; PPV returned to baseline after VR. Dexmedetomidine caused sustained increases in systemic vascular resistance (HG and NG), and prevented the ...O objetivo do presente estudo foi avaliar o efeito da dexmedetomidina sob a variação da pressão de pulso (VPP) induzida pela hemorragia seguida por reposição volêmica (RV) em cães anestesiados com isoflurano. Em um estudo prospectivo, aleatorizado e cruzado, 8 cães adultos (19,5 a 29,2 kg) foram anestesiados com 1,3 de concentração alveolar mínima de isoflurano isolado isoflurano associado a infusão contínua de dexmedetomidina (2 μg/kg/h) com intervalo de 2 semanas entre os tratamentos. Administrou-se atropina (0,03 mg/kg pela via intramuscular, IM e 0,01 mg/kg pela via intravenosa, IV) 30 minutos antes da hemorragia no tratamento dexmedetomidina. Em ambos os tratamentos produziu-se bloqueio neuromuscular com atracúrio (bolus de 0,3 mg/kg, seguido por 0,3 mg/kg/hora) para realização de ventilação com volume controlado (volume corrente: 12 mL/kg, relação inspiração/expiração: 1:1,3, frequência respiratória de 16-20 mov/min) com pressão positiva no final da expiração de 7 cmH2O. Após a mensuração dos parâmetros no momento basal, iniciou-se a retirada progressiva de sangue na proporção de 10, 20 e 30% do volume total estimado (HV10, HV20, HV30, respectivamente), e na sequência realizou-se a reposição volêmica com sangue autólogo na mesma proporção (RV10, RV20 e RV30, respectivamente). Quatro dos 8 cães anestesiados com isoflurano apresentaram hipotensão [pressão arterial média (PAM) < 60 mmHg]. Com base nas alterações da PAM após a hemorragia nos cães anestesiados com isoflurano, os cães foram divididos em dois grupos: hipotenso (GH) e normotenso (GN). Durante a anestesia com isoflurano (GH e GN) o índice sistólico (IS) e o índice cardíaco (IC) reduziram-se significativamente (P < 0,05) em relação aos valores basais, enquanto após a reposição volêmica estas variáveis retornaram aos valores basais ou apresentaram aumento significativo. A VPP (%) [média (valores máximo e mínimo)] ..

A comparison of detomidine in combination with saline, morphine or methadone in horses submitted to experimental oral stimuli

This study aimed to compare the sedative and cardiopulmonary effects of detomidine in combination with saline, morphine or methadone and to determine whether the addition of these opioids increases the degree of sedation in horses submitted to experimental oral stimuli. In a blinded, randomized, experimental study, six adult mares were evaluated using a crossover design with at least 15 days between trials: 10?g/kg detomidine in combination with saline (D/SAL), 0.1mg/kg morphine (D/ MORPH) or 0.1mg/kg methadone (D/METH). The degree of sedation, response to oral stimuli and cardiopulmonary parameters were monitored for 120 minutes. Parametric data were analyzed using the ANOVA and Tukey’s tests, and non- parametric data were analyzed with the Kruskal-Wallis and Friedman’s tests with the post-Dunn test (P&lt;0.05). The degree of sedation was significantly greater for the D/SAL than for the D/MORPH and D/METH treatments at 30 min. The horses´ responses to the oral stimuli decreased significantly following all treatments at 5 and 30 min from baseline values. The heart rate, respiratory rate, arterial pH and blood gas variables were all similar among the treatment groups. Mean arterial blood pressure was significantly higher in the D/MORPH group when compared with the D/SAL group between 75 and 120 min. It was concluded that all treatments provided sedative effects with mild cardiopulmonary changes. However the addition of morphine or methadone to detomidine did not improve the degree of sedation in horses submitted to experimental oral stimuli.</p

Infusão contínua intravenosa de midazolam isolado ou associado ao fentanil para realização de endoscopia em suínos Continuous infusion rate of midazolam alone or in combination with fentanyl for endoscopy in swine

Com este estudo objetivou-se avaliar o efeito cardiorrespiratório e a qualidade da anestesia e da recuperação pós-anestésica decorrentes da associação cetamina e xilazina seguida da infusão contínua intravenosa (IV) de midazolam isolado ou associado ao fentanil, em suínos. Foram avaliadas 10 porcas adultas, da raça Landrace, com peso médio de 170±4kg, submetidas à endoscopia. Todos os animais foram medicados pela via intramuscular com cetamina (4mg kg-1) associada à xilazina (2mg kg-1). Vinte minutos após, foi realizado um bolus IV de cetamina (2mg kg-1), seguida da infusão contínua IV de midazolam (0,5mg kg-1h-1 GM, n=5), ou midazolam (0,25mg kg-1h-1) associado ao fentanil (4µg kg-1 h-1 GMF, n=5). Foram avaliados: frequência cardíaca (FC) e ritmo cardíaco, pressão arterial sistólica (PAS), temperatura retal (T), frequência respiratória (f), variáveis hemogasométricas (PaO2, PaCO2, pH, HCO3-, SaO2), qualidade da anestesia e qualidade e tempo da recuperação anestésica (RA). A análise estatística foi realizada por meio de análise de variância, teste de Tukey e o teste não paramétrico de Mann-Whitney (PThe aim of this study was to evaluate the cardiopulmonary effects, the quality of anesthesia and the post-anesthetic recovery of ketamine and xylazine premedication following intravenous (IV) continuous rate infusion of midazolam alone or in combination with fentanyl, in swine. Ten Landrace adult pigs that underwent endoscopy were evaluated. All pigs were premedicated with ketamine (4mg kg-1) and xylazine (2mg kg-1) by intramuscular administration. After twenty minutes, intravenous ketamine (2mg kg-1) was injected, following IV continuous rate infusion of midazolam (0.5mg kg-1 h-1 GM, n=5) or midazolam (0.25mg kg-1 h-1) plus fentanyl (4µg kg-1 h¹ GMF, n=5). Heart and respiratory rates, systolic arterial blood pressure, rectal temperature, arterial blood gases, quality of anesthesia and recovery, and time for recovery were investigated. Statistical analysis was performed with One-Way ANOVA, Tukey test and Mann-Whitney test (P<0.05). The quality of anesthesia was similar between treatments, and endoscopy was able to be performed in both groups. Cardiopulmonary variables and blood gases did not differ between groups. The recovery time was 98±15 and 79±17 minutes in GM and GMF, respectively, without significant difference between treatments. The quality of recovery did not differ between groups. The results allowed us to conclude that both treatments provide cardiopulmonary stability and were satisfactory to swine endoscopy. However, despite of absence of significant difference, shorter time of recovery was observed with midazolam/fentanyl infusion

Effects of different inspired oxygen fractions on sildenafil-induced pulmonary anti-hypertensive effects in a sheep model of acute pulmonary embolism

Aims: Sildenafil is a pulmonary anti-hypertensive agent whose action could be modified by different fractions of inspired oxygen (FiO(2)). We compared the effects of pure oxygen (FiO(2) &gt; 90%) or room air (21% FiO(2)) on the cardiopulmonary actions of sildenafil in sheep with acute pulmonary embolism (APE).Main methods: Forty anesthetized, mechanically ventilated sheep (34.9 +/- 5.4 kg), were randomly distributed into four groups (n = 4 per group): FiO(2) &gt; 90% without intervention; APE induced by microspheres with FiO(2) &gt; 90%, followed 30 min later by placebo (Emb(90)); or APE followed 30 min later by intravenous sildenafil (0.7 mg/kg over 30 min) with FiO(2) &gt; 90% (Emb + Sild(90)) or 21% FiO(2) (Emb + Sild(21)). Variables were recorded until 30 min after the end of treatment administration.Key findings: Microsphere injection increased (P &lt; 0.05) mean pulmonary artery pressure (MPAP) in all embolized groups (111-140% higher than that of baseline). Compared with values recorded 30 min after induction of APE (E-30), sildenafil induced greater decreases in MPAP in the Emb + Sil(90) group than in the Emb + Sil(21) group (23% and 14% lower than E-30, respectively). Hypotension (mean arterial pressure &lt;60 mm Hg) Hg) was precipitated by sildenafil due to systemic vasodilation in the Emb + Sil(21) group. Embolization lowered the PaO2/FiO(2) ratio and increased venous admixture, but sildenafil did not alter the oxygenation impairment induced by APE.Significance: Sildenafil induces a more consistent pulmonary anti-hypertensive effect and causes less interference with the systemic circulation with the concomitant use of pure oxygen than that with room air in the APE setting. (C) 2015 Elsevier Inc. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq