Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective was to compare the hemodynamic and metabolic effects of treatment with hypertonic saline and colloid (expanders) associated with different vasoconstrictors in dogs subjected to experimental hemorrhagic shock. Twenty-four healthy adult mongrel dogs were included in the study, with mean body weight of 10.84±3.3kg, males and females. Following anesthetic induction by isoflurane inhalation, the animals were intubated and connected to a partial rebreathing system, and subjected to general inhalational anesthesia with isoflurane using a calibrated vaporizer, which were then maintained at 1MAC (minimum alveolar concentration). Hypovolemia was induced by withdrawal of 5mL kg-1 min-1 of blood from the femoral artery, until the mean arterial pressure reached values between 45 and 50mmHg. After 60 minutes, basal parameters were measured and the treatments were initiated. At this moment, the treatment with colloid and hypertonic solution (4mL kg-1) was carried out. After 10 minutes, the animals were randomly allocated into four groups, according to the continuous infusion to be administered. In GD (dopamine group, n=06), a continuous infusion of dopamine (10μg kg-1 min-1) was administered. The animals in GDB (dobutamine group, n=06) received a continuous infusion of dobutamine (5μg kg-1 min-1) and GV (vasopressin group, n=06) vasopressin at the dose of 0.02IU-1 min-1 by continuous infusion, both diluted in 0.9% NaCl. The GC (n=06), control group, was only treated with the association of hypertonic saline and colloid . The animals were monitored with regards to heart rate, respiratory rate, rectal temperature, systolic, diastolic and mean arterial pressure, central venous pressure, concentration of expired isoflurane, concentration of expired carbon dioxide, fraction of inspired oxygen and arterial blood gas analysis to obtain values of PO2, PCO2, bicarbonate, pH, Na+, K+ and base deficit, hemoglobin and hematocrit. In addition, blood samples were collected to evaluate serum lactate, thromboplastin time, prothrombin time, platelets and complete blood count. The collected data were submitted to variance analysis, where the mean values between groups were analyzed using t-test, and between times within the same group using Tukey test, where the differences were considered statistically significant when p≤0.05. The differences between times within each group were not observed only in the variables of HR in GV and GC, PaO2, K+, MCV, MCHC, total leukocytes (except in GC), segmented neutrophils, monocytes, PT and APTT. The differences between groups were essentially regarding HR (with less proportion of alteration in GV and GC), MAP (GV with higher pressure), PaO2 (lower in GV), K+ (only one time higher in GV) and platelets, in which GC showed the lowest mean value. It can be concluded that the evaluated experimental model is efficient for hemorrhagic shock induction in dogs and requires a blood withdrawal of 42.75±9.2% of the circulating blood volume; the volemia expansion with hypertonic saline and colloid (4mL kg-1) associated or not with dopamine (10μg kg-1 min-1), dobutamine (5μg kg-1 min-1) or vasopressin (0.02IU-1 min-1) is efficient for hemodynamic recovery and metabolic stabilization; and the vasopressin group (GV), though not statistically significant, shows a more favorable clinical tendency in the recovery of hemodynamic and metabolic status in dogs submitted to experimental hemorrhagic shock. / Objetivou-se comparar os efeitos hemodinâmicos e metabólicos do tratamento com solução hipertônica e colóide (expansores) associada a diferentes vasopressores em cães submetidos a choque hemorrágico experimental. Foram utilizados 24 cães adultos, SRD, peso médio de 10,84+3,3kg, de ambos os sexos, hígidos. Os animais foram induzidos a anestesia geral por meio da vaporização de isofluorano, intubados e conectados a um sistema com reinalação parcial de gases, e anestesia geral inalatória com isofluorano em vaporizador calibrado, sendo após, mantidos em 1CAM (concentração alveolar mínima). Induziu-se a hipovolemia, por meio da retirada de 5mL kg-1 min-1 de sangue da artéria femoral, até que a pressão arterial média atingisse valores entre 45 e 50mmHg. Após 60 minutos mensurou-se os parâmetros basais e deu-se início aos tratamentos. Neste momento realizava-se o tratamento com os expansores (4ml kg-1). Após 10 minutos os animais foram alocados aleatoriamente em quatro grupos, conforme a infusão contínua que receberiam. No GD (grupo dopamina, n=06), a infusão contínua de dopamina (10μg kg-1 min-1). Os animais do GDB (grupo dobutamina, n=06), infusão contínua de dobutamina (5μg kg-1 min-1) e o GV (grupo vasopressina, n=6), vasopressina (0,02UI-1min-1) em infusão continua ambos em diluição com NaCl 0,9%. O GC (n=6), grupo controle, contou apenas com o tratamento dos expansores. Os animais foram monitorados quanto a freqüência cardíaca, freqüência respiratória, temperatura retal, pressão arterial sistólica, pressão arterial diastólica, pressão arterial média, pressão venosa central, concentração expirada de isofluorano, concentração expirada de dióxido de carbono, fração inspirada de oxigênio e, hemogasometria do sangue arterial, obtendo-se valores de PO2, PCO2, Bicarbonato, pH, Na+, K+, déficit de base, hemoglobina e hematócrito. Foram coletadas ainda amostras de sangue para avaliação de lactato sérico, tempo de tromboplastina, tempo de protrombina, plaquetas e hemograma completo. Os dados coletados foram submetidos à análise de variância, sendo que as médias entre grupos foram analisadas pelo Teste t e entre os tempos dentro do mesmo grupo pelo Teste de Tukey, sendo as diferenças consideradas estatisticamente significativas quando P0,05. Não ocorreram diferenças entre os tempos dentro de cada grupo quanto as variáveis de FC para GV e GC, PaO2, K+, VCM, CHCM, leucócitos totais (exceção de GC), bastonetes segmentados, monócitos, TP e TTPA. Ente grupos, as diferenças fixaram-se basicamente em FC (sendo que o GV e o GC, alterou com menor proporção), PAM (GV com pressão mais alta), PaO2 (GV menor), K+ (apenas um tempo com GV maior) e Plaquetas, tendo o GC o menor valor médio desta. Conclui-se que o modelo experimental, avaliado é eficiente para indução de choque hemorrágico em cães e requer uma expoliação de sangue de 42,75+9,2% do volume sanguíneo circulante; a expansão da volemia com a associação de hipertônica e colóide (4ml kg-1) associada ou não à dopamina (10μg kg-1 min-1), dobutamina (5μg kg-1 min-1) ou vasopressina (0,02UI-1min-1) é eficaz na restauração hemodinâmica e estabilização metabólica; e o grupo vasopressina (GV), embora não estatisticamente significativo, demonstra clinicamente ser mais eficaz na restauração dos padrões hemodinâmicos e metabólicos de cães induzidos a choque hemorrágico experimental.

L’optimisation hémodynamique péri-opératoire est une stratégie qui vise à maximaliser le transport artériel en oxygène et/ou le volume d’éjection systolique lors de chirurgie à risque. Ce concept a beaucoup évolué lors de ces trente dernières années, vers une approche plus simple, plus réalisable en pratique clinique et moins invasive. Les principales thérapeutiques utilisées dans les différents protocoles d’optimisation hémodynamique sont le remplissage vasculaire, l’administration d’agents inotropes et de vasopresseurs. Cependant, les conséquences physiopathologiques de l’agression chirurgicale peuvent impacter grandement les modalités d’administration et l’efficacité des thérapeutiques précitées. Dans la première étude, nous avons décrit l’impact de l’acidose respiratoire et métabolique (fréquemment rencontrées lors de chirurgie majeure et/ou de coeliochirurgie) sur l’efficacité des agents α et β-adrénergiques sur le myocarde sain de rat. Dans un deuxième travail nous avons mis en évidence que le remplissage vasculaire ne pouvait pas être guidé par des indices dynamiques de précharge dépendance lors du clampage chirurgicale de l’aorte abdominale sous-rénale, dans un modèle porcin. Enfin, dans la troisième étude, nous avons montré dans un modèle clinique, que le positionnement en décubitus ventral lors d’une chirurgie du rachis entrainait des modifications majeures des interactions cardiorespiratoires et que les indices dynamiques devaient être interprétés avec prudence pour guider le remplissage vasculaire dans ce contexte. Ces études translationnelles soulignent trois situations fréquentes impactant l’efficacité et/ou les modalités d’administration des thérapeutiques nécessaires à une optimisation hémodynamique peropératoire / The aim of perioperative haemodynamic optimization is to maximize oxygen delivery and/or stroke volume during high risk surgery. This concept has evolved during the last thirty years, to a simpler, more feasible and less invasive approach. Main treatments used in different hemodynamic optimization protocols are fluid loading, inotropes and vasopressors administration. However, pathophysiological consequences of surgical stress can greatly impact the mode of administration and the efficacy of the above therapeutics. In the first study, we described the impact of respiratory and metabolic acidosis (frequently encountered during major surgery and/or laparoscopic surgery) on the effectiveness of α and β-adrenergic agents in healthy rat myocardium. In a second work, we demonstrated that intravenous fluids cannot be guided by dynamic indices of preload dependency during surgical clamping of the infrarenal abdominal aorta in a porcine model. Finally, in the third study, we demonstrated in a clinical model, that positioning in prone position during spine surgery induced major changes in cardiorespiratory interactions and dynamic indices should be interpreted with caution to guide fluid therapy in this context. These translational studies highlight three common situations impacting the effectiveness and/or administration of therapeutic necessary for intraoperative hemodynamic optimization.