[Early hemodynamic effects of the rapid infusion of sodium chloride Dextran-70 hypertonic solution as treatment for hemorrhagic shock in dogs]. / Efeitos hemodinâmicos imediatos da infusão rápida de solução hipertônica de cloreto de sódio-dextran-70 para tratamento de choque hemorrágico em cães.

PURPOSE: To study the early hemodynamic effects of the rapid infusion of 7.5g/dl NaCl/ 6g/dl dextran-70 solution in dogs submitted to hemorrhagic shock. METHODS: Mongrel dogs were anesthetized with pentobarbital and a electromagnetic flowmeter probe was placed around the ascending aorta or the portal vein. By external bleeding the arterial pressure was lowered to 40mmHg and held for 30min. The animals received a 4ml/kg infusion of the hypertonic solution in 90s. Arterial blood pressure and flow were registered continuously during 3min and the derived hemodynamic variables were calculated at regular time intervals. RESULTS: The total plasma protein concentration decreased and the cardiac output showed a continuous elevation during the infusion. The arterial blood pressure showed two oscillations and then decreased during a short period of time. This moment was coincident with the initial increase of the portal flow and preceded the elevation of the systemic vascular resistance and the arterial pressure. CONCLUSION: The rapid infusion of hypertonic NaCl/dextran solution to dogs in hemorrhagic shock determines immediate and intense hemodynamic effects. During the infusion period there is volemic expansion and the cardiac output increases rapidly. The arterial pressure shows oscillations and decreases as a consequence of visceral arterial dilation before starting its final elevation that occurs as the vascular resistance increases.

[Ligation of the right coronary artery in dogs. Hemodynamic and pathological effects]. / Ligadura da artéria coronária direita do cão. Efeitos hemodinâmicos e patológicos.

PURPOSE: To assess the hemodynamic and pathologic effects of the right coronary artery occlusion in anesthetized dogs submitted to pericardiotomy. METHODS: Ten mongrel dogs were anesthetized with pentobarbital and submitted to a right thoracotomy, pericardiotomy and ligation of the right coronary artery. The pericardium was kept opened throughout the entire experiment. The circulatory pressures and the cardiac output were determined twice before and three times after the right coronary artery ligation. The hearts were then excised, barium was injected in the coronary arteries and radiographs were taken to confirm the artery occlusion. Three dogs were kept alive to later pathologic examination of the hearts. RESULTS: The observation of the radiographs showed proximal occlusion of the right coronary artery and absence of the right ventricle free wall vascularization. There was ischemic necrosis of about three quarters of this area, whereas the septum was normal. The cardiac index and the systemic mean arterial decreased 14% without significant variation of the central venous and the pulmonary artery pressures, although marked right ventricular dilation was observed. CONCLUSION: The proximal right coronary artery ligation in the dog determines ischemia and infarction of the right ventricular free wall, without affecting the interventricular septum. There are few hemodynamic consequences with open pericardium and at rest.