The rats of left ventrcular pressure change was significantly decreased in rabbits 1 hr after hemorrhage (P

Microscopic studies of the skin and visceral microcirculation were made in rabbits with burn shock. Based upon the observations, the development of burn shock can be divided into 3 stages, namely: stage of excitation, stage of relative compensation and stage of decompensation. In the stage of relative decompensation, there is dilatation of the venules, margination of the WBC, agglomeration of RBC, stagnation of blood flow in the microcirculation. Margination of WBC increases the post-capillary resistance, and agglomeration of RBC hinders the blood flow in the microcirculation.Consequently, the stage of decompensation ensues. Histologically, extensive congestion of the heart, liver, spleen, lungs and kidneys was found. Hemorrhage in the lungs and thrombi in the pulmonary and renal venules were found as well.We suspected that the masses of the agglomerated cells or small thrombi obstructing pulmonary vessels might be one of the direct causes leading to the temporary stagnation or slowing down of the blood flow. As the shear velocity of the blood flow increases, dissociation of the agglomerated cell masses occurs, blood pressure will be lowered temporarily and blood flow will slow down. Obstruction of the pulmonary vessels by the cell masses, therefore, may play an important part in the development of burn shock.