The American journal of emergency medicine
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Shock is defined as inadequate circulating blood volume producing decreased peripheral vascular perfusion and cellular metabolic derangements, first in the nonvital tissues (the gastrointestinal tract, muscle, connective tissue, and skin) and later in the vital tissues (the brain, heart, lung, liver, and kidneys). This inadequate microcirculatory perfusion is the common denominator of all types of shock. Septic shock is caused by an immunologic reaction characterized by a hyperdynamic state, which produces increased cardiac output and decreased peripheral resistance. ⋯ There are no priorities; all aspects of treatment must be rendered concomitantly and rapidly. It is essential that the septic and hypovolemic processes be treated concomitantly, since preventing the complexing of antigen-antibody and complement will deter vascular permeability and its consequent hypovolemia. Prompt and adequate treatment of hypovolemia prevents the development of attendant cellular metabolic derangements.(ABSTRACT TRUNCATED AT 250 WORDS)
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Historical Article
Electrolytes and plasma volume regulation in hypovolemic shock.
The concept of hypovolemic shock and its effects on plasma volume were described in the 1700s. It has been left for more recent investigators to elucidate the role of plasma volume and its mechanisms of regulation and interaction with the interstitial and intracellular fluid spaces. ⋯ The merits and characteristics of the current fluids available for resuscitation are reviewed. The choices of fluid for resuscitation should be made with the overall goal of an efficient and effective restoration of circulating volume without producing excessive, avoidable, potentially harmful distortion of other organ systems and body fluid compartments.
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Blood loss is followed by compensatory cardiovascular readjustments that favor the maintenance of blood flow to central vital organs rather than to peripheral tissues. The microcirculatory changes that occur in skeletal muscle in shock states are of major importance, since skeletal muscle is not only the largest cell mass of the body but also one of the major target organs for neurohumorally mediated compensatory vascular readjustments. Intravital microscopic studies show that the microvascular blood flow in skeletal muscle is intermittent in the early posthemorrhagic period. ⋯ Obstruction of many capillaries by white blood cells and their slow passage through other capillaries seem to be the main reasons for the maldistribution of capillary blood flow in shock. Red blood cell aggregates obstructing capillary blood flow are not seen. The heterogeneous tissue perfusion is accompanied by local variations in cellular hypoxic injury, as is evidenced by multifocal measurements of tissue oxygen tension and by cellular transmembrane potential registrations.(ABSTRACT TRUNCATED AT 250 WORDS)