Intravascular volume expansion, excessive

Intravascular volume expansion is a major pathogenic factor in renal parenchymal hypertension. In these patients, excessive renin secretion relative to volume status and heightened sympathetic nerve activity are observed, and those contribute to hypertension in patients with renal injury. Potential mechanisms include afferent stimuli from the injured kidneys to the brain, reduced central dopaminergic tone, reduced baroreceptor sensitivity, abnormal vagal function and endothelial dysfunction in patients with renal dysfunction [45, 46, 49],... 

Hydroxyethyl starch has been widely used as plasma volume expander in bleeding patients. Each product is characterized by its molecular weight, concentration, molar substitution, origin, and solvent [44. Adverse reactions include excessive intravascular volume expansion, metabolic acidosis, anaphylaxis, renal dysfunction, hepatic dysfunction, and coagulopathy [45 ]. It has been suggested that adapting the formulation to the... 

Albumin 5% and 25% concentrations are available. It takes approximately three to four times as much lactated Ringer s or normal saline solution to yield the same volume expansion as 5% albumin solution. However, albumin is much more costly than crystalloid solutions. The 5% albumin solution is relatively iso-oncotic, whereas 25% albumin is hyperoncotic and tends to pull fluid into the compartment containing the albumin molecules. In general, 5% albumin is used for hypovolemic states. The 25% solution should not be used for acute circulatory insufficiency unless diluted with other fluids or unless it is being used in patients with excess total body water but intravascular depletion, as a means of pulling fluid into the intravascular space. 

Proper attention to plasma expansion must be continued into the intraoperative and postoperative periods. A number of neurohormonal changes take place that affect urine output, and patients may have substantial third-spacing of fluid depending on the operation and the preexisting condition of the patient. Furthermore, postoperative patients are prone to hyponatremia from renal generation of electrolyte-free water and from antidiuretic hormone release. As in acute resuscitation, the administration of hypotonic solutions in the perioperative period does not prevent the decrease in extracellular volume that often occurs. Therefore, although excess fluid administration is to be avoided in the perioperative setting, isotonic crystalloid solutions should be used when fluids are indicated to prevent intravascular depletion and circulatory insufficiency. 

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