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NUR 200 chapter 38 Fluids, Electrolytes, and Acid- Base Balance

Key Concepts:

Terms in this set (32)

Hypovolemia occurs when there is a proportional loss of fluid and electrolytes from the ECF. Loss of blood volume is called hypovolemia.

Dehydration describes a state of negative fluid balance in which there is a loss of water (hydro water) from the intracellular, extracellular, or intravascular spaces.

Weight loss of a sudden 5% loss of body weight is considered clinically significant. When loss approaches 8%, fluid loss is severe. A sudden loss of 15% of body weight due to fluid loss is usually fatal.

The patient with fluid volume deficit usually has elevated blood urea nitrogen (BUN)-to-creatinine ratio and elevated hematocrit. Both values increase because there is less water in proportion to the solid substances being measured.


Hypervolemia: This involves excessive retention of sodium and water in the ECF. Fluid volume excess can result from excessive salt intake, disease affecting kidney or liver function, or poor pumping action of the heart. The retained sodium increases osmotic pressure in the ECF. This pressure pulls fluid from the cells into the ECF.

Overhydration: The blood pressure is elevated, pulse is bounding, and respirations are increased and shallow. The neck veins may become distended. Along with increased intravascular volume, excess ECF may accumulate in the tissues, especially in dependent areas, as edema. The skin is pale and cool. Urine output becomes dilute, and volume increases. The patient rapidly gains weight. In severe fluid overload, the patient develops moist crackles in the lungs, dyspnea, and ascites (excess peritoneal fluid). Hemodilution causes BUN, hematocrit, and the specific gravity of the urine to decrease.