Online Companion: Fundamentals of Nursing Standards and Practice 2E

Frequently Asked Questions

How does capillary permeability affect movement of fluids?

Capillary integrity provides the basis for the movement of fluids and electrolytes across the cell membrane. If there is increased capillary permeability then substances can freely cross the cell membrane leading to shifting of body fluids and electrolytes. Conditions that increase capillary permeability include burns, shock or trauma states where cellular integrity is altered or damaged. If there is decreased capillary permeability then there is no effective net movement of substances and homeostatic mechanisms are maintained.

What are the components of fluid assessment that are critical in assessing fluid status?

In order to make an accurate assessment of a client’s fluid status, the following components must be included: daily weight, intake parameters related to fluid intake, fluid content of foods ingested and fluid (water) formed by the oxidation process, and output parameters related to urinary excretion via the kidneys, water loss by the lungs, skin and gastrointestinal tract. The nurse must make sure to account for all components of fluid intake and output in order to make accurate assessment. Diagnostic labs such as calculation of serum osmolality and serum chemistries (electrolytes) will also help to complete the clinical assessment.

How do the different buffer systems help to regulate acid-base balance in the body?

The body has several buffer systems to help accomplish the task of maintaining a normal pH range in the body so that metabolic and respiratory homeostasis can be maintained. The bicarbonate-carbonic acid system represents the body’s primary buffer system. This bicarbonate system helps to maintain normal pH range by effectively responding to changes in the hydrogen ion concentration in the extracellular fluid. The respiratory buffer system is controlled by the amount of carbon dioxide present in the extracellular fluid. This response operates quickly and is the body’s initial mechanism to maintain normal pH. The kidneys control the metabolic response to the amount of hydrogen ion concentration. This response is slower to occur but is more effective in maintaining a normal pH. All of these buffer systems function together in order to assist the client in compensation and restoration of normal pH values.

Name the three different types of parenteral IV solutions with regard to tonicity and explain how they are utilized in the clinical setting.

The three different types of parenteral IV solution defined according to tonicity are isotonic, hypotonic and hypertonic solutions. Isotonic solutions have the same concentration as normal plasma and therefore increase the extracellular volume. Isotonic fluids are used to hydrate the client who is volume depleted. Excessive administration of isotonic fluids can lead to cardiac compromise. Hypotonic solutions have a decreased plasma osmolality, lower the osmotic pressure and cause fluid shifting into the cell leading to cellular swelling. Hypotonic solutions are indicated when there is cellular dehydration. Hypertonic solutions have an increased plasma osmolality, increase the osmotic pressure and move fluid out of the cells. Hypertonic solutions are indicated where there are edema states. Excessive or improper administration of hypotonic or hypertonic solutions can lead to fluid shifting with compromised client outcomes. It is critical that IV solutions be properly administered and the client continually monitored so as to prevent potential signs of fluid compromise.