cardiopulmonary resuscitation. Potassium must be diluted in IV fluids as stated
above. Don’t give potassium if the patient suffers from renal insufficiency, renal
failure, or Addison’s disease. Do not give potassium if the patient has hyper-
kalemia, severe dehydration, acidosis, or takes potassium-sparing diuretics. Use
with caution with patients who have cardiac disorders or burns.Sodium
Sodium is the major cation in extracellular fluid found in tissue spaces and ves-
sels. Sodium plays an important role in the regeneration and transmission of
nerve impulses and affects water distribution inside and outside cells. It is part
of the sodium/potassium pump that causes cellular activity. When it shifts into
the cell, depolarization (contraction) occurs; when it shifts out of the cell, potas-
sium goes back into the cell and repolarization (relaxation) occurs. Sodium also
combines readily in the body with chloride (Cl) or bicarbonate (HCO 3 ) to pro-
mote acid-base balance (pH).
The patient receives sodium when food is absorbed in the GI tract. Typically,
a patient takes in more sodium than the patient’s daily requirement. The kidneys
regulate the sodium balance by retaining urine when the sodium concentration
is low and excreting urine when the sodium concentration is high. Most excess
sodium is excreted in urine although sodium also leaves the patient as perspira-
tion and in feces.
The serum sodium level, which is the ratio of sodium to water, is the indicator
of the sodium level in a patient’s body. Sodium is measured in milliequivalents
per liter (mEq/L). The normal range of serum sodium is from 135 mEq/L to
145 mEq/L.
A patient’s serum sodium level moves out of the normal range when the patient
is retaining too much or too little water, has a high or low concentrations of sodium,
or a combination of both. A patient is hypernatremic when there is a high concen-
tration of sodium and hyponatremic when there is a low concentration of sodium.Hypernatremia
Hypernatremia occurs when the patient’s serum sodium is greater than 145 mEq/L.
This happens for one of two reasons: The patient’s sodium concentration has
increased while the volume of water remains unchanged or the patient’s water
volume has decreased while the sodium concentration remains unchanged.
Regardless of what happened, the patient experiences hyperosmolality, which
is a higher-than-normal concentration of sodium. This causes water to shift out
of cells and into extracellular space resulting in cellular dehydration. A patient
who is alert and can drink water to quench a thirst is at less risk for hyperna-(^168) CHAPTER 10 Fluid and Electrolyte Therapy