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• Heart block.


• Loss of deep tendon reflexes.


• Hypotension.

Hypomagnesemia

Hypomagnesemia happens when the serum magnesium level is less than
1.5 mEq/L. This can be caused by long-term administration of saline infusions
which can result in the loss of magnesium and calcium. Diuretics, certain
antibiotics, laxatives, and steroids are drug groups that promote magnesium
loss. Hypomagnesemia also enhances the action of digitalis and can cause dig-
italis toxicity.
Patients who have hypomagnesemia may exhibit no signs and symptoms
until the serum level approaches 1.0 mEq/L. Signs of severe hypomagnesemia
include tetany-like symptoms caused by hyperexcitability (tremors, twitching
of the face), ventricular tachycardia that leads to ventricular fibrillation, and
hypertension.
Treatment for hypomagnesemia includes:

• Administering intravenous magnesium sulfate in solution slowly. Use an
  infusion pump to prevent rapid infusion that might result in cardiac arrest.


• Monitoring signs of magnesium toxicity such as hot flushed skin, anxiety,
  lethargy, hypotension and laryngeal stridor.


• Monitoring EKG and pulse.


• Taking safety precautions for patients who are at risk for seizures and men-
  tal confusion.


• Increasing the dietary sources of magnesium including nuts, whole grains,
  cornmeal, spinach, bananas, and oranges.

Keep calcium gluconate available for emergency reversal of hypermagne-
semia as a result of overcorrecting hypomagnesemia.

Phosphorus

Phosphate is the primary anion inside the cell and plays a key role in the func-
tion of red blood cells, muscles, and the nervous system. Phosphate is also
involved the acid–base buffering and is involved with metabolizing carbohy-
drates, proteins, and fats. Most of the body’s phosphate (about 85%) is found in
bones. The rest of it is stored in tissues throughout the body.

CHAPTER 10 Fluid and Electrolyte Therapy^177