The nurse caring for a client receiving intravenous magnesium sulfate must closely observe for side effects associated with drug therapy. An expected side effect of magnesium sulfate is:
A. Decreased urinary output
B. Hypersomnolence
C. Absence of knee jerk reflex
D. Decreased respiratory rate
Correct Answer: B. Hypersomnolence
The client is expected to become sleepy, have hot flashes, and be lethargic. Patients most commonly complain of minor facial flushing and warmth with the administration; however, symptoms typically resolve spontaneously. In patients with neuromuscular disease, such as in myasthenia gravis, the neuromuscular function may become worse at lower concentrations of medication.
Option A: Magnesium levels must be monitored frequently by checking serum levels every 6 to 8 hours or clinically by following patellar reflexes or urinary output. If serum concentration levels are low, a proper dose of magnesium sulfate can be given parenterally to replete low serum concentrations with recommended follow up laboratory testing.
Option C: If the patient is on a continuous magnesium sulfate infusion, serum levels must be accounted for as symptoms related to hypermagnesemia may become clinically evident. At supratherapeutic serum concentrations, absent reflexes, abnormal cardiac conduction, and muscle weakness may occur.
Option D: Decreased respirations indicate a magnesium sulfate toxicity. If patients exhibit signs and symptoms of hypermagnesemia, the recommendation is to discontinue magnesium sulfate products immediately. If the patient consumed magnesium sulfate orally, then the use of magnesium-free enemas or cathartics can be useful in removing excess magnesium from the GI tract.