A nurse is caring for a client who has hypomagnesemia and is receiving intravenous (IV) magnesium replacement.
Which of the following findings indicates the client is experiencing magnesium toxicity?
Presence of nystagmus.
Kussmaul's respirations.
The client becomes lethargic.
Hypoactive bowel sounds in all quadrants.
The Correct Answer is C
Choice A rationale
Nystagmus, or involuntary rapid eye movements, is actually a clinical sign associated with hypomagnesemia rather than magnesium toxicity. Low magnesium levels lead to neuromuscular hyperexcitability because magnesium normally acts as a calcium channel blocker; its absence allows for increased acetylcholine release at the neuromuscular junction. Normal serum magnesium levels range from 1.3 to 2.1 mEq/L. Since nystagmus reflects an irritable nervous system, it indicates that the magnesium deficiency has not yet been corrected or has become severe.
Choice B rationale
Kussmaul's respirations are deep, rapid, and labored breathing patterns typically seen in patients with metabolic acidosis, such as diabetic ketoacidosis. This respiratory pattern is a compensatory mechanism to blow off excess carbon dioxide and is not a characteristic finding of hypermagnesemia. In contrast, magnesium toxicity causes central nervous system depression, leading to respiratory depression or a decreased respiratory rate rather than the hyperventilation seen in Kussmaul's. This finding would point toward a different metabolic or acid-base emergency.
Choice C rationale
Lethargy is a hallmark sign of magnesium toxicity, reflecting the sedative effect of high magnesium levels on the central nervous system. As magnesium levels rise above the normal range of 1.3 to 2.1 mEq/L, the mineral acts as a potent depressant. This occurs because excess magnesium inhibits the release of neurotransmitters and reduces the sensitivity of the postsynaptic membrane. If levels continue to rise, this lethargy can progress to a loss of deep tendon reflexes, coma, and cardiac arrest.
Choice D rationale
While magnesium can affect smooth muscle motility, hypoactive bowel sounds are not the primary or definitive indicator of magnesium toxicity used in clinical monitoring. Hypermagnesemia typically causes systemic muscle weakness and vasodilation. A more classic gastrointestinal symptom of magnesium administration is diarrhea, as magnesium acts as an osmotic laxative. The nurse should prioritize assessing neurological status, deep tendon reflexes, and respiratory rate over bowel sounds when specifically monitoring for life-threatening magnesium toxicity during an active intravenous infusion.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale
Freezing insulin is dangerous because it causes the proteins to denature and lose their physiological activity. When insulin molecules are subjected to temperatures below 0 degrees Celsius, the structural integrity of the hormone is permanently compromised. This results in unpredictable glycemic control and potential crystallization. Patients must be taught that once insulin has been frozen, it must be discarded immediately, even if it has thawed, because its potency is gone.
Choice B rationale
Storing backup medical supplies in a vehicle is inappropriate due to extreme temperature fluctuations that occur within a car. Insulin is a sensitive protein that degrades when exposed to excessive heat or cold. High temperatures can cause the insulin to clump or lose its effectiveness, leading to hyperglycemia. Medical supplies like glucose monitors and test strips are also sensitive to environmental stressors, which can lead to inaccurate readings and unsafe clinical decisions.
Choice C rationale
Not all insulin types are compatible for mixing within a single syringe. While intermediate-acting NPH can often be mixed with rapid-acting or short-acting insulins, long-acting basal insulins like glargine or detemir must never be mixed. These long-acting analogs have a specific pH that maintains their slow-release properties. Mixing them with other insulins alters their pH and changes their absorption rate, which significantly increases the risk of unpredictable hypoglycemia or poor glucose management.
Choice D rationale
Most insulin vials and pens currently in use remain stable and potent at room temperature, typically between 15 and 30 degrees Celsius, for approximately 28 to 30 days. This practice helps reduce local tissue irritation and injection site discomfort that often occurs when injecting cold insulin. After one month at room temperature, the preservative and the insulin protein itself begin to degrade, necessitating the disposal of any remaining medication to ensure patient safety.
Correct Answer is ["0.8"]
Explanation
Step 1 is 100 mg ÷ 250 mg = 0.4.
Step 2 is 0.4 × 2 mL = 0.8. Final calculated answer is 0.8 mL
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