Which of the following medications does the nurse identify as a calcium channel blocker used to treat tachycardia and manage heart rate?

Choice A rationale:

Calcium gluconate is the antidote for magnesium sulfate toxicity. It directly counteracts the effects of magnesium on the neuromuscular system, cardiovascular system, and central nervous system. It is essential to have calcium gluconate readily available at the bedside of any client receiving magnesium sulfate, as toxicity can occur quickly and without warning.

Mechanism of action:

Calcium gluconate competes with magnesium for binding sites on cell membranes and proteins. It displaces magnesium from these sites, thereby restoring normal cellular function.

Calcium gluconate also enhances calcium influx into cells, which further counteracts the effects of magnesium. Indications for use in magnesium sulfate toxicity:

Respiratory depression (respiratory rate <12 breaths per minute) Loss of deep tendon reflexes

Seizures

Cardiac arrhythmias (including heart block and cardiac arrest) Hypotension (systolic blood pressure <90 mmHg)

Dosage and administration:

The typical dose of calcium gluconate for magnesium sulfate toxicity is 1 gram (10 mL of a 10% solution) given IV push over 3- 5 minutes.

This dose may be repeated as needed, depending on the severity of the toxicity and the client's response to treatment. Nursing considerations:

Monitor the client's vital signs, respiratory status, and deep tendon reflexes closely during magnesium sulfate infusion and after administration of calcium gluconate.

Have a crash cart and code equipment readily available in case of cardiac arrest. Document the administration of calcium gluconate and the client's response to treatment.

Choice A rationale:

Respiratory distress is not a direct side effect of metformin. While metformin can cause a rare condition called lactic acidosis, which can lead to rapid breathing, respiratory distress is not a primary concern with metformin use.

Respiratory distress typically involves difficulty breathing due to other causes such as asthma, pneumonia, heart failure, or chronic obstructive pulmonary disease (COPD).

Choice B rationale:

Seizures are not a known side effect of metformin.

Seizures are typically associated with neurological conditions, such as epilepsy, or metabolic disturbances such as hypoglycemia or electrolyte imbalances.

Metformin does not directly affect the central nervous system in a way that would increase the risk of seizures.

Choice C rationale:

Lactic acidosis:

This is a rare but serious condition that can occur with metformin use.

It happens when lactic acid builds up in the bloodstream, causing the blood to become too acidic. Symptoms of lactic acidosis include:

Rapid breathing Nausea and vomiting Abdominal pain Muscle weakness Unusual sleepiness Feeling cold

Risk factors for lactic acidosis in patients taking metformin include:

Kidney disease Congestive heart failure Liver disease Dehydration

Excessive alcohol intake Recent surgery or heart attack

It's important to note that lactic acidosis is rare, occurring in about 3 to 10 cases per 100,000 people taking metformin per year.

Renal failure:

Metformin is primarily eliminated by the kidneys.

If kidney function is impaired, metformin can build up in the body, increasing the risk of lactic acidosis. Additionally, metformin can potentially cause kidney damage in rare cases, further worsening kidney function. It's crucial to monitor kidney function regularly in patients taking metformin.

Choice D rationale:

Hyperglycemia (high blood sugar) is not a side effect of metformin.

In fact, metformin is a medication used to lower blood sugar levels in people with type 2 diabetes. It works by:

Decreasing the amount of glucose produced by the liver Improving the body's sensitivity to insulin

Slowing the absorption of glucose from the intestines