A patient with congestive heart failure and pulmonary edema is experiencing chest pain.
The patient has been prescribed morphine sulfate IV 4 mg every 5-30 minutes as needed until chest pain subsides.
The last dose of 4 mg was administered 15 minutes ago, and the patient is still complaining of chest pain and showing signs of increased respiratory effort.
The nurse observes a heart rate of 82 beats per minute, a respiratory rate of 18 breaths per minute, and a blood pressure of 135/88 mm Hg. What should the nurse do next?

Choice A rationale:

COPD (Chronic Obstructive Pulmonary Disease) is a chronic lung disease that causes airflow obstruction. While labetalol can cause some bronchoconstriction, it is generally considered safe for use in patients with COPD. However, it's essential to monitor respiratory status closely, especially in those with severe COPD.

Choice B rationale:

Narrow-angle glaucoma is an eye condition characterized by increased intraocular pressure (IOP) due to impaired drainage of aqueous humor. Labetalol can exacerbate this condition by further increasing IOP through its beta-blocking effects. This can lead to acute angle-closure glaucoma, a medical emergency that can result in permanent vision loss.

Specific mechanisms by which labetalol can increase IOP:

Reduced aqueous humor production: Beta-blockers like labetalol can decrease the production of aqueous humor, the fluid that maintains eye pressure. While this might seem beneficial, a significant reduction can lead to anterior chamber shallowing, which can mechanically block the drainage angle and trigger angle closure.

Impaired uveoscleral outflow: Beta-blockers can also impair the uveoscleral outflow pathway, an alternative route for aqueous humor drainage that becomes more important in glaucoma patients. This can further contribute to IOP elevation.

Vasoconstriction of ciliary blood vessels: Labetalol's alpha-blocking effects can cause vasoconstriction of the ciliary blood vessels, which supply blood to the ciliary body responsible for aqueous humor production. This can reduce blood flow and indirectly hinder aqueous humor drainage.

Pupillary dilation: Beta-blockers can cause pupillary dilation, which can mechanically narrow the anterior chamber angle and obstruct aqueous humor outflow.

Therefore, labetalol is generally contraindicated in patients with known narrow-angle glaucoma.

Choice C rationale:

Hypertension (high blood pressure) is one of the primary indications for labetalol. It is an effective antihypertensive medication that works by blocking beta receptors, leading to decreased heart rate, contractility, and blood pressure.

Choice D rationale:

Tachycardia (fast heart rate) can also be treated with labetalol due to its beta-blocking effects. It helps to slow down the heart rate and restore a normal rhythm.

Choice A rationale:

Glucagon directly addresses the underlying issue of severe hypoglycemia: In a patient with Type 1 diabetes mellitus, a blood glucose level of 40 mg/dL signifies a critical condition known as severe hypoglycemia. This condition occurs when blood sugar levels drop dangerously low, depriving the brain and other vital organs of glucose, their primary source of energy. Glucagon, a hormone that acts opposite to insulin, is the most effective and rapid treatment for severe hypoglycemia. It works by stimulating the liver to release stored glucose into the bloodstream, quickly raising blood sugar levels and restoring normal brain function.

Rationale for other choices:

Choice B: Give orange juice: While orange juice contains carbohydrates that can raise blood sugar, it is not ideal for treating severe hypoglycemia due to its slower absorption rate compared to glucagon. In an unconscious patient, there's also a risk of aspiration if given orally.

Choice C: Perform CPR: CPR is not indicated in this scenario as the patient has a pulse. CPR is a lifesaving technique that is only used when a person's heart has stopped beating.

Choice D: Give insulin: Insulin, which lowers blood glucose, would be contraindicated in this situation as the patient is already experiencing severe hypoglycemia. Administering insulin would further decrease blood sugar levels, worsening the patient's condition.

Key points to remember:

Severe hypoglycemia is a medical emergency that requires prompt treatment with glucagon.

Glucagon is the only medication that can effectively and quickly raise blood glucose levels in severe hypoglycemia. It's crucial to administer glucagon as soon as possible to prevent irreversible brain damage or even death.

Healthcare professionals should be proficient in recognizing the signs and symptoms of severe hypoglycemia and administering glucagon appropriately.