Correct Answer: A

Rationale: Acetylcholine is the correct answer. It is a neurotransmitter released by the parasympathetic nervous system that can decrease heart rate. Norepinephrine, dopamine, and serotonin are neurotransmitters that usually have different effects on the body and are not specifically associated with decreasing heart rate. Norepinephrine, for example, is often related to the fight-or-flight response and can increase heart rate.

Correct Answer: A

Rationale: The correct answer is to hold the beta blocker and notify the healthcare provider. A heart rate of 52 bpm is low, and beta blockers can further decrease the heart rate, potentially causing harm. Therefore, withholding the medication and promptly informing the healthcare provider is crucial for further assessment and possible adjustment of the treatment plan. Administering the beta blocker as ordered (Choice B) can exacerbate the bradycardia. Increasing the dose of the beta blocker (Choice C) would further suppress the heart rate. Continuing to monitor the client and reassessing in 30 minutes (Choice D) might delay necessary interventions and increase the risk of complications in a client with a heart rate of 52 bpm.

Correct Answer: A

Rationale: Oxygen therapy is the correct answer because it specifically refers to a treatment that delivers high concentrations of oxygen to the lungs. This therapy is used for patients who require additional oxygen due to conditions affecting their breathing. Ventilator therapy (B), mechanical ventilation (C), and CPAP therapy (D) involve different mechanisms and purposes than delivering high concentrations of oxygen to the lungs.

Correct Answer: B

Rationale: The correct answer is to hold the digoxin and notify the healthcare provider. A potassium level of 3.0 mEq/L indicates hypokalemia, which can increase the risk of digoxin toxicity. Digoxin and low potassium levels can lead to serious cardiac arrhythmias. Administering a potassium supplement (choice A) without healthcare provider guidance can worsen the situation. Continuing the current digoxin dose (choice C) can further increase the risk of toxicity. Administering Digibind (choice D) is used in severe cases of digoxin toxicity, not for addressing low potassium levels.

Correct Answer: A

Rationale: The correct answer is A: Arrhythmia. Arrhythmia is a broad term that refers to any irregularity in the heart's rhythm, which can manifest as a heartbeat that is too fast (tachycardia), too slow (bradycardia), or irregular. Choice B, Bradycardia, specifically denotes a slow heart rate, while choice C, Tachycardia, refers to a fast heart rate. Choice D, Conductivity, is not the correct term to describe an abnormal heartbeat characterized by speed irregularities.