Correct Answer: A

Rationale: Administering oxygen therapy is the initial priority in managing chest pain in a client with a history of myocardial infarction. Oxygen therapy helps improve oxygenation, which is crucial in reducing myocardial damage. While administering aspirin and nitroglycerin are essential interventions in the treatment of myocardial infarction, oxygen therapy takes precedence because it addresses the immediate need for oxygen supply to the heart muscle. Obtaining an ECG is important but can be done after ensuring adequate oxygenation.

Correct Answer: A

Rationale: The correct answer is A: Nausea and indigestion. Diphenhydramine, an antihistamine, commonly causes gastrointestinal side effects such as nausea and indigestion. These symptoms are often reported by individuals taking this medication. Choices B, C, and D are incorrect because hypersalivation, eyelid and facial twitching, and increased appetite are not typically associated with diphenhydramine use.

Correct Answer: C

Rationale: The INR should be closely monitored in a client prescribed warfarin (Coumadin) to assess the effectiveness and safety of anticoagulation therapy. Monitoring the INR helps determine if the client's blood is clotting appropriately. While prothrombin time (PT) is related to warfarin therapy, the INR is a more precise measure. Hemoglobin level and serum sodium level are not directly related to monitoring warfarin therapy.

Correct Answer: C

Rationale: When the PR interval is prolonged, it signifies an increased conduction time from the SA node through the AV junction. This finding is characteristic of a first-degree heart block where there is a delay in the electrical conduction at the level of the AV node. Choices A, B, and D are incorrect as they do not accurately reflect the significance of a prolonged PR interval.

Correct Answer: B

Rationale: The correct answer is B. A serum potassium level of 6.5 mEq/L is dangerously high and should be reported before hemodialysis to prevent cardiac complications. High potassium levels can lead to life-threatening arrhythmias. Serum creatinine (Choice A) is elevated in renal dysfunction but not the most critical value to report before hemodialysis. Serum calcium (Choice C) and serum bicarbonate (Choice D) levels are within normal limits and are not immediate concerns before hemodialysis.