Correct Answer: A

Rationale: Corrected Rationale: An electrocardiogram (ECG) should be performed first to assess for cardiac ischemia in a client with a history of myocardial infarction and chest pain. An ECG provides immediate information about the heart's electrical activity, helping to identify changes indicative of cardiac ischemia or infarction. Chest X-ray (Choice B) is not the initial diagnostic test for assessing chest pain related to myocardial infarction. Arterial blood gases (Choice C) are used to assess oxygenation and acid-base balance but are not the primary diagnostic test for myocardial infarction. An echocardiogram (Choice D) may provide valuable information about cardiac structure and function, but it is not the first-line diagnostic test for acute chest pain in a client with a history of myocardial infarction.

Correct Answer: A

Rationale: An INR of 3.0 is most concerning in a client prescribed warfarin (Coumadin) as it indicates a high risk of bleeding, requiring immediate intervention. A high INR value suggests that the blood is taking longer to clot, putting the patient at an increased risk of hemorrhage. Prothrombin time (PT) measures how long it takes for blood to clot, but the specific value of 15 seconds is within the normal range. Hemoglobin of 10 g/dl indicates mild anemia and does not directly relate to the risk of bleeding associated with warfarin therapy. White blood cell count assesses immune function and infection risk, but it is not directly related to the anticoagulant effects of warfarin.

Correct Answer: B

Rationale: The correct answer is B: Serum creatinine. Aminoglycosides, such as gentamicin, are known to cause nephrotoxicity, which can lead to kidney damage. Monitoring serum creatinine levels is crucial in assessing renal function and detecting any potential kidney problems early. Choices A, C, and D are incorrect because urinalysis primarily assesses urine composition, serum osmolarity measures the concentration of solutes in the blood, and liver enzymes are not directly impacted by aminoglycoside antibiotics like gentamicin.

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. This medication can have anticholinergic effects, leading to these symptoms. 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 correct answer is C. Crackles in the lungs indicate fluid overload, a common issue in heart failure patients. Immediate intervention is necessary to prevent worsening heart failure symptoms and potential complications. A heart rate of 60 beats per minute and a blood pressure of 100/60 mmHg are within normal ranges for many individuals and do not typically require immediate intervention in this context. The presence of a new murmur may be important to monitor but is not the priority when crackles in the lungs suggest fluid overload.