Correct Answer: A

Rationale: The correct answer is A: Atrial fibrillation. In thyroid storm, excess thyroid hormone levels can lead to increased sympathetic activity, causing tachycardia and arrhythmias like atrial fibrillation. Atrial fibrillation is common in thyroid storm due to the hypermetabolic state and increased risk of atrial arrhythmias. Other choices are incorrect: B (Idioventricular rhythm) is not typically associated with thyroid storm, C (Junctional rhythm) is less likely since atrial arrhythmias are more common, and D (Sinus bradycardia) is unlikely due to the hypermetabolic state causing tachycardia.

Correct Answer: A

Rationale: The correct answer is A: administration of a 1-L normal saline fluid bolus. In this scenario, the patient is likely experiencing diabetic ketoacidosis (DKA) due to the extremely high glucose levels, low bicarbonate, and anion gap metabolic acidosis. The priority is to correct the dehydration and electrolyte imbalances through fluid resuscitation with normal saline to improve perfusion and reverse the metabolic derangements. Options B, C, and D do not address the immediate need for volume resuscitation and correction of dehydration. Administering insulin or potassium without first addressing the fluid deficit could lead to further complications. Sodium bicarbonate is not recommended in DKA as it can worsen acidosis and has not been shown to improve outcomes.

Correct Answer: C

Rationale: The correct answer is C, Serum sodium 115 mEq/L. In syndrome of inappropriate secretion of antidiuretic hormone (SIADH), there is excess release of ADH leading to water retention and dilutional hyponatremia. Low serum sodium levels (hyponatremia) are characteristic of SIADH due to water retention without proportional sodium retention. Choices A and B are not indicative of SIADH. Choice D, high serum sodium, is more likely in conditions causing dehydration or excessive sodium intake.

Correct Answer: B

Rationale: The correct answer is B because peritoneal dialysis uses the patient's own semipermeable membrane, the peritoneal membrane, to filter waste and excess fluid from the blood. This membrane allows for the exchange of fluids and solutes, making it an effective method for dialysis. A is incorrect because peritoneal dialysis can be used for acute kidney injury. C is incorrect as peritoneal dialysis can address drug overdose and electrolyte imbalance by removing toxins and balancing electrolytes. D is incorrect as peritoneal dialysis can be used in cases of water intoxication by helping to remove excess fluid from the body.

Correct Answer: A

Rationale: The correct answer is A because acute kidney injury from postrenal etiology is caused by obstruction of the flow of urine, leading to back pressure and damage to the kidneys. Choices B and C relate to prerenal causes, affecting renal perfusion and volume status. Choice D refers to intrinsic renal causes, directly affecting kidney tissue function, not postrenal obstruction. Therefore, A is correct due to the nature of postrenal etiology.