Continuous venovenous hemofiltration is used to

Correct Answer: A

Rationale: The correct answer is A because continuous venovenous hemofiltration primarily removes fluids and solutes through convection. Convection involves the movement of solutes across a semi-permeable membrane by the force of the fluid flow. This process helps to achieve fluid balance and manage electrolyte levels in patients with renal failure. Choice B is incorrect because hemofiltration does not specifically target plasma water; it aims to remove both fluids and solutes. Choice C is incorrect as hemofiltration does not involve adding dialysate; it relies on the patient's blood passing through a filter to remove waste products. Choice D is incorrect because while hemofiltration may involve aspects of ultrafiltration and dialysis, the primary mechanism is convection for removing fluids and solutes.

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 renal dysfunction is a common issue in critically ill patients due to factors like sepsis or hypoperfusion. This affects nearly two thirds of patients, leading to potential complications. Choice A is incorrect as renal dysfunction is common, not rare. Choice C is incorrect as mortality rates can still be high even with renal replacement therapy. Choice D is incorrect as renal dysfunction can significantly impact morbidity, mortality, and quality of life in critically ill patients.

Correct Answer: D

Rationale: Correct Answer: D Rationale: In diabetic emergencies, starting IV dextrose at 250 mg/dL prevents hypoglycemia while resolving ketoacidosis. Below 250 mg/dL, the body can use endogenous glucose, so IV dextrose is not necessary. Summary: A: Incorrect. Normal saline may be used for initial fluid resuscitation but does not address the need for glucose. B: Incorrect. Starting dextrose at 70 mg/dL may lead to unnecessary hyperglycemia and complications. C: Incorrect. Waiting until 150 mg/dL delays the provision of necessary glucose for metabolic functions.

Correct Answer: A

Rationale: The correct answer is A: Sodium polystyrene sulfonate. It works by exchanging sodium ions for potassium ions in the colon, leading to potassium excretion. A is the safest option without the risk of causing hypernatremia or intestinal necrosis like B. Regular insulin (C) may cause hypoglycemia and is not as effective as A in reducing potassium levels. Calcium gluconate (D) does not directly reduce potassium levels and is used for treating hyperkalemia-related cardiac toxicity.

Correct Answer: C

Rationale: The correct answer is C: intrarenal disease, probably acute tubular necrosis. The presence of coarse, muddy brown granular casts and hematuria in the urinalysis indicates damage to the renal tubules, which is characteristic of acute tubular necrosis. This condition is a type of intrarenal disease where there is direct damage to the kidney tubules, leading to decreased urinary output and symptoms like malaise and fatigue. Prerenal and postrenal conditions do not typically present with granular casts and hematuria, making choices A and B incorrect. Urinary tract infection is also unlikely to cause the specific findings seen in this case, ruling out choice D. Therefore, choice C is the most appropriate based on the urinalysis results and clinical presentation.

Correct Answer: A

Rationale: The correct answer is A. Bladder catheterization helps relieve urinary obstruction, a common postrenal cause of acute kidney injury. It allows urine to drain freely from the bladder. - B: Increasing fluid volume intake may worsen the condition by increasing the pressure on the obstructed kidneys. - C: Ureteral stenting is used for intrarenal causes, not postrenal causes. - D: Placement of nephrostomy tubes bypasses the obstruction but is usually reserved for more severe cases.

Correct Answer: A

Rationale: The correct answer is A: Heredity. Nephrogenic diabetes insipidus can be inherited as a genetic condition. The mutation in genes responsible for regulating water balance in the kidneys can lead to this disorder. Other choices are incorrect: B: Medications like lithium can cause acquired nephrogenic diabetes insipidus, not its development. C: Meningitis is an inflammatory condition that does not directly relate to nephrogenic diabetes insipidus. D: Pituitary tumors are associated with central diabetes insipidus, not nephrogenic.

Correct Answer: A

Rationale: The correct answer is A: Cerebral salt wasting. This is indicated by the low serum sodium level (115 mEq/L), which can occur in patients with head trauma and lead to excessive sodium loss through the kidneys. This results in hypovolemia, leading to low blood pressure and tachycardia. The elevated BUN (50 mg/dL) and creatinine (8 mg/dL) levels suggest dehydration and renal impairment due to volume depletion. The patient's poor skin turgor, dry mucous membranes, confusion, and restlessness further support the diagnosis of cerebral salt wasting. Summary: B: Diabetes insipidus is characterized by excessive urination and thirst due to insufficient production of antidiuretic hormone (ADH). This patient's symptoms are not consistent with diabetes insipidus. C: Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is characterized by excessive release of ADH, leading to water retention and