Correct Answer: C

Rationale: Rationale: 1. Acute tubular necrosis (ATN) is the most common intrarenal condition as it directly affects kidney tubules. 2. ATN is characterized by damage to renal tubular cells due to various factors like toxins or ischemia. 3. Prolonged ischemia (choice A) can lead to ATN but is not the most common intrarenal condition. 4. Exposure to nephrotoxic substances (choice B) can cause ATN, but ATN itself is more common. 5. Hypotension for several hours (choice D) can result in ischemia and subsequent ATN, but ATN is still the primary intrarenal condition.

Correct Answer: C

Rationale: The correct interpretation is uncompensated respiratory acidosis (Choice C) based on the values. Step 1: Evaluate pH - pH is <7.35, indicating acidosis. Step 2: Determine PaCO2 - PaCO2 is >45 mmHg, indicating respiratory cause. Step 3: Check HCO3- - HCO3- is within normal range, indicating uncompensated state. Choices A, B, and D are incorrect because they do not align with the given blood gas values.

Correct Answer: A

Rationale: The correct answer is A because in ARDS, there is a severe impairment in gas exchange leading to hypoxemia. Decreasing PaO2 levels despite increased FiO2 administration indicate poor oxygenation, a hallmark of ARDS. Elevated alveolar surfactant levels (Choice B) do not directly correlate with ARDS pathophysiology. Increased lung compliance with increased FiO2 administration (Choice C) is not characteristic of ARDS, as ARDS leads to decreased lung compliance. Respiratory acidosis associated with hyperventilation (Choice D) is not a typical finding in ARDS, as hyperventilation is usually present in an attempt to compensate for hypoxemia.

Correct Answer: D

Rationale: The correct answer is D: Adequate pain control. Pain can significantly disrupt sleep in critically ill patients. By ensuring adequate pain control, the nurse can help improve the patient's ability to rest and sleep. This intervention targets a key factor affecting sleep cycles in critically ill patients. Repositioning every 2 hours (A) may help prevent pressure ulcers but does not directly address sleep improvement. Hypnotic medications (B) may have adverse effects and are not recommended as a first-line intervention. Five-minute back effleurage (C) may provide temporary relaxation but is not as effective as adequate pain control in improving sleep quality.

Correct Answer: C

Rationale: The correct answer is C: Brain death has occurred if there is no breathing and certain reflexes are absent. Brain death is defined as the irreversible cessation of all functions of the entire brain, including the brainstem. The absence of breathing and certain reflexes, such as no response to painful stimuli or no pupillary response to light, are key indicators of brain death. This definition is crucial for determining eligibility for organ donation. Incorrect choices: A: Brain death occurs if a person is flaccid and unresponsive. Flaccidity and unresponsiveness are not specific criteria for diagnosing brain death. B: If CPR is ineffective in restoring a heartbeat, the brain cannot function. The absence of a heartbeat alone does not indicate brain death. D: If respiratory efforts cease and no apical pulse is audible, brain death is present. Respiratory cessation and the absence of pulse are not definitive signs of brain death.