Correct Answer: A

Rationale: The correct answer is A: Absence of cerebral blood flow. Brain death is determined by the irreversible cessation of all brain functions, including blood flow to the brain. When there is no cerebral blood flow, the brain is unable to function, leading to brain death. This criterion is essential in diagnosing brain death as it indicates a complete loss of brain function. Explanation for why the other choices are incorrect: - B: Absence of brainstem reflexes on neurological examination is a common sign of brain death, but it is not the primary criterion. - C: Presence of Cheyne-Stokes respirations is not indicative of brain death. It is a pattern of breathing that can be seen in various conditions, not specifically brain death. - D: Confirmation of a flat electroencephalogram is a supportive test for brain death but not the primary criterion. The absence of brain activity on an EEG can help confirm brain death but is not as definitive as the absence of cerebral blood flow.

Correct Answer: A

Rationale: The correct answer is A, the 21-year-old with a C4 fracture and quadriplegia. This patient is likely to benefit most from patient-controlled analgesia (PCA) due to the inability to self-administer traditional pain medications. With quadriplegia, the patient may have limited mobility and sensation, making it challenging to communicate pain levels effectively. PCA allows the patient to control their pain relief within preset limits, enhancing autonomy and optimizing pain management. Summary: - Choice B: The 45-year-old with femur fracture and closed head injury may benefit from PCA, but the severity of the head injury could affect their ability to use the device effectively. - Choice C: The 59-year-old postoperative elective bariatric surgery patient can typically manage pain with traditional methods postoperatively. - Choice D: The 70-year-old postoperative cardiac surgery patient with mild dementia may have the cognitive ability to use PCA but could potentially benefit more from other pain management strategies due

Correct Answer: B

Rationale: The correct answer is B because after brain death is confirmed, maintaining perfusion and oxygenation of organs is crucial to ensure their viability for donation. This process allows organs to be retrieved in optimal condition during the operation. Choice A is incorrect because a signed donor card is not a legal mandate for organ retrieval. Choice C is incorrect as the healthcare proxy's consent is typically required for organ donation. Choice D is incorrect because life support is not immediately withdrawn upon brain death confirmation; instead, organ preservation measures are initiated.

Correct Answer: B

Rationale: The correct answer is B: Hypovolemia. When the ventilator settings are adjusted to treat hypoxemia by increasing FiO2 and PEEP, it can lead to increased oxygenation but also potentially decrease venous return to the heart, causing a decrease in blood pressure. This decrease in blood pressure is most likely due to hypovolemia, as the increased PEEP can increase intrathoracic pressure, reducing venous return and preload, leading to a decrease in cardiac output and subsequent decrease in blood pressure. This choice is the most likely cause as the other options (A: Decrease in cardiac output, C: Increase in venous return, D: Oxygen toxicity) do not directly correlate with the changes in ventilator settings described in the question.

Correct Answer: C

Rationale: The correct answer is C: Treatment for elevated blood pressure. In the initial stress response, the body releases adrenaline and cortisol, leading to increased heart rate and blood pressure. Treating elevated blood pressure is crucial to prevent complications like heart attack or stroke. Adequate pain control (A) and intravenous sedation (B) may help manage symptoms but do not directly address the physiological response to stress. Ignoring an elevated glucose level (D) is not recommended as stress can impact blood sugar levels. Treatment for elevated blood pressure directly targets the physiological response to stress, making it the best nursing action in this scenario.