Correct Answer: A

Rationale: A troponin level of 0.5 ng/mL is elevated, indicating myocardial damage, making it the most concerning finding in a client with a myocardial infarction (MI). Troponin is a highly specific marker for cardiac muscle damage, and elevated levels suggest ongoing injury to the heart muscle. While Creatine kinase-MB (CK-MB) is also a cardiac enzyme, troponin is more specific and sensitive for myocardial damage. Serum potassium and blood glucose levels are important parameters to monitor in MI patients, but in this scenario, the elevated troponin level takes precedence as it directly reflects cardiac injury.

Correct Answer: B

Rationale: The correct answer is B. Advance directives specify the type of medical treatment a client wishes to receive or avoid in the event of a serious illness. Choice A is incorrect because advance directives do not allow the court to overrule a client's refusal of medical treatment; they empower the client to make their own healthcare decisions. Choice C is incorrect because advance directives do not permit a client to withhold medical information; they provide guidance on the client's treatment preferences. Choice D is incorrect because advance directives do not specifically address the actions of health care personnel in the emergency department; they focus on the client's treatment preferences in general.

Correct Answer: A

Rationale: The correct instruction is to use tracheostomy covers when outdoors. Tracheostomy covers serve to protect the airway from environmental contaminants, reducing the risk of infection. Choice B is incorrect because hydrogen peroxide can be irritating to the skin and is not recommended for cleaning the tracheostomy site. Choice C is incorrect as tracheostomy tubes should not be routinely changed weekly unless there is a specific medical indication. Changing it without a need can introduce infection or damage the stoma. Choice D is incorrect as applying ointment around the tracheostomy site can lead to occlusion of the stoma and interfere with breathing.

Correct Answer: D

Rationale: The absence of breath sounds on the affected side is a critical finding that may indicate a tension pneumothorax, a life-threatening condition requiring immediate intervention. This situation can lead to a shift of the mediastinum and impaired ventilation. Bubbling in the water seal chamber is an expected finding in a chest tube drainage system and indicates proper functioning. Drainage greater than 70 ml/hour is a concern but does not require immediate reporting unless it continues at a high rate or is associated with other symptoms. Tidaling in the water seal chamber is a normal fluctuation and indicates the chest tube system is patent and functioning correctly.

Correct Answer: C

Rationale: The correct answer is C, 'Proximate cause.' Proximate cause establishes the link between the harm suffered and the negligent actions performed by the nurse. In a malpractice lawsuit, proving proximate cause is essential to demonstrate that the nurse's actions directly led to the harm experienced by the client. Choice A, 'Evidence,' is incorrect as evidence is the information presented to support or refute a claim, not specifically the link between harm and negligence. Choice B, 'Tort discovery,' is incorrect as it does not specifically refer to establishing the link between harm and negligence. Choice D, 'Common cause,' is incorrect as it does not capture the legal concept of proximate cause in establishing liability in malpractice cases.