The nurse is caring for a patient with lung metastases who just underwent a mediastinotomy. What should be the focus of the nurse's postprocedure care?

Correct Answer: B

Rationale: The correct answer is B: Maintaining the patient's chest tube. After a mediastinotomy, the focus of postprocedure care is to ensure proper drainage and prevent pneumothorax. Chest tube maintenance is crucial for monitoring drainage, preventing complications, and promoting lung expansion. Assisting with PFT (A) is not a priority immediately post mediastinotomy. Administering oral suction (C) can disrupt the chest tube and increase infection risk. Performing chest physiotherapy (D) may be indicated later but is not the immediate priority.

Correct Answer: A

Rationale: The correct answer is A because the partial pressure of oxygen decreases with increasing altitude due to the decrease in atmospheric pressure. At sea level, the atmospheric pressure is higher, resulting in a higher partial pressure of oxygen compared to the top of Mt. Everest. Choice B is incorrect because the partial pressure of oxygen is not higher at higher altitudes. Choice C is incorrect because the partial pressure of oxygen is not equal at sea level and Mt. Everest. Choice D is incorrect because the question specifically asks about the partial pressure of oxygen only, not the sum of partial pressures from other gases.

Correct Answer: B

Rationale: The correct answer is B: carbon dioxide. Carbon dioxide is the most important chemical regulator of respiration as it directly affects the respiratory rate and depth. An increase in carbon dioxide levels in the blood triggers the body to increase respiration to expel the excess carbon dioxide. Conversely, a decrease in carbon dioxide levels signals the body to decrease respiration. Oxygen (choice A) is important for cellular respiration but does not directly regulate breathing. Bicarbonate ion (choice C) and sodium ion (choice D) do not play a direct role in regulating respiration.

Correct Answer: D

Rationale: The correct answer is D, pseudostratified ciliated columnar epithelium. This type of epithelium lines the conducting portion of the respiratory tract because it contains cilia that help sweep mucus and debris out of the airways. It appears to be stratified but is actually a single layer of cells with varying heights, giving it a pseudostratified appearance. Simple squamous epithelium (choice A) is too thin for the respiratory tract, simple columnar epithelium (choice B) lacks cilia for mucus clearance, and stratified ciliated columnar epithelium (choice C) is not a valid type of epithelium.

Correct Answer: C

Rationale: The correct answer is C: Beta-blockers. Beta-blockers are commonly prescribed in heart failure to manage symptoms and improve outcomes by reducing the heart's workload and improving its efficiency. They help lower blood pressure, decrease heart rate, and improve heart function. Antibiotics (A) are used to treat bacterial infections, not heart failure. Antidepressants (B) are used for mental health conditions, not heart failure. Antihistamines (D) are used to treat allergies, not heart failure.