The nurse is performing a respiratory assessment of a patient who has been experiencing episodes of hypoxia. The nurse is aware that this is ultimately attributable to impaired gas exchange. On what factor does adequate gas exchange primarily depend?

Correct Answer: B

Rationale: The correct answer is B: An adequate ventilation-perfusion ratio. Adequate gas exchange primarily depends on the matching of ventilation (air reaching the alveoli) and perfusion (blood flow to the alveoli). A mismatch in this ratio can lead to impaired gas exchange, resulting in hypoxia. Option A relates to gas movement efficiency but does not address the matching of ventilation and perfusion. Option C mentions shunted blood, which is not directly related to the ventilation-perfusion ratio. Option D is unrelated to gas exchange. In summary, the ventilation-perfusion ratio is crucial for optimal gas exchange, making it the correct choice.

Correct Answer: D

Rationale: The correct answer is D: PN2 of the alveoli. The rate of external respiration is primarily influenced by the partial pressure of oxygen (PO2) in the alveoli, as it drives oxygen diffusion into the blood. PCO2 affects the removal of carbon dioxide. The thickness of the respiratory membrane impacts gas exchange efficiency. However, PN2 does not significantly impact gas exchange in the lungs, as nitrogen (N2) is inert and does not participate in gas exchange. Thus, PN2 of the alveoli does not affect the rate of external respiration.

Correct Answer: B

Rationale: The correct answer is B: Bohr effect. This effect describes how pH affects hemoglobin saturation. When pH decreases (becomes more acidic), hemoglobin's affinity for oxygen decreases, promoting oxygen unloading in tissues. This is due to the protonation of histidine residues in hemoglobin, altering its structure. The other choices are incorrect because the Bainbridge reflex is related to heart rate regulation in response to changes in blood volume, the pulmonary reflex relates to the regulation of breathing in response to changes in blood oxygen levels, and the respiratory effect is a general term that does not specifically describe the pH effect on hemoglobin saturation.

Correct Answer: B

Rationale: The correct answer is B: stop smoking. Smoking can damage the lungs and reduce respiratory function. By quitting smoking, lung health can improve, leading to better respiratory performance with age. Eating smaller meals, sleeping longer, and maintaining normal glucose levels do not directly impact respiratory performance. Smoking cessation is the most effective way to improve lung function and overall respiratory health.

Correct Answer: D

Rationale: The correct answer is D: Low-sodium diet. Sodium can exacerbate fluid retention in heart failure patients, leading to increased workload on the heart. A low-sodium diet helps reduce fluid retention and manage symptoms. High-sodium diet (A) is detrimental to heart failure patients. Low-fat diet (B) and low-sugar diet (C) may be beneficial for overall health but are not specific recommendations for managing heart failure.