A 21-year-old man presents to his physician because he has been feeling increasingly tired and short of breath at work. He has previously had these symptoms but cannot recall the diagnosis he was given. Chart review reveals the following results: Oxygen tension in inspired air = 150 mmHg Alveolar carbon dioxide tension = 50 mmHg Arterial oxygen tension = 71 mmHg Respiratory exchange ratio = 0.80 Diffusion studies reveal normal diffusion distance. The patient is administered 100% oxygen but the patient's blood oxygen concentration does not improve. Which of the following conditions would best explain this patient's findings?
ASeptal defect since birth
BUse of opioid medications
CPulmonary fibrosis
DPulmonary embolism
EVacation at the top of a mountain
A 19-year-old man comes to the emergency department with sharp, left-sided chest pain and shortness of breath. He has no history of recent trauma. He does not smoke or use illicit drugs. He is 196 cm (6 feet 5 in) tall and weighs 70 kg (154 lb); BMI is 18 kg/m2. Examination shows reduced breath sounds over the left lung field. An x-ray of the chest is shown. Which of the following changes is most likely to immediately result from this patient's current condition?
AIncreased intra-alveolar pressure
BIncreased right-to-left shunting
CIncreased lung compliance
DIncreased transpulmonary pressure
EIncreased physiological dead space
During exercise, what is the primary mechanism for increased oxygen delivery to active muscles?
ADecreased blood viscosity
BIncreased cardiac output
CIncreased hemoglobin affinity
DEnhanced oxygen diffusion
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