Asthma USMLE Step 1 Practice Question
A 63-year-old man with progressive exertional dyspnea has bibasilar crackles and clubbing. Pulmonary function tests show reduced total lung capacity and reduced DLCO. During treadmill testing his oxygen saturation drops substantially despite an appropriate increase in cardiac output. Which of the following gases is most likely becoming diffusion limited across his alveolar membrane during exercise?
Answer choices
- AHelium
- BCarbon dioxide
- COxygenCorrect answer
- DNitrous oxide
- ENitrogen
- FArgon
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