During a 6-minute Walk Test, you document that the patient’s…

During a 6-minute Walk Test, you document that the patient’s SpO2 decreases from 97% to 89% and the HR increased from 82 to 121 bpm. Use principles of gas diffusion and lung physiology to explain how these results would be indicative of a pulmonary diffusion defect. (ie What happened during exercise to cause a diffusion defect?)