### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
Hi, I am a 50 yr old woman with athsma (not severe) Anemia,(borderline 10-11 on a good month) and an MVP. I breath fine during normal activity. I can go to the gym and enjoy long walks without difficulty. However, when I fly longer than 3 hours I find it very difficult to get enough oxygen, I cannot sleep on long flights and my heart races on planes as well as when I am at higher altitudes (such as skiing in Colorado) Or hiking in the Adirondacks. My family thinks I make up my discomfort. Is there a scientific connection? If so what can I do to prepare better? We traveled to Italy last summer and after 10 hours of flying I felt awful. Partially lack of sleep, but I just felt gray. I am concerned about a flight to Vietnam in Dec.

### output:

Hello dear, thanks for your question on Chat Doctor. I can understand your situation and problem. Your problem is genuine. And it is mostly because of the anemia. In anemia, hemoglobin (He) is low. He is the only source for oxygen to the tissues. In normal air oxygen concentration is sufficient to meet the demand of body tissue. But in long flight or at high altitude the oxygen concentration in air is low. This low concentration will not affect normal, healthy individuals because their He is normal, and they are not having asthma. Since your He is low, oxygen supply to the tissues is also low and body starts hyperventilating to meet the oxygen need. So you feel breathlessness, and this made worse by your mild asthma. This is the scientific reason for your breathlessness on long flights and at high altitude. Correction of anemia and control of asthma are needed for you to avoid such breathlessness.