Brief Answer:
there is a scoring system regarding prognosis

Detailed Answer:
Hello,

I suppose you're talking about his oxygen saturation?
80% is very low, which means that he needs oxygen supplementation.

The scoring system I've mentioned in the short answer takes various factors into account: FEV1, a grading of dyspnea, walking distance within certain time limits (6 minutes) and body mass index. The aforementioned data determine the 4 year survival of COPD patients.

Let me provide some more details. He gets 3, 2 or 1 for FEV1 less than 35%, 49%, 64% respectively. Otherwise he gets 0 points.
Less than 150 meters within 6 minutes gives 3 points. Less than 250 gives 2 points. Less than 350 gives 1 point. 0 points for the rest obviously.
He gets 1 point for a body mass index (his weight in kilograms divided by the square of his height in meters) equal to or lower than 21 (or 0 points otherwise).
Finally dyspnea may be classified depending on its severity as follows:
- if the patient cannot carry out ordinary daily activities and cannot even leave his home then he gets 3 points.
- if the patient feels shortness of breath after walking a short distance (less than 100 yards) or for a few minutes he gets 2 points.
- if the patient has symptoms when walking on ground level and needs to stop every so often he gets 1 point.
- if the patient only feels shortness of breath when carrying out strenuous exercise then he gets 0 points.

After you complete this kind of assessment, you have to add the points. The 4 year survival rate is as follows:
- 0 to 2 points = 80%
- 3 to 4 points = 67%
- 5 to 6 points = 57%
- 7 to 10 points = 18%

Obviously this is a rough estimation and different patients may not follow this 'rule'. For example a patient who has COPD and also has diabetes and heart disease is in a much less favorable situation.

I hope you find this information helpful!
You can contact me again, if you'd like any clarification or further information.

Kind Regards!

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