Is it true that a medical device (portable oxygen concentrator) is exempt from the carryon baggage allowance?

Is it true that a medical device (portable oxygen concentrator) is exempt from the carryon baggage allowance?



Can you give me a link showing (online) the actual regulation? I looked at the IATA website and could not find it. When I say exempt from the carry on bag allowance, I mean that it is my understanding that a person who needs an oxygen concentrator can carry the machine PLUS one carry one bag PLUS a personal bag (e.g. briefcase, purse, etc). But I wanted to see the actual regulation and download it. The person is flying from the US to Asia on Singapore Airlines. Thanks.

https://answers.yahoo.com/question/index?qid=20090328225058AAhMYEF