- As Barnaby Golden has stated, it is not a good idea to share the content of a retro. It is very important for teams to know that the retro is a "safe place". What happens there, stays there - unless the team wants toyou to volunteer information about. But I wouldn't push them.
Also note that not all teams are talking about impediments during their retros. Most teams I've worked with are talking about a) how they felt during certain situations and b) how to reach technical excellence. But the impediments are (also) talked about during the daily stand-ups. And it's the Scrum Master's job to solve those impediments. So... - Change Management could definitely help. You could cut through red tape and arrange a short line of communication between Scrum Masters and CM. So impediments can be turned into change requests without generating additional overhead. And this helps all persons involved.