As it was noted there were and currently are some major tech companies who tried to tackle this problem unsuccessfully up until now; the fact that they haven't managed to offer a viable solution yet speaks for itself. If you believe you have the knowledge and experience to work on something that truly is a very complex problem to solve you should prepare for a battle. There are literally hundreds of closed proprietary systems for medical record keeping only in the US. They have established marketing channels and collaborations and in fact are so deeply rooted to the workings of a hospital that feels like you would have to physically tear down and rebuild the whole thing from scratch! As we speak there are also some great cloud based alternatives with a different approach and business model (eg patient fusion).
On the other hand what you are describing is the future; some of the most important healthcare evangelists are pointing out that our fixation on the preservation of health data in these closed systems is costing us both in money and quality of services received. My opinion is it will happen once the general public embraces the idea of sharing (anonymised) personal health information which in turn will only happen when we realise that the benefit of such outweighs the possible risks of exposure of this information to a third party.