Fast encryption for Medical System? For part of my bachelor thesis (which will be involved in a commercial product), I need to build a cryptosystem that will be used to encrypt and decrypt continuous medical data that is transmitted from a patient to their doctor. The data must be encrypted and decrypted very fast in case of emergency.

Which encryption algorithm should I use? I think I should use AES. Should I involve a public key encryption to exchange shared keys? But I am afraid it may slow down the system and compromise the consistency of data transfer.

Update: The data will be sent from wearable devices on a patient to their doctor so the computing power might be limited.
My thesis will not touch on the hardware and networking aspects directly. However, they should be included in the discussion and analysis of my report.
The data must be encrypted and decrypted very fast in case of
  emergency.
  
  Which encryption algorithm should I use? I think I should use AES.


Indeed, symmetric cryptography (such as AES) is a good choice for performances. But a significant factor that you did not mentioned is the platform on which the algorithms will run. Does it contains cryptographic hardware accelerators? If yes, for which kind of algorithms (ECC, AES, RSA, ...)?

That will determine which algorithm will be the most relevant.

For example, if you have hardware accelerators for ECC or RSA, involving asymmetric cryptography to exchange the secret keys used for encryption should not slow down the system that much. In the other case, it can be very challenging to implement it in software with good performances on an embedded device.

This is also the same compromise for the choice of the symmetric algorithm. If you have a hardware accelerator for AES, then you should probably use it. In the other case, AES will not be the fastest algorithm. For efficient software implementations on embedded devices, you can take a look at lightweight ciphers.