No. Its not actually required, and is not really a secure way (IT Security wise) of handling it.
Access control is not only to prevent a authorized user to do prohibited things, but to limit damage if an attacker would in some way aquire a authorized user's credential. Then no "Break the glass" systems will prevent access, the attacker will just click through.
A better way of handling it, is to use terminal restrictions instead. This means that you give different access policies based on WHERE the access comes from.
For example, if the ambulance has a laptop or terminal, you could assign so this terminal can access any medical record, but then you have some limitation put in place that prevents abuse.
You could for example have that the dispatch center can set how many medical records that can be accessed during a "dispatch", since they know roughly how many people at the target location requiring medical attention.
Then in for example patient rooms, you can have so certain non-medical personell on-site responsible for a corridor or a set of rooms, can "book in" patients into the room, and "book out" patients from the room (but not access records). And ofcourse dispatch personell should be able to "book in" and "book out" patients from any room, but only patients that have partipicated in a recent "dispatch" so to say.
And same way here, physicians which "have" a patient, should also be able to "book in" and "book out" patients into any room in the facility.
Any patient that is "booked in" that room, can then be accessed by ANY medical personell, but only from a terminal located in that particular room where the patient is "booked in".
And of course, no more patients than the room can hold should be able to be "booked in", and of course it should not be possible to "book in" patients "booked in" somewhere else, first the patient have to be released from the previous room first.
Using such limitations greatly increases security, because you can then totally block the possibility to access "foregin" medical records, while still allowing emergency response in emergency situations.