Can someone tell me the origin of the ambulance design and the changes over the years?

I’m not quite sure exactly how to answer this question, but I’ll try my best. I may need clarification on a few things, such as specifically what you are asking. I’m going to assume you are talking about the modern ambulance design?

“Ambulances” have been around for a long time. You could consider horse-drawn carriages used to transport sick and injured people as ambulances. Many of those were hospital-based services.

Obviously, things changed when the automobile was invented. WWI was the first wide-spread use of motor ambulances. They had basic medical equipment, but were mostly used to transport wounded to field hospitals, not so much treatment. Shortly after WWI, ambulances got 2-way radios. At this point, the general design is pretty much the same as today. A truck or van with a patient compartment in the back.

The 1960’s brought about big changes to the civilian ambulance services. Up until then, they were mostly run out of funeral homes, and still mostly just for transporting. Thus, the didn’t have a whole lot of medical equipment, and looked a lot like hearses (they were probably built on them).

At this time, when modern EMS was evolving, so did the ambulances. Stretchers, lights and sirens, medical equipment such as defibrillators, etc. These changes were due to the changing mission of EMS: from simple transport, to treatment on scene in addition to transport. Sort of “bringing the ER to the patient”.

Nowadays, they’re custom built, and have all the toys that we know and love.

Did that help at all?