I never used one personally, but as an EMT-Basic on a small-town volunteer ambulance service, one time we brought a patient in for something minor but as soon as we entered the Emergency Department we heard this awful sounding, rhythmic "thump THUMP thump THUMP" in a perfect beat that could keep time to a musical piece, but much more non-melodic sounding, and it was actually quite awful to hear, as we heard from one of the nurses that it was a young drowning victim, and they had been attempting resuscitation for a long, long time, unsuccessfully. But as she put it, "...with drowning victims they're not dead, until they're warm and dead." It was SO LOUD, and very depressing as the young patient they were trying to bring back was a teenager. The dying (dead) patient was also fully intubated and on the vent, which is normally rather loud too, but that thumper unit drowned out the sound of anything and everything else in that entire emergency department. The sounds of trying to bring someone back to life who had just suffered an incredibly traumatic event, are very mechanical, the thumper sounded very "pneumatically" mechanical, along with the awful sounds of suctioning, the vent, all together made for a very somber occasion; especially since the parents were sitting right outside the E.R. holding hands and praying still in their swimming attire, and surely they knew what all those horrible sounds meant, too.
