A standard sign of death on TV and film seems to be someone's heart rate machine flatlining with a long, drawn out BEEEEEEEEEEP.

However, this is not what actually happens - apparently this noise just means the machine is unplugged.

Does anyone know when this 'movie fact' first started?

  • 3
    The long noise means the machine is not detecting a pulse. Normal beeping just indicates the rhythm of the heart. When the machine is unplugged, it would not make any sound as it does not have any power.
    – Origin
    May 16, 2013 at 15:45
  • 1
    I was under this impression too but I watched an episode of QI where they explained that this was a myth. The machine has a backup battery which emits the beep when the machine is not plugged in (or something similar), so if you accidentally pull the plug you realise. If no pulse is being detected a more ... noticeable alarm is given to alert doctors who are probably not in the room.
    – Stefan
    May 16, 2013 at 15:54
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    Not all those machines work the same way so it's possible some of them have some alert to prevent accidental unplugging. It's main function is just to beep during normal circumstances and alert when something is wrong (like cardiac arrest or unplugging). The specific sound could be the same for all problems.
    – Origin
    May 16, 2013 at 17:38
  • I don't know the origin of the idea to use the flatline sound and machine effect in movies, but it must be very old. It is certainly an effective conveyance to passionately and sadly get the point across that someone has died to the viewer.
    – BB Stacker
    May 16, 2013 at 19:19
  • At the hospital near me they don't use those machines. The heart monitoring is done via computer at the nurses station. The on duty nurse can see all the patients heart beats for that entire department. When they have to do it by the patients bed, then the machine just displays a digital number of the current heart rate. I don't know if it beeps, but there is no visual dot moving horizontally. That's been my experience. EDIT: Maybe they use them, but I haven't seen any.
    – Reactgular
    May 17, 2013 at 2:09

1 Answer 1


Here is a medical products company video of a Siemens SC 7000 patient monitor which starts off with the flat-lining sound. If you watch and inspect the configuration menus, you'll see that a wide variety of sounds can be configured for any of several conditions: high and/or low heart rate, high/low partial-pressure of oxygen saturation, high/low partial-pressure of carbon dioxide, high/low arterial pressure, high/low breathing rate.

With an old-fashioned single purpose cardiac monitor like the Graseby PM 3, those beep on every heartbeat, and are quiet at first when there is no heartbeat, but then gives the flat line sound after a few seconds.

Why do you think the sound is not genuine?

  • Have you watched the tv show QI? They said on there that the idea of the continuous beep meaning no heartbeat was a myth and, if anything, it would mean the plug was out and the alarm for a stopped heart was loud and clear to attract the attention of staff. A quiet beep is unlikely to do that unless they are leaning over the bed watching (like they often are on tv).
    – Stefan
    May 16, 2013 at 21:00
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    @Stefan: I haven't watched it. My wife is a surgical nurse and used to work "on the floor". The patient monitors really do give a tone when heartbeats are not detected. However, just like a car alarm, almost all staff are unreactive when the alarm goes off. 98% of the time, the ECG leads have come loose from the patient or the cable is unplugged.
    – wallyk
    May 16, 2013 at 21:16
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    Ah, well if you get the chance to see it I would recommend it, it is very good. However, I have had a look through their forum and apparently it is quite a bit more subtle than they said on the show. As your wife indicates old.qi.com/talk/…
    – Stefan
    May 16, 2013 at 21:54
  • QI is entertaining but isn't always right.
    – Hugo
    May 17, 2013 at 19:20

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