Assuming medieval level technology. How long could a human remain unconscious without dying? What technology could be employed to preserve the life of an unconscious person?

I can see several specific challenges:

  • Eating
  • Drinking
  • Defecating
  • Pressure sores
  • Muscle tissue loss

Would it be possible to solve these issues without modern technology?

  • How unconscious are they? In a coma? Just sleeping? – Rob Watts Sep 17 '15 at 21:35
  • Without water intake, an unconscious human would start to suffer from medical problems after 3 or 4 days. – the_OTHER_DJMethaneMan Sep 17 '15 at 21:38
  • Badly knocked about, suffering from hypothermia, probably delirious. They have to be unaware of their surroundings, without speech or memory for an extended period, ideally weeks. Is this possible given medieval tech? – superluminary Sep 17 '15 at 21:47
  • A really bad sickness could make them feel as if they've been through all that, without remembering much - but its not really possible to make them sick on purpose without a high risk of actually killing them, using medieval technology, and while its probably within their technology, they probably wouldn't have the knowledge to do it on purpose. – DoubleDouble Sep 17 '15 at 21:57

TL;DR; Patient must be provided with liquids and food, anything else isn't life threatening.
Comatose people usual can't swallow.
Putting in a tube is more likely to hit the trachea than the esophagus.
Putting food into the trachea will kill the patient.
So a reasonable estimate is only a few days. The patient will then die of dehydration.

What does a comatose person needs to stay alive?
(I assume, the patient will still breathe on his/her own and the heart beats properly.)

  • Oxygen - Since the patient will breathe on their own this shouldn't be a problem unless their breathing is restricted somehow. We should ensure that their mouth is unrestricted.
  • Temperature - The patient can't change clothes depending on the temperature, somebody has to keep him at a reasonable temperature.
  • Liquid - Without drinking, people tend to die within a few days, 2-3 maybe 4, depending on air humidity, kidney activity and other factors.
  • Nutrients - Without food, people tend to die after a couple of weeks. This has enough factors that we can't precisely time it, but since comatose people won't do hard work it will probably take longer, let's say 2-4 weeks.

How to apply the needs?

Ensure mouth remains unrestricted.

Temperature This shouldn't be a significant problem as long as the patient remains inside. Mostly, one should use common sense. If they are noticeably cold then you can add blankets.

Liquid and Nutrients
Now, this is difficult. In medieval times, they had no easy material to use for tubes, but for now lets assume they can acquire something. People who are unconscious usually lack the ability to swallow (They do in some cases, but this isn't reliable). Using a tube to get food into the esophagus isn't a trivial task. In normal state, the larynx is open and the esophagus is closed. By swallowing something, you actively close the larynx to prevent aspiration. When you try putting a tubes in, you'll probably hit the trachea, not the esophagus. If this happens, applying water will make the patient drown. In modern times, we have machines to help hitting the esophagus like sonographic units. Feeding the patient with medieval knowledge is basically impossible.

Even if you can manage to get into esophagus, what material is the tube? With medieval materials, it's really likely to hurt the esophagus. So even if you manage to feed the patient, an infection is likely. This infection would swell and maybe make it impossible to breath. If patient can breath anyway, treating inner infections isn't trivial either. In medieval times, best they could do is applying alcoholic drinks to disinfect a little.

So in the end, it's not reasonable to keep a comatose person alive with medieval techniques.

  • 3
    What about cutting open their throat and inserting a thin-carved wood, bone, or copper tube into the esophagus? You have the huge problems with infections and such (liberal application of alcohol, maybe?), but you avoid the tube material issues (straight tube vs. flexible). Yes, it would rely on actual anatomical knowledge (a bit of a rarity in our history at that time). – user3082 Sep 22 '15 at 21:08

Until you slip up and they die of an infection. Feeding tubes don't require high tech. Infection will be a serious threat due to the lack of antibiotics, though.

You can certainly use a tube to pour liquids and soft foods into the stomach with trivial finding an animal intestine. The other issues only require cleanup and moving the body around.

  • How exactly should this intestine tube be applied without hurting the person? – Sempie Sep 18 '15 at 9:00
  • If he doesn't complain, it must not hurt that bad. But seriously, you just shove it down the throat like paramedics do. Ever hear of "force feeding"? That's how they do it, so you can't spit it back out. – Oldcat Sep 18 '15 at 21:12
  • 1
    Ive worked as paramedic. Its not that easy. See my answer. – Sempie Sep 18 '15 at 21:24
  • I never said it was easy, just doable. – Oldcat Sep 18 '15 at 21:34
  • Its "worth a try and hoping it works" but with "doable" I assume one could do it, and repeat it at any time. It's pure luck to hit esophagus just by pushing in a tube. One could als throw up a penny and hope it falls inside the pocket of his own jeans - unlikely. – Sempie Sep 18 '15 at 22:39

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