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In this society, the citizens are given a bracelet-like device that is connected to the radial artery in their dominant hand. The device monitors their health, offers advice, etc and also serves as a tracking device. It is never taken off, it is a permanent part of that person, expanding and contracting as the person grows or shrinks.

An important character in this story suffered a traumatic event during which his bracelet was removed/torn off. At first, I simply believed that this wouldn't have a big effect on his health aside from blood loss and that he'd be fine afterwards. But after a bit of research, I've realized that is unrealistic. What physical/mental effects would damage to the artery cause? Could he even survive this? If the removal were more 'gentle' and systematic instead of just being violently torn off, would the effects be significantly different?

Technology in this society is more advanced than our current modern technology (levitating transportation exists, cloning exists, etc). This character loses his bracelet at a young age (about 6-7 years) during a violent struggle with an adult male. The device is quite literally torn off, leaving a jagged gash up his forearm until it was torn free. The character is left like this for at least 10 to 20 minutes before he is found.

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    $\begingroup$ Arteries can be sutured you know. Any hospital emergency room can fix the hole. And I don't understand what you mean by damage other than blood loss. $\endgroup$ – AlexP May 1 '18 at 17:34
  • $\begingroup$ Hey, Alex. Yes, I'm aware of this, I'm just making sure if this is survivable since there is a certain point at which there isn't any going back. $\endgroup$ – Mop May 1 '18 at 17:37
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    $\begingroup$ There are lots of people with missing hands, arms, limbs due to accident and/or war. While having this happening without receiving medical care means a probable death, if medical care is provided in time such incidents are reasonably survivable. $\endgroup$ – SJuan76 May 1 '18 at 17:38
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    $\begingroup$ Completely torn artery would require surgery. Not sure if it can heal on its own. If the artery is just punctured, healing is very probable (assuming blood loss is stopped). $\endgroup$ – Alexander May 1 '18 at 17:40
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    $\begingroup$ I'm torn about the applicability of this question. Can he survive it? Sure... depending on your story. A tourniquet will save his life and, if he receives medical attention quickly enough, it will save his hand. On the other hand, if he just sits there he'll bleed out depending on how invasive the bracelet really is. My conclusion: this question isn't ready for prime time. Tell us exactly what the situation is at the moment the device is torn off including presence of others, tech level, locality of medical help, etc. and we can answer the question. Without all this, it's too broad. $\endgroup$ – JBH May 1 '18 at 17:48
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If he does not bleed to death, worst case scenario is ischemia / gangrene of the hand. But probably not even that.

The ulnar artery and the radial artery both supply the hand. If your arteries are normal, the ulnar can supply the whole hand by itself. If there is any doubt about the ulnar artery or about the connections between radial and ulnary ateries, the Allen test assesses what each artery contributes to circulation of the hand.

arterial anatomy of the hand

https://en.wikipedia.org/wiki/Allen%27s_test

In the modified Allen test, one hand is examined at a time:[2] 1.The hand is elevated and the patient is asked to clench their fist for about 30 seconds. 2.Pressure is applied over the ulnar and the radial arteries so as to occlude both of them. 3.Still elevated, the hand is then opened. It should appear blanched (pallor may be observed at the finger nails). 4.Ulnar pressure is released while radial pressure is maintained, and the colour should return within 5 to 15 seconds.

If color returns as described, Allen's test is considered to be normal. If color fails to return, the test is considered abnormal and it suggests that the ulnar artery supply to the hand is not sufficient. This indicates that it may not be safe to cannulate or needle the radial artery.

Procedures are done using the radial artery all the time and there can be complications if the radial artery is damaged and it is the sole supply to the hand.

Radial artery occlusion after transradial coronary catheterization

Radial artery occlusion (RAO) is, in the majority of patients, asymptomatic. This is due to dual blood supply of the hand and the usually rich network of collateral circulation: the radial and ulnar arteries undergo multiple anastomoses before they are connected in the hand by the superficial and deep palmar arches. Thus, if the radial artery is occluded, blood supply of the hand can be maintained by the ulnar collateral circulation and RAO is a quiescent event. However, cases of hand ischemia after RAO have been described in the setting of inadequate collateral circulation. Some patients may experience pain at the site of the occlusion, paresthesias or reduced limb function.

For narrative purposes, your hero might survive the radial artery damage but have some lasting issue with his hand - for example a buzzing electrical feel on his thumb or a reduced grip or the like. As neuropathic pain the buzzing feeling would probably get worse at night and he can have it enter his dreams.

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  • $\begingroup$ Aaarrgh - so exactly on point; well summarized. In fact, one can end up with ongoing neuropathy from tingles and lack of sensation to significant ongoing pain, grip strength waxing and waning, sensitivity to illness / infection which can result in temporary total dysfunction of the entire hand and so on. $\endgroup$ – GerardFalla May 1 '18 at 21:34
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    $\begingroup$ I will add: if one is conscious enough to apply direct pressure, and one does so quickly enough, it's not unreasonable to survive this kind of injury; if you are briefly unconscious and so lose a fair amount of blood through radial artery bleed, it can be very challenging to stay fully conscious and keep applying direct pressure: as you weaken, and your BP drops, you become less and less well oriented and concentration becomes much harder. If you are a polytrauma, you may well exsanguinate without care; a tourniquet may then save your life. $\endgroup$ – GerardFalla May 1 '18 at 21:38
  • $\begingroup$ I'm currently looking back and forth between the image you posted and my own hand in front of a bright right. So cool! Thanks for this write up. $\endgroup$ – Pink Sweetener May 1 '18 at 22:38
  • $\begingroup$ As an addition, even a complete severance of the hand isnt necessarily lethal. In certain individuals the arteries and veins can close themselves off and prevent bleeding to death. For a prostetics seminar I spoke to someone from Africa who was forced to kill off the people in his Village (who had all been rounded up). When he refused they cut both his hands off and killed the rest anyway. He had put his stumps in nearby mud which helped him survive the walk to another Village and finally to medical care. $\endgroup$ – Demigan Jul 24 '18 at 16:24
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Given the placement of the radial artery in the wrist, I will add several thoughts:

1) If one is conscious enough to apply direct pressure, and one does so quickly enough, it's not unreasonable to survive this kind of injury; if you are briefly unconscious and so lose a fair amount of blood through radial artery bleed, it can be very challenging to stay fully conscious and keep applying direct pressure: as you weaken, and your BP drops, you become less and less well oriented to reality and concentration becomes much harder. (If you are a polytrauma, you may well exsanguinate without care; a tourniquet may then save your life.)

2) If this device is in the wrist, and penetrates the radial artery, and the initial device-removing injury was essentially blunt-force trauma, there will also have been massive damage to the radial nerve which enervates the hand, both sensory and motor functions - especially the thumb and lower two fingers. As a direct result, one would expect your character to end up with ongoing neuropathy (might be only years long, or their whole life) ranging from tingles and lack of sensation to significant ongoing pain, grip strength waxing and waning, sensitivity to illness / infection which can result in temporary total dysfunction of the entire hand lasting a week or more and then slowly fading, and so on.

3) It's likely given the proximity of all these elements in the human wrist that the radius bone itself will have been at the least bruised or traumatized if not broken or shattered. This will add complications to all these considerations, as the wrist will need to be immobilized / splinted for some time.

4) The mental and emotional aspect of this is in fact quite daunting, as one then both goes through a long and arduous recovery process with a prognosis of severely limited recovery results, (say 50%-75% grip strength at best) and then must come to terms with the complete un reliability and un predictability of that hand in the long term: your character will occasionally drop thing that they were sure they had a good hold of, (bad proprioception nerve responses, bad sensory responses and bad motor nerve output) fumble things etc - and that's all after 3-6 months of total incapacity of that hand (think dead fish hanging off the arm the first 3 months) whilst they learn to use it again as though it were a newly-grafted on piece of flesh. During the time the hand is "coming back" and they are learning to use it again, it will feel almost completely numb except for excruciating bursts of pain and "fireball" feelings racing along nerve channels as individual nerve bundles get back to functioning; moreover, as the local nerve clusters have been scrambled, that relearning is not only hard, it's deeply disturbing - just imagine telling your little finger to curl as you always have, and having your ring finger straighten instead. It's as though the whole darn thing was... rewired. Randomly.

How do I know all this when I'm not a medical professional? Happened to me.

Link below is to a picture of that injury, on that day, in the ER - do NOT click on that link if you've a weak stomach.

gnarly picture of wound to radial area of wrist - don't click if weak stomached - really. Don't.

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A technology that could build such a device would presumably build in a fail safe mechanism that would e.g. detect the forced disconnect and try and seal the artery in some way. It seems unlikely you'd design such a device to not be removable (by accident).

So I'd expect some bleeding, but no major issue.

Note that puncturing the radial artery is quite common for medical procedures.

The device is quite literally torn off, leaving a jagged gash up his forearm until it was torn free.

I cannot see a reason why the device would leave such a large wound. You'd not design a device like this to be so invasive (you'd probably design it not to be invasive at all !).

In making such a device you'd be aware of the potential of such damage. You'd make such the device was removable and replaceable. There's no rational reason to make it so heavily embedded in the arm that removing it would result in such a major injury.

it is a permanent part of that person, expanding and contracting as the person grows or shrinks.

This would require a device that was adapting actively to the local conditions around it. If it can do that it can certainly detect a disconnection and safely disconnect.

Disconnection of the device as a precaution would not be a life threatening issue, so as an engineer I'd design it to initiate a controlled disconnection well before a forced disconnection was likely.

In such a scenario the devices would be disconnecting relatively frequently and a trip to e.g. the GP or a Health Clinic would be enough to replace it. "What happened Mr. G ? Well, I was playing football and the darn thing must have got caught on the ground when I was sliding. No problem - have that fixed in a jiffy." Events like that would be as common as muck.

So I think you've created a problem that would have been foreseen and prevented by the makers.

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    $\begingroup$ "You'd make such the device was removable and replaceable." I can definitely see a totalitarian state creating such a device. (Not in children, though, since they're still growing. But definitely in 18 year olds.) $\endgroup$ – RonJohn May 1 '18 at 19:00
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    $\begingroup$ +1. This really makes total sense. I could not envision a society in which all it would take to kill someone is simply removing a bracelet violently from their arm. Imagine how protective people would be if that was the risk. You'd have people wearing armored braces that cover the whole device to remove the risk. I think OP should consider the implications of such a risk on the behavior of people in this world. $\endgroup$ – BaseHobo May 1 '18 at 20:15
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Can the character survive? Almost certainly, the radial artery is small enough and distal enough (and thus under low enough pressure) to close with direct pressure, or a tourniquet, with relative ease at a reasonable distance up the arm, as far as the armpit in fact. Do they get to keep the hand? That's going to be entirely Story Based as are any other after effects.

Post Edit: Again story issues are paramount including but not limited to the character's level of consciousness and knowledge of anatomy etc...

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