The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 09-16-2011, 01:07 AM
AaronX AaronX is offline
Guest
 
Join Date: Feb 2011
Can you injure a limb if you sleep on it and cut off blood supply?

Sometimes I've woken up with my arm totally numb. Is this dangerous, or will I wake up before anything happens? I'm afraid loss of circulation will lead to gangrene.
Reply With Quote
Advertisements  
  #2  
Old 09-16-2011, 01:50 AM
BowlOfDucks BowlOfDucks is offline
Guest
 
Join Date: Jun 2011
When you wake up with a numb limb, you haven't cut off the blood supply. You've just been putting pressure on a nerve.
Reply With Quote
  #3  
Old 09-16-2011, 01:52 AM
Blake Blake is offline
Member
 
Join Date: Mar 2001
Posts: 10,207
The numbness in the arm is caused by pinching the nerve, not by loss of circulation. The circulation is just fine and can't be cut off by sleeping on the arm.
Reply With Quote
  #4  
Old 09-16-2011, 02:07 AM
psychonaut psychonaut is offline
Guest
 
Join Date: Apr 2001
I'm pretty sure that if you rest on the affected area long enough (say, several days or weeks), you will indeed cut off the blood supply, and severely or even fatally injure yourself. Isn't that what a bedsore is? It's not a concern for most people, but if you are immobilized in bed due to other injuries or in a coma, then you or whoever looks after you needs to make sure that you're not putting pressure on any one part of your body for too long.
Reply With Quote
  #5  
Old 09-16-2011, 02:26 AM
Otara Otara is offline
Guest
 
Join Date: Jun 2003
My understanding is this can happen if you get extremely drunk, normally we move in our sleep to avoid this issue, but it can get suppressed if intoxicated enough, and people have lost limbs as a result.

http://en.wikipedia.org/wiki/Radial_neuropathy

Otara
Reply With Quote
  #6  
Old 09-16-2011, 02:29 AM
AClockworkMelon AClockworkMelon is offline
Guest
 
Join Date: Mar 2010
Quote:
Originally Posted by BowlOfDucks View Post
When you wake up with a numb limb, you haven't cut off the blood supply. You've just been putting pressure on a nerve.
Quote:
Originally Posted by Blake View Post
The numbness in the arm is caused by pinching the nerve, not by loss of circulation. The circulation is just fine and can't be cut off by sleeping on the arm.
Wait wait, so if I say, sit in such a way that I'm sitting on top of one of my legs and it falls asleep that isn't because I'm partially cutting off circulation?

If that's true, consider my mind blown. I'd always thought that's what was happening when a limb fell asleep.
Reply With Quote
  #7  
Old 09-16-2011, 02:31 AM
Der Trihs Der Trihs is offline
Guest
 
Join Date: Aug 2005
Quote:
Originally Posted by psychonaut View Post
I'm pretty sure that if you rest on the affected area long enough (say, several days or weeks), you will indeed cut off the blood supply, and severely or even fatally injure yourself. Isn't that what a bedsore is? It's not a concern for most people, but if you are immobilized in bed due to other injuries or in a coma, then you or whoever looks after you needs to make sure that you're not putting pressure on any one part of your body for too long.
Quote:
Originally Posted by Otara View Post
My understanding is this can happen if you get extremely drunk, normally we move in our sleep to avoid this issue, but it can get suppressed if intoxicated enough, and people have lost limbs as a result.

http://en.wikipedia.org/wiki/Radial_neuropathy

Otara
I've also read that people born without the ability to feel pain tend to injure themselves while sleeping the same way.

Quote:
Originally Posted by AClockworkMelon View Post
Wait wait, so if I say, sit in such a way that I'm sitting on top of one of my legs and it falls asleep that isn't because I'm partially cutting off circulation?

If that's true, consider my mind blown. I'd always thought that's what was happening when a limb fell asleep.
Yup, it's the nerves not the blood. I used to think it was a matter of bloodflow too, for years.
Reply With Quote
  #8  
Old 09-16-2011, 07:37 AM
Hari Seldon Hari Seldon is online now
Guest
 
Join Date: Mar 2002
I knew a woman whose arm was partially paralyzed for months after she slept on it. It did eventually recover. But from reading that wiki page it looks like it was nerve damage. Maybe she fell asleep drunk.
Reply With Quote
  #9  
Old 09-16-2011, 08:18 AM
pravnik pravnik is offline
Member
 
Join Date: Apr 2002
Location: TX
Posts: 13,378
The OP immediately reminded me of this little horror story I saw in the news a while back:

Quote:
WTAE's news exchange partners at the Pittsburgh Tribune-Review reported Shanna Hiles, 20, passed out after drinking and ended up sitting on her legs for 12 hours....

[snip]

According to the lawsuit, Hiles had a treatable condition called "acute compartment syndrome." But the hospital instead diagnosed Hiles with alcohol toxicity and waited six hours before transferring her to UPMC for treatment, the lawsuit claims.

The Trib reported Hiles claims the delay in proper treatment resulted in the need for UPMC doctors to amputate her legs at the knee.
Woman Whose Legs Amputated After She Sat On Them Sues Hospital
Reply With Quote
  #10  
Old 09-16-2011, 08:36 AM
kanicbird kanicbird is online now
Guest
 
Join Date: May 1999
OK, if it's just pressure on the nerve, as opposed to circulation being cut off, what is the mechanism that limbs are lost?
Reply With Quote
  #11  
Old 09-16-2011, 09:10 AM
Blake Blake is offline
Member
 
Join Date: Mar 2001
Posts: 10,207
Limbs are not literally lost. The function of the limb can be lost, but the limb doesn't actually drop off.
Reply With Quote
  #12  
Old 09-16-2011, 09:26 AM
kanicbird kanicbird is online now
Guest
 
Join Date: May 1999
Also adding the process in common usage to castrate bulls - apply a tight band around the testicles, and a similar process with dealing with hemorrhoids. Surely there is some way of cutting off circulation by pressure.that could lead to loss of a body part.
Reply With Quote
  #13  
Old 09-16-2011, 09:42 AM
Blake Blake is offline
Member
 
Join Date: Mar 2001
Posts: 10,207
Quote:
Originally Posted by kanicbird View Post
Also adding the process in common usage to castrate bulls - apply a tight band around the testicles, and a similar process with dealing with hemorrhoids. Surely there is some way of cutting off circulation by pressure.that could lead to loss of a body part.
Through constrictive pressure, sure. Putting pressure on it from a single angle, as in sleeping on it, isn't going to cause the limb to drop off under any normal conditions.
Reply With Quote
  #14  
Old 09-16-2011, 10:00 AM
AaronX AaronX is offline
Guest
 
Join Date: Feb 2011
Oh wow, I didn't know it was the nerve and not blood supply. Why doesn't it happen immediately then?

About the rubber band castration, I'd heard of that too. I always wondered how do they get the band over the balls? If they were that tight, wouldn't it be impossible to stretch them that much?
Reply With Quote
  #15  
Old 09-16-2011, 10:05 AM
levdrakon levdrakon is online now
Guest
 
Join Date: Apr 2002
Wow, when I was younger and was fairly worried about this. I've always been prone to arms & legs falling asleep, and finding yourself with a big, cold lump of flesh that used to be my arm was always freaky.

Thanks Dope, I'll sleep a teensy bit better now!
Reply With Quote
  #16  
Old 09-16-2011, 10:57 AM
needscoffee needscoffee is offline
Guest
 
Join Date: Oct 2009
I worked with a guy this happened to - he passed out drunk on New Year's Eve sitting with his legs crossed, and when he finally came to, his legs were paralyzed. When I knew him about 9 months later, he'd had some surgeries, was partially recovered, but walked very hobbled and stiff-legged.
Reply With Quote
  #17  
Old 09-16-2011, 11:24 AM
Frylock Frylock is online now
Guest
 
Join Date: Jun 2001
I thought it was loss of blood supply to the nerve. Is that not what causes troube when a nerve is pinched?
Reply With Quote
  #18  
Old 09-16-2011, 11:31 AM
Lancia Lancia is offline
Guest
 
Join Date: Jan 2007
The Master speaketh:

http://www.straightdope.com/columns/...g-falls-asleep
Reply With Quote
  #19  
Old 09-16-2011, 12:42 PM
dracoi dracoi is offline
Guest
 
Join Date: Dec 2008
Quote:
Originally Posted by AaronX View Post
Oh wow, I didn't know it was the nerve and not blood supply. Why doesn't it happen immediately then?

About the rubber band castration, I'd heard of that too. I always wondered how do they get the band over the balls? If they were that tight, wouldn't it be impossible to stretch them that much?
Rubber bands really do stretch just fine.

I don't know about castration, but I did have something like that happen with a cat's leg. Somebody wrapped rubber bands around our cat's leg, tightly enough to constrict the blood flow. The cat didn't come back to us for a couple of days. By the time it did, damage had already been done. The vet had to cut off the paw and all of the skin sloughed off up to the point where the rubber bands had been. It took years to heal to the point where we didn't need to keep a bandage over the lower leg.
Reply With Quote
  #20  
Old 09-16-2011, 07:24 PM
brossa brossa is offline
Guest
 
Join Date: Feb 2005
It's true that the tingling you get in an extremity when you've slept on it wrong does not mean that the blood supply to the limb has been cut off. However, it is quite possible to damage a limb by 'sleeping' on it to such an extent that it causes a life-threatening problem that can require surgery and/or amputation - and not just because of loss of nerve function, but because of significant tissue destruction.

Normal sleepers on a nice soft bed move around enough to prevent compression damage to their tissues. However, people who are more deeply unconscious, otherwise immobile, and/or lying on hard surfaces can indeed cut off circulation locally. Skin damage can occur with as little as two hours of immobility at points of maximum pressure, leading to decubitus ulcers (bedsores). Deeper tissues can also suffer decreased blood supply because of local pressure. In a worst-case scenario, damage to muscles of an extremity due to prolonged compression leads to a cycle of swelling, worsening of blood flow, tissue damage, and more swelling. The result is 'compartment syndrome' as has already been mentioned. If the inelastic sheath that surrounds the muscle group is not cut open to relieve pressure, the damage can result in permanent deformity or even death.

Compartment syndrome can arise in persons who are immobile for multiple hours - a classic presentation is someone who sits on the toilet for an extended period either due to unconsciousness or simple inability to stand up. Patients in the OR also are susceptible, which is why so much care is put into making sure that extremities are padded properly.

So, while it's true that you aren't really cutting off blood flow to an entire arm or leg due to an awkward position, it is quite possible to compress muscles in such a way with simple body weight that an arm or leg has to be amputated or suffers permanent damage.
Reply With Quote
  #21  
Old 09-16-2011, 07:29 PM
Blake Blake is offline
Member
 
Join Date: Mar 2001
Posts: 10,207
Quote:
Originally Posted by AaronX View Post
About the rubber band castration, I'd heard of that too. I always wondered how do they get the band over the balls? If they were that tight, wouldn't it be impossible to stretch them that much?
You use a tool called an elastrator.
Reply With Quote
  #22  
Old 09-16-2011, 09:14 PM
Euryphaessa Euryphaessa is offline
Guest
 
Join Date: Sep 2007
Quote:
Originally Posted by dracoi View Post
Rubber bands really do stretch just fine.

I don't know about castration, but I did have something like that happen with a cat's leg. Somebody wrapped rubber bands around our cat's leg, tightly enough to constrict the blood flow. The cat didn't come back to us for a couple of days. By the time it did, damage had already been done. The vet had to cut off the paw and all of the skin sloughed off up to the point where the rubber bands had been. It took years to heal to the point where we didn't need to keep a bandage over the lower leg.
Sorry for the hijack, but this made me incredibly sad. Poor kitty.
Reply With Quote
  #23  
Old 09-17-2011, 01:14 AM
horsetech horsetech is offline
Guest
 
Join Date: Jul 2008
Dracoi, poor kitty indeed, and sadly not uncommon.

To follow up on brossa's post, lying in one position for a long time on a hard surface can cause widespread rhabdomyolysis (skeletal muscle breakdown). This doesn't just cause muscle damage and cramping: the lysed cells release their contents, including potassium (which is normally present at much higher concentrations within cells than outside cells) and myoglobin. If it gets severe enough, the elevated potassium level can cause heart arrhythmias. Also, myoglobin can damage the kidneys if there is enough floating around, and the dehydration often present in these scenarios exacerbates the problems of impaired renal function and electrolyte abnormalities. This can happen if, say, an elderly person falls, breaks a hip, and lies on the floor, unable to move themselves to a phone, until they are found.
Reply With Quote
  #24  
Old 09-17-2011, 04:07 AM
KarlGauss KarlGauss is offline
Out of the slimy mud of words
Charter Member
 
Join Date: Mar 2000
Location: Between pole and tropic
Posts: 6,991
Quote:
Originally Posted by kanicbird View Post
OK, if it's just pressure on the nerve, as opposed to circulation being cut off, what is the mechanism that limbs are lost?
Don't be so fast to abandon that mechanism . . . That being said, although it's theoretically possible to lose a limb by cutting off its blood supply (say, by passing out drunk in a position where the blood flow to the limb is compromised), it's much likely that one loses a (large) patch of skin.

As an example, imagine that someone has a stroke, becomes paralyzed, and thus cannot move. Let's say they're on their back. Those points of the body (skin) in contact with the floor (often in the form of 'bony prominences') are being subjected to continuous and uninterrupted pressure. Very often, that pressure is higher than the blood pressure. That means that blood won't be able to flow into the 'squashed' tissues. If it persists long enough, the squashed tissue (e.g. skin) will die (so-called pressure necrosis).
Reply With Quote
  #25  
Old 09-18-2011, 03:05 AM
jnglmassiv jnglmassiv is offline
Charter Member
 
Join Date: Nov 2002
Location: Chicago's Northside
Posts: 2,001
Quote:
Originally Posted by Blake View Post
You use a tool called an elastrator.
Get that thing away from me.
Reply With Quote
  #26  
Old 09-18-2011, 03:39 AM
BigT BigT is offline
Guest
 
Join Date: Aug 2008
Quote:
Originally Posted by jnglmassiv View Post
Get that thing away from me.
At least one guy on Dirty Jobs argued that this was more inhumane than just cutting it off, judging by recovery time of the sheep they used it on.
Reply With Quote
  #27  
Old 09-18-2011, 08:53 AM
Wesley Clark Wesley Clark is online now
Guest
 
Join Date: Aug 2003
The lead singer of megadeth, after years of risky behavior and drug abuse, once fell asleep with his arm hanging over the back of a hard bench (which put a lot of pressure on I believe his radial nerve). After waking up and it taking a long time to get use of his hand again he was told he'd never play guitar again. However after a year or so of rehab he was back. So that was ironic that the drugs didn't hurt him but sleeping on a bench did.

Personally I get this all the time and it worries me. But carpal tunnel syndrome involves compression too and as far as I know people don't get amputations or lose a limb due to that.
Reply With Quote
Reply



Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 10:26 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.