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elevenblade t1_j9e0ztx wrote

Surgeon here: You wouldn’t want to connect a major artery to a major vein — that would result in high pressure oxygenated blood pouring rapidly into the vein, raising pressure in the venous system and wasting oxygen. For large blood vessels we tie them off with ligatures (surgical thread, basically) or clip them shut with metal or plastic clips. Bleeding from smaller vessels is handled with cautery, usually electrocautery or sometimes ultrasonic cautery.

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ThinkBlueCountOneTwo t1_j9e6y2t wrote

Would an amputee (or double, triple, quadruple amputee for eg) have increased blood flow to the rest of the body since there is less "body" that the heart needs to pump to? Or does the heart just work less hard?
Are there positive/negative side effects because of this?

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bonerfiedmurican t1_j9g2fif wrote

Depends on the size of amputation. A pinky toe? No different. Both legs at the hip? Yeah they can run into some cardiac issues which there are theories about why. I've attached a very topical paper on this if you'd like to read. https://pubmed.ncbi.nlm.nih.gov/18281705/

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Ronaldoooope t1_j9hm0ab wrote

In a lot of cases the reason they got an amputation was decreased blood flow (diabetics) so they likely just normalize in that case lol

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Delicatebody t1_j9hrfa5 wrote

What is the part about the “patients’ devious behavior” referring to?

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esobofh t1_j9lxac3 wrote

in this case deviant behavior means alcohol consumption or eating disorders.

Imaging if you were able to drink a whole 26oz bottle of vodka without issue, and then you then had half of your body removed. attempting to drink the same amount would be like drinking double what you had been, since you have half the body left to absorb and buffer the effects of alcohol. Could be a recipe for death. Same as with food.. with half a body, you don't need to eat as much, and so you could literally eat yourself to death.

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MiniMooseMan t1_j9hs0hz wrote

Could they... drain them a bit? Blood is made in the bones, and if you got a few fewer bones, technically you could have slightly less to pass around lol

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dryingsocks t1_j9hz8i2 wrote

blood isn't made at a constant rate but as needed, otherwise donating blood would permanently lower your blood pressure

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SchlauFuchs t1_j9hzt24 wrote

it is not so much the amount of blood that is the problem but that the heart is used to pump against a given flow resistance and that resistance changes with the number of reduced "consumers". It is a little like with the electrical grid, when large consumers suddenly go offline/online, the power plants have to adjust their generation to not cause a systemic failure.

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CompleteNumpty t1_j9g9kb2 wrote

The calves actually work as secondary pumps for the cardiovascular system (specifically helping to return blood upwards towards the heart).

As such, the loss of one or more calves has a detrimental effect on your cardiovascular health, with many countries treating below knee amputees as if they have heart disease.

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edjumication t1_j9hfkwc wrote

Interesting! I knew about the calve thing from my interest in spaceflight but I didn't know about the heart disease thing.

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natgibounet t1_j9hi7ml wrote

Wich countries ?

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CompleteNumpty t1_j9hl0av wrote

I was just going off what my old prosthetics lecturer told us, but the UK and USA definitely do. The exact action taken (preventative medication and exercise programmes vs routine monitoring of cardiac function) may differ within the countries due to different states, health boards etc.

To be honest I'd be amazed if any Western country didn't have some sort of policy to monitor or preventatively treat amputees, as the increased risk of heart disease is well-known.

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natgibounet t1_j9hma2j wrote

I should look into it, i'm surprised i never heard that even though i live in a western european country

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CompleteNumpty t1_j9hn73i wrote

As a significant quantity of amputations (maybe even most) aren't a result of trauma, but due to things like diabetes or peripheral vascular disease, a lot of amputees will already be getting treated/monitored for heart disease, which will muddy the waters.

I tried to find a source for you, but I struggled to find anything other than a few studies confirming the increased risk in traumatic amputation patients.

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EnchantedCatto OP t1_j9e4id6 wrote

Where does the blood go then? Wont the heart just keep pumping blood into that now closed system, increasing the pressure?

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CastorTJ t1_j9e5ari wrote

I think you are imagining the artery in question to be like a long hose with no where to go and the tab wont shut off. There are offshoots from the artery to smaller vessels ‘arterioles’ and then to the capillary system. The body had a fascinating ability to produce these vessels and essentially redirect that flow as needed.

Also imagine if the tap of the hose is the heart. The vascular system would be a hose with like thousands of other tubes attached to it. If one gets blocked the water just goes to the other tubes. It doesn’t just fill the blocked one up uncontrollably

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EnchantedCatto OP t1_j9e6mce wrote

Right, but what happens to the blood still in the vessel? Does it just dry up?

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jackity_splat t1_j9e9hrz wrote

The blood will still flow up to the point where the artery was cauterized. Then it will turn around and go back to your heart just like all the other blood.

I had one of my toes amputated, the blood still works there just like my other toes. That ones just shorter now.

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ruzzophobia t1_j9f4kqx wrote

aren't arteries like some one-way streets? Blood can flow in both directions?

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Georgie___Best t1_j9f9dsi wrote

Yes, arteries take oxygenated blood to the body and veins return deoxygenated blood to the lungs/heart.

But it isn't like a loop where at some point it becomes a vein. The artery splits and branches like plant roots until it's down to the scale of arterioles, tiny vessels which actually spread the oxygenated blood throughout your tissues via capillaries.

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Krail t1_j9hlwx4 wrote

This is making me realize a question I didn't know I had about the circulatory system.

How do the "delivery" vessels connect back to the "return to the heart" vessels? Does blood come out from the capillaries and then get taken up by other capillaries?

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dcs1289 t1_j9huya2 wrote

The blood cells don't actually leave the capillaries if everything is going fine. The capillary bed is basically a mesh of VERY tiny blood vessels - picture two sets of tree roots with the bottom portion of the roots aiming towards each other and connected - arteries (tree trunk on the left of your mental image) diverge into smaller arterioles which diverge more into capillaries.. which merge back together into venules, which merge into veins (tree trunk on the right).

When the blood is moving through the capillaries, exchange of oxygen and nutrients is able to occur through small pores in the cells (or straight across the cells in some cases). The blood cells don't leave the circulation, but the plasma that they float around in can move back and forth through the tiny gaps.

Here's a good picture to describe the mental image I'm trying to verbalize above.

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Krail t1_j9i6e4e wrote

Ahh, okay.

I think I have one more follow up question, about how the nutrients actually get from blood to the cells. I guess it's... capillaries have pretty broad coverage throughout the whole body, right? What's the furthest a living cell is likely to be from any capillaries?

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dcs1289 t1_j9i74cj wrote

Capillaries are everywhere. It's the end point of the circulatory system everywhere, so there are beds of capillaries in basically any living tissue.

Probably the most well-known tissue with poor/limited blood supply is tendons/ligaments - these are connective tissues with a lot of intracellular matrix made up of collagen, and blood supply to these tissues is poor the further you get from the source blood vessel as there is often very little collateral circulation (what it's called when an area has multiple arteries that feed the capillary beds).

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Georgie___Best t1_j9j3r5b wrote

Capillaries are very small. We are talking of a scale where red blood cells might only fit through single file. At this microscale, diffusion/osmosis are what predominantly facilitates the movement of useful stuff out of the blood and into the extracellular fluid/cells, and waste back into the blood vessels to be taken away.

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seto555 t1_j9l45c2 wrote

To add to the other answers. The process of oxygenation of the cells from the capillaries is called diffusion. Basically the capillary wall is thin enough, that it is leaking Oxygen molecules to the surrounding tissues. The rate of oxygenation depends on partial pressure of oxygen and carbon dioxide (and some other factors) in the surrounding tissues, but usually you can't diffuse farther then a few mm's in a living organism.

Diffusion is mostly used by insects as the main oxygenation process since they are small enough to just have some air filled pipes (tracheas) inside their bodies where the oxygen is directly absorbed from the air.

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jackity_splat t1_j9ipqsn wrote

Thanks! This is what I knew happened but didn’t remember enough to explain it. I just know my veins and arteries still work pretty normally.

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Squiggy226 t1_j9hcvpv wrote

Yes that made it sound like the blood gets to the end of the cauterized or tied off artery and then turns around and goes back the way it came. It branches off to the capillaries which then connect to veins for the return trip.

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jawshoeaw t1_j9fr5bu wrote

That’s not how blood works. The blood at the terminal end of a clipped artery will quickly clot

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chairfairy t1_j9ewtc4 wrote

It has a return path through all the branches that come off it before the amputation point.

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Bax_Cadarn t1_j9fbmpq wrote

Close but not precisely. Think of it like a road system. Whdn You drive off a highway going north, You don't use the same way to go south. You need to drive to a smaller road to later rejoin increasingly larger roads until You enter the main flow from another side.

In ither words arteries branch off into increasingly smaller vessels up to the capillaries, then those collect into bigger and bigger veins

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concealed_cat t1_j9hqoeh wrote

But if you're driving down a freeway, and then encounter a road block 3 miles past the last exit, then what do you do? The cars will just accumulate there with no obvious way out of there. If you cut the artery at a location without any branches, there will be some blood there that will just sit in place, won't it?

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Bax_Cadarn t1_j9hqyhn wrote

Some will clot at the end, some will leave by freshly built microscopic roads, some will go up a bit and leave by the past few junctions afaik. For more details, ask a vascular surgeon ;-)

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chairfairy t1_j9ftns7 wrote

The implication was that the branches lead to "increasingly smaller vessels up to capillaries". Not sure where else someone would think they go...

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Bax_Cadarn t1_j9fvpam wrote

You made it sound like the blood would go "nothing to see here" and turn back through the arteries. I made it so people wouldn't get confused.

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__Beef__Supreme__ t1_j9fkc49 wrote

Think of cutting off a major road. Cars will just start driving off onto other roads (blood will divert into other arteries) . Some cars may start driving across fields and make "new roads" (i.e. your body will make more blood vessels).

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daoliveman t1_j9frdls wrote

I’m think of it like your at home plumbing system. We tie off the end of the blood vessel and it’s now a dead end. Same thing at home. When you turn off the faucet your pipes don’t just explode. The water just stops.

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positive_express t1_j9fc3yt wrote

I was a licensed veterinary technician for a specialty surgical practice. What got me the first few limb amputations was for some reason I though that a blood transfusion would benefit the dog or cat. They lost a fair amount of blood because the limb is now gone that contained that blood.... smh makes me laugh now.

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beaver_nipples t1_j9e7tje wrote

But isn't that how they make a fistula for hemo-dialysis?

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Mneurosci t1_j9ewiyb wrote

Yes, but much smaller arteries than the femoral artery in your leg. Usually you’re anastomosing (connecting) an approx 3mm vein to an artery

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kinbeat t1_j9pk9r5 wrote

Yes, and it comes with a number of side effects (ofc the alternative is death, so they do it anyway)

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LilyFish- t1_j9e3pq7 wrote

if you just close off the large blood vessels, where does the blood inside them go?

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joalheagney t1_j9e5eua wrote

Into all the arteries that feed off them before the point of closure. Think of it like a giant city where one highway has been closed. The traffic goes onto other roads.

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Jaffacakereddit t1_j9e6woj wrote

If you switch off a water tap, where does the water go instead? To all the other places in your town that need water. Ditto the artery. Except mostly it stays in your body.

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911derbread t1_j9ehqse wrote

Any blood caught at the end of the artery will just eddy and swirl until the vessel regresses or grows new connections. It may also clot and get eaten up. It's not a significant concern.

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GeorgeCauldron7 t1_j9f9l4m wrote

Fascinating. I guess this answers a question I've had for a long time about how amputation works. I always assumed that during, for example, a leg amputation, the arterial system was like a 1-way highway for blood that went around your body in a circle, and into your leg and back out (with various exits and off-ramps for blood to go to your tissue), and you would have to connect the two halves of the pipe system if the connection was severed. But now it seems obvious that there is no "back out", or at least not a "back out" artery. It goes from the arteries to your tissue, and then it goes out through veins, right?

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ozspook t1_j9fcvb6 wrote

It takes an off-ramp from the highway, down some streets, into the laneways, drops off it's parcel of oxygen, then makes it's way back up to another highway back to the heart.

There are loads and loads of little streets.

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MrGeekman t1_j9g6llp wrote

>electrocautery or sometimes ultrasonic cautery

​

I'm usually pretty squeamish with medical stuff like this, but those sound pretty neat! I only knew about chemical and heat-based cauterization.

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Gsogso123 t1_j9h7no6 wrote

Thanks, replies like this are what make this sub great!

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JCoco17 t1_j9hunr6 wrote

Them what happens to them? Do they grow new capillary beds?

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elevenblade t1_j9il6wq wrote

Blood vessels have branches. If you seal off one branch the blood still flows to the tissues through other branches. It’s like turning off the kitchen tap in your house — water can still flow to the bathroom sink or shower.

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