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I’m sorry but this is confidently incorrect. You don’t connect arteries to veins during amputations. You just ligate them to cut off the bleeding.

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Well maybe if Paw-paw splurged for the leech, it would've fed off his blood and grown to be leg-sized. Then Paw-paw and his leech-leg would've been able to travel the world as a medical marvel. Some real PT Barnum stuff.

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That sounds amazing!! I wonder how much weight a leg sized leech could bear.

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

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

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

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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I'm so impressed with the comments so far from surgeons and folks who know what they are talking about, I would like to extend the inquiry. When an average citizen or family member comes upon somebody with a profound limb injury, say a teenage girl with a major shark bite below the knee, or a gunshot wound to the lower arm, would it be correct (after calling for help etcetera) to immediately apply a tourniquet of some sort as a life saving measure? As opposed to attempting to apply pressure for instance? I'm just wondering what average people should consider in the absence of immediate first responder care.

unless you are first aid trained i reckon follow the advice of the medical professionals that guide you through it after you call 111

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

Its debatable whether an untrained person could help more than harm by applying a tourniquet. Some sources say yes, some say no. If you are familiar with how it works and there is uncontrollable bleeding from an appendage, then yes, wind that sucker down tight.

Edit is to reflect more up-to-date instruction. You can see discussion in below comments for context.

Tourniquet use is appropriate for a bleed from a limb which cannot be controlled by direct pressure alone. Without training or instruction, an improvised tourniquet applied by a layperson isn't likely to be effective. Fortunately, proper tourniquet use can be learned in only a few minutes and an emergency services dispatcher can instruct you on tourniquet use if you find yourself in a situation where it is necessary and you don't know how to do it. If in doubt and the patient is conscious, it may be a good idea to first attempt to control bleeding with direct pressure alone. Note that direct pressure is not appropriate if there are significant amounts of sharp, foreign bodies within the wound which may make the injury worse than it already is. In that case, elevation, manual arterial compression, and tourniquet use as needed will be the appropriate first-aid.

Tourniquet or not, you can help by finding a clean and dry cloth, garment, towel, applying firm pressure, and don't remove the cloth. If it bleeds through, put another cloth on top and keep the pressure on! You can also apply pressure to the artery above the bleed. Groin for the leg and under the biceps for the arm.

Don't remove any foreign object that may be sticking out of the person, don't put yourself in danger that might cause a second casualty, and don't move a patient who may have suffered a spinal trauma unless absolutely necessary.

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.

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?

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

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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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This is a great question! The short, unhelpful answer is do whatever you have to to stop the bleeding. It really depends on the injury as to whether pressure would be a good start. If it's bleeding a lot, put a tourniquet on it, we'll figure it out in the ED. And check out the Stop the Bleed campaign, ask your boss to host a class!

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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Hey doctor who performs amputations, I'm an ER doctor who sees amputated feet. I've always wondered what goes into the decision of whether a part can be reattached. I remember on my trauma rotation the senior resident looked at an amputated foot for two seconds and then just casually threw it in the garbage. I'd be mad if that were my foot.

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If you don't stop arterial bleeding until after you've gotten through to the emergency service, then the person will bleed out 10-20 times.

Ps: You can realistically only bleed out 1 time....

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

If direct pressure is working, continue that. If it is still bleeding, then Tourniquet.

Also, for reference, any arm injury below the elbow should be able to be controlled with direct pressure.

• source general surgery resident

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

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

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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.

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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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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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.

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.

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

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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.

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

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.

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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>electrocautery or sometimes ultrasonic cautery

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

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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It’s really not debatable. If someone is hemorrhaging, they will die of blood loss. Anyone who can do anything to help stem that blood loss is saving their life, no debate.

Plus, tbh, the risks of tourniquets are greatly over-stated in both popular culture and even in the medical world. All of the time limits people discuss for tourniquets are essentially made up theoretical limits without much data to back them up.

Look up the MESS score (mangled extremity severity scale)…that’s a great baseline reference point.

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Thanks for the link

So I know there have been a lot of answers basically stating 'it gets circulated back into the system.' But I guess I don't understand what happens to the blood that exists in the end of the closed artery, after the last exit to a smaller artery. At some point, the system dead-ends with nowhere to go. What happens to the blood at the end of the cul-de-sac?

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No superglue?

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Medical student with expressed interest in surgery here.

Amputation is not simply chopping off a limb. If planned well, it involves several steps of careful surgical interventions.

The most important thing to note about amputations is that, you would want to keep the mobility as high as possible. Depending on the amount of tissue left, you would generally want to keep joints and a bit more tissue distal to the joint.

So let's start with the innermost part, the bone. You would not want to expose the bone or leave a thin layer of tissue around it. That would lead to pain using prosthetics and during daily life even without the use of prosthetics.

In order to prevent this, the surrounding soft tissues, muscle and fat and skin needs to be slightly longer than the bone so that it can cover the bone well enough.

As stated above by a surgeon, directly connecting big arteries and veins leads to poor cardiovascular outcomes. It certainly depends on the type of trauma and the amount of salvagable tissue but you would want to rely on capillaries and angiogenesis (new vessel formation) for venous return in the long run.

There must also be enough skin to cover the resulting "stump" of a tissue without puckering the skin and while trying to achieve the best cosmesis and surgical outcomes.

I have explained all these steps because many people imagine sawing a leg off when someone says amputation but in modern surgical practice, that's far from truth.

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For closure of superficial skin wounds, sure, but not so great for arteries.

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Stopping blood loss is so critical that even the military changed from the ABC's of first aid (airway, breathing, circulation) to MARCH (Major hemmorage, airway, respiration, circulation, hypothermia). No one survives massive blood loss.

Controlled, sure, but at some point you’ve got to be able to take your hands off and MOVE the person. Tourniquets are great for that, as are some pressure bandages but making a good one of those is a more advanced skill for the lay person

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

Anytime the subject of amputation comes up, I always think about the many men who lost limbs during the Civil War. I've always wondered if most of it was really necessary or if the surgeons were overwhelmed and made quick decisions. I know there was a problem with lead poisoning. But didn’t some survive torso wounds?

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.

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

Would a Good Samaritan law apply in this situation if you try to help someone and they end up dying?

They still end at the end of limbs for a person that doesn’t have any amputation. Blood goes from arteries to smaller blood vessels then to veins.

Wich countries ?

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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.

I vaguely remember the aid training shifting in the late oughts from a kinda checklist/hierarchy of things to do before applying a tourniquet into something close to "when in doubt if they might need a tourniquet, put a tourniquet on it."

Aside from the reasons you gave, I think it probably came down to the fact that there was an expectation that you would be getting treated by an expert in a hospital or purpose-fitted vehicle within an hour (whenever life/limb/eyesight was in jeopardy)

I have a lot of mixed feelings about my country and my service, but am still very impressed/proud of the extreme lengths the medical corps and supporting units went through to make MEDEVACs and treatment such a priority.

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?

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

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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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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My understanding is that arteries branch off to smaller and smaller branches, ultimately becoming capillaries where oxygen is exchanged, and then from those capillaries, they then flow to larger and larger veins, until the blood returns to the heart and lungs. This is, essentially, a closed-loop system.

In the case of an amputated artery, there must be some length of artery with no exit - it does not reach a capillary and I assume it does not just slowly seep blood into the surrounding tissue. The system at that specific point is no longer part of the loop. Is that correct?

So at the cul-de-sac end of the amputated artery, what happens to the blood stuck in that cul-de-sac?

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?

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 ;-)

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

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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Generally, yes! There's really not a lot you can do to someone even as a layman that's really going to hurt them if you're trying to help, with maybe the exception of moving someone with a broken neck. It gets fuzzier for us doctors who might try to save someone with a procedure in the field that goes wrong, like a cricothyrotomy or c-section.

Pretty sure the old cook county hospital (a nice hotel now) has some civil war ghosts haunting about

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

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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.

The logic was basically : Even if you stop the bleeding, the survival chances are low, and other injured patients have had to wait longer for treatment and could die. And even if you were to save someone without amputation they have a high risk of infection risking it all be for nothing.

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

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.

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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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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A doctor in this thread said that the body will form new capillaries to make up for that. But you’ll have to ask him for anymore about that I’m sorry

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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.

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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Isn’t a tourniquet more likely to cause a need for amputation? Maybe the idea is to avoid that if pressure is working?

That’s the…presumed risk of tourniquets, but again, the data just isn’t there to show that much of a risk.

If you are just sitting there waiting for EMS, by all means continue holding pressure.

But if you need your hands for something else (like calling EMS) or you need to move, or you have multiple people you’re trying to help, or any other reason why sitting there with your hands ON the wound applying pressure isn’t sustainable…sure, apply the tourniquet.

I think you’d be surprised at how frequently little branches come off of arteries. The area after the last exit is going to be quite short…less than a centimeter, likely far less. Some of the blood will likely clot, but only in sections with NO flow, making your dead end a little shorter.

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.

As I was instructed when I had received first aid courses, you should first try to use pressure. If it's not enough to stop the bleading you should consider using a tourniquet.

Please note also the time where the tourniquet where put in place, it's importent for doctors. also please note that she tourniquet should only be removed by a doctor ;).

In any case, the tourniquet should be the last attempt

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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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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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Hum, I don't know the US law, but in my country the same kind of law is applyable.

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

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OK, prior caveat: This will be a long post and will not directly cite publications for every claim

So first off, I'll say that my advice on the topic is informed by (but not infringing on any intellectual property) my time working as a 911 dispatcher using data-informed protocols for prehospital treatment by laypeople (created by a Salt Lake City-based organization that is generally recognized as the standard for these protocols, and which sells them to most public-safety emergency answering centers.) [Bohm and Kurland, 2018] While this raises doubts about its accuracy, it establishes its uniquity] I understand that instructions for tourniquet use by non-healthcare personnel is changing as newer data shows that, as you said, improperly applied tourniquets are not as harmful as once believed and that laypeople can apply tourniquets effectively and quickly with proper instruction. [Scott, et. al. 2020] I believe that the previously mentioned company may have altered their product to reflect this, but I've been out of that gig for a few years now.

That said, the reason why (at the time) laypeople were generally not advised to apply tourniquets in the absence of unambiguously lethal, uncontrollable hemorrhage was not that a poorly applied tourniquet could worsen the outcome for a person with an otherwise lethal hemorrhage. Instead, it was to discourage the use of tourniquets when not necessary, as it was believed that a layperson may not be able to make this distinction and thus use them excessively. The vast majority of prehospital appendicular bleeds probably do not require tourniquet use (anecdotal, but it was probably close to 1 in 100 during my time answering phones). This is probably due to the low threshold some people have for requesting emergency medical transport. For a layperson who may have trouble telling the difference, attempting to control bleeding by direct pressure first is often a good idea in the absence of unquestionably uncontrollable, arterial (or massive venous/tissue capillary bed) hemorrhage.

TLDR: Until recently, tourniquet use by untrained laypeople was generally discouraged, but things have changed within the past few years.

This is true, but the amount of damage done by tourniquets is overstated, whereas the damage done by uncontrolled hemorrhage is…death.

Let’s say that, as you posited, only one of every hundred wounds needs a tourniquet to prevent death. If the perception is that tourniquets cause minor injury every time they’re used and permanent damage one time in 10, then you’ve hurt 99 people and caused permanent damage to 10 for every life saved with a torniquet.

Now let’s do the math if, say, you see minor injury one time in 10 and permanent damage once in 1000 applications. All of a sudden, you’re only causing 10 people minor harm for each life saved. Completely different math.

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