#tourniquets

Good evening, folks. Time for a One Hour Post- I post I research, craft, write, and publish in under an hour. Today's topic was sent in by @exuberantocean:

Dressing a wound is something nurses get masters degrees in, so to make it something I could do in an hour, I decided to select tourniquets.

Tourniquets are devices used to stop bleeding in a limb. They are commercially available for purchase, but you can also improvise them without too much trouble.

What they look like:

Tourniquets are basically a strip of tough cloth with a windlass- basically a stick- that is used to tighten the cloth around a limb above where the bleeding is. The commercial ones look like this:

How they work:

Inside the upper part of every limb runs a really big artery. That artery's job is to carry blood at high pressure to the rest of the limb. If the artery (or a smaller artery in the lower part of the limb) gets torn or severed, a lot of blood can rush out of it very quickly, causing the person to be at risk of death from blood loss.

A tourniquet puts pressure on that artery- enough that it overcomes the pressure inside the artery (the top number in a blood pressure reading), preventing blood from flowing through it. The blood stops flowing through the artery and can no longer get to the part of the artery that is damaged, and bleeding stops.

When to use one:

There are basically two times you use a tourniquet. Time number one is when other methods to stop arterial bleeding have failed, and the person will die without it.

Tourniquets stop everything below the tourniquet from getting blood. Blood brings oxygen and glucose to a limb and removes metabolic waste. Muscle (the main blood-using thing in a limb) can go many hours without fresh blood before it begins to die, but when you use a tourniquet, a timer does start.

Ideally, you're trying to use direct pressure on a wound first. Direct pressure on an arterial bleed will deprive some tissue of blood (you have to compress the damaged part of the artery to stop bleeding, which will stop blood from getting anywhere downstream, but the artery is already not working well as an artery at this point, so some tissue is just gonna be SOL). Tourniqueting a limb will deprive a lot more tissue of blood, so it's technically the second option. Of course, if there's a spurting wound you can't get under control in a few seconds with pressure, tourniquet is definitely and always better than death.

The second reason you use a tourniquet is logistical. Tourniquets are going to stop bleeding quickly and reliably. So if there's a lot of bleeding people and few rescuers, the rescuers are going to be able to save more people slapping tourniquets on bleeds that maybe technically could have been stopped with pressure if they had been able to devote the time to any single wound. Also, if someone is bleeding somewhere a rescuer can't get to, like if a limb was crushed by a boulder, you can put the tourniquet around that limb and stop the bleeding without needing to be able to see the wound itself.

How to use one:

Take the (commercial) tourniquet and place the strap part around the upper part of the limb. You want the upper limb because there's only one artery there instead of two or more lower in the limb, and it's easier to compress against a single large bone. Tighten it down to finger tightness, then twist the windlass to put more and more pressure on the artery until bloodflow stops.

You know you're done tightening when the bleeding stops. Not slows down, stops completely. There should be no pulse below the site of the tourniquet. In commercial tourniquets there is usually a clip to keep the windlass in place once you've tightened it down enough. Here's a video:

Considerations:

If you put a tourniquet on someone because you could not stop bleeding and were afraid they were going to die, their artery is severely damaged and can't bring enough blood to the tissue below the site of the injury. They need surgery to repair the artery even if the tourniquet is removed. There is no version of this story where they don't get surgery and still get to keep the limb.

Also, without blood to carry it away, waste builds up in the muscle in the limb. When muscle starts to die, cells also release lots of electrolytes (potassium). This toxic soup stays in the limb until the tourniquet is removed, when it is released all at once. This is bad and needs to be accounted for medically.

Combining with:

Hey nonnies! Thanks for your asks!

A tourniquet is the only thing that will save your characters' lives.

Generally the wider the better (2" is best), wrapped around the leg, then around something to use as a windlass. (A stick, a pair of scissors -- I've lost good scissors this way -- a broken off broom handle....)

The windlass is then twisted until the tourniquet is tight enough that the bleeding stops. (Yes, this fucking hurts, but if the tourniquet is wide enough it won't hurt as much as you think, at least at first -- I've had this done to me in training multiple times.)

Like all tourniquets, the character then has about 4 hours to get definitive care before you start to see tissue damage distal to the tourniquet. Typically that will mean EITHER a vascular surgeon repairs the damaged artery OR someone sutures off the end of the artery and the character gets an amputation.

Depending on how rapidly the tourniquet is applied, the character may suffer some blood loss, or a life-threatening amount of blood loss; the femoral artery bleeds FAST. For that reason it's not unreasonable to expect them to get transfusions of blood products to help them remain alive and in the lighter stages of shock.

One additional treatment: if the wound is deep enough (for example, a big chunk of flesh has been gouged out of them), a doctor or military medic (not civilian*) may decide to pack the wound -- literally stuff it with gauze.

Which brings me to THIS LOVELY ASK:

The general rule with packing a wound is, "pack until you can't pack any more, and then keep packing." It is reported to hurt like hell.

Surgical packing is indeed done. When I woke up from bottom surgery with a brand-new, incredibly bruised, incredibly swollen vagina, it was packed completely full of gauze and sutured shut (to prevent the "wound" from "healing" and closing up).

Generally speaking, suturing closed large gaping hollowed-out wounds (traumatic or surgical) actually breeds infection, so in the case of large-area trauma, wounds will still be packed, and then un-packed later as they heal and allowed to close. In the surgical context I've also seen this happen with super invasive ("radical") surgery to correct neck cancer.

Thanks for your asks and good luck with your stories!

When hypovolemic shock is caused by blood loss, the first aid is to stop the bleeding. This is done either with direct pressure or by applying a tourniquet at least 2 inches above the bleeding part.

In the leg, the most deadly artery to cut would be the femoral artery, but there are several others. The femoral runs along the inner thigh near the bone. The popliteal artery runs behind the knee, and the tibial artery runs along the back of the tibia in the lower leg. Either of these could cause also life threatening bleeding, just slightly slower than the femoral would. Severing or tearing any of the mentioned arteries would cause bright red, spurting blood. Severing a vein would cause a steady stream of darker blood and is much easier to stop and substantially less dangerous.

Pressure would be directly over the wound, perhaps after packing the wound with gauze or cloth to increase the pressure specifically on the bleediest part. A tourniquet, as mentioned above, would be placed either two inches above the part that was bleeding, or somewhere on the upper leg (if a lower-leg injury). It would be tightened until the bleeding stopped.

But that's just the first aid- tourniquets and direct pressure stop bleeding, but they don't do anything to solve the hypovolemic shock or treat the injury itself.

Hypovolemic shock occurs when the circulatory system doesn't have enough liquid in the blood vessels to maintain blood pressure. When blood pressure drops, the heart rate increases to try to compensate by moving what blood there still is faster. This helps get oxygen to the tissues that need it, but is very energy intensive and cannot be sustained for long. Eventually, the heart rate can no longer compensate, the blood pressure drops further, and certain organs (usually the digestive system and kidneys first) begin to starve for oxygen and die.

Replacing the lost blood cells and volume is a top priority, and assuming the bleeding has stopped completely, is really all that's needed. If it happens quickly, there may not be any long-term repercussions.

The blood is replaced by IV fluids and either whole blood or a combination of different specific blood components like albumin, platelets, and packed red blood cells. The albumin helps maintain the blood pressure by keeping fluids in the blood vessles, the platlets help control bleeding, and the red blood cells replace the cells that were lost to bleeding and maintain the blood's ability to carry oxygen.

Prompt administration of IV fluids and blood will very, very quickly resolve symptoms of shock. Essentially as soon as those blood cells get in there and start doing their job, the patient's color comes back, their heart rate and blood pressure go back to normal, they begin to think clearly again, and can sit up and move around again with less dizziness.

Now, the leg is a different story. The leg needs surgery to repair the artery. If that doesn't happen, the leg will die and need to be amputated. There is essentially a 48 hour window from tourniquet application to completed surgery where it can be expected that the leg will be useful again. Even within 48 hours, the leg is dying and the dead muscle bits are falling into the blood. When circulation is restored, those muscle bits (along with waste products and electrolytes from inside damaged and dead cells) return to circulation, and can clog up the kidneys and other organs. A minor version of this can be mitigated by giving a lot of IV fluids. A more severe version might need dialysis to help the kidneys get rid of the waste products before they are damaged by them.