What is a Tourniquet? Everything You Need to Know
A tourniquet is a device used to stop the flow of blood to an area of the body using pressure. In emergencies, when a limb has suffered a serious injury or even been amputated, and the casualty is losing a lot of blood, a tourniquet can help save their life by restricting the flow of blood to that area and then out of the body.
From makeshift tourniquets made with rope and a stick to cutting-edge tactical designs, tourniquets are a piece of lifesaving equipment. Here’s what you need to know about them.
What does a tourniquet do?
When the body suffers a severe wound and experiences haemorrhaging (heavy bleeding), the person might only have minutes to live. That’s why tourniquets are included in critical injury first response and bleed trauma kits so that paramedics can treat casualties of severe injuries as fast as possible.
Why do we use a tourniquet to stop blood flow?
It can take just five minutes to bleed to death. Haemorrhagic shock occurs when the body loses 20% of its blood, which means the heart can’t sufficiently pump blood around. When the body loses 40% of its total blood, the person is at high risk of exsanguination, and unless it’s treated very quickly, this could be fatal.
Sometimes a wound is too extensive to use a trauma dressing and pressure to stop blood flowing out of the body. For example, a deep stab wound can be quite clean and small, and a first responder can use a haemostatic dressing to seal off the area and prevent blood from escaping. But if the casualty suffers from deep lacerations across a large area or loses a limb, it’s impossible to stop blood from flowing out.
We use tourniquets to cut the blood supply to a specific body area so that blood flowing out of the wounded area is ceased. Using a tourniquet to cut off blood supply to a severely injured arm means all bleeding on that arm can be handled at the source.
How do you pronounce tourniquet?
Taw · nuh · kay
When are tourniquets still used?
A tourniquet can be used in any situation where someone has heavy blood loss, and less drastic measures like applying pressure to a trauma dressing or haemostatic dressing over the wound won’t work. Here are some examples of times when a tourniquet can be used.
- Road accidents: can result in severe trauma, and help might not always be close by. We recommend keeping a car first aid kit in your vehicle at all times, which contains more commonly used items (excluding a tourniquet) you might need in an accident.
- Heavy machinery plants: factories, warehouses, production lines, and automated processes all present the risk of injuries such as maceration, crushing, and amputation of a limb.
- Military: soldiers in the army need to know how to use a tourniquet to handle life-threatening injuries resulting from war.
Tourniquets in Non-Life Threatening Situations
A tourniquet is not always used to save a life in a crisis. Phlebotomists used a small tourniquet to increase venous filling and make it easier to puncture a vein.
Do they use a tourniquet during knee replacement surgery? Yes, many surgeons prefer to apply a tourniquet to the thigh to create a bloodless field for safety and to make surgery easier to perform. If a tourniquet is only on the limb for a short amount of time (less than two hours generally), there won’t be any permanent damage.
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How does a tourniquet work?
How do tourniquets work? The mechanism is very simple and was created in 1674 by a French army surgeon. The name tourniquet comes from the French word ‘tourner’, which means ‘to turn’.
The original design of the tourniquet consists of a strap or band placed around the limb and a rod or ‘windlass’ tied to the strap. The windlass is twisted, gathering up more of the strap with each turn which constricts the strap around the limb. This action applies pressure to the veins and arteries in the limb to the point that no blood can pass through and enter the limb. When this happens, it means blood cannot reach a wound and leave the body.
In our guide, How to Apply a Tourniquet, we cover step-by-step instructions and videos on how different kinds of tourniquets should be used.
A number of different tourniquets have been developed that work in different ways to suit a variety of people and situations.
Windlass-Operated
The standard and original design of tourniquet. This windlass-operated device helps the user apply maximum pressure without needing a high level of strength.
Zip-Tie Style
This style of tourniquet resembles a giant zip tie. The locking buckle works by catching onto the ridges on the strap in such a way that it cannot come loose. This design also comes with a one-hour automatic timer button, so there’s no need to write down the time it was applied.
Elastic Band Style
The S.W.A.T (Stretch, Wrap, and Tuck) tourniquet is one consisting of a stretchy band that is stretched and wrapped over itself. The rubber band clings to itself to prevent loosening, and the band is marked with designs that help the user determine if they are applying it with enough pressure.
Can a tourniquet cause damage?
Tourniqueting a limb can save someone’s life if they have a haemorrhaging wound. They’re also used to create bloodless surgical fields and are even known to reduce muscular atrophy and stimulate bone growth through blood-restrictive therapy. So why are tourniquets dangerous, as so many people think? If a tourniquet is misapplied or left on for too long, it can cause temporary or permanent nerve and tissue damage.
Some Injuries Caused by Tourniquets
- Compartment syndrome: nerve damage can occur when too much blood becomes stuck in the limb (often due to venous restriction but not arterial restriction). This is one reason why applying a tourniquet correctly and tight enough is essential.
- Ischemia: from mild sensory impairment to loss of function. Nerve damage, muscle damage, tissue necrosis, and vascular impairment can affect the body’s ability to detect heat, pain, and pressure and prevent the body from performing functions the brain instructs it to.
- Post-tourniquet syndrome: swelling of the limb and area that experienced blood flow restriction. Half of the post-tourniquet swelling is caused by blood returning to the limb, but patients can also experience post-ischemic reactive hyperemia, which occurs as the body works to restore normal acid-base tissue balance and cleanse the body of metabolic products of anoxia.
Knowing where to place tourniquets is important to ensure they work effectively. Generally, it’s best to aim three inches above the wound on the limb. Find out how to use a tourniquet correctly.
How painful is a tourniquet?
Having a tourniquet applied is known to be quite painful, and the casualty may need pain relief if possible. In a study of pain tolerance in tourniquet volunteers published by the Association of Anaesthetists, the sensation of having a tourniquet was described as follows.
“Just after the tourniquet was inflated, the first sensation felt was a pressure pain at the site of the tourniquet cuff (first component of pain). Rapidly, within 3 (2) min, a tingling sensation developed, mainly in the hand. This tingling sensation increased progressively and after 10–15 min [12 (1) min] the arm began to ache more than the original pain and became even worse (second component of pain). Hypoaesthesia occurred about 10 min after the tourniquet has been inflated [10 (1) min] causing numbness mainly in the hand. After about 20 min, the fingers became completely anaesthetised [22 (7) min], and, 5 min later, the muscles were completely paralysed up to the wrist [27 (3) min; third component of pain].
At first, tourniquet deflation seemed to relieve the subject's pain within a few seconds and to produce a sensation of well-being. But within less than 1 min, all of the subjects described a warming sensation which quickly turned into an aching sensation of burning. Limb reperfusion was accompanied by other pain, such as a tickling feeling, which soon became a throbbing sensation that grew even more painful when touched and was accompanied by muscle cramps. Pain reached a peak, mean VAS = 7 (4) cm, after 2 min, but it was not significantly greater than the pain experienced before tourniquet deflation occurred. Both groups reacted the same way and the pain subsided within 6–7 min.”
Tourniquet pain should be managed with pain medication if possible, and the casualty should be supported and comforted to ensure their distress is minimised. If you need to apply a tourniquet to someone, make sure you continue to talk to them calmly as you do so if you can, or ask someone else to help you keep the casualty calm.
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