You may have seen a tourniquet (TQ) in a movie, or heard about someone using a stick and some cloth to stop a bleed (spoiler alert! Don’t do this!). In NZ, many people still don’t really know what they are, how to choose them or when to use them. There are also the faction who have ‘all the gear, but no idea’ so we though we’d break it down for you.
How do tourniquets work?
Before we delve in to the science, it is important to note that there are many different products that fall under the ‘tourniquet’ banner.
Some are used in clinical settings during surgery or when people are taking blood.
For this article, we are talking specifically about Emergency Pre-Hospital Limb Tourniquets, commonly known as Commercial arterial tourniquet’s or “TQ” for short… but what does this mean?
These TQ’s are designed to completely occlude – a fancy word for completely block – all blood vessels within a limb. The primary goal is to completely stop blood exiting the body, maintaining blood pressure and keeping as much blood in circulation as possible. They are designed for pre-hospital emergencies, making them ideal for use for first-aiders or first-responders.
They achieve this via a fastened strap made from a strong material which is then tightened via mechanical advantage, typically in the form of a windlass.
Understanding basic anatomy
Arteries carry oxygenated blood away from your heart, providing fuel and nutrients to the various tissues of the body. Arterial flow is a high-pressure system and when cut, they present by an obvious squirting or pulsing of bright red (due to oxygenation) blood, causing a rapid loss in pressure and volume within the circulatory system. In comparison, veins which are responsible for venous return are low-pressure, carrying deoxygenated blood through the veins back to the heart and lungs – these rarely, require the intervention of a tourniquet to be managed or controlled.
Major arteries with few exceptions, lie deep within the muscle tissue on the inside of bone structure, protecting them from external strike. This can make them difficult to control as the force required to achieve occlusion can be significant and if there is extensive musculoskeletal trauma there can be multiple arteries compromised which compounds the problem. The amount of force that select commercial tourniquets can deliver is a simple and effective solution to manage life threatening extremity bleeding.
Not all bleeds require a tourniquet
To understand how a TQ works, it is important to understand what they are used for. They are indicated for bleeds that are cannot be controlled with direct pressure, or when there are large amounts of musculoskeletal tissue and associated vascular trauma i.e. an amputation where the trauma is so significant direct pressure simply will not be effective.
Keep in mind just because there is significant musculoskeletal trauma doesn’t mean that there will always be a life threatening bleed – get to skin quickly, assess and appropriately manage the bleeding.
Our students have provided anecdotes of TQ use in NZ from injuries such as glass window cuts, surf-board fin strikes, slips and falls, motor vehicle accidents, assaults and accidental gun-shot wounds.
Conversely, we have had many previous students reach out who wished they had a TQ, but didn’t. These incidents include forestry accidents, amputations in manufacturing plants, mountain biking stacks and farming mishaps.
It doesn’t matter what causes the bleed – massive haemorrhage needs to be managed. We need blood to remain inside of our circulatory system or we very simply expire, don’t be afraid to use a TQ however bear in mind once it is on, it stays on.
Components of a commercial tourniquet
Most commercial TQ’s have the following components:
- A strap: The TQ strap is placed above the wound, wrapping around the circumference of the injured limb and secured in place. Depending on the make and model, it could use a hook and loop system or buckles.
- Mechanical Advantage: The circumference of the TQ’s strap is then decreased by using mechanical advantage typically from a ratchet or a windlass. A windlass is a type of winch – essentially a crank handle. The bleeding stops when the circumference of the strap decreases enough to compress the arteries, veins and surrounding tissues.
- Retainer: When the bleeding has stopped, the TQ has been tightened adequately. The retainer prevents the pressure from being released. Again, there are a variety of different systems depending on the TQ’s make and model. Retaining the windlass or ratchet prevents the loosening of the system, and thus, further blood loss.
- Time Tab: This is used to record the time the TQ was applied. The length of time a TQ has been on will dictate what treatment is required when they arrive at the hospital. Not all TQ’s have a time tab, however it is a very useful feature.
If the TQ was applied correctly and is fit-for-purpose, it should completely occlude the blood vessels in the limb below the TQ. For a casualty suffering massive bleeding from a limb, this could be life-saving.
Mechanical advantage is what separates most improvised TQ’s to commercial TQ’s. This is why “using a belt” does not work – despite what pop-culture may lead you to believe.
In one study, improvised TQ’s without a windlass failed to stop bleeding in 79 of 80 tests in a clinical environment.
Even with a windlass, improvised TQ’s still failed over 40% of tests – and often caused further issues such as nerve palsy not to mention extreme pain to the subject having the improvised TQ applied.
The simple answer – carry a commercial TQ as part of your every-day carry. More on this in another article.
Not all TQ’s are created equal
There has been a rapid advancement in the evidence around TQ use in the last 15 years- largely thanks to data collected and compiled from various combat theatres around the world. At the forefront of the science is the Committee of Tactical Combat Casualty Care (CoTCCC), their evidence based approach is the gold standard for recommendations on which TQ’s which are safe and effective.
All TQ’s are not all created equal; there is a huge variance in the quality, efficacy and authenticity of TQ’s available today.
Similarly, they come in many shapes, sizes, price points and have different mechanisms of action. In fact, in 2018, there were 1,627 devices approved by the US Food and Drug Administration as TQ’s.
The CoTCCC reviewed their list of approved tourniquets in 2019, recommending only eight different models including the Tactical Medical Solutions Special Operations Forces Tactical Tourniquet – Wide Gen 5. This is the TQ of choice for us here at PracMed NZ.
Sadly, there are many knock-offs and fakes hitting the market as the popularity and understanding of TQ’s grows. In NZ, there are several reputable companies selling fakes as genuine products. This is extremely dangerous, as they have little to no evidence regarding their safety or efficacy, often made with sub-par materials that break under pressure.
This fake (below) made its way into one of our classes. We put it to the test to see if it would work – the windlass bent, the buckle stretched and the pain the user felt was enormous.
In short, where ever you get your TQ from, make sure it is reputable!
But aren’t tourniquet’s dangerous?
There are many myths and rumours surrounding the use of TQ’s in a civilian setting, many of which are based on outdated science. We dispel many of these myths in our Stop the Bleed® and other range of first aid courses.
The New Zealand Resuscitation Council, the standard setting body for first aid in New Zealand, updated their bleeding control guidelines in 2017. As a result, they now include the use of arterial tourniquet for life-threatening limb bleeding. Sadly, the changes did not flow through to the basic-life support courses. Many providers are still spreading misguided and outdated opinions (rather than evidence based medicine) blanketing all TQ’s as unsafe. This is where PracMed NZ leads the way.
The evidence has been mounting for years that prehospital tourniquet use should be more aggressively pushed. One study from the Journal of the American College of Surgeons found a 6-fold mortality reduction across their six year study. Another review of TQ use in civilian settings, states that they are safe for most uses.
…most uses are safe and effective in civilian settings, as they are in military settings.”
Simply put, incorrect use of a TQ can be dangerous. Most of the dangers occur when they have been incorrectly applied, used when they are not required, or they are not fit-for-purpose. It is important to be trained properly in how to use them.
Improvised TQ’s are another area where some of these rumours were sprouted. Many improvised TQ’s do not completely stop all bleeding – they often stop venous flow but not arterial, which can harmful. This is a whole other topic, which we we will cover soon!
The importance of tourniquet training
One study, measuring TQ efficacy in a civilian wilderness setting states that there is a link between the quality of training and quality of the outcome for the casualty. When choosing a provider, ensure your training provider has relevant experience rather than just theoretical knowledge, like ours – there is a reason why our first-aid Trainers are primarily veterans. Their exposure to these life-saving tools has been far greater than their civilian counterparts.
Finally, and as always, PracMed NZ cannot stress the importance of training with and normalising the use of arterial TQ’s.
In life, we do not rise to the occasion, but fall to our level of training. Learn how to use TQ’s correctly and train with them often. Although we advocate for their use, we also understand the implications of their incorrect use. As such, we strongly advise you take a PracMed NZ first aid course, such as Stop The Bleed®, to get hands on experience from trainers with relevant real world experience prior to purchasing a TQ.
Excellent writeup on TQ’s … very informative … Thank you!
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