Tourniquets are back

Largely due evidence from increased military use in conflicts in the last two decades, tourniquet use has re-emerged as an effective way to control haemorrhage from limb injury, usually due to partial or complete amputation or severe crush injury (so called “mangled limbs”) or severe penetrating trauma with major tissue or vascular disruption. Based on reasonable quality data from recent military (and some civilian) studies, tourniquet use for the arrest of life-threatening haemorrhage from exsanguinating limb trauma is now being advocated.

This post provides some general and specific information and practical tips on tourniquet use.

When should I use a tourniquet?

Tourniquets are an effective way to control major haemorrhage from severe limb injury.

Examples of cases where tourniquets may be used include motor vehicle crashes with entrapped/mangled limbs, motorbike crashes with lower limb mangling/amputation, devastating penetrating injuries such as military blast injuries (e.g. land mines, improvised explosive devices), severe crush injuries (e.g.industrial accidents) or deep penetrating injuries such as shark bites. Large, deep incised wounds (e.g. from falls through broken glass or blows from large bladed weapons such as machetes) or firearm injury with major muscle or vascular disruption can also lead to fatal haemorrhage and may benefit from tourniquet use.

TOURNIQUETS SHOULD NOT BE USED FOR SIMPLE PENETRATING WOUNDS, OR HAEMORRHAGE THAT CAN BE CONTROLLED WITH DIRECT COMPRESSION.

Which tourniquet should I use?

Purpose built tourniquets such as the C-A-T tourniquet device or SOF T device (see below) are recommended over improvised devices. Studies comparing different commercially available tourniquets have produced mixed results so no single device can be recommended over another. Simple windlass-style tourniquets are relatively inexpensive, easy to apply and easy to operate.

If a purpose built tourniquet is not available a manual blood pressure cuff (with the tubing clamped) or Bier’s block machine can be used in the emergency department for patients with exsanguinating limb trauma may serve as a temporising measure only as a bridge to more definitive haemorrhage control, however these techniques are not as effective as purpose built tourniquets. Potential dangers of improvised tourniquets include poor fit, inability to control haemorrhage, un-noticed cuff deflation/device failure leading to re-bleeding and difficulty transporting the patient (intra or inter-hospital) with the device in-situ.

General principles of tourniquet use:

Tourniquets should not be used for injuries where haemorrhage control can be achieved by direct pressure.

TOURNIQUETS SHOULD BE TIGHTENED UNTIL LOSS OF THE DISTAL PULSE, OR UNTIL BLEEDING CEASES

There are no clear guidelines on the safe time a tourniquet can be left in place, or to what pressure tourniquets should be inflated. Tourniquet’s left on for too long can cause ischemia to distal tissue, which may lead to cell death or permanent tissue damage and reperfusion of the limb on release of the tourniquet can cause a post-tourniquet reperfusion syndrome characterised by elevated levels of creatinine kinase and lactate, acidosis and hyperkalaemia, as well as distal limb effects including oedema, compartment syndrome, and venous thrombosis, however the absolute risk of these complications is surprisingly low.

Tourniquets also cause compression and ischaemia of the tissues directly under the cuff, which can cause neuropraxia (which may be permanent) and prolonged muscle weakness, although these are also rare complications.

Inflation pressures should not exceed 250-300mmHg in the upper limb, and 300-350mmHg in the lower limb.

Pressures that are high enough to impede venous flow, but not high enough to interrupt arterial flow, will result in continued perfusion of a non-draining limb, leading to oedema, swelling and an increased risk of compartment syndrome.

In elective surgical cases, a maximum tourniquet time of 2-3 hours is usually observed before intermittent release is required. It is important to note that in the emergency trauma setting, mortality and morbidity increases rapidly in patients with vascular limb trauma if tourniquets are left on for more than 45-60 minutes, however this may be more likely related to the overall injury burden sustained leading to tourniquet necessity, rather than due to any potential adverse effects from the tourniquet itself. If there will be a delay of more than an hour to definitive surgical care (for example, delayed retrieval or prolonged transport time), all efforts should be made to obtain vascular haemorrhage control by a surgeon in the referring hospital. If a local surgeon is unavailable, consideration should be given to transporting a surgeon to the patient if this will expedite definitive treatment.

Under no circumstances should periodic loosening of tourniquets be performed without surgical assistance present, as this may lead to uncontrollable re-bleeding.

Patients should not undergo inter-hospital transfer with a tourniquet in-situ if a local surgeon is available to perform temporising surgical control.

Tourniquet use can be very painful and patients will require intravenous analgesia and possibly intubation if pain is uncontrollable.

Practical points for tourniquet use:

Do not apply tourniquets over clothing – remove all clothing before applying
Do not apply directly over wounds
Do not apply over joints – the bony prominences prevent adequate pressure from being applied
Tighten until bleeding stops/slows or until distal pulse is absent (if distal limb intact/not amputated)
- NB This can be quite painful and the patient may require intubation for pain control/humanitarian reasons
There is no consensus as to whether more proximal application (i.e. closer to major junctional vessels) or distal application (i.e. closer to wound) is better.
- It is thought that the more proximal the application, the more muscle bulk will be present and less pressure will reach the underlying arteries, hence some providers recommend application as distally as possible (generally 5-10cm proximal to the wound)
- A risk of distal placement is application distal to a missed, more proximal bleeding wound, hence the need for full limb exposure/inspection prior to tourniquet application
- The main determinant of effectiveness of tourniquets is the ratio of device width-to-limb circumference/girth (i.e. the wider the limb, the wider the tourniquet needs to be to be effective)
Hence, if one tourniquet is ineffective, side-by side (in sequence longitudinally) dual tourniquet use may be effective
Tourniquet application prior to the onset of shock drastically lowers mortality from haemorrhage compared to application after the onset of shock
Periodic re-assessment and if required, re-tightening of tourniquets is essential as they can loosen during transport and movement, which can cause re-bleeding and death
Periodic loosening (e.g. to check for ongoing bleeding) should not be performed until a surgeon is available to address the source of haemorrhage
There is no defined maximum time for tourniquet application, however it is generally accepted that definitive surgical management should ideally commence within 2 hours of tourniquet application if possible.
If required to prevent exsanguinating haemorrhage tourniquets can and should be left on until such time as definitive treatment is available

Complications of tourniquets:

Recent battlefield experience in the wars in Middle East have shown a clear risk:benefit ratio and mortality benefit in favour of tourniquet use for exsanguinating limb haemorrhage.

The actual morbidity associated with tourniquets is low

Potential complications of tourniquet use include:

Ischaemia of distal limb requiring amputation/fasciotomy
- Tourniquet use has not been shown to increase the need for amputation, as the injuries in which tourniquets are used makes it difficult to differentiate between direct or primary limb injury and new or secondary injuries related to tourniquet use.
- In one study approximately 25% of patients with tourniquets applied needed either fasciotomy or amputation, however these were in severely and multiply injured patients with major limb damage.
Nerve palsies – rare (approx 2% risk)
- Due to peripheral nerve compression
- These are rare and most are transient
Thrombosis – rare (approx 2%)
- Deep venous thrombosis is a rare complication
- Difficult to distinguish those directly caused by tourniquet versus those occurring as a result of the limb injury
Skin damage: abrasion, bruising, blisters – rare (approx 1-2%)
Rhabdomyolysis (rare – approx 1% risk) & acute renal failure (very rare <1% risk)
- Myonecrosis from ischaemic muscle is a rare complication
- Rhabdomyolysis secondary to tourniquet use severe enough to cause acute renal failure is exceptionally rare

Types of tourniquets:

Newer tourniquet devices such as the Combat Application Tourniquet (C-A-T) and SOF Tactical (SOF T) Tourniquet are being used by some pre-hospital services in Australasia.

C-A-T Tourniquet