AT4 Tourniquet System

AT4 Tourniquet System - maximising safety and efficiency

Over half a million people in the UK are currently waiting for trauma and orthopaedic procedures (including upper and lower limb surgery), which is over 42,900 more than in 2019: almost 35,000 have been on the waiting list for longer than 12 months. 

A proportion of these will require the use of a tourniquet: an item of equipment whose effectiveness can significantly impact efficiency in theatre. 

While the principle of creating a bloodless field for surgery has been around since the Stone Age, the fundamental requirements of modern-day equipment are more sophisticated and complex, including: 

  • reliable and consistent methods of inflation – particularly the accurate maintenance of pressure for the duration of a procedure (sometime for several hours) 

  • intuitive controls for staff dealing with multiple aspects of patient care 

  • accurate recording systems to document pressures and durations 

  • failsafe systems for dealing with the potential risk associated with intravenous regional block anaesthesia (IVRA) 

  • easy cleaning, disinfection and maintenance for infection control and minimal downtime of valuable equipment 

Tourniquet inflation mechanisms 

The traditional tourniquet inflation mechanism for many years has been medical air – using a pneumatic tourniquet device. The medical air supply is piped into theatre at a pressure of either 4 or 7 bar (MA4 or MA7) – but this can be problematic, as it limits options for positioning the device (because it has to be within range of the air hose – which in itself can be a trip hazard). 

 There may also be other devices – ventilators or power tools such as saws and drills – which require air from the same source, and sufficient outlets are not always available. Outlet splitters (or ‘Y’ connectors) are a solution, but this is further complicated because British Standards specify that probe connections all have to be bar specific - and cannot be supplied as a universal fit. This can all mean the tourniquet is in a competition for its medical air source – hardly an ideal scenario. 

A separate medical air cylinder (mounted on the tourniquet stand) is an alternative, but again regulations are strict, so the cylinder will need a contents gauge, regulator, and outlet. It must also be ‘self-compensating’ to ensure pressure is evenly maintained. So even when not in use, if the medical air hose is connected to the cylinder mounting outlet and the medical air cylinder is open, air is being drawn into the unit and released to atmosphere within the device casing – resulting in the risk of the air cylinder being empty when staff next need to use the device. 

Medical air supplies are costly, with an average sized teaching hospital spending in the region of £70,000 per calendar month on supplies. Just taking the 53 teaching hospitals based in England, that would equate to a sum in the region of £44.5 million in medical air costs per annum. 

Advances through electronics – a partial solution 

In the late 1970s, electronic tourniquets started to become available - no longer reliant on analogue gauges, manual dials and inflate / deflate switches, and, most importantly - no longer reliant on medical air. 

These devices were manufactured with their own internal compressor and were powered from AC mains, possibly with a battery as a back-up power source. 

Originally available in the United States and Europe, they became more prevalent within UK healthcare during the mid to late 1990s and have steadily increased in popularity throughout the 2000s. 

Although these devices offered a solution to the medical air supply issue, the majority were still reliant on mains power, meaning their position in the theatre could still be compromised by their reliance on cabling and sockets, the latter also possibly being required for other equipment. 

Practicalities drive further technological innovation 

In 2012, having taken over 40 years of experience and first-hand feedback from tourniquet users to inform the development, a new concept electronic tourniquet was introduced. 

The key feature was complete independence: something virtually no tourniquet had previously been able to offer. 

It featured a rechargeable lead acid battery: not simply a back-up, but all of the power required for a complete day’s use of the tourniquet, i.e. back-to-back 30-minute procedures (with both channels inflated to 300mmHg) for 17.5* hours before needing to be charged. 

Obviously, the battery has to be of a certain quality – manufacturer approved and well maintained – but it means the tourniquet can be used all day and be placed in any convenient position in the operating theatre – without the restrictions of being close to an air supply or mains socket. 

One particular benefit is the inclusion of an internal air reservoir that provides the cuff leak compensation safety feature, so the actual compressor only needs to run for short periods – reducing its impact on noise levels within the operating theatre. 

Other aspects which support usability are intuitive controls, large, easily visible OLED displays, colour-coded single or independently working bi-lateral channel operation, and an IVRA (Bier’s block) safety guidance feature which means it is simply not possible to deflate cuffs in the wrong order. 

Set up time is minimal and additional safety features include self-calibration, self-diagnostic routines, precision-controlled pressure regulation and visual and audible warnings and alarms. 

The overall design is compact, with smooth moulded surfaces to facilitate cleaning and disinfection, while the robust castors and specially weighted base offer manoeuvrability combined with intrinsic stability. 

With all its innovations, this tourniquet is an example of UK technology at its best in terms of quality and reliability: encompassing design, manufacture and aftercare. 

* equates to 35 bi-lateral procedures. 


Since 2012, more than 700 AT4™ Electronic Tourniquets have been supplied to UK healthcare facilities, and a further 1100+ internationally. 

A conservative estimate of usage would be around 4 times per day, 4 days per week, for 48 weeks of the year – so on that basis, an AT4™ Electronic Tourniquet is used for upper or lower limb surgery around 887,808 times per annum. 

Over the nine-year period it has been in existence, an AT4™ Electronic Tourniquet will therefore have been used millions of times, so the conclusion must surely be that it is a device which is safe, effective and proven. 

For more details on Anetic Aid's AT4™ Electronic Tourniquet System, click here. Alternatively, please contact us here and we'll get back in touch! You can also download our white paper by clicking the link below.

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