What is a tourniquet?
A tourniquet can be defined as a constricting or compressing device used to control arterial and venous blood flow to a portion of an extremity for a period of time. Pressure is applied circumferentially around a portion of a limb at a desired location; this pressure is transferred to the walls of blood vessels, causing them to become temporarily occluded or restricted. In surgical settings, a tourniquet is used to occlude arterial blood flow following exsanguination to produce a relatively bloodless operative field and to minimize blood loss. In rehabilitation settings, a tourniquet is used to restrict arterial blood flow at a consistent and safe pressure for short periods of time during low intensity exercise to more rapidly increase muscle size and strength.
The following sections present the state-of-the-art surgical tourniquet system and the history of surgical tourniquets. Click here to learn more about Personalized Blood Flow Restricted Rehabilitation and Training.
Personalized tourniquet systems
It is well established by evidence in the clinical literature that higher tourniquet pressures are associated with higher probabilities of tourniquet-related injuries [1, 2]. As a result, modern tourniquet systems aim to use the minimum pressure required to stop blood flow in a limb over the duration of a surgical procedure. This has led to the development of personalized tourniquet systems. These state-of-the-art tourniquet systems allow perioperative staff to provide personalized, safe and effective care for their patients. They consist of personalized tourniquet cuffs, matching limb protection sleeves, and personalized tourniquet instruments that together minimize the risk of tourniquet-related injuries by enabling the application of lower and safer tourniquet pressures and pressure gradients to the patient.
Personalized tourniquet cuffs
Personalized tourniquet cuffs are state-of-the-art tourniquet cuffs that are designed to better match patient limb shape and size, and thus provide more efficient application of cuff pressure to the limb, allowing lower and safer tourniquet pressures to be used . Personalized cuffs better match patient limb shape through a variable-contour design that allows the user to adapt the shape of the tourniquet cuff to a wide range of non-cylindrical (or tapered) limb shapes. They also better match patient limb size through pediatric, adult and bariatric cuff designs.
Matching limb protection sleeves
High pressures, high pressure gradients and shear forces applied to skin and soft tissues underlying a tourniquet cuff can cause injuries to the skin and soft tissues. To reduce the nature and extent of these injuries, studies have been published that evaluate the relative effectiveness of no protective material, underlying padding, underlying stockinette, and underlying limb protection sleeves that are matched to specific limb sizes and cuff sizes [4-6]. Study results provide evidence that limb protection sleeves improve safety by protecting the skin underlying tourniquet cuffs during tourniquet use, and further provide evidence that greatest safety is achieved through the use of limb protection sleeves specifically matched to the limb size and cuff size.
Personalized tourniquet instrument
Many studies published in the medical literature have shown that higher tourniquet pressures and pressure gradients are associated with higher risks of tourniquet-related injuries [2, 7-12]. Studies have also shown that lower tourniquet pressures are associated with lower complications and pain [13, 14]. Therefore, when a tourniquet is used in surgery, surgical staff generally try to use the lowest tourniquet pressure that in their judgement is safely possible.
Personalized tourniquet instruments reduce the risk of tourniquet-related injuries by enabling the application of lower tourniquet pressures and pressure gradients to the patient. This is accomplished by the instrument automatically measuring each patient’s Limb Occlusion Pressure (LOP) and recommending a tourniquet pressure based on LOP. LOP can be defined as the minimum pressure required, at a specific time in a selected tourniquet cuff applied to an individual patient’s limb at a desired location, to stop the flow of arterial blood into the limb distal to the cuff . LOP is affected by variables including the patient’s limb characteristics, characteristics of the selected tourniquet cuff, the technique of application of the cuff to the limb, physiologic characteristics of the patient including blood pressure and limb temperature and other clinical factors (for example, the extent of any elevation of the limb during LOP measurement and the extent of any limb movement during measurement). Click here to learn more about how a tourniquet pressure based on LOP reduces risk of tourniquet-related injuries.
How did personalized tourniquet systems evolve from early tourniquets?
Personalized tourniquet systems trace their roots to the time of the Roman Empire (199 BCE-500 CE), when non-pneumatic bronze-and-leather devices (Fig. 3) were used to control bleeding from limb amputations during war. The goal was to save a life without regard to salvaging the limb.
The elementary tourniquet devices used by the Greeks and the Romans remained virtually unchanged until 1718, when a French surgeon, Jean-Louis Petit, created a screw device to occlude blood flow at the surgical site, as shown in Figure 4. He named the device “tourniquet”, from the French verb “tourner” (to turn).
Joseph Lister is credited for being the first to use a tourniquet to create a bloodless surgical field in 1864. For exsanguination, he recommended elevation of a limb for 4 minutes before applying the tourniquet. In 1873, Friedrich von Esmarch devised a rubber bandage for exsanguination and tourniquet use. The device was superior to Petit’s screw device, because Petit’s cloth bandages tore, the screw could untwist, and pressures that were very high, unknown and uneven were applied to the underlying limb, resulting in hazards and injuries. In 1881, Volkmann demonstrated that limb paralysis could result from use of the Esmarch tourniquet. Many cases of serious and permanent limb paralysis were reported from the use of non-pneumatic Esmarch tourniquets [15-22].
Early Pneumatic Tourniquet Systems
In view of reports of serious injuries and limb paralysis with non-pneumatic tourniquets, in 1904 Harvey Cushing developed the first pneumatic tourniquet . Cushing used a compressed gas source to inflate a cylindrical bladder encircling the limb to control the flow of blood into the scalp to facilitate neurosurgery. This device had two advantages over the Esmarch tourniquet: rapid application and removal; and decreased incidence of nerve paralysis.
Modern Pneumatic Tourniquet Systems
Modern tourniquet systems are microcomputer-based, allowing more accurate and automatic pressure control and many important safety features not possible in the early pneumatic tourniquet systems [1, 2].
Early pneumatic tourniquets like those used by Cushing required an external source of compressed gas and used a mechanical regulator to control the pressure of gas in the tourniquet cuff. These now-obsolete mechanically-regulated pneumatic tourniquet systems did not have any of the alarms and safety features common in modern systems. For example, they relied on mechanical pressure regulators that were inherently less accurate, they lacked any audiovisual alarms to promptly warn users of hazardously high and low pressures in tourniquet cuffs, they lacked automatic timers and elapsed time alarms, and they lacked self-test apparatus to automatically check the tourniquet instrument at start-up and prior to patient use. All of these limitations were overcome by the commercial introduction of the first automatic tourniquet systems in 1981, and their subsequent acceptance and use in orthopaedics and other surgical specialties has been widespread.
The first electronic tourniquet system was invented by Dr. James McEwen, Ph.D., P.Eng., in the late 1970s . The first US patent for an automatic tourniquet system was awarded to Dr. McEwen in 1984 . Modern tourniquet systems based on Dr. McEwen’s invention have self-checks and self-calibration to ensure that the systems are safe for use. They are also self-contained as they do not require external compressed gas sources to function. They provide accurate control over the cuff pressure through electronic regulators, and have various safety features such as audio-visual alarms for pneumatic leakage and inflation time. Click here to find out more about Tourniquet Instrument Technology. As a result of these advances in tourniquet technology, the U.S. Food and Drug Administration classified pneumatic tourniquets as Class I medical devices, indicating that they present minimal harm to the user and do not present a reasonable source of injury through normal use by properly trained clinicians.
Personalized Tourniquet Systems:
Recent advances in tourniquet technology have led to the development of personalized tourniquet systems. These state-of-the-art modern pneumatic tourniquet systems automatically measure the minimum pressure required to occlude or stop arterial blood flow in a limb (Limb Occlusion Pressure – LOP) and recommend a cuff pressure to be used during surgery that is personalized for each individual patient based on the LOP. They also have specially designed personalized tourniquet cuffs and matching limb protection sleeves that can conform to the limb shape and size of each individual patient. The personalization of the tourniquet instrument, cuff and sleeve for each patient further improves safety by allowing lower cuff pressures and lower pressure gradients to be used [2, 4, 5, 14, 25].
It is estimated that modern pneumatic tourniquets are used in over one million surgical cases annually . However, despite the frequency of use, the numerous benefits of modern surgical tourniquets, and the trend towards personalized tourniquet use, risks to patient safety remain. As with all aspects of perioperative care, patient safety should be the primary consideration in the evaluation, selection, and use of pneumatic tourniquets and accessories . Therefore, in order to improve patient safety, it is vital that perioperative staff understand the following tourniquet concepts:
- Mechanisms of tourniquet-related injuries and preventative measures
- Surgical tourniquet safety and use:
 Tredwell SJ, Wilmink M, Inkpen K, McEwen JA. Pediatric tourniquets: analysis of cuff and limb interface, current practice, and guidelines for use. Journal of Pediatric Orthopaedics. 2001 Sep 1;21(5):671-6.
 Olivecrona C, Tidermark J, Hamberg P, Ponzer S, Cederfjäll C. Skin protection underneath the pneumatic tourniquet during total knee arthroplasty: a randomized controlled trial of 92 patients. Acta orthopaedica. 2006 Jan 1;77(3):519-23.
 McEwen J, Casey V. Measurement of hazardous pressure levels and gradients produced on human limbs by non-pneumatic tourniquets. In: Proceedings of the 32nd Conference of the Canadian Medical and Biological Engineering Society 2009. Calgary, Canada; 2009 May 20-22. p 1-4.
 Graham B, Breault MJ, McEwen JA, McGraw RW. Perineural pressures under the pneumatic tourniquet in the upper extremity. The Journal of Hand Surgery: British & European Volume. 1992 Jun 1;17(3):262-6.
 Olivecrona C, Ponzer S, Hamberg P, Blomfeldt R. Lower tourniquet cuff pressure reduces postoperative wound complications after total knee arthroplasty. J Bone Joint Surg Am. 2012 Dec 19;94(24):2216-21.
 Younger AS, McEwen JA, Inkpen K. Wide contoured thigh cuffs and automated limb occlusion measurement allow lower tourniquet pressures. Clinical orthopaedics and related research. 2004 Nov 1;428:286-93.