Tourniquet
A tourniquet is a medical device used to stop the flow of blood to a limb or extremity via the application of localized pressure. It may be used in emergencies, in surgery, or in post-operative rehabilitation.
A simple tourniquet can be made from a stick and a rope, but the use of makeshift tourniquets has been reduced over time due to their ineffectiveness compared to a commercial and professional tourniquet. This may stem the flow of blood, but side effects such as soft tissue damage and nerve damage may occur.
History
During Alexander the Great's military campaigns in the fourth century BC, tourniquets were used to stanch the bleeding of wounded soldiers. Romans used them to control bleeding, especially during amputations. These tourniquets were narrow straps made of bronze, using only leather for comfort.In 1718, French surgeon Jean Louis Petit developed a screw device for occluding blood flow in surgical sites. Before this invention, the tourniquet was a simple garrot, tightened by twisting a rod.
In 1785, Sir Gilbert Blane advocated that, in battle, each Royal Navy sailor should carry a tourniquet:
It frequently happens that men bleed to death before assistance can be procured, or lose so much blood as not to be able to go through an operation. In order to prevent this, it has been proposed, and on some occasions practised, to make each man carry about him a garter, or piece of rope yarn, in order to bind up a limb in case of profuse bleeding. If it be objected, that this, from its solemnity may be apt to intimidate common men, officers at least should make use of some precaution, especially as many of them, and those of the highest rank, are stationed on the quarter deck, which is one of the most exposed situations, and far removed from the cockpit, where the surgeon and his assistants are placed. This was the cause of the death of my friend Captain Bayne, of the Alfred, who having had his knee so shattered with round shot that it was necessary to amputate the limb, expired under the operation, in consequence of the weakness induced by loss of blood in carrying him so far. As the Admiral on these occasions allowed me the honour of being at his side, I carried in my pocket several tourniquets of a simple construction, in case that accidents to any person on the quarter deck should have required their use.
In 1864, Joseph Lister created a bloodless surgical field using a tourniquet device. In 1873, Friedrich von Esmarch introduced a rubber bandage that would both control bleeding and exsanguinate. This device is known as Esmarch's bandage. In 1881, Richard von Volkmann noted paralysis can occur from the use of the Esmarch tourniquet, if wrapped too tightly. Many cases of serious and permanent limb paralysis were reported from the use of non-pneumatic Esmarch tourniquets.
After observing considerable number of pressure paralysis with non-pneumatic, elastic, tourniquets, Harvey Cushing created a pneumatic tourniquet, in 1904. Pneumatic tourniquets were superior over Esmarch's tourniquet in two ways: faster application and removal; and decrease the risk of nerve palsy.
In 1908, August Bier used two pneumatic tourniquets with intravenous local anesthesia to anesthetize the limb without general anesthetics.
In the early 1980s, microprocessor-based pneumatic tourniquet systems were invented by James McEwen. These modern electronic pneumatic tourniquet systems generally regulate the pressure in the tourniquet cuff within 1% of the target pressure and allows real-time monitoring of the inflation time. Modern pneumatic tourniquet systems include audiovisual alarms to alarm the user if hazardously high or low cuff pressures are present, automatic self-test and calibration, and backup power source.
In the 2000s, the silicon ring tourniquet, or elastic ring tourniquet, was developed by Noam Gavriely, a professor of medicine and former emergency physician. The tourniquet consists of an elastic ring made of silicone, stockinet, and pull straps made from ribbon that are used to roll the device onto the limb. The silicone ring tourniquet exsanguinates the blood from the limb while the device is being rolled on, and then occludes the limb once the desired occlusion location is reached. Unlike the historical mechanical tourniquets, the device reduces the risk of nerve paralysis. The surgical tourniquet version of the device is completely sterile, and provides improved surgical accessibility due to its narrow profile that results in a larger surgical field. It has been found to be a safe alternative method for most orthopedic limb procedures, but it does not completely replace the use of contemporary tourniquet devices. More recently the silicone ring tourniquet has been used in the fields of emergency medicine and vascular procedures. However, in 2015 Feldman et. al. reported two cases of pulmonary embolism after silicon ring exsanguination tourniquet application in patients with traumatic injuries. In one case of exsanguination tourniquet induced bilateral pulmonary emboli, after rapid intervention a 65-year-old woman was discharged in good condition 7 days after surgery. In a second case with multiple pulmonary emboli, despite extensive efforts of intervention a 53-year-old man's condition quickly deteriorated after surgery, and was declared brain dead 2 days after. While Feldman et. al. discuss the potential risk of DVT for various types of tourniquets and exsanguination methods, the authors recommend extreme caution and suggest avoiding the use of an exsanguination tourniquet in patients with risk factors for DVT, including patients with traumatic injury of the extremities.
Most modern pneumatic tourniquet systems include the ability to measure the patient's limb occlusion pressure and recommend a tourniquet pressure based on the measured LOP to set safer and lower tourniquet pressures. Limb occlusion pressure is defined as "the minimum pressure required, at a specific time by a specific tourniquet cuff applied to a specific patient's limb at a specific location, to stop the flow of arterial blood into the limb distal to the cuff."
After World War II, the US military reduced use of the tourniquet because the time between application and reaching medical attention was so long that the damage from stopped circulation was worse than that from blood loss.
Since the beginning of the 21st century, US authorities have resuscitated its use in both military and non-military situations because treatment delays have been dramatically reduced. The Virginia State Police and police departments in Dallas, Philadelphia and other major cities provide tourniquets and other advanced bandages. In Afghanistan and Iraq, only 2 percent of soldiers with severe bleeding died compared with 7 percent in the Vietnam War, in part because of the combination of tourniquets and rapid access to doctors. Between 2005 and 2011, tourniquets saved 2,000 American lives from the wars in Iraq and Afghanistan. In civilian use, emerging practices include transporting tourniquetted patients even before emergency responders arrive and including tourniquets with defibrillators for emergency use.
There are currently no standards for testing tourniquets although there have been several proposed devices to ensure that the appropriate pressures could be generated including many commercial systems and an open source system that can be largely 3D printed. This would allow distributed manufacturing of tourniquets.
Risks
Risks and contraindications related to the use of a surgical tourniquet include: nerve injuries, skin injuries, compartment syndrome, deep venous thrombosis, and pain. Risk of injury can be minimized by minimizing tourniquet pressure and pressure gradients. Tourniquet pressure and pressure gradients can be minimized by using a tourniquet pressure based on the patient's limb occlusion pressure, and by using a wider, contoured pneumatic tourniquet cuff.In some elective surgical procedures such as total knee arthroplasty, some research suggests tourniquet use may be associated with an increased risk of adverse events, pain, and a longer hospital stay, despite tourniquet use allowing shorter times in the operating room. However, such evidence often omit the analysis of key tourniquet parameters and their correlation to outcomes leading to limited, inconclusive, and conflicting results.
A study by Pavao et al compared no tourniquet use to optimized tourniquet use in total knee arthroplasty and found no significant differences in surgical timing, blood loss, thigh and knee pain, edema, range of motion, functional scores, and complications, thus allowing surgery to occur with the benefits of a clean and dry surgical field from an optimized tourniquet without increase procedure-related comorbidities. Therefore, tourniquet use optimized to mitigate tourniquet related-risks while maintaining the benefits of a clear bloodless field and faster operating times may be achieved by minimizing tourniquet pressure and inflated tourniquet times.