Tourniquet

A tourniquet is a device that is used to apply pressure to a limb or extremity in order to limit – but not stop – the flow of blood. It may be used in emergencies, in surgery, or in post-operative rehabilitation. Also a tourniquet is used by the phlebotomist to assess and determine the location of a suitable vein for venipuncture. 
Proper application of a tourniquet will partially impede venous blood flow back toward the heart and cause the blood to temporarily pool in the vein so the vein is more prominent and the blood is more easily obtained. The tourniquet is applied three to four inches above the needle insertion point and should remain in place no longer than one minute to prevent hemoconcentration.
A simple tourniquet can be made from a stick and a rope (or leather belt), 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.
Types.
There are four types of tourniquets: surgical tourniquets, emergency tourniquets, rehabilitation tourniquets and A tourniquet is used by the phlebotomist to assess and determine the location of a suitable vein for venipuncture
Surgical tourniquets.
Silicone ring tourniquets, or elastic ring tourniquets, are self-contained mechanical devices that do not require any electricity, wires or tubes. The tourniquet comes in a variety of sizes. To determine the correct product size, the patient's limb circumference at the desired occlusion location should be measured, as well as their blood pressure to determine the best model. Once the correct model is selected, typically two sterile medical personnel will be needed to apply the device. Unlike with the pneumatic tourniquet, the silicone ring tourniquet should be applied after the drapes have been placed on the patient. This is due to the device being completely sterile. The majority of the devices require a two-man operation (with the exception of the extra large model):
The elastic ring tourniquet follows similar recommendations noted for pneumatic tourniquet use:
Emergency tourniquets.
Silicone ring auto-transfusion tourniquet.
The silicone ring auto-transfusion tourniquet (SRT/ATT/EED), or surgical auto-transfusion tourniquet (HemaClear), is a simple to use, self-contained, mechanical tourniquet that consists of a silicone ring, stockinet, and pull straps that results in the limb being exsanguinated and occluded within seconds of application. The tourniquet can be used for limb procedures in the operating room, or in emergency medicine as a means to stabilize a patient until further treatment can be applied.
Combat application tourniquet.
The combat application tourniquet (CAT) was developed by Ted Westmoreland. It is used by the U.S. and coalition militaries to provide soldiers a small and effective tourniquet in field combat situations. It is also used in the UK by NHS ambulance services, along with some UK fire and rescue services. The unit utilizes a windlass with a locking mechanism and can be self-applied. The CAT has been adopted by military and emergency personnel around the world.
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 (thus its name "tourniquet", from "tourner" = to turn).
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 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.
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.