A tourniquet is a constricting or compressing device used to control venous and arterial circulation to an extremity for a period of time. Pressure is applied circumferentially upon the skin and underlying tissues of a limb; this pressure is transferred to the walls of vessels, causing them to become temporarily occluded. It is generally used as a tool for a medical professional in applications such as cannulation or to stop the flow of traumatic bleeding, especially by military medics.

HISTORYThe earliest known usage

of a tourniquet dates back to 199 BC. It was used by the Romans to control bleeding, especially during amputations.

In 1718, French surgeon Jean Louis Petit developed a screw device for occluding blood flow in surgical sites. He named this device after the French verb tourner (to turn), “tourniquet” as it is commonly known today.

Joseph Lister is credited for being the first to use a tourniquet device to create a bloodless surgical field in 1864.

In 1873, Friedrich von Esmarch developed a rubber bandage that would both control bleeding and exsanguinate. This device is known as Esmarch's bandage for surgical haemostasis or Eschmarch's Tourniquet

In 1904, Harvey Cushing created a pneumatic tourniquet.

TYPES TOURNIQUET

SURGICAL TOURNIQUET EMERGENCY TOURNIQUET

Surgical tourniquets are frequently used in orthopedic surgery while emergency tourniquets are limited to emergency situations to control blood loss.

Surgical tourniquets prevent blood flow to a limb and enable surgeons to work in a bloodless operative field. This allows surgical procedures to be performed with improved precision, safety and speed. Tourniquets are widely used in orthopaedic and plastic surgery, as well as in intravenous regional anaesthesia (Bier block anaesthesia) where they serve the additional function of preventing local anaesthetic in the limb from entering general circulations.

Emergency tourniquets are used in emergency bleeding control to prevent severe blood loss from limb trauma. Emergency tourniquets are generally used as a last resort, especially in civilian applications, for all blood flow below the application of an emergency tourniquet is stopped, and can subsequently kill the tissue, leading to eventual loss of the limb below application.

Current technologyLimb occlusion pressure (LOP) is the minimum

tourniquet pressure required to occlude blood flow to a specific patient's limb at a specific time and accounts for a patient’s limb and vessel characteristics, and the type and fit of the cuff. LOP can be determined by gradually increasing tourniquet pressure until distal arterial pulses cease, as indicated by a device sensing blood flow, such as a Doppler stethoscope. Studies have shown that cuff pressure based on LOP measured immediately prior to surgery is generally lower than commonly used cuff pressures and is sufficient to maintain a satisfactory surgical field.

The Combat Application Tourniquet (C-A-T) is used by the U.S. and British military to provide soldiers a small, effective tourniquet in field combat situations, and is also in use by NHS ambulance services, and some UK fire and rescue services

Automatic tourniquet systems are capable of providing safety features that are not possible in older mechanical tourniquets. These systems can monitor the cuff inflation time as well as regulate the cuff pressure to a known pressure throughout the surgical procedure. Some microprocessor controlled tourniquets are capable of calculating the proper pressure to ensure complete blood occlusion in about 30 seconds. This assists the operating room staff in deciding what the tourniquet pressure should be set at on a per-patient basis.

METHOD OF APPLYING TOURNIQUET IN AN EMERGENCT SET-UP

USESOrthopedics

Reduction of certain fractures.Kirschner wire removal.Replacement or revision of the joints of the knee,

wrist, digits, hand, or elbow.Arthroscopy of the knee, elbow, wrist, hand, or

digits.Bone grafts.Graft and repair of lacerated tendons.Subcutaneous fasciotomy.Repair of traumatic nerve damage.Carpal tunnel release.Traumatic or non traumatic amputation.Correction of a hammer toe.Podiatry.

Plastic and Reconstructive SurgeryRepair of burn contractures.Excision of lesions or tumors of the limbs.Split - thickness skin grafts on burned patients.Amputations or replantations.Repair of bone, cartilage, tendons, nerves, or

blood vessels.Resection of invasive tumors or lesions.Repair of congenital anomalies (e.g., syndactyly

or polydactyly).Bilateral extremity surgery (e.g., foot - to - hand

transfer of digits, related to the amputation).

Intravenous Regional Anesthesia

In intravenous regional anesthesia (IVRA), local anesthesia and a bloodless operative field are produced by inflation of a dual - bladder tourniquet proximal to the operative site, followed by injection of a local anesthetic agent distal to the tourniquet.

Use in a Non - surgical SettingThe nonsurgical use of pneumatic compression

devices is commonly directed toward manipulation of venous and arterial circulation for the purpose of reducing primary or secondary circulatory problems.

External pneumatic calf compression is a preventive therapy for patients at risk for deep venous thrombosis. Knee - length inflatable plastic boots with an alternating pressure cycle are used to prevent sluggish venous blood flow.

Military Anti - Shock Trousers (MAST suits) can be used for early treatment of hypovolemic shock in trauma victims. The trouser pressure acts like an inflatable tourniquet to reverse shock by redirecting blood from the legs and pelvis into central circulation, thus raising the blood pressure and increasing perfusion to vital body organs.

COMPLICATIONS

The final decision on whether or not to use a tourniquet rests with the attending physician. A few possible contraindications that the physician may take into consideration are:

Open fractures of the leg.Post - traumatic lengthy hand reconstruction.Severe crushing injuries.Elbow surgery (with concomitant excess

swelling).Severe hypertensionSkin grafts (to help distinguish all bleeding

points).Compromised circulation (e.g., peripheral artery

disease).Diabetes mellitus.

Post - Tourniquet SyndromePost - tourniquet syndrome (PTS) is manifested

by pronounced and, at times, prolonged postoperative swelling of the extremity. Approximately half of all post - tourniquet swelling is caused by blood returning to the limb after the release of the tourniquet (hyperemia). The remainder is the result of post ischemic reactive hyperemia, an additional increase of blood to restore normal acid - base balance in tissue. Post - tourniquet syndrome is characterized by edema, stiffness, pallor, weakness without paralysis, and subjective numbness without objective anesthesia.

The complication occurs in patients who have had tourniquets applied for a prolonged time and also in patients whose tourniquet cuff pressures were insufficient to prevent arterial inflow while preventing venous outflow. Under inflation of the tourniquet cuff is a particular risk for elderly patients who frequently have extensive calcification of the major arteries, which renders the vessels noncompliant to tourniquet pressure. Rheumatoid arthritis patients on steroid treatment experience the same problem in which a bloodless field cannot be obtained because of steroid - induced vascular calcification. Because of the significance of postoperative bleeding, patients with prolonged clotting times also are at risk for post - tourniquet syndrome.

PREVENTIVE MEASURESMedication history. A patient's drug history

should detect the routine ingestion of any drug that will influence clotting time or promote development of atherosclerotic vascular disease. Among these are steroids, aspirin, and birth control substances.

History of hypertension.Clotting time.History of past thromboembolic occurrences.Evidence of arterial calcification.

Comply strictly with the recommended tourniquet time limit. A higher than normal pressure may be required, particularly in larger limbs, and it is particularly important with these at - risk patients to use arterial occlusion pressure (see LOP section above) rather than systolic blood pressure to determine the most appropriate tourniquet cuff pressure and if possible to avoid exceeding the recommended maximum cuff pressure limits (typically recommended to be 300 - 350 mmHg for the thigh and 250 - 300 mmHg for the arm and lower leg).

HAIR TOURNIQUET

Hair tourniquet is a medical condition where in a hair or other thread becomes tied around a toe or finger tightly, so as to put the digit at risk of damage. Occasionally this is known as Toe tourniquet.

The problem usually arises in babies and small children when hairs and thread are lost loosely inside socks. They can become spontaneously tied round a toe and will tend to tighten with wriggling. Natural hair is much more likely to undergo this phenomenon than spun thread.

TREATMENTThe ligature must be cut or dissolved as

quickly as possible. Often it is possible to lift a portion of it to enable cutting, but in a severe case the ligature must be cut through the skin. This is, of course, injurious to the child, but does prevent loss of the digit.

Despite the distressing nature of the condition, outcomes are excellent. Loss of the toe is extremely rare, as is any residual disability.

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