Tourniquet

A tourniquet is a constricting or compressing device, specifically a bandage, used to control venous and 
arterialcirculation 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 stem the flow of traumatic bleeding, especially by military medics. The tourniquet is
usually applied when the patient is in a life-threatening state as a result of continuous bleeding.

A primitive tourniquet can be made from a stick and a rope (or leather belt). The rope is made into a loop
that fits over the damaged limb and the stick is inserted through the loop. The loop is tightened by twisting
the stick. This primitive device stems the flow of blood but side-effects such as tissue damage and nerve
damage may occur. In modern medicine, pre-assembled devices have been developed.They avoid
side-effects of the traditional rope-and-stick tourniquets and can be faster or easier to apply. Some modern
tourniquets, such as the Combat Application Tourniquet or the SOF Tourniquet can be applied with one
hand by the injured person himself. However, it does require some practice to ensure it is applied correctly
and quickly.

1. 1. What is a tourniquet?

   1.  Types

      There are two types of tourniquets: surgical tourniquets and emergency tourniquets. Surgical tourniquets
      are frequently used in orthopedic surgery while emergency tourniquets are limited to emergency situations
      to control blood loss.

      a.Surgical tourniquet

      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 orthopedic and plastic surgery, as well as in intravenous regional anesthesia (Bier block
      anesthesia) where they serve the additional function of preventing local anesthetic in the limb from
      entering general circulations.

      Complications of tourniquet application 
      1. Tourniquet pain - Characterized by hyperemia, hyperthermia and pain following reperfusion
      2. Post-tourniquet syndrome - Manifesting as pain, numbness, paresis, stiffness and pallor
      3. Skin changes - Blistering, ischemic necrosis
      4. Compartment syndrome
      5. Cerebral hypoxia

      b.Emergency tourniquet

      Emergency tourniquets are used in emergency bleeding control to prevent severe blood loss from limb
      trauma. Traditionally, emergency tourniquets are generally used as a last resort, especially in civilian
      applications, due to the understanding that if all blood flow below the application of an emergency
      tourniquet is stopped, it would subsequently kill the tissue, leading to eventual loss of the limb below
      application. More recently, experience in treatment of patients in civilian attacks such as the Boston
      Marathon bombing, and combat in Iraq and Afghanistan has changed the view of some within the
      emergency medicine field.

       

      Uncontrolled hemorrhage is the most preventable cause of deaths on both the battlefield and the streets
      of the United States. Studies show up to 50% of combat fatalities and 39% of civilian trauma fatalities are
      due to uncontrolled hemorrhage from an extremity.It is possible to die of exsanguination from femoral
      arterial bleeding in as little as three minutes. Use of tourniquets is widespread in military applications,
      as they have the potential to save lives during major limb trauma. Analysis has shown that in cases of
      major limb trauma, there is no apparent link between tourniquet application and morbidity of the limb.