Abrasions, Lacerations, Avulsions, Punctures, Hematomas and Amputations are all common injuries.  These injuries have one thing in Common.   They all bleed, sometimes causing severe blood loss.     Severe bleeding can quickly lead to shock (Hypovolemia) that can result in organ failure and death.     

It is critical to control severe bleeding to prevent the onset of shock.  Bleeding can be either Internal or External, and usually results from damage to blood vessels.  There are three major vessel groups inside our bodies (Arteries, Veins, and Capillary vessels).

   Bleeding may come from arteries, veins and capillaries.  Arteries carry oxygen-rich blood from the heart throughout the body.  Veins carry blood back to the heart and lungs to be oxygenated.  Capillaries are the smallest type of blood vessel.  They serve as conduits for the exchange of Oxygen, Nutrients, Carbon Dioxide and Waste..  Major bleeding is a life-threatening condition needing immediate attention.
Arterial Bleeding:
Arteries carry oxygen rich blood away from the heart to muscles and organs.   Arterial bleeding is characterized by spurting blood flow.  Blood from an arterial bleed is typically bright red in color, severe and difficult to control.   This type of bleeding requires immediate attention (Call 911).

Venus Bleeding:
Veins carry oxygen-depleted blood from muscles and organs back to the heart and lungs.  Venous bleeding is characterized by steady flowing blood.  You may notice that the blood is a much darker shade due to the lack of oxygen.  This type of bleeding can be as dangerous as arterial bleeds. 

Capillary Bleeding:
Capillary vessels are tiny structures located just below the skin.  Capillary bleeding is characterized by slow, oozing blood (As seen in a scrape or road rash).  
Controlling Bleeding:
  There are three primary methods for controlling bleeding:    1) Direct Pressure,  2) Elevation, and  3) Pressure Points.
Important:  Blood may carry dangerous pathogens.  It's very important that you take precautions against direct contact with someone else's blood.   Latex or vinyl gloves should be worn as a barrier to prevent blood born pathogens from entering your body through breaks in your skin.  It is also a good idea to wear eye protection, a mask and protective clothing.

Direct Pressure:  
Is the most common and effective field method to control bleeding.  Direct pressure may be applied with your gloved fingertips or hand for larger wounds.   If available, a sterile dressing should be placed over the wound.  If a sterile dressing is not available, a rag or piece of clothing may be used.   

Note:  Do Not remove Blood Soaked Dressings!   Instead add more dressings over the old.  Removing a blood soaked dressing will disturb the wound and will likely cause more bleeding.

If direct pressure does not stop the bleeding, consider Elevating the injured body part.   Elevate the wound above the heart while continuing to apply direct pressure.   Elevation should only be used if there are no broken bones suspected.

Pressure Points:
Should direct pressure and elevation fail to stop the bleeding, locate and apply pressure to the nearest arterial pressure point.  Pressure points are found wherever an artery passes over a bone.  For Arm and Hand injuries, apply pressure to the (Brachial Artery) located in the upper inside arm.   The Femoral Artery is located in the crease of the groin area.   Pressure placed here will stop bleeding in leg wounds.    Direct Pressure and Elevation should be continued while applying pressure to pressure points.
Finally, A pressure bandage should be placed over the dressing and wound.   Check for circulation before and after applying bandage.  If the fingers or toes become cold, pale or bluish, the bandage may be to tight.  Once you have loosened the bandage recheck circulation.   You may also attempt to locate a pulse in the extremity below the injured area. (For example, for a forearm injury, place your bandage over the injury site and check for pulse at the inside of the wrist also known as Radial Pulse).

Tourniquets should be avoided without prior medical direction from a 911 Operator or Emergency Room Director.  Once applied, a tourniquet should not be removed in the field.   Doing so will allow clotting blood to travel back to the heart and can result in death.   Tourniquets should be used as a last resort when all else has failed and death is imminent.   Once a Tourniquet is set, it is likely that the limb will be lost.   Be sure to log and communicate the exact time when a tourniquet is applied (it's common practice to write the time on the victim's forehead).
Internal Bleeding:
Field treatment for Internal Bleeding is limited to calling 911, keeping the victim warm, comfortable and calm.  The patient should be closely monitored and treated for signs of shock.    Signs of internal bleeding may include:
- Rigid Abdomen
- Blood in vomit, saliva or fecal matter 
- Heavy bleeding from rectum or vagina
- Vomiting blood (will appear like coffee grounds in the vomitus)
- Skin may be cool and moist
- There may be difficulty breathing with internal bleeding within the chest (Build up of blood may cause pressure on lungs).
- Suspect internal bleeding with any puncture or crushing type wounds to the Chest or Abdomen
Did that actually happen to you
<p>some of this contradicts what is described as current teaching elsewhere on the net, for example, elevation is not considered worthwhile by some. Not saying this is all wrong, just that there are differing views currently. What is agreed is that if the choice is life or limb, then use a tourniquet.</p>
<p>I'm guessing that the contradictions stem from the degree of first aid being taught. I'm sure that what is taught in combat situations will differ vastly from Red Cross first aid classes. Most of my article is based on training we offered through CERT. </p>
Good instructable! I never knew that you shouldn't take tourniquets off!