(Most) Characters Bleed
Unless he’s Superman, your character is going to bleed when he’s scratched or bruise after bumping into something. A great deal of writers don’t understand the lasting or immediate impacts of an injury- which makes their work unrealistic. The most obvious and overlooked of these impacts is blood loss. Bleeding (major or otherwise) has varying effects on people, so fixing or editing your character’s movements after getting a wound isn’t simple, especially if you haven’t thought about it for a page or two.
The scientific term for bleeding is hemorrhaging. Bleeding to death is commonly called desanguination (massive loss of blood) or exsanguination (complete loss of blood). The most affected are smaller bodies which have less blood. High heart rates make the blood pump out quicker and cause a faster death, although interestingly healthy people are less affected by a loss of blood due to their daily work outs. Alcoholics or those with liver disease are particularly at risk for de/exsanguination because an impaired liver reduces the blood’s clotting ability.
The average body has 5 to 8 liters of blood in their body. Here’s what happens as you lose those liters.
Half a liter: Not too dangerous, only about 10% of the body’s blood is gone. The body’s blood pressure, heart rate and pulse remain normal.
One liter: Losing 20% of the body’s blood elevates the heart rate to 100 or more beats per minute (bpm). Blood pressure and respiratory rate elevate if the body is active, but remain normal when the body is lying down. The pulse appears almost normal, and the person remains completely alert to their surroundings.
A liter and a half: Now the body’s lost 30% of its total blood volume, and will need medical attention or someone to stop the bleeding. Blood pressure and the pulse is weakening. Since blood isn’t being delivered at it’s normal speed the body blames it on a slowing blood flow. The body increases its respiratory rate to 30 breaths per minute and increasing, to naturally increase blood flow speed. Unfortunately the blood is only flowing that much faster out of the wound. Now the person is suffering from anxiousness and confusion caused by blood loss.
Two liters of blood (40%): Heart rate is above 120 bpm and the pulse is super weak. The person enters a lethargic and more confused state, breathing fast and shallow. There’s a very real possibility of death now.
Two and a half liters (50% of the body’s blood volume): Heart rate is 140 bpm or higher- the equivalent state of exercising. Blood pressure is dangerously low and there’s an ABSENCE OF PULSE. The person is breathing VERY fast and shallow now, completely unconscious. Death is very nearly inevitable by this point.
A body may bleed out within several minutes if one of the arteries or veins are cut open. It’s important to remember that a character who’s been fighting for some time will have more blood rushing to provide their body with oxygen. Rushing blood + stab or other opening = heavily bleeding wound.