Bleeding

Bleeding is the loss of blood from the body. Hemorrhage (AE) or haemorrhage (BE) is the medical term for bleeding. In common usage, a hemorrhage means particularly severe bleeding; although technically it means escape of blood to extravascular space. The complete loss of blood is referred to as exsanguination.

The circulating blood volume is approximately 70 ml / kg of ideal body weight. Thus the average 70 kg male has approximately 5000 ml of circulating blood. Loss of 10-15% of total blood volume can be endured without clinical sequalae in healthy person.

The human body generates blood at a rate of about 2 litres (2 quarts) per week. The technique of blood transfusion is used to replace severe quantities of lost blood.

Causes, prevalence, and risk factors

Hemorrhage generally becomes dangerous, or even fatal, when it causes hypovolemia (low blood volume) or hypotension (low blood pressure). In these scenarios various mechanisms come into play to maintain the body's homeostasis. These include the "retro-stress-relaxation" mechanism of cardiac muscle, the baroreceptor reflex and renal and endocrine responses such as the renin - angiotensin - aldosterone effect.

Certain diseases or medical conditions, such as hemophilia and low platelet count (thrombocytopenia) may increase the risk of bleeding or exacerbate minor bleeding. "Blood thinner" medications, such as warfarin can increase the risk of bleeding.

Death from hemorrhage can generally occur surprisingly quickly. This is because of 'negative feedback'. An example of this is 'cardiac repression', when poor heart contraction depletes blood flow to the heart, causing even poorer heart contraction. This kind of effect causes death to occur more quickly than expected.

Types of bleeding

Hemorrhage is broken down into 4 classes by the American College of Surgeons' Advanced Trauma Life Support (ATLS). ^[1]

Class I Hemorrhage involves up to 15% of blood volume. There is typically no change in vital signs and fluid resuscitation is not usually necessary.
Class II Hemorrhage involves 15-30% of total blood volume. A patient is often tachycardic (rapid heart beat) with a narrowing of the difference between the systolic and diastolic blood pressures. The body attempts to compensate with peripheral vasoconstriction. Skin may start to look pale and be cool to the the touch. The patient might start acting differently. Volume resuscitation with crystaloids (Normal Saline or Lactated Ringer's Solution) is all that is typically required. Blood transfusion is not typically required.
Class III Hemorrhage involves loss of 30-40% of circulating blood volume. The patient's blood pressure drops, the heart rate increases, peripheral perfusion, such as capillary refill worsens, and the mental status worsens. Fluid resuscitation with crystaloid and blood transfusion are usually necessary.
Class IV Hemorrhage involves loss of >40% of circulating blood volume. The limit of the body's compensation are reached and aggressive resuscitation is required to prevent death.

Individuals in excellent physical and cardiovascular shape may have more effective compensatory mechanisms before experiencing cardiovascular collapse. These patients may look deceptively stable, with minimal derangements in vital sounds, while having poor peripheral perfusion(shock). Elderly patients or those with chronic medical conditions may have less tolerance to blood loss, less ability to compensate and take medications, such as betablockers, which may blunt the cardiovascular response. Care must be taken in the assessment of these patients.

Causes of Bleeding

The cause of bleeding is usually divided into two main categories: traumatic and medical

Traumatic bleeding is caused by some type of injury. The injury may be from a blunt trauma (e.g. assault with a club, fall, motor vehicle accident) or penetrating trauma (e.g. knife or gun). The pattern of injury, evaluation and treatment will vary with the mechanism of the injury. Blunt trauma causes injury via a shock effect; delivering energy over and area. Wounds are often not straight and unbroken skin may hide significant injury. Penetrating trauma follows the course of the injurious device. As the energy is applied in a more focused fashion, it requires less energy to cause significant injury. Any body organ, including bone and brain, can be injured and bleed. Bleeding may not be readily apparent; internal organs such as the liver, kidney and spleen may bleed into the abdominal cavity. The only apparent signs may come with blood loss. Bleeding from a bodily oriface, such as the rectum, nose, ears may signal internal bleeding, but cannot be relied upon. Bleeding from a medical procedure also falls into this category.

Medical bleeding is caused by a non-traumatic process. Some medical causes include weaknesses in blood vessels (aneurysm or dissection), arteriovenous malformation, ulcerations, tissue death, cancer, or infection. Some of these causes can be treated with medication and observation, however some require surgery.

First aid

All people who have been injured should receive and thorough assessment. It should be divided into a primary and secondary survey and performed in a stepwise fashion, following the "ABCs". Notification of EMS or other rescue agencies should be performed in a timely manner and as the situation requires.

The primary survey examines and verifies that the patient's Airway is intact, that s/he is Breathing and that Circulation is working. A similar schema and pnemonic is used as in CPR. However, during the pulse check of C, attempts should also be made to control bleeding and to asses perfusion, usually by checking capillary refill. Additionally a persons mental status should be assessed (Disability) or either an AVPU scale or via a formal Glascow Coma Scale. In all but the most minor cases, the patient should be Exposed by removal of clothing and a seconday survery performed, examining the patient from head to toe for other injuries. The survey should not delay treatment and transport, especially if a non-correctable problem is identified.

Minor bleeding

Minor bleeding is bleeding that falls under a Class I hemorrhage and the bleeding is easily stopped with pressure.

The biggest danger in a minor wound is infection. Bleeding should be stopped with direct pressure and the wound should be washed well with soap and water. A dressing, typically made of gauze, should be applied. Peroxide or iodine solutions (such as Betadine) can injure the cells that promote healing and may actually impair proper wound healing and delay closure ^[2]. In a major medical emergency involving many casualties; minor bleeding, or casualties where a minor bleeding is their only condition, take lowest priority in medical aid and supplies.

Severe traumatic bleeding

Severe bleeding poses a very real risk of death to the casualty if not treated quickly, therefore major bleeds should take priority over most all conditions, save failure of the heart or lungs. Perform a casualty assessment and follow the necisary first aid steps leading up to treatment of the bleed before moving on. First assess the bleed itself; if there is a foreign object in the wound (such as a bullet) or if a broken bone appears to be the cause of the wound DO NOT attempt to remove any object you may find yourself unless you have advanced first aid training, and NEVER apply direct pressure to an open fracture or object wound. If this is not the case, apply a medical pad (this can be supplimented with a folded bandage) and then apply a firm bandage over the pad and around the body, if the bleed is isolated to a limb, bandage around the circumference of the limb, if on the torso, bandage around the entire torso, etc. after applying the bandage, try to raise that area of the body to lessen bloodflow and increase net blood pressure. If this is not sufficient to quell bloodflow from the wound, apply direct pressure on the pad, if the casualty is concious, you can get them, or an untrained bystander to do this for you while you continue treatment. If the wound is an open fracture or contains an object, do not apply a pad and proceed to bandage above and below the wound firmly.

If the above steps do not stop the bleeding or reduce bloodloss sufficiently, a pressure bandage, or direct pressure with your hand or fingers can be applied to an appropriate pressure point. The use of a torniquet is not advised; but if you have been taught to use one always remember to leave it in plain sight and enscribe the letter T, as well as the time of application on the casualties forehead. NEVER remove a torniquet after application, this will release clotted blood from the area and likley result in an infarction.

If a limb has been completely amputated by the trauma, retain the limb (if possible) wrapped in plastic, submerged in an ice slurry and out of sight of the casualty. To stop the bloodflow from the stump of the limb, apply a pressure bandage above the amputation and a torniquet (in the case of total amputation a torniquet is always used) do this as soon as possible, even if the limb does not appear to be bleeding, this effect is simply due to reflexive contraction of the blood vessels and will cease without warning.

After the bleeding has been controlled, ensure the patient is lying on their back comfortably and raise the casualties legs to prevent them going into shock.

Externalised bleeding

The only minor situation is a spontaneous nosebleed, or a nosebleed caused by a slight trauma (such as a child putting his finger in the nose). Just sit down, slightly tilt your head forward, and pinch the bridge of your nose. Do not blow your nose! Keep doing this for about ten minutes, which is the time the clot forms correctly (a shorter compression is not efficient). Consult a doctor when the bleeding does not stop or starts again.

Externalised bleeding from the ear often indicated the brain has suffered trauma, in this case, lay the casualty in the recovery position with the bleeding ear downwards to permit drainage, failure to do this will likely result in swelling of the brain and possibly death. No further action can be taken by you other than to call for mediall assistance, which you should do in every instance of using first aid to prevent death.

Internal bleeding

Main article: Internal bleeding

Symptoms of internal bleeding include; pale, clammy skin, an increased heart rate and a stupor or confused state

After identifying that a casualty is suffering internal bleeding, call for medical assistance immidiately, the only further step you can perform as a first aider is to raise the casualties legs.

Risk of blood contamination

Concerning the direct exposure of the first-aider's skin to the blood: the skin is watertight, so if the skin is not wounded (skin disease or very recent wound), there is no risk of contamination by a disease of the casualty. Before any further activity (especially eating, drinking, touching the eyes, the mouth or the nose), the hand must be carefully and softly washed with clear water, then bathed five minutes in diluted bleach (sodium hypochlorite).

However, to avoid any risk, it is highly recommended to protect the hands, e.g. by a plastic bag or a cloth, before pressing the wound. If there is nothing to protect the hands, examine your hand to be sure it is not wounded, or use a distant compression of the artery (pressure point with your hand if you know the anatomic references, or a tourniquet).

In case of blood exposure, even on safe skin, the first-aider should go to the emergency department, where an antiretroviral drug to prevent HIV infection will be started.

Notes

Before the advent of modern medicine the technique of bloodletting, or phlebotomy, was used for a number of conditions: causing bleeding intentionally to remove a controlled amount of excess or "bad" blood.