Bleeding
From Wikipedia, the free encyclopedia
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 (154 lbs) male has approximately 5000 ml (5.3 quarts) of circulating blood. Loss of 10-15% of total blood volume can be endured without clinical sequelae in a healthy person.
The human body generates blood at a rate of about 2 litres (2.1 quarts) per week. The technique of blood transfusion is used to replace severe quantities of lost blood.
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[edit] 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 'positive 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.
[edit] 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 touch. The patient might start acting differently. Volume resuscitation with crystaloids (Saline solution 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.
[edit] Causes of bleeding
[edit] Traumatic bleeding
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), laceration, 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 an 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 orifice, 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.
[edit] Bleeding due to underlying medical conditions
Medical bleeding is that associated with an increased risk of bleeding due to an underlying medical condition. It will increase the risk of bleeding related to underlying anatomic deformities, such as weaknesses in blood vessels (aneurysm or dissection), arteriovenous malformation, ulcerations. Similarly, other conditions that disrupt the integrity of the body such as tissue death, cancer, or infection may lead to bleeding.
The underlying scientific basis for blood clotting and hemostasis is discussed in detail in the articles, Coagulation, haemostasis and related articles. The discussion here is limited to the common practical aspects of blood clot formation which manifest as bleeding.
Certain medical conditions can also make patients susceptible to bleeding. These are conditions that affect the normal "hemostatic" functions of the body. Hemostasis involves several components. The main components of the hemostatic system include platelets and the coagulation system.
Platelets are small blood components that form a plug in the blood vessel wall that stops bleeding. Platelets also produce a variety of substances that stimulate the production of a blood clot. One of the most common causes of increased bleeding risk is exposure to non-steroidal anti-inflammatory drugs (or "NSAIDs"). The prototype for these drugs is aspirin, which inhibits the production of thromboxane. NSAIDs inhibit the activation of platelets, and thereby increase the risk of bleeding. The effect of aspirin is irreversible; therefore, the inhibitory effect of aspirin is present until the platelets have been replaced (about ten days). Other NSAIDs, such as "ibuprofen" (Motrin) and related drugs, are reversible and therefore, the effect on platelets is not as long-lived.
There are several named coagulation factors that interact in a complex way to form blood clots, as discussed in the article on coagulation. Deficiencies of coagulation factors are associated with clinical bleeding. For instance, deficiency of Factor VIII causes classic Hemophilia A while deficiencies of Factor IX cause "Christmas disease"(hemophilia B). Antibodies to Factor VIII can also inactivate the Factor VII and precipitate bleeding that is very difficult to control. This is a rare condition that is most likely to occur in older patients and in those with autoimmune diseases. von Willebrand disease is another common bleeding disorder. It is caused by a deficiency of or abnormal function of the "von Willebrand" factor, which is involved in platelet activation. Deficiencies in other factors, such as factor XIII or factor VII are occasionally seen, but may not be associated with severe bleeding and are not as commonly diagnosed.
In addition to NSAID-related bleeding, another common cause of bleeding is that related to the medication, warfarin ("Coumadin" and others). This medication needs to be closely monitored as the bleeding risk can be markedly increased by interactions with other medications. Warfarin acts by inhibiting the production of Vitamin K in the gut. Vitamin K is required for the production of the clotting factors, II, VII, IX, and X in the liver. One of the most common causes of warfarin-related bleeding is taking antibiotics. The gut bacteria make vitamin K and are killed by antibiotics. This decreases vitamin K levels and therefore the production of these clotting factors.
Deficiencies of platelet function may require platelet transfusion while deficiciencies of clotting factors may require transfusion of either fresh frozen plasma of specific clotting factors, such as Factor VIII for patients with hemophilia.
[edit] First aid
All people who have been injured should receive a 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 scheme and mnemonic is used as in CPR. However, during the pulse check of C, attempts should also be made to control bleeding and to assess perfusion, usually by checking capillary refill. Additionally a persons mental status should be assessed (Disability) or either an AVPU scale or via a formal Glasgow Coma Scale. In all but the most minor cases, the patient should be Exposed by removal of clothing and a secondary 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.
[edit] Minor bleeding
Minor bleeding is bleeding that falls under a Class I hemorrhage and the bleeding is easily stopped with pressure.
The largest 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.
[edit] 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 necessary 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, in most cases, you should not remove any object you may find yourself. Also, it is advisable to avoid applying direct pressure to an open fracture or object wound. However, in case of severe and active bleeding, it is possible that the person may bleed to death or suffer serious blood loss, it is better to apply direct pressure if needed to save the person's life. It is important to be aware of the risk of causing further injury and this must be balanced against the risk of loss of life in case of severe bleeding.
Apply a bandage and secure it firmly. Take care to avoid cutting off the circulation to an extremity, unless this is absolutely necessary. Sometimes it is possible to raise the bleeding extremity to lessen bloodflow and increase net blood pressure. The head can also be placed flat or downwards to increase circulation to the brain and avoid shock. If there is any possibility of a neck, head, or spine injury, take extra care to make sure that the spine position is maintained when moving the patient. It is best to use medical bandages whenever possible. However, in the absence of appropriate supplies, use any clean cloth. Try to avoid contaminating yourself with the person's blood or excrements, as these may put you at risk for infections, such as HIV. If you do get blood on yourself, wash the blood off and seek medical advice as soon as practical. See below for more information.
The use of a tourniquet 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. Tourniquets should rarely be used as it is usually possible to stop bleeding by the application of direct pressure.
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 tourniquet (in the case of total amputation a tourniquet 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.
[edit] Bleeding that indicates more serious internal bleeding
[edit] Epistaxis, nosebleeds
The only minor situation is a spontaneous nosebleed, or a nosebleed caused by a slight trauma (such as a child putting his finger in his 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 it takes for the clot to form correctly (a shorter compression is not efficient). Consult a doctor if the bleeding does not stop or starts again. DO NOT put your head back.
Externalised bleeding from the ear may indicate brain trauma if there has been a serious head injury. Loss of consciousness, amnesia, or fall from a height increases the likelihood that there has been a severe injury. Also, in motor vehicle accidents associated with death or severe injury to other passengers, it is important to be aware that other passengers are more likely to have suffered a serious injury. It is important, in case of serious injury, to call for medical assistance as soon as possible.
Hemoptysis, or coughing up blood, may be a sign that the person is at risk for serious bleeding. This is especially the case for patients with cancer. Hematemesis is vomiting up blood from the stomach. Often, the source of bleeding is difficult to distinguish and either should prompt a visit to the emergency department, immediately if more than bits of blood are present.
[edit] 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 person is suffering internal bleeding, call for medical assistance immediately. The best thing you can do while waiting is raise the person's legs.
[edit] 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 post-exposure prophylaxis can be started to prevent an HIV infection.
[edit] 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. Phlebotomy is still used as an extremely effective treatment for Haemochromatosis.
[edit] See also
- Aneurysm
- Coagulation
- Upper gastrointestinal bleed
- Vaginal bleeding
- Intracerebral hemorrhage - bleeding in the brain caused by the rupture of a blood vessel within the head. See also hemorrhagic stroke.
- Subarachnoid hemorrhage (SAH) implies the presence of blood within the subarachnoid space from some pathologic process. The common medical use of the term SAH refers to the nontraumatic types of hemorrhages, usually from rupture of a berry aneurysm or arteriovenous malformation(AVM). The scope of this article is limited to these nontraumatic hemorrhages.
- Intracranial hemorrhage
- Hypertensive hemorrhage
- Cerebral hemorrhage
- Postoperative hemorrhage
- Postpartum hemorrhage
- Arterial hemorrhage - from an artery
- Venous hemorrhage - from a vein
- Capillary hemorrhage - from a capillary
- Primary hemorrhage - if bleeding immediately follows an injury
- Reactionary hemorrhage - delayed bleeding after injury
- Secondary hemorrhage - delayed bleeding from sepsis
- Hematuria - blood in the urine from urinary bleeding
- Hemoptysis - coughing up blood from the lungs
- Hematemesis - vomiting fresh blood
- Hematochezia - rectal blood
