Editing Bleeding (section)

====Blood loss====
Hemorrhaging is broken down into four classes by the American College of Surgeons' [[advanced trauma life support]] (ATLS).<ref name="EM2004">{{cite book|veditors = Tintinalli JE, Kelen GD, Stapczynski JS|vauthors = Manning JE|title=Emergency Medicine: A Comprehensive Study Guide |edition=6th |chapter=Fluid and Blood Resuscitation|date=2003|publisher=McGraw Hill |isbn=978-0-07-150091-3|page=227}}</ref>
* '''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 [[Tachycardia|tachycardic]] (rapid heart beat) with a reduction in the difference between the [[Systole (medicine)|systolic]] and [[diastolic]] blood pressures. The body attempts to compensate with [[Vasoconstriction|peripheral vasoconstriction]]. Skin may start to look pale and be cool to the touch. The patient may exhibit slight changes in behavior. Volume resuscitation with crystalloids ([[Saline (medicine)|Saline solution]] or [[Lactated Ringer's solution]]) is all that is typically required. [[Blood transfusion]] is not usually required.
* '''Class III Hemorrhage''' involves loss of 30–40% of circulating blood volume. The patient's [[blood pressure]] drops, the [[heart rate]] increases, peripheral hypoperfusion ([[shock (circulatory)|shock]]) with diminished [[capillary refill]] occurs, and the mental status worsens. Fluid resuscitation with crystalloid and blood transfusion are usually necessary.
* '''Class IV Hemorrhage''' involves loss of >40% of circulating blood volume. The limit of the body's compensation is reached and aggressive resuscitation is required to prevent death.

This system is basically the same as used in the staging of [[hypovolemia|hypovolemic shock]].

Individuals in excellent physical and [[Circulatory system|cardiovascular]] shape may have more effective compensatory mechanisms before experiencing cardiovascular collapse. These patients may look deceptively stable, with minimal derangements in vital signs, while having poor peripheral perfusion. Elderly patients or those with chronic medical conditions may have less tolerance to blood loss, less ability to compensate, and may take medications such as betablockers that can potentially blunt the cardiovascular response. Care must be taken in the assessment.{{citation needed|date=November 2021}}