Examine individual changes

'{{Technical|date=June 2009}} {{Infobox disease | Name = Hypovolemia | Image = | Caption = | DiseasesDB = | ICD10 = {{ICD10|E|86||e|70}}, {{ICD10|R|57|1|r|50}}, {{ICD10|T|81|1|t|80}} | ICD9 = {{ICD9|276.52}} | ICDO = | OMIM = | MedlinePlus = 000167 | eMedicineSubj = | eMedicineTopic = | MeshID = D020896 }} In [[physiology]] and [[medicine]], '''hypovolemia''' (also '''hypovolaemia''', '''oligemia''' or '''[[Shock (circulatory)|shock]]''') is a state of decreased [[blood volume]]; more specifically, decrease in volume of [[blood plasma]].<ref>[http://www.medterms.com/script/main/art.asp?articlekey=3871 MedicineNet > Definition of Hypovolemia] Retrieved on July 2, 2009</ref><ref>[http://medical-dictionary.thefreedictionary.com/hypovolemia TheFreeDictionary.com --> hypovolemia] Citing Saunders Comprehensive Veterinary Dictionary, 3 ed. Retrieved on July 2, 2009</ref> It is thus the intravascular component of [[volume contraction]] (or loss of blood volume due to things such as [[hemorrhaging]] or [[dehydration]]), but, as it also is the most essential one, ''hypovolemia'' and ''volume contraction'' are sometimes used synonymously. Hypovolemia is characterized by salt (sodium) depletion and thus differs from [[dehydration]], which is defined as excessive loss of [[body water]].<ref>[http://www.medterms.com/script/main/art.asp?articlekey=2933 MedicineNet > Definition of Dehydration] Retrieved on July 2, 2009</ref> ==Causes== Common causes of hypovolemia are<ref>Sircar, S. Principles of Medical Physiology. Thieme Medical Pub. ISBN 9781588905727</ref> * Loss of blood (external or internal [[bleeding]] or [[blood donation]]<ref>{{cite journal |author=Danic B, Gouézec H, Bigant E, Thomas T |title=[Incidents of blood donation] |language=French |journal=Transfus Clin Biol |volume=12 |issue=2 |pages=153–9 |year=2005 |month=June |pmid=15894504 |doi=10.1016/j.tracli.2005.04.003 |url=}}</ref>) * Loss of plasma (severe [[Burn (injury)|burns]]<ref>http://www.totalburncare.com/orientation_burn_shock.htm</ref><ref>http://www.patient.co.uk/doctor/Resuscitation-in-Hypovolaemic-Shock.htm</ref> and [[lesions]] discharging fluid) * Loss of body sodium and consequent intravascular water; e.g. excessive sweating, diarrhea or vomiting * Vasodilatory (involving widening of blood vessels) such as trauma leading to dysfunction of nerve activity on blood vessels and inhibition of the [[vasomotor center]] in the brain or drugs such as [[vasodilator]]s typically used to treat [[hypertension|hypertensive]] individuals. ==Diagnosis== Clinical symptoms may not be present until 10–20% of total whole-blood volume is lost. Hypovolemia can be recognized by [[tachycardia]], diminished blood pressure,<ref>http://www.stagesofshock.com/stage3/index.html</ref> and the absence of [[perfusion]] as assessed by skin signs (skin turning pale) and/or [[capillary refill]] on [[forehead]], [[lip]]s and [[nail beds]]. The patient may feel dizzy, faint, nauseated, or very thirsty. These signs are also characteristic of most types of [[Shock (circulatory)|shock]]. Note that in children, compensation can result in an artificially high blood pressure despite hypovolemia. Children will typically compensate (maintain blood pressure despite loss of blood volume) for a longer period than adults, but will deteriorate rapidly and severely once they do begin to decompensate. This is another reason (aside from initial lower blood volume) that even the possibility of [[internal bleeding]] in children should almost always be treated aggressively. Also look for obvious signs of external bleeding while remembering that people can bleed to death internally without any external blood loss. ("Blood on the floor, plus 4 more" = intrathoracic, intraperitoneal, retroperitoneal, pelvis/thigh) Also consider possible mechanisms of injury that may have caused internal bleeding such as ruptured or bruised internal organs. If trained to do so and the situation permits, conduct a [[Advanced_Trauma_Life_Support#Secondary_survey|secondary survey]] and check the chest and abdomen for pain, deformity, guarding, discoloration or swelling. Bleeding into the abdominal cavity can cause the classical bruising patterns of [[Grey Turner's sign]] or [[Cullen's sign]]. ===Stages of hypovolemic shock=== Usually referred to as "Class" of shock. Most sources state that there are 4 stages of hypovolemic shock,<ref name="dynamicnursingeducation.com">http://dynamicnursingeducation.com/class.php?class_id=47&pid=18</ref> however a number of other systems exist with as many as 6 stages.<ref>http://www.stagesofshock.com/stage1/index.html</ref> The 4 stages are sometimes known as the "Tennis" staging of hypovolemic shock, as the 4 stages of % volume of blood loss mimic the scores in a game of tennis: 15, 15-30, 30-40, 40.<ref name="dynamicnursingeducation.com"/> It is basically the same as used in classifying [[bleeding]] by blood loss. ====Stage 1==== * Up to 15% blood volume loss (750 mL) hi:) * Compensated by constriction of vascular bed * Blood pressure maintained * Normal respiratory rate * Pallor of the skin * Normal mental status<ref name=agabegi2nd/> to slight anxiety * Normal [[capillary refill]]<ref name=agabegi2nd/> * Normal urine output<ref name=agabegi2nd/> ====Stage 2==== * 15–30% blood volume loss (750–1500 mL) * Cardiac output cannot be maintained by arterial constriction * Tachycardia >100bpm * Increased respiratory rate * [[Systolic blood pressure]] maintained * Increased [[diastolic blood pressure]] * Narrow [[pulse pressure]] (gap between the systolic and diastolic pressure) * Sweating from [[sympathetic nervous system]] stimulation * Mildly anxious/Restless * Delayed [[capillary refill]]<ref name=agabegi2nd/> * Urine output of 20-30 milliliters/hour<ref name=agabegi2nd/> ====Stage 3==== * 30–40% blood volume loss (1500–2000 mL) * Systolic BP falls to 100mmHg or less * Classic signs of [[hypovolemic shock]] * Marked [[tachycardia]] (increased heart rate) >120 bpm * Marked [[tachypnea]] (increased rate of respiration) >30 bpm * Alteration in mental status (confusion,<ref name=agabegi2nd/> anxiety, agitation) * Sweating with cool, pale skin * Delayed capillary refill<ref name=agabegi2nd/> * Urine output of approximately 20 milliliters/hour<ref name=agabegi2nd/> ====Stage 4==== * Loss greater than 40% (>2000 mL) * Extreme tachycardia (>140<ref name=agabegi2nd>{{cite book |author=Elizabeth D Agabegi; Agabegi, Steven S. |title=Step-Up to Medicine (Step-Up Series) |publisher=Lippincott Williams & Wilkins |location=Hagerstwon, MD |year=2008 |pages= |isbn=0-7817-7153-6 |oclc= |doi= |accessdate=}}</ref>) with weak pulse * Pronounced [[tachypnea]] * Significantly decreased systolic blood pressure of 70 mmHg or less * Decreased level of consciousness, lethargy,<ref name=agabegi2nd/> coma<ref name=agabegi2nd/> * Skin is sweaty, cool, and extremely pale (moribund) * Absent capillary refill<ref name=agabegi2nd/> * Negligible urine output<ref name=agabegi2nd/> ==Treatment== {{Unreferenced section|date=February 2009}} Minor hypovolemia from a known cause that has been completely controlled (such as a blood donation from a healthy patient who is not anemic) may be countered with initial rest for up to half an hour. Oral fluids that include moderate sugars and [[electrolytes]] are needed to replenish depleted sodium ions. Furthermore the advice for the donor is to eat good solid meals with proteins for the next few days. Typically, this would involve a fluid volume of less than one [[liter]], although this is highly dependent on body weight. Larger people can tolerate slightly more blood loss than smaller people. More serious hypovolemia should be assessed by a physician. ===First aid=== External bleeding should be controlled by direct pressure. If direct pressure fails, a [[Emergency tourniquet|tourniquet]] should be used in the case of severe [[hemorrhage]] that cannot be controlled by direct pressure. Tourniquet use in civilian first-aid, is now [[Joint_Royal_Colleges_Ambulance_Liaison_Committee#Guidelines|advocated]] as part of the C-ABC approach. Other techniques such as elevation and pressure points are not always effective but should still be attempted. As a rule of thumb, anywhere you can feel a pulse can be used as a pressure point to stop bleeding (with the obvious exception of the carotid pulses!). If a first-aid provider recognizes internal bleeding the life-saving measure to take is to immediately call for emergency assistance. ===Field care=== Emergency oxygen should be immediately employed to increase the efficiency of the patient's remaining blood supply. This intervention can be life-saving. <ref>Takasu A, Prueckner S, Tisherman SA, Stezoski SW, Stezoski J, Safar P. (2000), ''Effects of increased oxygen breathing in a volume controlled hemorrhagic shock outcome model in rats.'', PMID 10959021</ref> The use of [[intravenous drip|intravenous fluids]] (IVs) may help compensate for lost fluid volume, but IV fluids cannot carry oxygen in the way that blood can, however [[blood substitutes]] are being developed which can. Infusion of [[colloid fluids|colloid]] or [[crystalloid fluid|crystalloid]] IV fluids will also dilute [[clotting factor]]s within the blood, increasing the risk of bleeding. It is current best practice to allow [[permissive hypotension]] in patients suffering from hypovolemic shock<ref>http://www.trauma.org/archive/resus/permissivehypotension.html Permissive Hypotension</ref> both to ensure clotting factors are not overly diluted but also to stop blood pressure being artificially raised to a point where it "blows off" clots that have formed. ===Hospital treatment=== If the hypovolemia was caused by medication, the administration of antidotes may be appropriate but should be carefully monitored to avoid shock or the emergence of other pre-existing conditions{{Citation needed|date=April 2010}}. [[Fluid replacement]] is beneficial in hypovolemia of stage 2, and is necessary in stage 3 and 4.<ref name=agabegi2nd/> [[Blood transfusion]]s coupled with surgical repair are the definitive treatment for hypovolemia caused by [[Physical trauma|trauma]]{{Citation needed|date=April 2010}}. See also the discussion of [[Shock (circulatory)|shock]] and the importance of treating reversible shock while it can still be countered. For a patient presenting with hypovolemic shock in hospital the following investigations would be carried out: *Blood tests: U+Es/Chem7, FBC, Glucose, Cross-match *[[Central venous catheter|Central Venous Line]]/Blood Pressure *[[Arterial line]]/[[Arterial Blood Gas]]es *Urine output measurements (via [[urinary catheterization|urinary catheter]]) *Blood pressure *SpO2 Oxygen saturations The following interventions would be carried out: *IV access *Oxygen as required *Surgical repair at sites of hemorrhage *[[Inotrope]] therapy ([[Dopamine]], [[Noradrenaline]]) which increase the [[contractility]] of the heart muscle *Fresh frozen plasma/whole blood ==History== {{Unreferenced section|date=February 2009}} Historically a term ''desanguination'' (from Latin ''sanguis'', blood) was in use, meaning a massive loss of blood. The term was widely used by the [[Hippocrates]] in traditional medicine practiced in the Greco-Roman civilization and in Europe during the Middle Ages. The word was possibly used to describe the lack of personality (by death or by weakness) that often occurred once a person suffered [[hemorrhage]] or massive blood loss. In cases in which loss of blood volume is clearly attributable to bleeding (as opposed to, ''e.g.'', dehydration), most medical practitioners of today prefer the term ''[[exsanguination]]'' for its greater specificity and descriptiveness, with the effect that the latter term is now more common in the relevant context.<ref>{{cite journal | author = L. Geeraedts Jr., H. Kaasjager, A. van Vugt, and J. Frölke, | year = | title = Exsanguination in trauma: A review of diagnostics and treatment options | url = | journal = Injury | volume = 40 | issue = 1| pages = 11–20 }}</ref> ==See also== * [[Volume status]] * [[Hypervolemia]] * [[Exsanguination]] ==References== {{Reflist}} ==External links== * {{CrispThesaurus|00004050}} * {{DiseasesDB|29217}} {{Water-electrolyte imbalance and acid-base imbalance}} [[Category:Blood]] [[Category:Medical emergencies]]'