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Hypovolemia, also known as volume depletion or volume contraction, is a state of abnormally low
extracellular fluid In cell biology, extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese typically have a lower ...
in the body. This may be due to either a loss of both salt and water or a decrease in
blood volume Blood volume (volemia) is the volume of blood (blood cells and plasma) in the circulatory system of any individual. Humans A typical adult has a blood volume of approximately 5 liters, with females and males having approximately the same blood per ...
. Hypovolemia refers to the loss of extracellular fluid and should not be confused with
dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
. Hypovolemia is caused by a variety of events, but these can be simplified into two categories: those that are associated with
kidney function Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging. Functions of a healthy kidney include maintaining a person's fluid ...
and those that are not. The signs and symptoms of hypovolemia worsen as the amount of fluid lost increases. Immediately or shortly after mild fluid loss (from
blood donation A blood donation occurs when a person voluntarily has blood drawn and used for blood transfusion, transfusions and/or made into biopharmaceutical medications by a process called Blood fractionation, fractionation (separation of whole blood com ...
,
diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...
,
vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the Human nose, nose. Vomiting can be the result of ailments like Food-poisoning, foo ...
, bleeding from trauma, etc.), one may experience
headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...
,
fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...
,
weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...
,
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...
, or
thirst Thirst is the craving for potable fluids, resulting in the basic instinct of animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids or an increase in the concentration of certain osmolites, suc ...
. Untreated hypovolemia or excessive and rapid losses of volume may lead to
hypovolemic shock Hypovolemic shock is a form of shock caused by severe hypovolemia (insufficient blood volume or extracellular fluid in the body). It could be the result of severe dehydration through a variety of mechanisms or blood loss. Hypovolemic shock is a ...
. Signs and symptoms of hypovolemic shock include
increased heart rate Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (su ...
,
low blood pressure Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...
, pale or cold skin, and
altered mental status An altered level of consciousness is any measure of arousal other than normal. Level of consciousness (LOC) is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousne ...
. When these signs are seen, immediate action should be taken to restore the lost volume.


Signs and symptoms

Signs and symptoms of hypovolemia progress with increased loss of fluid volume. Early symptoms of hypovolemia include headache, fatigue, weakness, thirst, and dizziness. The more severe signs and symptoms are often associated with hypovolemic shock. These include
oliguria Oliguria or hypouresis is the low output of urine specifically more than 80 ml/day but less than 400ml/day.Boon et al, Davidson's Principles & Practice of Medicine (20th Ed), p475 The decreased output of urine may be a sign of dehydration, kidney ...
,
cyanosis Cyanosis is the change of body tissue color to a bluish-purple hue as a result of having decreased amounts of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Body tissues that show cyanosis are usually in locations ...
, abdominal and chest pain,
hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dias ...
,
tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (su ...
, cold hands and feet, and progressively altering mental status.


Causes

The causes of hypovolemia can be characterized into two categories:


Kidney

* Loss of body
sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
and consequent intravascular water (due to impaired reabsorption of salt and water in the
tubule In biology, a tubule is a general term referring to small tube or similar type of structure. Specifically, tubule can refer to: * a small tube or fistular structure * a minute tube lined with glandular epithelium * any hollow cylindrical body stru ...
s of the kidneys) **
Osmotic diuresis Diuresis () is increased urination (polyuria) or, in the related word senses more often intended, the physiological process that produces such an increase or the administration of medications to encourage that process. It involves extra urine pro ...
: the increase in urine production due to an excess of osmotic (namely
glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
and
urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important r ...
) load in the tubules of the kidneys ** Overuse of pharmacologic
diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics in ...
s ** Impaired response to hormones controlling salt and water balance (see
mineralocorticoid Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances (electrolyte balance and fluid balance). The primary mi ...
s) ** Impaired kidney function due to tubular injury or other diseases


Other

* Loss of bodily fluids due to: ** Gastrointestinal losses; e.g. vomiting and diarrhea ** Skin losses; e.g. excessive sweating and burns ** Respiratory losses; e.g. hyperventilation (breathing fast) * Build up of fluid in empty spaces ( third spaces) of the body due to: **
Acute pancreatitis Acute pancreatitis (AP) is a sudden inflammation of the pancreas. Causes in order of frequency include: 1) a gallstone impacted in the common bile duct beyond the point where the pancreatic duct joins it; 2) heavy alcohol use; 3) systemic disease; ...
** Intestinal obstruction ** Increase in
vascular permeability Vascular permeability, often in the form of capillary permeability or microvascular permeability, characterizes the capacity of a blood vessel wall to allow for the flow of small molecules (drugs, nutrients, water, ions) or even whole cells (lymph ...
**
Hypoalbuminemia Hypoalbuminemia (or hypoalbuminaemia) is a medical sign in which the level of albumin in the blood is low. This can be due to decreased production in the liver, increased loss in the gastrointestinal tract or kidneys, increased use in the body, or ...
* Loss of blood (external or internal
bleeding Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...
or
blood donation A blood donation occurs when a person voluntarily has blood drawn and used for blood transfusion, transfusions and/or made into biopharmaceutical medications by a process called Blood fractionation, fractionation (separation of whole blood com ...
)


Pathophysiology

The signs and symptoms of hypovolemia are primarily due to the consequences of decreased circulating volume and a subsequent reduction in the amount of blood reaching the tissues of the body. In order to properly perform their functions, tissues require the oxygen transported in the blood. A decrease in circulating volume can lead to a decrease in bloodflow to the brain, resulting in headache and dizziness.
Baroreceptor Baroreceptors (or archaically, pressoreceptors) are sensors located in the carotid sinus (at the bifurcation of external and internal carotids) and in the aortic arch. They sense the blood pressure and relay the information to the brain, so that a ...
s in the body (primarily those located in the
carotid sinus In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid ...
es and
aortic arch The aortic arch, arch of the aorta, or transverse aortic arch () is the part of the aorta between the ascending and descending aorta. The arch travels backward, so that it ultimately runs to the left of the trachea. Structure The aorta begins a ...
) sense the reduction of circulating fluid and send signals to the brain to increase sympathetic response (''see also:
baroreflex The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the ...
''). This sympathetic response is to release
epinephrine Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...
and
norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...
, which results in peripheral
vasoconstriction Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
(reducing size of blood vessels) in order to conserve the circulating fluids for organs vital to survival (i.e. brain and heart). Peripheral vasoconstriction accounts for the cold extremities (hands and feet), increased heart rate, increased cardiac output (and associated chest pain). Eventually, there will be less
perfusion Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion is measured as the rate at which blood is deliver ...
to the kidneys, resulting in decreased urine output.


Diagnosis

Hypovolemia can be recognized by a
fast heart rate Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (su ...
,
low blood pressure Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...
, and the absence of
perfusion Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion is measured as the rate at which blood is deliver ...
as assessed by skin signs (skin turning pale) and/or
capillary refill Capillary refill time (CRT) is defined as the time taken for color to return to an external capillary bed after pressure is applied to cause blanching. It can be measured by holding a hand higher than heart-level and pressing the soft pad of a f ...
on
forehead In human anatomy, the forehead is an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp grows. The bottom of the fore ...
,
lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...
s and
nail beds A nail is a claw-like plate found at the tip of the fingers and toes on most primates. Nails correspond to the claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin, which is a polymer ...
. The patient may feel dizzy, faint, nauseated, or very thirsty. These signs are also characteristic of most types of
shock Shock may refer to: Common uses Collective noun *Shock, a historic commercial term for a group of 60, see English numerals#Special names * Stook, or shock of grain, stacked sheaves Healthcare * Shock (circulatory), circulatory medical emergen ...
. In children, compensation can result in an artificially high blood pressure despite hypovolemia (a decrease in blood volume). Children typically are able to compensate (maintain blood pressure despite hypovolemia) for a longer period than adults, but deteriorate rapidly and severely once they are unable to compensate ( decompensate). Consequently, any possibility of
internal bleeding Internal bleeding (also called internal hemorrhage) is a loss of blood from a blood vessel that collects inside the body. Internal bleeding is usually not visible from the outside. It is a serious medical emergency but the extent of severity depen ...
in children should be treated aggressively. Signs of external bleeding should be assessed, noting that individuals can bleed internally without external blood loss or otherwise apparent signs. There should be considered possible mechanisms of injury that may have caused internal bleeding, such as ruptured or bruised internal organs. If trained to do so and if the situation permits, there should be conducted a secondary survey and checked 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 Grey Turner's sign refers to bruising of the flanks, the part of the body between the last rib and the top of the hip. The bruising appears as a blue discoloration, and is a sign of retroperitoneal hemorrhage, or bleeding behind the peritoneum, wh ...
(bruising along the sides) or
Cullen's sign Cullen's sign is superficial edema and bruising in the subcutaneous fatty tissue around the umbilicus. It is named for gynecologist Thomas Stephen Cullen (1869–1953), who first described the sign in ruptured ectopic pregnancy in 1916.T.S. Cu ...
(around the navel).


Investigation

In a hospital, physicians respond to a case of hypovolemic shock by conducting these investigations: * Blood tests: U+Es/Chem7, full blood count, glucose, blood type and screen *
Central venous catheter A central venous catheter (CVC), also known as a central line(c-line), central venous line, or central venous access catheter, is a catheter placed into a large vein. It is a form of venous access. Placement of larger catheters in more central ...
*
Arterial line An arterial line (also art-line or a-line) is a thin catheter inserted into an artery. Use Arterial lines are most commonly used in intensive care medicine and anesthesia to monitor blood pressure directly and in real-time (rather than by i ...
* Urine output measurements (via
urinary catheter In urinary catheterization a latex, polyurethane, or silicone tube known as a urinary catheter is inserted into the bladder through the urethra to allow urine to drain from the bladder for collection. It may also be used to inject liquids used ...
) * Blood pressure * SpO2
oxygen saturation Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It ca ...
monitoring


Stages

Untreated hypovolemia can lead to shock (see also:
hypovolemic shock Hypovolemic shock is a form of shock caused by severe hypovolemia (insufficient blood volume or extracellular fluid in the body). It could be the result of severe dehydration through a variety of mechanisms or blood loss. Hypovolemic shock is a ...
). Most sources state that there are 4 stages of hypovolemia and subsequent shock; however, a number of other systems exist with as many as 6 stages. The 4 stages are sometimes known as the "Tennis" staging of hypovolemic shock, as the stages of blood loss (under 15% of volume, 15–30% of volume, 30–40% of volume and above 40% of volume) mimic the scores in a game of tennis: 15, 15–30, 30–40 and 40. It is basically the same as used in classifying
bleeding Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...
by blood loss. The signs and symptoms of the major stages of hypovolemic shock include:


Treatment


Field care

The most important step in treatment of hypovolemic shock is to identify and control the source of bleeding. Medical personnel should immediately supply emergency oxygen to increase efficiency of the patient's remaining blood supply. This intervention can be life-saving. Also, the respiratory pump is especially important during hypovolemia as spontaneous breathing may help reduce the effect of this loss of blood pressure on stroke volume by increasing venous return. The use of
intravenous fluids Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...
(IVs) may help compensate for lost fluid volume, but IV fluids cannot carry oxygen the way blood does—however, researchers are developing
blood substitutes A blood substitute (also called artificial blood or blood surrogate) is a substance used to mimic and fulfill some functions of biological blood. It aims to provide an alternative to blood transfusion, which is transferring blood or blood-based ...
that can. Infusing
colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...
or crystalloid IV fluids also dilutes
clotting factor Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...
s in the blood, increasing the risk of bleeding. Current best practice allow
permissive hypotension Permissive hypotension or hypotensive resuscitation is the use of restrictive fluid therapy, specifically in the trauma patient, that increases systemic blood pressure without reaching normotension (normal blood pressures). The goal blood pressure f ...
in patients with hypovolemic shock, both avoid overly diluting clotting factors and avoid artificially raising blood pressure to a point where it "blows off" clots that have formed.


Hospital treatment

Fluid replacement Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced with oral rehydration therapy (drinking), intravenous ...
is beneficial in hypovolemia of stage 2, and is necessary in stage 3 and 4. See also the discussion of
shock Shock may refer to: Common uses Collective noun *Shock, a historic commercial term for a group of 60, see English numerals#Special names * Stook, or shock of grain, stacked sheaves Healthcare * Shock (circulatory), circulatory medical emergen ...
and the importance of treating reversible shock while it can still be countered. The following interventions are carried out: * IV access * Oxygen as required * Fresh frozen
plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral), a green translucent silica mineral * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood pla ...
or
blood transfusion Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but mo ...
* Surgical repair at sites of bleeding
Vasopressor An antihypotensive agent, also known as a vasopressor agent or simply vasopressor, or pressor, is any substance, whether endogenous or a medication, that tends to raise low blood pressure. Some antihypotensive drugs act as vasoconstrictors to inc ...
s (such as
dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...
and
noradrenaline Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...
) should generally be avoided, as they may result in further tissue
ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...
and don't correct the primary problem. Fluids are the preferred choice of therapy.


History

In cases where loss of blood volume is clearly attributable to bleeding (as opposed to, e.g., dehydration), most medical practitioners prefer the term ''
exsanguination Exsanguination is death caused by loss of blood. Depending upon the health of the individual, people usually die from losing half to two-thirds of their blood; a loss of roughly one-third of the blood volume is considered very serious. Even a sing ...
'' for its greater specificity and descriptiveness, with the effect that the latter term is now more common in the relevant context.


See also

*
Hypervolemia Hypervolemia, also known as fluid overload, is the medical condition where there is too much fluid in the blood. The opposite condition is hypovolemia, which is too little fluid volume in the blood. Fluid volume excess in the intravascular compa ...
*
Non-pneumatic anti-shock garment The non-pneumatic anti-shock garment (NASG) is a low-technology first-aid device used to treat hypovolemic shock. Its efficacy for reducing maternal deaths due to obstetrical hemorrhage is being researched. Obstetrical hemorrhage is heavy bleedi ...
*
Polycythemia Polycythemia (also known as polycythaemia) is a laboratory finding in which the hematocrit (the volume percentage of red blood cells in the blood) and/or hemoglobin concentration are increased in the blood. Polycythemia is sometimes called erythr ...
, an increase of the
hematocrit The hematocrit () (Ht or HCT), also known by several other names, is the volume percentage (vol%) of red blood cells (RBCs) in blood, measured as part of a blood test. The measurement depends on the number and size of red blood cells. It is norm ...
level, with the "relative polycythemia" being a decrease in the volume of plasma *
Volume status In medicine, intravascular volume status refers to the volume of blood in a patient's circulatory system, and is essentially the blood plasma component of the overall volume status of the body, which otherwise includes both intracellular fluid and e ...


References

{{Cardiovascular system symptoms and signs Blood disorders Medical emergencies