Hypovolemic shock is a form 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 emerge ...
caused by severe
hypovolemia (insufficient blood volume or
extracellular fluid in the body).
It could be the result of severe
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 ...
through a variety of mechanisms or
blood loss
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, ...
.
Hypovolemic shock is a
medical emergency
A medical emergency is an acute injury or illness that poses an immediate risk to a person's life or long-term health, sometimes referred to as a situation risking "life or limb". These emergencies may require assistance from another, qualified ...
; if left untreated, the
insufficient blood flow can cause damage to
organs, leading to
multiple organ failure.
In treating hypovolemic shock, it is important to determine the cause of the underlying hypovolemia, which may be the result of
bleeding or other
fluid loss
Volume contraction is a decrease in the volume of body fluid, including the dissolved substances that maintain osmotic balance ( osmolytes). The loss of the water component of body fluid is specifically termed dehydration.
By body fluid compartme ...
es. To minimize
ischemic damage to tissues, treatment involves quickly replacing lost blood or fluids, with consideration of both rate and the type of fluids used.
Tachycardia, a fast heart rate, is typically the first abnormal vital sign. When resulting from blood loss, trauma is the most common root cause, but severe blood loss can also happen in various body systems without clear traumatic injury. The body in hypovolemic shock prioritizes getting oxygen to the brain and heart, which reduces blood flow to nonvital organs and extremities, causing them to grow cold, look mottled, and exhibit delayed
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 ...
. The lack of adequate oxygen delivery ultimately leads to a worsening increase in the acidity of the blood (acidosis). The "lethal triad" of ways trauma can lead to death is
acidosis
Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma.
The term ''acidemia'' describe ...
,
hypothermia
Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
, and
coagulopathy
Coagulopathy (also called a bleeding disorder) is a condition in which the blood's ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding ( bleeding diathesis), which may occur s ...
. It is possible for trauma to cause clotting problems even without
resuscitation efforts.
Damage control resuscitation is based on three principles:
*
permissive hypotension: tries to balance temporary suboptimal
perfusion to organs with conditions for halting blood loss by setting a goal of 90 mmHg
systolic blood pressure
*
hemostatic resuscitation: restoring blood volume in ways (with whole blood or equivalent) that interfere minimally with the natural process of stopping bleeding.
* damage control surgery.
Signs and symptoms
Symptoms of hypovolemic shock can be related to
volume depletion,
electrolyte imbalances, or
acid–base disorder
Acid–base imbalance is an abnormality of the human body's normal balance of acids and bases that causes the plasma pH to deviate out of the normal range (7.35 to 7.45). In the fetus, the normal range differs based on which umbilical vessel ...
s that accompany hypovolemic shock.
Patients with volume depletion may complain of
thirst,
muscle cramps, and/or
orthostatic hypotension
Orthostatic hypotension, also known as postural hypotension, is a medical condition wherein a person's blood pressure drops when standing up or sitting down. Primary orthostatic hypertension is also often referred to as neurogenic orthostatic hyp ...
. Severe hypovolemic shock can result in
mesenteric and
coronary ischemia that can cause
abdominal
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
or
chest pain.
Agitation,
lethargy
Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overwo ...
, or
confusion may characterize brain mal-perfusion.
Dry
mucous membranes, decreased
skin turgor, low
jugular venous distention
The jugular venous pressure (JVP, sometimes referred to as ''jugular venous pulse'') is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different for ...
,
tachycardia, and
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 di ...
can be seen along with decreased
urinary output
Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
. Patients in shock can appear cold,
clammy, and
cyanotic.
Early signs and symptoms include tachycardia given rise to by catecholamine release; skin pallor due to
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 vess ...
triggered by catecholamine release; hypotension followed by hypovolaemia and perhaps arising after myocardial insufficiency; and confusion, aggression, drowsiness and coma caused by cerebral hypoxia or acidosis.
Tachypnoea owing to hypoxia and acidosis, general weakness caused by hypoxia and acidosis,
thirst induced by hypovolaemia, and
oliguria caused by reduced
perfusion may also arise.
Abnormal growing central venous pressure indicates either hypotension or hypovolemia. Tachycardia accompanied by declined urine outflow implies either
tension pneumothorax,
cardiac tamponade or
cardiac failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...
which is thought secondary to
cardiac contusion
A blunt cardiac injury is an injury to the heart as the result of blunt trauma, typically to the anterior chest wall. It can result in a variety of specific injuries to the heart, the most common of which is a myocardial contusion, which is a term ...
or
ischaemic heart disease.
Echocardiography in such case may be helpful to distinguish cardiac failure from other diseases.
Cardiac failure manifests a weak contractibility myocardium; treatment with an inotropic drug such as dobutamine may be appropriate.
Cause
The annual incidence of shock of any etiology is 0.3 to 0.7 per 1000, with hemorrhagic shock being most common in the
intensive care unit
220px, Intensive care unit
An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensi ...
. Hypovolemic shock is the most common type of shock in children, most commonly due to
diarrheal illness
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 ...
in the
developing world.
Hypovolemic shock occurs as a result of either blood loss or extracellular fluid loss.
Blood loss
Hemorrhagic shock is hypovolemic shock from blood loss. Traumatic injury is by far the most common cause of hemorrhagic shock, particularly blunt and penetrating trauma, followed by upper and lower gastrointestinal sources, such as
gastrointestinal (GI) bleed. Other causes of hemorrhagic shock include bleed from an
ectopic pregnancy, bleeding from
surgical intervention,
vaginal bleeding, and
splenic rupture.
Obstetrical
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a surgic ...
,
vascular,
iatrogenic, and even
urological source
Urology (from Greek οὖρον ''ouron'' "urine" and ''-logia'' "study of"), also known as genitourinary surgery, is the branch of medicine that focuses on surgical and medical diseases of the urinary-tract system and the reproductive organ ...
s have all been described. Bleeding may be either external or internal. A substantial amount of blood loss to the point of hemodynamic compromise may occur in the
chest,
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
, or the
retroperitoneum. The
thigh itself can hold up to 1 L to 2 L of blood.
Localizing and controlling the source of bleeding is of utmost importance to the treatment of hemorrhagic shock.
The sequence of the most-commonly-seen causes that lead to hemorrhagic type of hypovolemic shock is given in order of frequencies: blunt or penetrating trauma including multiple
fractures
Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displ ...
absent from vessel impairment, upper gastrointestinal bleeding e.g.,
variceal hemorrhage,
peptic ulcer., or lower GI bleeding e.g.,
diverticular, and
arteriovenous malformation.
Except for the two most common causes, the less common causes are intra-operative and post-operative bleeding,
abdominal aortic rupture
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
or left ventricle aneurysm rupture, aortic–enteric fistula, hemorrhagic
pancreatitis
Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types: acute pancreatitis, and chronic p ...
,
iatrogenic e.g.,
inadvertent biopsy of
arteriovenous malformation,
severed artery Severed may refer to:
*''Severed'', novel by Simon Kernick 2007
*''Severed'', novel Scott Snyder 2012
* ''Severed'' (film) by Carl Bessai 2005 Canadian zombie horror film
* ''Severed'' (video game)
*"Severed", song by Mudvayne from '' L.D. 50'' ...
.,
tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s or
abscess erosion into major vessels, post-
partum
Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births globally ...
hemorrhage,
uterine or
vaginal
In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen. ...
hemorrhage owing to
infection
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...
,
tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s,
lacerations,
spontaneous peritoneal hemorrhage
Spontaneous may refer to:
* Spontaneous abortion
* Spontaneous bacterial peritonitis
* Spontaneous combustion
* Spontaneous declaration
* Spontaneous emission
* Spontaneous fission
* Spontaneous generation
* Spontaneous human combustion
* Spontan ...
caused by
bleeding diathesis, and ruptured
hematoma.
Fluid loss
In spite of hemorrhage, the amount of circulating blood in the body may drop as well when one loses excessive body fluid owing to non-hemorrhagic reasons.
Hypovolemic shock as a result of extracellular fluid loss can be of the 4 etiologies.
Gastrointestinal
Gastrointestinal (GI) losses can occur via many different etiologies. The
gastrointestinal tract usually secretes between 3 and 6 liters of fluid per day. However, most of this fluid is reabsorbed as only 100 to 200 mL are lost in the
stool.
Volume depletion occurs when the fluid ordinarily secreted by the GI tract cannot be reabsorbed. This occurs when there is retractable
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 nose.
Vomiting can be the result of ailments like food poisoning, gastroenter ...
,
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 w ...
, or external drainage via
stoma or
fistulas.
Kidneys
Renal losses of
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
and
fluid can lead to hypovolemic shock. The
kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...
s usually excrete
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 ...
and
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
in a manner that matches
sodium intake
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 isot ...
and
water intake.
Diuretic therapy and
osmotic diuresis from
hyperglycemia can lead to excessive renal sodium and volume loss. In addition, there are several
tubular and
interstitial disease
An interstitial space or interstice is a space between structures or objects.
In particular, interstitial may refer to:
Biology
* Interstitial cell tumor
* Interstitial cell, any cell that lies between other cells
* Interstitial collagenase, ...
s beyond the scope of this article that cause severe
salt-wasting nephropathy.
Skin
Fluid loss also can occur from the skin. In a hot and dry climate, skin fluid losses can be as high as 1 to 2 liters/hour. Patients with a skin barrier interrupted by burns or other skin lesions also can experience large fluid losses that lead to hypovolemic shock.
Third-spacing
Sequestration of fluid into a third space also can lead to volume loss and hypovolemic shock. Third-spacing of fluid can occur in
intestinal obstruction,
pancreatitis
Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types: acute pancreatitis, and chronic p ...
, obstruction of a major
venous system
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...
,
vascular endothelium
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...
or any other pathological condition that results in a massive
inflammatory response.
Pathophysiology
Blood loss
Hemorrhagic shock is due to the depletion of intravascular volume through blood loss to the point of being unable to match the tissues demand for oxygen. As a result,
mitochondria are no longer able to sustain
aerobic metabolism for the production of oxygen and switch to the less efficient
anaerobic metabolism to meet the cellular demand for
adenosine triphosphate
Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms ...
. In the latter process, pyruvate is produced and converted to
lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
to regenerate nicotinamide adenine dinucleotide (NAD+) to maintain some degree of cellular respiration in the absence of oxygen.
The body compensates for volume loss by increasing
heart rate and
contractility, followed by
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 ...
activation resulting in
sympathetic nervous system activation and
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 vesse ...
. Typically, there is a slight increase in the
diastolic blood pressure with narrowing of the
pulse pressure. As
diastolic ventricular filling continues to decline and
cardiac output decreases, systolic blood pressure drops.
Due to sympathetic nervous system activation, blood is diverted away from noncritical organs and tissues to preserve blood supply to vital organs such as the heart and brain. While prolonging heart and brain function, this also leads to other tissues being further deprived of oxygen causing more
lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
production and worsening
acidosis
Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma.
The term ''acidemia'' describe ...
. This worsening acidosis along with
hypoxemia, if left uncorrected, eventually causes the loss of peripheral vasoconstriction, worsening hemodynamic compromise, and death.
The body's compensation varies by
cardiopulmonary comorbidities, age, and vasoactive medications. Due to these factors, heart rate and blood pressure responses are extremely variable and, therefore, cannot be relied upon as the sole means of diagnosis.
A key factor in the pathophysiology of hemorrhagic shock is the development of trauma-induced
coagulopathy
Coagulopathy (also called a bleeding disorder) is a condition in which the blood's ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding ( bleeding diathesis), which may occur s ...
. Coagulopathy develops as a combination of several processes. The simultaneous loss of coagulation factors via hemorrhage,
hemodilution with
resuscitation fluid
Resuscitation is the process of correcting physiological disorders (such as lack of breathing or heartbeat) in an acutely ill patient. It is an important part of intensive care medicine, anesthesiology, trauma surgery and emergency medicine. We ...
s, and
coagulation cascade dysfunction
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 mechani ...
secondary to
acidosis
Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma.
The term ''acidemia'' describe ...
and
hypothermia
Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
have been traditionally thought to be the cause of coagulopathy in trauma. However, this traditional model of trauma-induced coagulopathy may be too limited. Further studies have shown that a degree of coagulopathy begins in 25% to 56% of patients before initiation of the resuscitation. This has led to the recognition of trauma-induced coagulopathy as the sum of two distinct processes: ''acute coagulopathy of trauma'' and ''resuscitation-induced coagulopathy''.
Trauma-induced coagulopathy is acutely worsened by the presence of acidosis and hypothermia. The activity of coagulation factors,
fibrinogen depletion, and
platelet quantity are all adversely affected by acidosis.
Hypothermia
Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
(less than 34 C) compounds coagulopathy by impairing coagulation and is an independent risk factor for death in hemorrhagic shock.
Fluid loss
Hypovolemic shock results from depletion of
intravascular volume
Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the int ...
, whether by extracellular fluid loss or blood loss. The body compensates with increased
sympathetic tone
The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...
resulting in increased
heart rate, increased
cardiac contractility Myocardial contractility represents the innate ability of the heart muscle (cardiac muscle or myocardium) to contract. The ability to produce changes in force during contraction result from incremental degrees of binding between different types of ...
, and
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 vesse ...
. The first changes in
vital signs seen in hypovolemic shock include an increase in
diastolic blood pressure with narrowed
pulse pressure.
As volume status continues to decrease,
systolic blood pressure drops. As a result, oxygen delivery to vital organs is unable to meet the oxygen needs of the cells. Cells switch from
aerobic metabolism to
anaerobic metabolism, resulting in
lactic acidosis. As sympathetic drive increases, blood flow is diverted from other organs to preserve blood flow to the heart and brain. This propagates tissue ischemia and worsens lactic acidosis. If not corrected, there will be worsening hemodynamic compromise and, eventually, death.
Diagnosis
Shock index (SI) has been defined as
; SI
≥0.6 is a clinical shock.
Such ratio value is clinically employed to determine the scope or emergence of shock.
The SI correlates with the extent of hypovolemia and thus may facilitate the early identification of severely injured patients threatened by complications due to blood loss and therefore need urgent treatment, i.e. blood transfusion.
Data presented as n (%), mean ± standard deviation or median (interquartile range (IQR)). n = 21,853; P <0.001 for all parameters. ED Emergency department, GCS Glasgow coma scale, HR Heart rate, SBP Systolic blood pressure, SI = Shock index.
Bleeding
Recognizing the degree of blood loss via vital sign and mental status abnormalities is important. The American College of Surgeons Advanced Trauma Life Support (ATLS) hemorrhagic shock classification links the amount of blood loss to expected physiologic responses in a healthy 70 kg patient. As total circulating
blood volume accounts for approximately 7% of total
body weight
Human body weight is a person's mass or weight.
Strictly speaking, body weight is the measurement of weight without items located on the person. Practically though, body weight may be measured with clothes on, but without shoes or heavy accessor ...
, this equals approximately five liters in the average 70 kg male patient.
* Class 1: Volume loss up to 15% of total blood volume, approximately 750 mL. Heart rate is minimally elevated or normal. Typically, there is no change in blood pressure, pulse pressure, or respiratory rate.
* Class 2: Volume loss from 15% to 30% of total blood volume, from 750 mL to 1500 mL. Heart rate and respiratory rate become elevated (100 BPM to 120 BPM, 20 RR to 24 RR). Pulse pressure begins to narrow, but systolic blood pressure may be unchanged to slightly decreased.
* Class 3: Volume loss from 30% to 40% of total blood volume, from 1500 mL to 2000 mL. A significant drop in blood pressure and changes in mental status occur. Heart rate and respiratory rate are significantly elevated (more than 120 BPM). Urine output declines. Capillary refill is delayed.
* Class 4: Volume loss over 40% of total blood volume. Hypotension with narrow pulse pressure (less than 25 mmHg). Tachycardia becomes more pronounced (more than 120 BPM), and mental status becomes increasingly altered. Urine output is minimal or absent. Capillary refill is delayed.
Again, the above is outlined for a healthy 70 kg individual. Clinical factors must be taken into account when assessing patients. For example, elderly patients taking
beta blockers can alter the patient's physiologic response to decreased blood volume by inhibiting mechanism to increase heart rate. As another, patients with baseline hypertension may be functionally hypotensive with a systolic blood pressure of 110 mmHg.
Non-bleeding
Various laboratory values can be abnormal in hypovolemic shock. Patients can have increased
BUN and
serum creatinine as a result of
pre-renal kidney failure.
Hypernatremia or
hyponatremia can result, as can
hyperkalemia
Hyperkalemia is an elevated level of potassium (K+) in the blood. Normal potassium levels are between 3.5 and 5.0mmol/L (3.5 and 5.0mEq/L) with levels above 5.5mmol/L defined as hyperkalemia. Typically hyperkalemia does not cause symptoms. Occa ...
or
hypokalemia.
Lactic acidosis can result from increased anaerobic metabolism. However, the effect of acid–base balance can be variable as patients with large GI losses can become
alkalotic.
In cases of hemorrhagic shock,
hematocrit and
hemoglobin
Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythroc ...
can be severely decreased. However, with a reduction in plasma volume, hematocrit and hemoglobin can be increased due to hemoconcentration.
Low
urinary sodium
The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, con ...
is commonly found in hypovolemic patients as the kidneys attempt to conserve sodium and water to expand the extracellular volume. However, sodium urine can be low in a
euvolemic patient with
heart failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...
,
cirrhosis
Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue rep ...
, or
nephrotic syndrome. Fractional excretion of sodium under 1% is also suggestive of volume depletion. Elevated
urine osmolality
Urine osmolality is a measure of urine concentration, in which large values indicate concentrated urine and small values indicate diluted urine. Consumption of water (including water contained in food) affects the osmolality of urine.
Osmolality ...
can also suggest hypovolemia. However, this number also can be elevated in the setting of impaired concentrating ability by the kidneys.
Central venous pressure Central venous pressure (CVP) is the blood pressure in the venae cavae, near the right atrium of the heart. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood back into the arterial system. CVP ...
(CVP) is often used to assess volume status. However, its usefulness in determining
volume responsiveness
Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial units, imperial or United States customary units, US customary units (s ...
has recently come into question.
Ventilator settings,
chest wall
The thoracic wall or chest wall is the boundary of the thoracic cavity.
Structure
The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae.
The chest wall has 10 layers, namely (from sup ...
compliance, and
right-sided heart failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, an ...
can compromise CVPs accuracy as a measure of volume status. Measurements of
pulse pressure variation via various commercial devices has also been postulated as a measure of volume responsiveness. However, pulse pressure variation as a measure of fluid responsiveness is only valid in patients without spontaneous breaths or arrhythmias. The accuracy of pulse pressure variation also can be compromised in right heart failure, decreased lung or chest wall compliance, and high
respiratory rate
The respiratory rate is the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain. A person's respiratory rate is usually measured in breaths per minute.
Measurement
The respiratory rate in humans is me ...
s.
Similar to examining pulse pressure variation, measuring respiratory variation in inferior
vena cava
In anatomy, the venae cavae (; singular: vena cava ; ) are two large veins (great vessels) that return deoxygenated blood from the body into the heart. In humans they are the superior vena cava and the inferior vena cava, and both empty into th ...
diameter as a measure of volume responsiveness has only been validated in patients without spontaneous breaths or arrhythmias.
Measuring the effect of
passive leg
Passive may refer to:
* Passive voice, a grammatical voice common in many languages, see also Pseudopassive
* Passive language, a language from which an interpreter works
* Passivity (behavior), the condition of submitting to the influence of ...
raises on cardiac contractility by echo appears to be the most accurate measurement of volume responsiveness, although it is also subject to limitations.
History and physical can often make the diagnosis of hypovolemic shock. For patients with hemorrhagic shock, a history of
trauma
Trauma most often refers to:
*Major trauma, in physical medicine, severe physical injury caused by an external source
*Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event
*Traumatic inju ...
or recent
surgery
Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pa ...
is present. For hypovolemic shock due to fluid losses, history and physical should attempt to identify possible GI, renal, skin, or third-spacing as a cause of extracellular fluid loss.
Although relatively nonsensitive and nonspecific,
physical exam can be helpful in determining the presence of hypovolemic shock. Physical findings suggestive of volume depletion include dry
mucous membranes, decreased
skin turgor, and low
jugular venous distention
The jugular venous pressure (JVP, sometimes referred to as ''jugular venous pulse'') is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different for ...
.
Tachycardia and
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 di ...
can be seen along with decreased
urinary output
Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
.
Differential diagnosis
While hemorrhage is the most common cause of shock in the trauma patient, other causes of shock are to remain on the differential. Obstructive shock can occur in the setting of tension pneumothorax and cardiac tamponade. These etiologies should be uncovered in the primary survey. In the setting of head or neck trauma, an inadequate sympathetic response, or neurogenic shock, is a type of distributive shock that is caused by a decrease in peripheral vascular resistance. This is suggested by an inappropriately low heart rate in the setting of hypotension. Cardiac contusion and infarctions can result in cardiogenic shock. Finally, other causes should be considered that are not related to trauma or blood loss. In the undifferentiated patient with shock, septic shock and toxic causes are also on the differential.
Management
The first step in managing hemorrhagic shock is recognition. Ideally, This should occur before the development of hypotension. Close attention should be paid to physiological responses to low-blood volume. Tachycardia, tachypnea, and narrowing pulse pressure may be the initial signs. Cool extremities and delayed capillary refill are signs of peripheral vasoconstriction.
Bleeding
In the setting of trauma, an algorithmic approach via the primary and secondary surveys is suggested by ATLS. Physical exam and radiological evaluations can help localize sources of bleeding. A trauma ultrasound, or Focused Assessment with Sonography for Trauma (FAST), has been incorporated in many circumstances into the initial surveys. The specificity of a FAST scan has been reported above 99%, but a negative ultrasound does not rule out intra-abdominal pathology.
With a broader understanding of the pathophysiology of hemorrhagic shock, treatment in trauma has expanded from a simple massive transfusion method to a more comprehensive management strategy of "damage control resuscitation". The concept of damage control resuscitation focuses on permissive hypotension, hemostatic resuscitation, and hemorrhage control to adequately treat the "lethal triad" of coagulopathy, acidosis, and hypothermia that occurs in trauma.
Hypotensive resuscitation has been suggested for the hemorrhagic shock patient without head trauma. The aim is to achieve a systolic blood pressure of 90 mmHg in order to maintain tissue perfusion without inducing re-bleeding from recently clotted vessels. Permissive hypotension is a means of restricting fluid administration until hemorrhage is controlled while accepting a short period of suboptimal end-organ perfusion. Studies regarding permissive hypotension have yielded conflicting results and must take into account type of injury (penetrating versus blunt), the likelihood of intracranial injury, the severity of the injury, as well as proximity to a trauma center and definitive hemorrhage control.
The quantity, type of fluids to be used, and endpoints of resuscitation remain topics of much study and debate. For crystalloid resuscitation, normal saline and lactated ringers are the most commonly used fluids. Normal saline has the drawback of causing a non-anion gap hyperchloremic metabolic acidosis due to the high chloride content, while lactated ringers can cause a metabolic alkalosis as lactate metabolism regenerates into bicarbonate.
Recent trends in damage control resuscitation focus on "hemostatic resuscitation" which pushes for early use of blood products rather than an abundance of crystalloids in order to minimize the metabolic derangement, resuscitation-induced coagulopathy, and the hemodilution that occurs with crystalloid resuscitation. The end goal of resuscitation and the ratios of blood products remain at the center of much study and debate. A recent study has shown no significant difference in mortality at 24 hours or 30 days between ratios of 1:1:1 and 1:1:2 of plasma to platelets to packed RBCs. However, patients that received the more balanced ratio of 1:1:1 were less likely to die as a result of exsanguination in 24 hours and were more likely to achieve hemostasis. Additionally, reduction in time to first plasma transfusion has shown a significant reduction in mortality in damage control resuscitation.
In addition to blood products, products that prevent the breakdown of fibrin in clots, or antifibrinolytics, have been studied for their utility in the treatment of hemorrhagic shock in the trauma patient. Several antifibrinolytics have been shown to be safe and effective in elective surgery. The CRASH-2 study was a randomized control trial of tranexamic acid versus placebo in trauma has been shown to decrease overall mortality when given in the first three hours of injury. Follow-up analysis shows additional benefit to tranexamic acid when given in the first three hours after surgery.
Damage control resuscitation is to occur in conjunction with prompt intervention to control the source of bleeding. Strategies may differ depending on proximity to definitive treatment.
For patients in hemorrhagic shock, early use of
blood products over
crystalloid resuscitation
A volume expander is a type of intravenous therapy that has the function of providing volume for the circulatory system. It may be used for fluid replacement or during surgery to prevent nausea and vomiting after surgery.
Physiology
When blood i ...
results in better outcomes. Balanced transfusion using 1:1:1 or 1:1:2 of plasma to platelets to packed red blood cells results in better hemostasis.
Anti-fibrinolytic administration to patients with severe bleed within 3 hours of traumatic injury appears to decrease death from major bleed as shown in the CRASH-2 trial. Research on oxygen-carrying substitutes as an alternative to packed red blood cells is ongoing, although no blood substitutes have been approved for use in the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
.
Fluid loss
For patients in hypovolemic shock due to fluid losses, the exact fluid deficit cannot be determined. Therefore, it is prudent to start with 2 liters of
isotonic crystalloid solution
The term isotonic may refer to:
* Isotonic (exercise physiology), a type of muscle contraction
*Isotonic regression, a type of numerical analysis
*Isotonic, one of three types of tonicity that characterize a solution's concentration; see Tonicity# ...
infused rapidly as an attempt to quickly restore tissue perfusion. Fluid repletion can be monitored by measuring
blood pressure
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure ...
,
urine output
Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
,
mental status, and
peripheral edema. Multiple modalities exist for measuring fluid responsiveness such as
ultrasound
Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...
, central venous pressure monitoring, and pulse pressure fluctuation as described above.
Vasopressors may be used if blood pressure does not improve with fluids.
Crystalloid
fluid resuscitation is preferred over
colloid solution
A volume expander is a type of intravenous therapy that has the function of providing volume for the circulatory system. It may be used for fluid replacement or during surgery to prevent nausea and vomiting after surgery.
Physiology
When blood is ...
s for severe volume depletion not due to
bleeding. The type of crystalloid used to resuscitate the patient can be individualized based on the patients' chemistries, estimated volume of resuscitation, acid/base status, and physician or institutional preferences.
Isotonic saline is hyperchloremic relative to blood plasma, and resuscitation with large amounts can lead to
hyperchloremic metabolic acidosis
Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys ...
. Several other isotonic fluids with lower chloride concentrations exist, such as
lactated Ringer's solution
Ringer's lactate solution (RL), also known as sodium lactate solution, Lactated Ringer’s, and Hartmann's solution, is a mixture of sodium chloride, sodium lactate, potassium chloride, and calcium chloride in water. It is used for replacing f ...
or
PlasmaLyte. These solutions are often referred to as buffered or balanced crystalloids. Some evidence suggests that patients who need large volume resuscitation may have a less
renal injury with restrictive chloride strategies and use of balanced crystalloids. Crystalloid solutions are equally as effective and much less expensive than colloid. Commonly used colloid solutions include those containing
albumin
Albumin is a family of globular proteins, the most common of which are the serum albumins. All the proteins of the albumin family are water- soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Album ...
or
hyperoncotic starch. Studies examining albumin solutions for resuscitation have not shown improved outcomes, while other studies have shown resuscitation with hyper-oncotic starch leads to increased
mortality rate
Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of d ...
and
renal failure
Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...
. Patients in shock can appear cold, clammy, and cyanotic.
Hypothermia
Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
increases the mortality rate of patients with hypovolemic shock. It is advised to keep the patient warm for the sake of maintaining the temperatures of all kinds of fluids inside the patient.
Monitoring parameters
*
Oxygen saturation by
pulse oximetry (
SpO2
Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal arte ...
).
*
Respiratory rate
The respiratory rate is the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain. A person's respiratory rate is usually measured in breaths per minute.
Measurement
The respiratory rate in humans is me ...
.
*
Pulse rate.
*
Arterial blood pressure.
*
Pulse pressure.
*
Central venous pressure Central venous pressure (CVP) is the blood pressure in the venae cavae, near the right atrium of the heart. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood back into the arterial system. CVP ...
.
*
Urine output
Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
.
*
Base deficit
In physiology, base excess and base deficit refer to an excess or deficit, respectively, in the amount of base present in the blood. The value is usually reported as a concentration in units of mEq/L (mmol/L), with positive numbers indicating an ...
and/or
lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
.
*
Temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
.
*
Mental state
A mental state, or a mental property, is a state of mind of a person. Mental states comprise a diverse class, including perception, pain experience, belief, desire, intention, emotion, and memory. There is controversy concerning the exact definiti ...
.
* Changes in the
electrocardiogram.
Prognosis
If the vital organs are deprived of perfusion for more than just a short time, the prognosis is generally not good. Shock is still a medical emergency characterized by a high mortality rate. Early identification of patients who are likely to succumb to their illness is of utmost importance.
Epidemiology
Blood loss
Trauma remains a leading cause of death worldwide with approximately half of these attributed to hemorrhage. In the United States in 2001, trauma was the third leading cause of death overall, and the leading cause of death in those aged 1 to 44 years. While trauma spans all demographics, it disproportionately affects the young with 40% of injuries occurring in ages 20 to 39 years by one country's account. Of this 40%, the greatest incidence was in the 20 to 24-year-old range.
The preponderance of hemorrhagic shock cases resulting from trauma is high. During one year, one trauma center reported 62.2% of massive transfusions occur in the setting of trauma. The remaining cases are divided among
cardiovascular surgery
Cardiac surgery, or cardiovascular surgery, is surgery on the heart or great vessels performed by cardiac surgeons. It is often used to treat complications of ischemic heart disease (for example, with coronary artery bypass grafting); to corr ...
,
critical care,
cardiology
Cardiology () is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular h ...
,
obstetrics
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a sur ...
, and general surgery, with trauma utilizing over 75% of the blood products.
As patients age,
physiological reserve
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical a ...
s decrease the likelihood of anticoagulant use increases and the number of comorbidities increases. Due to this, elderly patients are less likely to handle the physiological stresses of hemorrhagic shock and may decompensate more quickly.
Fluid loss
While the incidence of hypovolemic shock from extracellular fluid loss is difficult to quantify, it is known that hemorrhagic shock is most commonly due to trauma. In one study, 62.2% of massive transfusions at a level 1 trauma center were due to traumatic injury. In this study, 75% of the blood products used were related to traumatic injury. Elderly patients are more likely to experience hypovolemic shock due to fluid losses as they have a less
physiologic reserve
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical an ...
.
Hypovolemia secondary to
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 w ...
and/or
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 ...
is thought to be predominant in low-income countries.
See also
*
Adipsia
*
Anemia
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, t ...
*
Cardiac index Cardiac index (CI) is a haemodynamic parameter that relates the cardiac output (CO) from left ventricle in one minute to body surface area (BSA), thus relating heart performance to the size of the individual. The unit of measurement is litres per mi ...
*
Heart murmur
References
{{Shock_types
Medical emergencies