Shock is the state of insufficient
blood flow
Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms of autoregulation, just as hydraulic circuits are controlled by control systems. The hemodynamic response continuously m ...
to the
tissues of the body as a result of problems with the
circulatory system
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
.
Initial symptoms of shock may include weakness, 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 ...
, fast breathing
Hyperventilation is irregular breathing that occurs when the rate or tidal volume of breathing eliminates more carbon dioxide than the body can produce. This leads to hypocapnia, a reduced concentration of carbon dioxide dissolved in the blood. ...
, sweating, anxiety, and increased thirst.[ This may be followed by confusion, ]unconsciousness
Unconsciousness is a state in which a living individual exhibits a complete, or near-complete, inability to maintain an awareness of self and environment or to respond to any human or environmental stimulus. Unconsciousness may occur as the re ...
, or cardiac arrest
Cardiac arrest is when the heart suddenly and unexpectedly stops beating. It is a medical emergency that, without immediate medical intervention, will result in sudden cardiac death within minutes. Cardiopulmonary resuscitation (CPR) and poss ...
, as complications worsen.
Shock is divided into four main types based on the underlying cause: low volume, cardiogenic, obstructive, and distributive shock
Distributive shock is a medical condition in which abnormal distribution of blood flow in the smallest blood vessels results in inadequate supply of blood to the body's tissues and organs. It is one of four categories of shock, a condition wher ...
.[ Low volume shock, also known as hypovolemic shock, may be from bleeding, ]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 vomiting.[ Cardiogenic shock may be due to a ]heart attack
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which ma ...
or 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 ...
.[ Obstructive shock may be due to ]cardiac tamponade
Cardiac tamponade, also known as pericardial tamponade (), is the buildup of fluid in the pericardium (the sac around the heart), resulting in compression of the heart. Onset may be rapid or gradual. Symptoms typically include those of obstructi ...
or a tension pneumothorax
A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve i ...
.[ Distributive shock may be due to ]sepsis
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
, anaphylaxis
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the foll ...
, injury to the upper spinal cord, or certain overdose
A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended. s.
The diagnosis is generally based on a combination of symptoms, physical examination
In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the pati ...
, and laboratory tests.[ A decreased ]pulse pressure
Pulse pressure is the difference between systolic and diastolic blood pressure. It is measured in millimeters of mercury (mmHg). It represents the force that the heart generates each time it contracts. Resting blood pressure is normally appro ...
(systolic 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" r ...
minus diastolic 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" r ...
) or a fast heart rate raises concerns.[ The heart rate divided by systolic blood pressure, known as the shock index (SI), of greater than 0.8 supports the diagnosis more than ]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 di ...
or 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 ...
in isolation.
Treatment of shock is based on the likely underlying cause.[ An open ]airway
The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa.
Air is breathed in through the nose to ...
and sufficient breathing should be established.[ Any ongoing bleeding should be stopped, which may require surgery or ]embolization
Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin ( pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially indu ...
.[ ]Intravenous fluid
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 ...
, such as Ringer's lactate
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 flu ...
or packed red blood cells
Packed red blood cells, also known as packed cells, are red blood cells that have been separated for blood transfusion. The packed cells are typically used in anemia that is either causing symptoms or when the hemoglobin is less than usually 70 ...
, is often given.[ Efforts to maintain a normal ]body temperature
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
are also important.[ ]Vasopressors
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 in ...
may be useful in certain cases.[ Shock is both common and has a high risk of death.][ In the United States about 1.2 million people present to the emergency room each year with shock and their risk of death is between 20 and 50%.]
Signs and symptoms
The presentation of shock is variable, with some people having only minimal symptoms such as confusion and weakness. While the general signs for all types of shock are 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 di ...
, decreased 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, ...
, and confusion, these may not always be present. While a fast heart rate is common, those on β-blockers
Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a second heart attack after a first heart attack (secondary prevention). They are al ...
, those who are athletic, and in 30% of cases of those with shock due to intra abdominal bleeding, heart rate may be normal or slow. Specific subtypes of shock may have additional symptoms.
Dry mucous membrane
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It i ...
, reduced skin turgor
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 ...
, prolonged capillary refill time
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 Blanch (medical), blanching. It can be measured by holding a hand higher than heart-level and pressing th ...
, weak peripheral pulses, and cold extremities can be early signs of shock.
Low volume
Hypovolemic shock is the most common type of shock and is caused by insufficient circulating volume
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 or US customary units (such as the gallon, quart, cubic inch). Th ...
. The most common cause of hypovolemic shock is hemorrhage
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, v ...
(internal or external); however, 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, gastroenteri ...
and 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 ...
are more common causes in children. Other causes include burns, as well as excess urine loss due to diabetic ketoacidosis
Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of diabetes mellitus. Signs and symptoms may include vomiting, abdominal pain, deep gasping breathing, increased urination, weakness, confusion and occasionally loss of ...
and diabetes insipidus
Diabetes insipidus (DI), recently renamed to Arginine Vasopressin Deficiency (AVP-D) and Arginine Vasopressin Resistance (AVP-R), is a condition characterized by large amounts of dilute urine and increased thirst. The amount of urine produced ...
.
Signs and symptoms of hypovolemic shock include:
*A rapid, weak, thready pulse due to decreased blood flow combined with 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 ( ...
*Cool skin 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 ...
and stimulation of vasoconstriction
*Rapid and shallow breathing
Shallow breathing, thoracic breathing, costal breathing or chest breathing is the drawing of minimal breath into the lungs, usually by drawing air into the chest area using the intercostal muscles rather than throughout the lungs via the diap ...
due to sympathetic nervous system stimulation and 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'' describes ...
*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 ...
due to decreased perfusion and evaporation of sweat
*Thirst and dry mouth, due to fluid depletion
*Cold and mottled skin (livedo reticularis
Livedo reticularis is a common skin finding consisting of a mottled reticulated vascular pattern that appears as a lace-like purplish discoloration of the skin. The discoloration is caused by reduction in blood flow through the arterioles that supp ...
), especially extremities, due to insufficient perfusion of the skin
The severity of hemorrhagic shock can be graded on a 1–4 scale on the physical signs. The shock index (heart rate divided by systolic blood pressure) is a stronger predictor of the impact of blood loss than heart rate and blood pressure alone.[ This relationship has not been well established in pregnancy-related bleeding.
]
Cardiogenic
Cardiogenic shock is caused by the failure of the heart to pump effectively. This can be due to damage to the heart muscle, most often from a large myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...
. Other causes of cardiogenic shock include dysrhythmias, cardiomyopathy/ myocarditis, congestive 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, ...
(CHF), myocardial 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 valvular heart disease
Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). These ...
problems.
Symptoms of cardiogenic shock include:
*Distended jugular vein
The jugular veins are veins that take deoxygenated blood from the head back to the heart via the superior vena cava. The internal jugular vein descends next to the internal carotid artery and continues posteriorly to the sternocleidomastoid mu ...
s due to increased jugular venous pressure
*Weak or absent pulse
* Abnormal heart rhythms, often 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 ...
*Pulsus paradoxus
Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure and pulse wave amplitude during inspiration. The normal fall in pressure is less than 10 mmHg. When the drop ...
in case of tamponade
Tamponade () is the closure or blockage (as of a wound or body cavity) by or as if by a tampon, especially to stop bleeding.
Tamponade is a useful method of stopping a hemorrhage. This can be achieved by applying an absorbent dressing directl ...
* Reduced blood pressure
*Shortness of breath
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...
, due to pulmonary congestion
Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due t ...
Obstructive
Obstructive shock is a form of shock associated with physical obstruction of the great vessels
Great vessels are the large vessels that bring blood to and from the heart. These are:
*Superior vena cava
*Inferior vena cava
*Pulmonary arteries
* Pulmonary veins
*Aorta
Transposition of the great vessels is a group of congenital heart defec ...
of the systemic or pulmonary circulation. Several conditions can result in this form of shock.
*Cardiac tamponade
Cardiac tamponade, also known as pericardial tamponade (), is the buildup of fluid in the pericardium (the sac around the heart), resulting in compression of the heart. Onset may be rapid or gradual. Symptoms typically include those of obstructi ...
in which fluid in the pericardium
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made o ...
prevents inflow of blood into the heart (venous return). Constrictive pericarditis
Constrictive pericarditis is a medical condition characterized by a thickened, fibrotic pericardium, limiting the heart's ability to function normally. In many cases, the condition continues to be difficult to diagnose and therefore benefits from ...
, in which the pericardium
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made o ...
shrinks and hardens, is similar in presentation.
*Tension pneumothorax
A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve i ...
Through increased intrathoracic pressure, bloodflow to the heart is prevented (venous return).
*Pulmonary embolism
Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream ( embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathin ...
is the result of a thromboembolic incident in the blood vessels of the lungs and hinders the return of blood to the heart.
*Aortic stenosis
Aortic stenosis (AS or AoS) is the narrowing of the exit of the left ventricle of the heart (where the aorta begins), such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets worse ov ...
hinders circulation by obstructing the ventricular outflow tract
A ventricular outflow tract is a portion of either the left ventricle or right ventricle of the heart through which blood passes in order to enter the great arteries.
The right ventricular outflow tract (RVOT) is an infundibular extension of ...
* Hypertrophic sub-aortic stenosis is overly thick ventricular muscle that dynamically occludes the ventricular outflow tract
A ventricular outflow tract is a portion of either the left ventricle or right ventricle of the heart through which blood passes in order to enter the great arteries.
The right ventricular outflow tract (RVOT) is an infundibular extension of ...
.
*Abdominal compartment syndrome
Abdominal compartment syndrome (ACS) occurs when the abdomen becomes subject to increased pressure reaching past the point of intra-abdominal hypertension (IAH). ACS is present when intra-abdominal pressure rises and is sustained at > 20 mmHg and ...
defined as an increase in intra-abdominal pressure to > 20 mmHg with organ dysfunction. Increased intraabdominal pressure can be due to sepsis
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
and severe abdominal trauma. This increased pressure reduces blood flow back to the heart, thereby reducing blood flow to the body and resulting in signs and symptoms of shock.
Many of the signs of obstructive shock are similar to cardiogenic shock, however treatments differ. Symptoms of obstructive shock include:
* Abnormal heart rhythms, often 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 ...
.
* Reduced blood pressure.
* Cool, clammy, mottled skin, often due to low blood pressure and vasoconstriction.
* Decreased urine output.
Distributive
Distributive shock
Distributive shock is a medical condition in which abnormal distribution of blood flow in the smallest blood vessels results in inadequate supply of blood to the body's tissues and organs. It is one of four categories of shock, a condition wher ...
is low blood pressure due to a dilation of blood vessels
Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstriction ...
within the body. This can be caused by systemic infection ( septic shock), a severe allergic reaction (anaphylaxis
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the foll ...
), or spinal cord injury (neurogenic shock
Neurogenic shock is a distributive type of shock resulting in hypotension (low blood pressure), often with bradycardia (slowed heart rate), caused by disruption of autonomic nervous system pathways. It can occur after damage to the central nerv ...
).
* Septic shock is the most common cause of distributive shock. It is caused by an overwhelming systemic infection resulting in vasodilation
Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstrictio ...
leading to hypotension. Septic shock can be caused by Gram negative
The gram (originally gramme; SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram.
Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to th ...
bacteria such as (among others) ''Escherichia coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...
'', Proteus
In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea" ''(hálios gérôn)''. ...
species, ''Klebsiella pneumoniae
''Klebsiella pneumoniae'' is a Gram-negative, non-motile, encapsulated, lactose- fermenting, facultative anaerobic, rod-shaped bacterium. It appears as a mucoid lactose fermenter on MacConkey agar.
Although found in the normal flora of the mo ...
'' (which have an endotoxin
Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by a covalent bond, and are found in the outer m ...
on their surface that produces adverse biochemical, immunological and occasionally neurological effects which are harmful to the body), other Gram-positive
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall.
Gram-positive bact ...
cocci, such as pneumococci
''Streptococcus pneumoniae'', or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic (under aerobic conditions) or beta-hemolytic (under anaerobic conditions), aerotolerant anaerobic member of the genus Streptococcus. They are ...
and streptococci, and certain fungi as well as Gram-positive bacterial toxins
Microbial toxins are toxins produced by micro-organisms, including bacteria, fungi, protozoa, dinoflagellates, and viruses. Many microbial toxins promote infection and disease by directly damaging host tissues and by disabling the immune system. ...
. Septic shock also includes some elements of cardiogenic shock. In 1992, the ACCP/ SCCM Consensus Conference Committee defined septic shock: " ... sepsis-induced hypotension (systolic blood pressure < 90 mmHg or a reduction of 40 mmHg from baseline) despite adequate fluid resuscitation along with the presence of perfusion abnormalities that may include, but are not limited to: lactic acidosis
Lactic acidosis is a medical condition characterized by a build-up of lactate (especially -lactate) in the body, with formation of an excessively low pH in the bloodstream. It is a form of metabolic acidosis, in which excessive acid accumulates d ...
, oliguria, or an acute alteration in mental status. Patients who are receiving inotropic
An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction.
The term ''inotro ...
or vasopressor agents may have a normalized blood pressure at the time that perfusion abnormalities are identified. The pathophysiology behind septic shock is as follows: 1) Systemic leukocyte adhesion to endothelial cells 2) Reduced contractility of the heart 3) Activation of the coagulation pathway
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 ...
s, resulting in disseminated intravascular coagulation 4). Increased levels of neutrophils
**The main manifestations of septic shock are due to the massive release of histamine
Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discovered ...
which causes intense dilation of the blood vessels. People with septic shock will also likely be positive for SIRS criteria. The most generally accepted treatment for these patients is early recognition of symptoms, and early administration of broad spectrum and organism specific antibiotics.
**Signs of septic shock include:
*** Abnormal heart rhythms, often 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 ...
*** Reduced blood pressure
*** Decreased urine output
*** Altered mental status
* Anaphylactic shock is caused by a severe anaphylactic reaction
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follo ...
to an allergen
An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies.
In technical terms ...
, antigen
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune respons ...
, drug, or foreign protein causing the release of histamine
Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discovered ...
which causes widespread vasodilation, leading to hypotension and increased capillary 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 ...
.
Signs typically occur after exposure to an allergen and may include:
** Skin changes, such as hives, itching, flushing, and swelling.
** Wheezing and shortness of breath
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...
.
**Abdominal pain
Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues.
Common causes of pain in the abdomen include gastroenteritis and irritable bowel syndrome. About 15% of people have a m ...
, 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 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, gastroenteri ...
.
** Lightheadedness, confusion
In medicine, confusion is the quality or state of being bewildered or unclear. The term "acute mental confusion" , headaches, loss of consciousness
Loss may refer to:
Arts, entertainment, and media Music
* ''Loss'' (Bass Communion album) (2006)
* ''Loss'' (Mull Historical Society album) (2001)
*"Loss", a song by God Is an Astronaut from their self-titled album (2008)
* Losses "(Lil Tjay son ...
.
*High spinal injuries may cause neurogenic shock
Neurogenic shock is a distributive type of shock resulting in hypotension (low blood pressure), often with bradycardia (slowed heart rate), caused by disruption of autonomic nervous system pathways. It can occur after damage to the central nerv ...
, which is commonly classified as a subset of distributive shock. The classic symptoms include a slow heart rate due to loss of cardiac sympathetic tone and warm skin due to dilation of the peripheral blood vessels. (This term can be confused with spinal shock Spinal shock was first explored by Whytt in 1750 as a loss of sensation accompanied by motor paralysis with initial loss but gradual recovery of reflexes, following a spinal cord injury (SCI) – most often a complete transection. Reflexes in the sp ...
which is a recoverable loss of function of the spinal cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...
after injury and does not refer to the hemodynamic instability.)
Endocrine
Although not officially classified as a subcategory of shock, many endocrinology disturbances in their severe form can result in shock.
* Hypothyroidism (can be considered a form of cardiogenic shock) in people who are critically ill patients, reduces cardiac output and can lead to 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 dia ...
and respiratory insufficiency.
*Thyrotoxicosis
Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. ...
( cardiogenic shock) may induce a reversible cardiomyopathy.
*Acute adrenal insufficiency (distributive shock
Distributive shock is a medical condition in which abnormal distribution of blood flow in the smallest blood vessels results in inadequate supply of blood to the body's tissues and organs. It is one of four categories of shock, a condition wher ...
) is frequently the result of discontinuing corticosteroid treatment without tapering the dosage. However, surgery and intercurrent disease in patients on corticosteroid therapy without adjusting the dosage to accommodate for increased requirements may also result in this condition.
*Relative adrenal insufficiency (distributive shock
Distributive shock is a medical condition in which abnormal distribution of blood flow in the smallest blood vessels results in inadequate supply of blood to the body's tissues and organs. It is one of four categories of shock, a condition wher ...
) in critically ill patients where present hormone levels are insufficient to meet the higher demands.
Cause
Shock is a common end point of many medical conditions. Shock triggered by a serious allergic reaction
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...
is known as anaphylactic shock, shock triggered by 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 ...
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, v ...
is known as hypovolemic shock, shock caused by sepsis is known as septic shock, etc. Shock itself is a life-threatening condition as a result of compromised body circulation. It can be divided into four main types based on the underlying cause: hypovolemic, distributive, cardiogenic, and obstructive. A few additional classifications are occasionally used, such as endocrinologic shock.
Pathophysiology
There are four stages of shock. Shock is a complex and continuous condition, and there is no sudden transition from one stage to the next. At a cellular level, shock is the process of oxygen demand becoming greater than oxygen supply.[
One of the key dangers of shock is that it progresses by a ]positive feedback
Positive feedback (exacerbating feedback, self-reinforcing feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in th ...
loop. Poor blood supply leads to cellular damage, which results in an inflammatory response to increase blood flow to the affected area. Normally, this causes the blood supply level to match with tissue demand for nutrients. However, if there is enough increased demand in some areas, it can deprive other areas of sufficient supply, which then start demanding more. This then leads to an ever escalating cascade.
As such, shock is a runaway condition of homeostatic
In biology, homeostasis (British also homoeostasis) (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and ...
failure, where the usual corrective mechanisms relating to oxygenation of the body no longer function in a stable way. When it occurs, immediate treatment is critical in order to return an individual's metabolism into a stable, self-correcting trajectory. Otherwise the condition can become increasingly difficult to correct, surprisingly quickly, and then progress to a fatal outcome. In the particular case of anaphylactic shock, progression to death might take just a few minutes.[
]
Initial
During the Initial stage (Stage 1), the state of hypoperfusion causes hypoxia. Due to the lack of oxygen, the cells perform lactic acid fermentation
Lactic acid fermentation is a metabolic process by which glucose or other six-carbon sugars (also, disaccharides of six-carbon sugars, e.g. sucrose or lactose) are converted into cellular energy and the metabolite lactate, which is lactic acid i ...
. Since oxygen, the terminal electron acceptor in the electron transport chain, is not abundant, this slows down entry of pyruvate into the Krebs cycle
The citric acid cycle (CAC)—also known as the Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and protein ...
, resulting in its accumulation. The accumulating pyruvate is converted to lactate (lactic acid) by lactate dehydrogenase
Lactate dehydrogenase (LDH or LD) is an enzyme found in nearly all living cells. LDH catalyzes the conversion of lactate to pyruvate and back, as it converts NAD+ to NADH and back. A dehydrogenase is an enzyme that transfers a hydride from one ...
. The accumulating lactate causes lactic acidosis
Lactic acidosis is a medical condition characterized by a build-up of lactate (especially -lactate) in the body, with formation of an excessively low pH in the bloodstream. It is a form of metabolic acidosis, in which excessive acid accumulates d ...
.
Compensatory
The Compensatory stage (Stage 2) is characterised by the body employing physiological mechanisms, including neural, hormonal, and bio-chemical mechanisms, in an attempt to reverse the condition. As a result of the 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'' describes ...
, the person will begin to hyperventilate in order to rid the body of carbon dioxide (CO2). CO2 indirectly acts to acidify the blood, so the body attempts to return to acid–base homeostasis
Acid–base homeostasis is the homeostatic regulation of the pH of the body's extracellular fluid (ECF). The proper balance between the acids and bases (i.e. the pH) in the ECF is crucial for the normal physiology of the body—and for cellu ...
by removing that acidifying agent. The baroreceptors
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 ...
in the arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...
detect the 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 dia ...
resulting from large amounts of blood being redirected to distant tissues, and cause the release of epinephrine 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' ...
. Norepinephrine causes predominately 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 ...
with a mild increase in heart rate
Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
, whereas epinephrine predominately causes an increase in heart rate
Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
with a small effect on the vascular
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 f ...
tone; the combined effect results in an increase in blood pressure. The renin–angiotensin axis is activated, and arginine vasopressin
Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then trave ...
(anti-diuretic hormone) is released to conserve fluid by reducing its excretion via the renal
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; bloo ...
system. These hormones cause the vasoconstriction of 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, gastrointestinal tract, and other organs to divert blood to the heart, lungs
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side ...
and brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
. The lack of blood to the renal system causes the characteristic low urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
Cellular ...
production. However the effects of the renin–angiotensin axis take time and are of little importance to the immediate homeostatic
In biology, homeostasis (British also homoeostasis) (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and ...
mediation of shock.
Progressive/decompensated
The Progressive stage (stage 3) results if the underlying cause of the shock is not successfully treated. During this stage, compensatory mechanisms begin to fail. Due to the decreased perfusion of the cells in the 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 ...
ions build up within the intracellular space while potassium
Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosph ...
ions leak out. Due to lack of oxygen, cellular respiration
Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be des ...
diminishes and anaerobic metabolism
Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain.
In aerobic organisms undergoing r ...
predominates. As anaerobic metabolism continues, the arteriolar smooth muscle and precapillary sphincters
A sphincter is a circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. Sphincters are found in many animals. There are over 60 types in the hum ...
relax such that blood remains in the capillaries
A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...
. Due to this, the hydrostatic pressure
Fluid statics or hydrostatics is the branch of fluid mechanics that studies the condition of the equilibrium of a floating body and submerged body " fluids at hydrostatic equilibrium and the pressure in a fluid, or exerted by a fluid, on an imm ...
will increase and, combined with histamine
Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discovered ...
release, will lead to leakage of fluid and protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
into the surrounding tissues. As this fluid is lost, the blood concentration and viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the inte ...
increase, causing sludging of the micro-circulation. The prolonged vasoconstriction will also cause the vital organs to be compromised due to reduced perfusion.[ If the bowel becomes sufficiently ]ischemic
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 w ...
, bacteria may enter the blood stream, resulting in the increased complication of endotoxic shock.[
]
Refractory
At Refractory stage (stage 4), the vital organs have failed and the shock can no longer be reversed. Brain damage and cell death are occurring, and death will occur imminently. One of the primary reasons that shock is irreversible at this point is that much of the cellular ATP (the basic energy source for cells) has been degraded into adenosine in the absence of oxygen as an electron receptor in the mitochondrial matrix
In the mitochondrion, the matrix is the space within the inner membrane. The word "matrix" stems from the fact that this space is viscous, compared to the relatively aqueous cytoplasm. The mitochondrial matrix contains the mitochondrial DNA, ribo ...
. Adenosine easily perfuses out of cellular membranes into extracellular fluid, furthering capillary vasodilation
Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstrictio ...
, and then is transformed into uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the metabolic breakdown ...
. Because cells can only produce adenosine at a rate of about 2% of the cell's total need per hour, even restoring oxygen is futile at this point because there is no adenosine to phosphorylate
In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, ...
into ATP.[
]
Diagnosis
The diagnosis of shock is commonly based on a combination of symptoms, physical examination
In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the pati ...
, and laboratory tests. Many signs and symptoms are not sensitive or specific for shock, thus many clinical decision-making tools have been developed to identify shock at an early stage. A high degree of suspicion is necessary for the proper diagnosis of shock.
The first change seen in shock is increased cardiac output followed by a decrease in mixed venous 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 ...
(SmvO2) as measured in the pulmonary artery
A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...
via a pulmonary artery catheter
A pulmonary artery catheter (PAC), also known as a Swan-Ganz catheter or right heart catheter, is a balloon-tipped catheter that is inserted into a pulmonary artery in a procedure known as pulmonary artery catheterization or right heart cathet ...
. Central venous oxygen saturation (ScvO2) as measured via a central line correlates well with SmvO2 and are easier to acquire. If shock progresses anaerobic metabolism
Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain.
In aerobic organisms undergoing r ...
will begin to occur with an increased blood 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 ...
as the result. While many laboratory tests are typically performed, there is no test that either conclusively makes or excludes the diagnosis. A chest X-ray or emergency department ultrasound may be useful to determine volume status.
Management
The best evidence exists for the treatment of septic shock in adults. However, the pathophysiology of shock in children appears to be similar so treatment methodologies have been extrapolated to children.[ Management may include securing the airway via ]intubation
Intubation (sometimes entubation) is a medical procedure involving the insertion of a tube into the body. Patients are generally anesthetized beforehand. Examples include tracheal intubation, and the balloon tamponade with a Sengstaken-Blake ...
if necessary to decrease the work of breathing and for guarding against respiratory arrest. Oxygen supplementation, intravenous fluids, passive leg raising (not Trendelenburg position
In the Trendelenburg position, the body is lain supine, or flat on the back on a 15–30 degree incline with the feet elevated above the head. The reverse Trendelenburg position, similarly, places the body supine on an incline but with the head ...
) should be started and blood transfusions
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 mod ...
added if blood loss is severe.[ In select cases, compression devices like ]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 ...
s (or the deprecated military anti-shock trousers Military anti-shock trousers (MAST), or pneumatic anti-shock garments (PASG), are medical devices used to treat severe blood loss. The device is usually applied to the patient's pelvis, abdomen, and lower parts of the body and is composed of man- ...
) can be used to prevent further blood loss and concentrate fluid in the body's head and core. It is important to keep the person warm to avoid 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 ...
as well as adequately manage pain and anxiety as these can increase oxygen consumption.[ Negative impact by shock is reversible if it's recognized and treated early in time.]
Fluids
Aggressive intravenous fluids are recommended in most types of shock (e.g. 1–2 liter normal saline
Saline (also known as saline solution) is a mixture of sodium chloride (salt) and water. It has a number of uses in medicine including cleaning wounds, removal and storage of contact lenses, and help with dry eyes. By injection into a vein i ...
bolus over 10 minutes or 20 mL/kg in a child) which is usually instituted as the person is being further evaluated. Colloids
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 ...
and crystalloids
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 ...
appear to be equally effective with respect to outcomes., Balanced crystalloids and normal saline also appear to be equally effective in critically ill patients. If the person remains in shock after initial resuscitation, packed red blood cells
Packed red blood cells, also known as packed cells, are red blood cells that have been separated for blood transfusion. The packed cells are typically used in anemia that is either causing symptoms or when the hemoglobin is less than usually 70 ...
should be administered to keep the 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 (erythrocyt ...
greater than 100 g/L.[
For those with hemorrhagic shock, the current evidence supports limiting the use of fluids for penetrating thorax and abdominal injuries allowing mild ]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 dia ...
to persist (known as 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 ...
). Targets include a mean arterial pressure
In medicine, the mean arterial pressure (MAP) is an average blood pressure in an individual during a single cardiac cycle. MAP is altered by cardiac output and systemic vascular resistance.
Testing
Mean arterial pressure can be measured dire ...
of 60 mmHg, a systolic 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" r ...
of 70–90 mmHg,[ or until the patient has adequate mentation and peripheral pulses.] Hypertonic fluid
In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane- ...
may also be an option in this group.
Medications
Vasopressors
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 in ...
may be used if blood pressure does not improve with fluids. Common vasopressors used in shock include: 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' ...
, phenylephrine
Phenylephrine is a medication primarily used as a decongestant, to dilate the pupil, to increase blood pressure, and to relieve hemorrhoids. In the United States, it was previously used orally as an over-the-counter decongestant to relieve nas ...
, dopamine, and dobutamine
Dobutamine is a medication used in the treatment of cardiogenic shock (as a result of inadequate tissue perfusion) and severe heart failure. It may also be used in certain types of cardiac stress tests. It is given by IV only, as an injection in ...
.
There is no evidence of substantial benefit of one vasopressor over another; however, using dopamine leads to an increased risk of arrhythmia when compared with norepinephrine. Vasopressors have not been found to improve outcomes when used for hemorrhagic 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 m ...
from 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 i ...
but may be of use in neurogenic shock
Neurogenic shock is a distributive type of shock resulting in hypotension (low blood pressure), often with bradycardia (slowed heart rate), caused by disruption of autonomic nervous system pathways. It can occur after damage to the central nerv ...
. Activated protein C
Protein C, also known as autoprothrombin IIA and blood coagulation factor XIX, is a zymogen, that is, an inactive enzyme. The activated form plays an important role in regulating anticoagulation, inflammation, and cell death and maintaini ...
(Xigris), while once aggressively promoted for the management of septic shock, has been found not to improve survival and is associated with a number of complications. Activated protein C was withdrawn from the market in 2011, and clinical trials were discontinued. The use of sodium bicarbonate is controversial as it has not been shown to improve outcomes. If used at all it should only be considered if the blood pH is less than 7.0.
People with anaphylactic shock are commonly treated with epinephrine. Antihistamine
Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provid ...
s, such as Benadryl
Benadryl is a brand of various antihistamine medications used to stop allergies, whose content varies in different countries, but which includes some combination of diphenhydramine, acrivastine, and/or cetirizine.
It is sold by Johnson & Joh ...
(diphenhydramine
Diphenhydramine (DPH) is an antihistamine and sedative mainly used to treat allergies, insomnia, and symptoms of the common cold. It is also less commonly used for tremor in parkinsonism, and nausea. It is taken by mouth, injected into ...
) or ranitidine
Ranitidine, sold under the brand name Zantac among others, is a medication used to decrease stomach acid production. It is commonly used in treatment of peptic ulcer disease, gastroesophageal reflux disease, and Zollinger–Ellison syndrome ...
are also commonly administered. Albuterol
Salbutamol, also known as albuterol and sold under the brand name Ventolin among others, is a medication that opens up the medium and large airways in the lungs. It is a short-acting β2 adrenergic receptor agonist which works by causing rel ...
, normal saline, and steroids are also commonly given.
Mechanical support
*Intra-aortic balloon pump
The intra-aortic balloon pump (IABP) is a mechanical device that increases myocardial oxygen perfusion and indirectly increases cardiac output through afterload reduction. It consists of a cylindrical polyurethane balloon that sits in the aorta ...
(IABP) – a device inserted into the aorta that mechanically raises the blood pressure. Use of Intra-aortic balloon pumps is not recommended in cardiogenic shock.
*Ventricular assist device
A ventricular assist device (VAD) is an electromechanical device for assisting cardiac circulation, which is used either to partially or to completely replace the function of a failing heart. The function of a VAD differs from that of an artific ...
(VAD) – A mechanical pump that helps pump blood throughout the body. Commonly used in short term cases of refractory primary cardiogenic shock.
*Artificial heart
An artificial heart is a device that replaces the heart. Artificial hearts are typically used to bridge the time to heart transplantation, or to permanently replace the heart in the case that a heart transplant (from a deceased human or, exper ...
(TAH)
* Extracorporeal membrane oxygenation (ECMO) – an external device that completely replaces the work of the heart.
Treatment goals
The goal of treatment is to achieve a urine output of greater than 0.5 mL/kg/h, a 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 ...
of 8–12 mmHg and a mean arterial pressure
In medicine, the mean arterial pressure (MAP) is an average blood pressure in an individual during a single cardiac cycle. MAP is altered by cardiac output and systemic vascular resistance.
Testing
Mean arterial pressure can be measured dire ...
of 65–95 mmHg. In trauma the goal is to stop the bleeding which in many cases requires surgical interventions. A good urine output indicates that the kidneys are getting enough blood flow.
Epidemiology
Septic shock (a form of distributive shock), is the most common form of shock. Shock from blood loss occurs in about 1–2% of trauma cases.[ Overall, up to one-third of people admitted to 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 ...
(ICU) are in circulatory shock. Of these, cardiogenic shock accounts for approximately 20%, hypovolemic about 20%, and septic shock about 60% of cases.
Prognosis
The prognosis of shock depends on the underlying cause and the nature and extent of concurrent problems. Low volume, anaphylactic, and neurogenic shock are readily treatable and respond well to medical therapy. Septic shock, especially septic shock where treatment is delayed or the antimicrobial drugs are ineffective, however has a mortality rate between 30% and 80%; cardiogenic shock has a mortality rate of up to 70% to 90%, though quick treatment with vasopressors and inotropic drugs, cardiac surgery, and the use of assistive devices can lower the mortality.
History
There is no evidence of the word shock being used in its modern-day form prior to 1743. However, there is evidence that Hippocrates
Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history o ...
used the word ''exemia'' to signify a state of being "drained of blood". Shock or "choc" was first described in a trauma victim in the English translation of Henri-François LeDran's 1740 text, Traité ou Reflexions Tire'es de la Pratique sur les Playes d'armes à feu (A treatise, or reflections, drawn from practice on gun-shot wounds.) In this text he describes "choc" as a reaction to the sudden impact of a missile. However, the first English writer to use the word shock in its modern-day connotation was James Latta, in 1795.
Prior to World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, there were several competing hypotheses behind the pathophysiology of shock. Of the various theories, the most well regarded was a theory penned by George W. Crile who suggested in his 1899 monograph, "''An Experimental Research into Surgical Shock"'', that shock was quintessentially defined as a state of circulatory collapse (vasodilation
Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstrictio ...
) due to excessive nervous stimulation. Other competing theories around the turn of the century included one penned by Malcom in 1907, in which the assertion was that prolonged vasoconstriction led to the pathophysiological signs and symptoms of shock. In the following World War I, research concerning shock resulted in experiments by Walter B. Cannon of Harvard and William M. Bayliss of London in 1919 that showed that an increase in permeability of the capillaries in response to trauma or toxins was responsible for many clinical manifestations of shock. In 1972 Hinshaw and Cox suggested the classification system for shock which is still used today.
References
External links
{{DEFAULTSORT:Shock (Circulatory)
Intensive care medicine
Medical emergencies
Causes of death
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