Systemic inflammatory response syndrome
Encyclopedia
Systemic inflammatory response syndrome (SIRS) is an inflammatory state
affecting the whole body, frequently a response of the immune system
to infection
, but not necessarily so. It is related to sepsis
, a condition in which individuals both meet criteria for SIRS and have a known or highly suspected infection.
, in which there is abnormal regulation of various cytokine
s. SIRS is also closely related to sepsis
, in which patients satisfy criteria for SIRS and have a suspected or proven infection.
deposition, platelet aggregation, coagulopathies
and leukocyte liposomal release
. The implication of such a definition suggests that recognition of the activation of one such pathway is often indicative of that additional pathophysiologic processes are also active and that these pathways are synergistically destructive. The clinical condition may lead to renal failure
, respiratory distress syndrome
, central nervous system
dysfunction and possible gastrointestinal bleeding
.
Criteria for SIRS were established in 1992 as part of the American College of Chest Physicians
/Society of Critical Care Medicine
Consensus Conference. The conference concluded that the manifestations of SIRS include, but are not limited to:
SIRS can be diagnosed when two or more of these criteria are present.
The International Pediatric Sepsis Consensus has proposed some changes to adapt these criteria to the pediatric population.
Fever and leukocytosis
are features of the acute-phase reaction, while tachycardia
is often the initial sign of hemodynamic compromise. Tachypnea
may be related to the increased metabolic stress due to infection and inflammation, but may also be an ominous sign of inadequate perfusion
resulting in the onset of anaerobic cellular metabolism.
In children, the SIRS criteria are modified in the following fashion:
Note that SIRS criteria are very non-specific, and must be interpreted carefully within the clinical context. These criteria exist primarily for the purpose of more objectively classifying critically ill patients so that future clinical studies may be more rigorous and more easily reproducible.
As an alternative, when two or more of the systemic inflammatory response syndrome criteria are met without evidence of infection, patients may be diagnosed simply with "SIRS." Patients with SIRS and acute organ dysfunction may be termed "severe SIRS."
. Noninfectious causes of SIRS include trauma
, burns
, pancreatitis
, ischemia
, and hemorrhage.
Other causes include:
Selenium
, glutamine
, and eicosapentaenoic acid
have shown effectiveness in improving symptoms in clinical trials. Other antioxidants such as vitamin E
may be helpful as well.
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
affecting the whole body, frequently a response of the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
to infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
, but not necessarily so. It is related to sepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
, a condition in which individuals both meet criteria for SIRS and have a known or highly suspected infection.
Classification
SIRS is a serious condition related to systemic inflammation, organ dysfunction, and organ failure. It is a subset of cytokine stormCytokine storm
A cytokine storm, or hypercytokinemia is a potentially fatal immune reaction consisting of a positive feedback loop between cytokines and immune cells, with highly elevated levels of various cytokines.-Symptoms:...
, in which there is abnormal regulation of various cytokine
Cytokine
Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
s. SIRS is also closely related to sepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
, in which patients satisfy criteria for SIRS and have a suspected or proven infection.
Definition
SIRS was first described by Dr. William R. Nelson, of the University of Toronto, in a presentation to the Nordic Micro Circulation meeting in Geilo, Norway in February 1983. There was intent to encourage a definition which dealt with the multiple (rather than a single) etiologies associated with organ dysfunction and failure following a hypotensive shock episode. The active pathways leading to such pathophysiology may include fibrinFibrin
Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....
deposition, platelet aggregation, coagulopathies
Coagulopathy
Coagulopathy is a condition in which the blood’s ability to clot is impaired. This condition can cause prolonged or excessive bleeding, which may occur spontaneously or following an injury or medical and dental procedures.The normal clotting process depends on the interplay of various proteins in...
and leukocyte liposomal release
Leukemoid reaction
The term leukemoid reaction describes an elevated white blood cell count, or leukocytosis, that is a physiological response to stress or infection .It may be lymphoid or myeloid....
. The implication of such a definition suggests that recognition of the activation of one such pathway is often indicative of that additional pathophysiologic processes are also active and that these pathways are synergistically destructive. The clinical condition may lead to renal failure
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
, respiratory distress syndrome
Acute respiratory distress syndrome
Acute respiratory distress syndrome , also known as respiratory distress syndrome or adult respiratory distress syndrome is a serious reaction to various forms of injuries to the lung....
, central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
dysfunction and possible gastrointestinal bleeding
Gastrointestinal bleeding
Gastrointestinal bleeding or gastrointestinal hemorrhage describes every form of hemorrhage in the gastrointestinal tract, from the pharynx to the rectum. It has diverse causes, and a medical history, as well as physical examination, generally distinguishes between the main forms...
.
Criteria for SIRS were established in 1992 as part of the American College of Chest Physicians
American College of Chest Physicians
The American College of Chest Physicians is a medical organization in the United States consisting of physicians and non-physician specialists in the field of chest medicine, which includes pulmonology, thoracic surgery, and critical care medicine....
/Society of Critical Care Medicine
Society of Critical Care Medicine
Society of Critical Care Medicine , established in 1970, is an independently incorporated, international, educational and scientific society, serving its 15,000 members world-wide who are dedicated to providing the highest quality care to all critically ill and injured patients...
Consensus Conference. The conference concluded that the manifestations of SIRS include, but are not limited to:
- Body temperatureNormal human body temperatureNormal human body temperature, also known as normothermia or euthermia, is a concept that depends upon the place in the body at which the measurement is made, and the time of day and level of activity of the person...
less than 36°C or greater than 38°C - Heart rateHeart rateHeart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....
greater than 90 beats per minute - TachypneaTachypneaTachypnea means rapid breathing. Any rate between 12-20 breaths per minute is normal. Tachypnea is a respiration rate greater than 20 breaths per minute. - Distinction from other breathing terms :...
(high respiratory rate), with greater than 20 breaths per minute; or, an arterial partial pressurePartial pressureIn a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
of carbon dioxideCarbon dioxideCarbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
less than 4.3 kPa (32 mmHg) - White blood cell count less than 4000 cells/mm³ (4 x 109 cells/L) or greater than 12,000 cells/mm³ (12 x 109 cells/L); or the presence of greater than 10% immature neutrophils (band forms)
SIRS can be diagnosed when two or more of these criteria are present.
The International Pediatric Sepsis Consensus has proposed some changes to adapt these criteria to the pediatric population.
Fever and leukocytosis
Leukocytosis
Leukocytosis is a raised white blood cell count above the normal range in the blood. It is frequently a sign of an inflammatory response, most commonly the result of infection, and is observed in certain parasitic infections...
are features of the acute-phase reaction, while tachycardia
Tachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
is often the initial sign of hemodynamic compromise. Tachypnea
Tachypnea
Tachypnea means rapid breathing. Any rate between 12-20 breaths per minute is normal. Tachypnea is a respiration rate greater than 20 breaths per minute. - Distinction from other breathing terms :...
may be related to the increased metabolic stress due to infection and inflammation, but may also be an ominous sign of inadequate perfusion
Perfusion
In physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue. The word is derived from the French verb "perfuser" meaning to "pour over or through."...
resulting in the onset of anaerobic cellular metabolism.
In children, the SIRS criteria are modified in the following fashion:
- Heart rateHeart rateHeart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....
is greater than 2 standard deviations above normal for age in the absence of stimuli such as pain and drug administration, or unexplained persistent elevation for greater than 30 minutes to 4 hours. In infants, also includes Heart rateHeart rateHeart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....
less than 10th percentile for age in the absence of vagal stimuli, beta-blockers, or congenital heart disease or unexplained persistent depression for greater than 30 minutes. - Body temperature obtained orally, rectally, from Foley catheterFoley catheterA Foley catheter is a flexible tube that is often passed through the urethra and into the bladder. The tube has two separated channels, or lumens, running down its length. One lumen is open at both ends, and allows urine to drain out into a collection bag...
probe, or from central venous catheterCentral venous catheterIn medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...
probe less than 36 °C or greater than 38.5 °C. Temperature must be abnormal to qualify as SIRS in pediatric patients. - Respiratory rateRespiratory rateRespiratory rate is also known by respiration rate, pulmonary ventilation rate, ventilation rate, or breathing frequency is the number of breaths taken within a set amount of time, typically 60 seconds....
greater than 2 standard deviations above normal for age or the requirement for mechanical ventilationMechanical ventilationIn medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
not related to neuromuscular disease or the administration of anesthesiaAnesthesiaAnesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
. - White blood cellWhite blood cellWhite blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
count elevated or depressed for age not related to chemotherapy, or greater than 10% bands plus other immature forms.
Note that SIRS criteria are very non-specific, and must be interpreted carefully within the clinical context. These criteria exist primarily for the purpose of more objectively classifying critically ill patients so that future clinical studies may be more rigorous and more easily reproducible.
As an alternative, when two or more of the systemic inflammatory response syndrome criteria are met without evidence of infection, patients may be diagnosed simply with "SIRS." Patients with SIRS and acute organ dysfunction may be termed "severe SIRS."
Causes
The causes of SIRS are broadly classified as infectious or noninfectious. As above, when SIRS is due to an infection, it is considered sepsisSepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
. Noninfectious causes of SIRS include trauma
Physical trauma
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
, burns
Burn (injury)
A burn is a type of injury to flesh caused by heat, electricity, chemicals, light, radiation or friction. Most burns affect only the skin . Rarely, deeper tissues, such as muscle, bone, and blood vessels can also be injured...
, pancreatitis
Pancreatitis
Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...
, ischemia
Ischemia
In medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
, and hemorrhage.
Other causes include:
- Complications of surgery
- Adrenal insufficiencyAdrenal insufficiencyAdrenal insufficiency is a condition in which the adrenal glands, located above the kidneys, do not produce adequate amounts of steroid hormones , primarily cortisol, but may also include impaired aldosterone production which regulates sodium, potassium and water retention...
- Pulmonary embolismPulmonary embolismPulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...
- Complicated aortic aneurysmAortic aneurysmAn aortic aneurysm is a general term for any swelling of the aorta to greater than 1.5 times normal, usually representing an underlying weakness in the wall of the aorta at that location...
- Cardiac tamponadeCardiac tamponadeCardiac tamponade, also known as pericardial tamponade, is an emergency condition in which fluid accumulates in the pericardium ....
- AnaphylaxisAnaphylaxisAnaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...
- Drug overdose
Treatment
Generally, the treatment for SIRS is directed towards the underlying problem or inciting cause (i.e. adequate fluid replacement for hypovolemia, IVF/NPO for pancreatitis, epinephrine/steroids/benadryl for anaphylaxis).http://emedicine.medscape.com/article/168943-treatmentSelenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
, glutamine
Glutamine
Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...
, and eicosapentaenoic acid
Eicosapentaenoic acid
Eicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...
have shown effectiveness in improving symptoms in clinical trials. Other antioxidants such as vitamin E
Vitamin E
Vitamin E is used to refer to a group of fat-soluble compounds that include both tocopherols and tocotrienols. There are many different forms of vitamin E, of which γ-tocopherol is the most common in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine and dressings...
may be helpful as well.
Complications
SIRS is frequently complicated by failure of one or more organs or organ systems. The complications of SIRS include:- Acute lung injuryAcute lung injuryAcute lung injury is a diffuse heterogeneous lung injury characterized by hypoxemia, non cardiogenic pulmonary edema, low lung compliance and widespread capillary leakage...
- Acute kidney injury
- Shock
- Multiple organ dysfunction syndromeMultiple organ dysfunction syndromeMultiple organ dysfunction syndrome ', previously known as multiple organ failure or multisystem organ failure , is altered organ function in an acutely ill patient requiring medical intervention to achieve homeostasis...