Croup
Encyclopedia
Croup is a respiratory condition that is usually triggered by an acute viral infection of the upper airway. The infection leads to swelling inside the throat, which interferes with normal breathing and produces the classical symptoms of a "barking" cough
, stridor
, and hoarseness. It may produce mild, moderate, or severe symptoms, which often worsen at night. It is often treated with a single dose of oral steroids; occasionally epinephrine
is used in more severe cases. Hospitalization is rarely required.
Croup is diagnosed on clinical grounds, once potentially more severe causes of symptoms have been excluded (i.e. epiglottitis
or an airway foreign body). Further investigations—such as blood tests, X-rays, and cultures—are usually not needed. It is a relatively common condition that affects about 15% of children at some point, most commonly between 6 months and 5–6 years of age. It is almost never seen in teenagers or adults.
Once due primarily to diphtheria
, this cause is now primarily of historical significance in the Western world due to the success of vaccination
, and improved hygiene and living standards.
, stridor
, hoarseness, and difficult breathing
which usually worsens at night. The "barking" cough is often described as resembling the call of a seal
or sea lion
. The stridor is worsened by agitation or crying
, and if it can be heard at rest, it may indicate critical narrowing of the airways. As croup worsens, stridor may decrease considerably.
Other symptoms include fever
, coryza
(symptoms typical of the common cold
), and chest wall indrawing. Drooling
or a very sick appearance indicate other medical conditions.
A and B, measles
, adenovirus and respiratory syncytial virus (RSV). Spasmodic croup is caused by the same group of viruses as acute laryngotracheitis, but lacks the usual signs of infection (such as fever, sore throat, and increased white blood cell count). Treatment, and response to treatment, are also similar.
while bacterial tracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis are usually due to a primary viral infection with secondary bacterial growth. The most common bacteria implicated are Staphylococcus aureus
, Streptococcus pneumoniae
, Hemophilus influenzae, and Moraxella catarrhalis
.
, trachea
, and large bronchi due to infiltration of white blood cells (especially histiocytes, lymphocytes, plasma cells, and neutrophils). Swelling produces airway obstruction which, when significant, leads to dramatically increased work of breathing and the characteristic turbulent, noisy airflow known as stridor.
Croup is a clinical diagnosis. The first step is to exclude other obstructive conditions of the upper airway, especially epiglottitis
, an airway foreign body
, subglottic stenosis
, angioedema
, retropharyngeal abscess
, and bacterial tracheitis.
A frontal X-ray
of the neck is not routinely performed, but if it is done, it may show a characteristic narrowing of the trachea, called the steeple sign
. The steeple sign is suggestive of the diagnosis, but is absent in half of cases.
Other investigations (such as blood test
s and viral culture
) are discouraged, as they may cause unnecessary agitation and thus worsen the stress on the compromised airway. While viral cultures, obtained via nasopharyngeal aspiration, can be used to confirm the exact cause, these are usually restricted to research settings. Bacterial infection should be considered if a person does not improve with standard treatment, at which point further investigations may be indicated.
Severity
The most commonly used system for classifying the severity of croup is the Westley score. It is primarily used for research purposes rather than in clinical practice. It is the sum of points assigned for five factors: level of consciousness, cyanosis, stridor, air entry, and retractions. The points given for each factor is listed in the table to the right, and the final score ranges from 0 to 17.
85% of children presenting to the emergency department have mild disease; severe croup is rare (<1%).
for influenza
and diphtheria
. At one time, croup referred to a diphtherial disease, but with vaccination, diphtheria is now rare in the developed world.
s under 92% should receive oxygen, and those with severe croup may be hospitalized for observation. If oxygen is needed, "blow-by" administration (holding an oxygen source near the child's face) is recommended, as it causes less agitation than use of a mask
. With treatment, less than 0.2% of people require endotracheal intubation.
and budesonide
, have been shown to improve outcomes in children with all severities of croup. Significant relief is obtained as early as six hours after administration. While effective when given orally, parenteral
ly, or by inhalation, the oral route is preferred. A single dose is usually all that is required, and is generally considered to be quite safe. Dexamethasone at doses of 0.15, 0.3 and 0.6 mg/kg appear to be all equally effective.
epinephrine
. While epinephrine typically produces a reduction in croup severity within 10–30 minutes, the benefits last for only about 2 hours. If the condition remains improved for 2–4 hours after treatment and no other complications arise, the child is typically discharged from the hospital.
treatment, but clinical studies have failed to show effectiveness and currently it is rarely used. The use of cough medicine
s, which usually contain dextromethorphan
and/or guiafenesin, are also discouraged. While breathing heliox
(a mixture of helium
and oxygen
) to decrease the work of breathing has been used in the past, there is very little evidence to support its use. Since croup is usually a viral disease, antibiotics are not used unless secondary bacterial infection is suspected. In cases of possible secondary bacterial infection, the antibiotics vancomycin
and cefotaxime
are recommended. In severe cases associated with influenza A or B, the antiviral
neuraminidase inhibitors may be administered.
disease, but can very rarely result in death from respiratory failure
and/or cardiac arrest
. Symptoms usually improve within two days, but may last for up to seven days. Other uncommon complications include bacterial tracheitis, pneumonia
, and pulmonary edema
.
in autumn (fall).
verb croup, meaning "to cry hoarsely"; the name was first applied to the disease in Scotland and popularized in the 18th century. Diphtheritic croup has been known since the time of Homer
's Ancient Greece
and it was not until 1826 that viral croup was differentiated from croup due to diphtheria
by Bretonneau. Viral croup was thus called "faux-croup" by the French, as "croup" then referred to a disease caused by the diphtheria bacteria. Croup due to diphtheria has become nearly unknown due to the advent of effective immunization
.
Cough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
, stridor
Stridor
Stridor is a high pitched wheezing sound resulting from turbulent air flow in the upper airway. Stridor is a physical sign which is produced by narrow or obstructed airway path. It can be inspiratory, expiratory or biphasic . Inspiratory stridor is common...
, and hoarseness. It may produce mild, moderate, or severe symptoms, which often worsen at night. It is often treated with a single dose of oral steroids; occasionally epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
is used in more severe cases. Hospitalization is rarely required.
Croup is diagnosed on clinical grounds, once potentially more severe causes of symptoms have been excluded (i.e. epiglottitis
Epiglottitis
Epiglottitis is an inflammation of the epiglottis - the flap that sits at the base of the tongue, which keeps food from going into the trachea . Due to its place in the airway, swelling of this structure can interfere with breathing and constitutes a medical emergency...
or an airway foreign body). Further investigations—such as blood tests, X-rays, and cultures—are usually not needed. It is a relatively common condition that affects about 15% of children at some point, most commonly between 6 months and 5–6 years of age. It is almost never seen in teenagers or adults.
Once due primarily to diphtheria
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
, this cause is now primarily of historical significance in the Western world due to the success of vaccination
Vaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
, and improved hygiene and living standards.
Signs and symptoms
Croup is characterized by a "barking" coughCough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
, stridor
Stridor
Stridor is a high pitched wheezing sound resulting from turbulent air flow in the upper airway. Stridor is a physical sign which is produced by narrow or obstructed airway path. It can be inspiratory, expiratory or biphasic . Inspiratory stridor is common...
, hoarseness, and difficult breathing
Respiratory distress
Respiratory distress may refer to either/both:* Labored breathing, the physical presentation of respiratory distress*Shortness of breath or dyspnea - a sensation of respiratory distress-See also:*List of terms of lung size and activity...
which usually worsens at night. The "barking" cough is often described as resembling the call of a seal
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
or sea lion
Sea Lion
Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...
. The stridor is worsened by agitation or crying
Crying
Crying is shedding tears as a response to an emotional state in humans. The act of crying has been defined as "a complex secretomotor phenomenon characterized by the shedding of tears from the lacrimal apparatus, without any irritation of the ocular structures"...
, and if it can be heard at rest, it may indicate critical narrowing of the airways. As croup worsens, stridor may decrease considerably.
Other symptoms include fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, coryza
Coryza
Coryza is a word describing the symptoms of a head cold. It describes the inflammation of the mucous membranes lining the nasal cavity which usually gives rise to the symptoms of nasal congestion and loss of smell, among other symptoms...
(symptoms typical of the common cold
Common cold
The common cold is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever...
), and chest wall indrawing. Drooling
Drooling
Drooling is when saliva flows outside the mouth...
or a very sick appearance indicate other medical conditions.
Causes
Croup is usually deemed to be due to a viral infection. Others use the term more broadly, to include acute laryngotracheitis, spasmodic croup, laryngeal diphtheria, bacterial tracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis. The first two conditions involve a viral infection and are generally milder with respect to symptomatology; the last four are due to bacterial infection and are usually of greater severity.Viral
Viral croup/acute laryngotracheitis is caused by parainfluenza virus, primarily types 1 and 2, in 75% of cases. Other viral etiologies include influenzaInfluenza
Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals...
A and B, measles
Measles
Measles, also known as rubeola or morbilli, is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses...
, adenovirus and respiratory syncytial virus (RSV). Spasmodic croup is caused by the same group of viruses as acute laryngotracheitis, but lacks the usual signs of infection (such as fever, sore throat, and increased white blood cell count). Treatment, and response to treatment, are also similar.
Bacterial
Bacterial croup may be divided into laryngeal diphtheria, bacterial tracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis. Laryngeal diphtheria is due to Corynebacterium diphtheriaeCorynebacterium diphtheriae
Corynebacterium diphtheriae is a pathogenic bacterium that causes diphtheria. It is also known as the Klebs-Löffler bacillus, because it was discovered in 1884 by German bacteriologists Edwin Klebs and Friedrich Löffler .-Classification:Four subspecies are recognized: C. diphtheriae mitis, C....
while bacterial tracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis are usually due to a primary viral infection with secondary bacterial growth. The most common bacteria implicated are Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
, Streptococcus pneumoniae
Streptococcus pneumoniae
Streptococcus pneumoniae, or pneumococcus, is Gram-positive, alpha-hemolytic, aerotolerant anaerobic member of the genus Streptococcus. A significant human pathogenic bacterium, S...
, Hemophilus influenzae, and Moraxella catarrhalis
Moraxella catarrhalis
Moraxella catarrhalis is a fastidious, nonmotile, Gram-negative, aerobic, oxidase-positive diplococcus that can cause infections of the respiratory system, middle ear, eye, central nervous system and joints of humans.-History:...
.
Pathophysiology
The viral infection that causes croup leads to swelling of the larynxLarynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
, trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
, and large bronchi due to infiltration of white blood cells (especially histiocytes, lymphocytes, plasma cells, and neutrophils). Swelling produces airway obstruction which, when significant, leads to dramatically increased work of breathing and the characteristic turbulent, noisy airflow known as stridor.
Diagnosis
| Feature | Number of points assigned for this feature | |||||
|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | |
| Chest wall retraction |
None | Mild | Moderate | Severe | ||
| Stridor Stridor Stridor is a high pitched wheezing sound resulting from turbulent air flow in the upper airway. Stridor is a physical sign which is produced by narrow or obstructed airway path. It can be inspiratory, expiratory or biphasic . Inspiratory stridor is common... |
None | With agitation |
At rest | |||
| Cyanosis Cyanosis Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is... |
None | With agitation |
At rest | |||
| Level of consciousness |
Normal | Disoriented | ||||
| Air entry | Normal | Decreased | Markedly decreased | |||
Croup is a clinical diagnosis. The first step is to exclude other obstructive conditions of the upper airway, especially epiglottitis
Epiglottitis
Epiglottitis is an inflammation of the epiglottis - the flap that sits at the base of the tongue, which keeps food from going into the trachea . Due to its place in the airway, swelling of this structure can interfere with breathing and constitutes a medical emergency...
, an airway foreign body
Foreign body
A foreign body is any object originating outside the body. In machinery, it can mean any unwanted intruding object.Most references to foreign bodies involve propulsion through natural orifices into hollow organs....
, subglottic stenosis
Subglottic stenosis
Subglottic stenosis is a congenital or acquired narrowing of the subglottic airway. Although it is relatively rare, it is the third most common congenital airway problem . Subglottic stenosis can present as a life-threatening airway emergency...
, angioedema
Angioedema
Angioedema or Quincke's edema is the rapid swelling of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis...
, retropharyngeal abscess
Retropharyngeal abscess
Most commonly seen in infants and young children, retropharyngeal abscess is an abscess located in the tissues in the back of the throat behind the posterior pharyngeal wall . Because RPA's typically occur in deep tissue, they are difficult to diagnose by physical examination alone...
, and bacterial tracheitis.
A frontal X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
of the neck is not routinely performed, but if it is done, it may show a characteristic narrowing of the trachea, called the steeple sign
Steeple sign
In radiology, the steeple sign is a sign on a frontal radiograph of tracheal narrowing and suggestive of the diagnosis of croup.In the figure you can see anteroposterior radiograph of the upper airway of a patient with croup. The subglottic tracheal narrowing produces an inverted V appearance known...
. The steeple sign is suggestive of the diagnosis, but is absent in half of cases.
Other investigations (such as blood test
Blood test
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick....
s and viral culture
Viral culture
Viral culture is a laboratory test in which samples are placed with a cell type that the virus being tested for is able to infect. If the cells show changes, known as cytopathic effects, then the culture is positive....
) are discouraged, as they may cause unnecessary agitation and thus worsen the stress on the compromised airway. While viral cultures, obtained via nasopharyngeal aspiration, can be used to confirm the exact cause, these are usually restricted to research settings. Bacterial infection should be considered if a person does not improve with standard treatment, at which point further investigations may be indicated.
Severity
The most commonly used system for classifying the severity of croup is the Westley score. It is primarily used for research purposes rather than in clinical practice. It is the sum of points assigned for five factors: level of consciousness, cyanosis, stridor, air entry, and retractions. The points given for each factor is listed in the table to the right, and the final score ranges from 0 to 17.
- A total score of ≤ 2 indicates mild croup. The characteristic barking cough and hoarseness may be present, but there is no stridor at rest.
- A total score of 3–5 is classified as moderate croup. It presents with easily heard stridor, but with few other signs.
- A total score of 6–11 is severe croup. It also presents with obvious stridor, but also features marked chest wall indrawing.
- A total score of ≥ 12 indicates impending respiratory failureRespiratory failureThe term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
. The barking cough and stridor may no longer be prominent at this stage.
85% of children presenting to the emergency department have mild disease; severe croup is rare (<1%).
Prevention
Many cases of croup have been prevented by immunizationImmunization
Immunization, or immunisation, is the process by which an individual's immune system becomes fortified against an agent ....
for influenza
Influenza
Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals...
and diphtheria
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
. At one time, croup referred to a diphtherial disease, but with vaccination, diphtheria is now rare in the developed world.
Treatment
Children with croup are generally kept as calm as possible. Steroids are given routinely, with epinephrine used in severe cases. Children with oxygen saturationOxygen saturation
Oxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...
s under 92% should receive oxygen, and those with severe croup may be hospitalized for observation. If oxygen is needed, "blow-by" administration (holding an oxygen source near the child's face) is recommended, as it causes less agitation than use of a mask
Oxygen mask
An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover the nose and mouth or the entire face...
. With treatment, less than 0.2% of people require endotracheal intubation.
Steroids
Corticosteroids, such as dexamethasoneDexamethasone
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...
and budesonide
Budesonide
Budesonide is a glucocorticoid steroid for the treatment of asthma and non-infectious rhinitis , and for treatment and prevention of nasal polyposis...
, have been shown to improve outcomes in children with all severities of croup. Significant relief is obtained as early as six hours after administration. While effective when given orally, parenteral
Parenteral
Parenteral is a route of administration that involves piercing the skin or mucous membrane. Parenteral nutrition refers to providing nutrition via the veins.-Etymology:...
ly, or by inhalation, the oral route is preferred. A single dose is usually all that is required, and is generally considered to be quite safe. Dexamethasone at doses of 0.15, 0.3 and 0.6 mg/kg appear to be all equally effective.
Epinephrine
Moderate to severe croup may be improved temporarily with nebulizedNebulizer
In medicine, a nebulizer is a device used to administer medication in the form of a mist inhaled into the lungs....
epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
. While epinephrine typically produces a reduction in croup severity within 10–30 minutes, the benefits last for only about 2 hours. If the condition remains improved for 2–4 hours after treatment and no other complications arise, the child is typically discharged from the hospital.
Other
While other treatments for croup have been studied, none have sufficient evidence to support their use. Inhalation of hot steam or humidified air is a traditional self-careSelf-care
Self care is personal health maintenance. It is any activity of an individual, family or community, with the intention of improving or restoring health, or treating or preventing disease....
treatment, but clinical studies have failed to show effectiveness and currently it is rarely used. The use of cough medicine
Cough medicine
A cough medicine is a medicinal drug used in an attempt to treat coughing and related conditions. For dry coughs, treatment with cough suppressants may be attempted to suppress the body's urge to cough...
s, which usually contain dextromethorphan
Dextromethorphan
Dextromethorphan is an antitussive drug. It is one of the active ingredients in many over-the-counter cold and cough medicines, such as Robitussin, NyQuil, Dimetapp, Vicks, Coricidin, Delsym, and others, including generic labels. Dextromethorphan has also found other uses in medicine, ranging...
and/or guiafenesin, are also discouraged. While breathing heliox
Heliox
Heliox is a breathing gas composed of a mixture of helium and oxygen .Heliox has been used medically since the 1930s, and although the medical community adopted it initially to alleviate symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, mostly because of...
(a mixture of helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
) to decrease the work of breathing has been used in the past, there is very little evidence to support its use. Since croup is usually a viral disease, antibiotics are not used unless secondary bacterial infection is suspected. In cases of possible secondary bacterial infection, the antibiotics vancomycin
Vancomycin
Vancomycin INN is a glycopeptide antibiotic used in the prophylaxis and treatment of infections caused by Gram-positive bacteria. It has traditionally been reserved as a drug of "last resort", used only after treatment with other antibiotics had failed, although the emergence of...
and cefotaxime
Cefotaxime
Cefotaxime is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram positive and Gram negative bacteria...
are recommended. In severe cases associated with influenza A or B, the antiviral
Antiviral
Antiviral may refer to:*Antiviral drug*Antiviral protein*Antivirus software*Antiviral Therapy, an academic journal...
neuraminidase inhibitors may be administered.
Prognosis
Viral croup is usually a self-limitedSelf-limiting (biology)
In biology, a self-limiting organism or colony of organisms limits its own growth by its actions. For example, a single organism may have a maximum size determined by genetics, or a colony of organisms may release waste which is ultimately toxic to the colony once it exceeds a certain population...
disease, but can very rarely result in death from respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
and/or cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
. Symptoms usually improve within two days, but may last for up to seven days. Other uncommon complications include bacterial tracheitis, pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
, and pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
.
Epidemiology
Croup affects about 15% of children, and usually presents between the ages of 6 months and 5–6 years. It accounts for about 5% of hospital admissions in this population. In rare cases, it may occur in children as young as 3 months and as old as 15 years. Males are affected 50% more frequently than are females, and there is an increased prevalencePrevalence
In epidemiology, the prevalence of a health-related state in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population...
in autumn (fall).
History
The word croup comes from the Early Modern EnglishEarly Modern English
Early Modern English is the stage of the English language used from about the end of the Middle English period to 1650. Thus, the first edition of the King James Bible and the works of William Shakespeare both belong to the late phase of Early Modern English...
verb croup, meaning "to cry hoarsely"; the name was first applied to the disease in Scotland and popularized in the 18th century. Diphtheritic croup has been known since the time of Homer
Homer
In the Western classical tradition Homer , is the author of the Iliad and the Odyssey, and is revered as the greatest ancient Greek epic poet. These epics lie at the beginning of the Western canon of literature, and have had an enormous influence on the history of literature.When he lived is...
's Ancient Greece
Ancient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...
and it was not until 1826 that viral croup was differentiated from croup due to diphtheria
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
by Bretonneau. Viral croup was thus called "faux-croup" by the French, as "croup" then referred to a disease caused by the diphtheria bacteria. Croup due to diphtheria has become nearly unknown due to the advent of effective immunization
Immunization
Immunization, or immunisation, is the process by which an individual's immune system becomes fortified against an agent ....
.