Croup

Croup (Template:IPAc-en Template:Respell), also known as croupy cough, is a type of respiratory infection that is usually caused by a virus.<ref name=Au10/> The infection leads to swelling inside the trachea, which interferes with normal breathing and produces the classic symptoms of "barking/brassy" cough, inspiratory stridor, and a hoarse voice.<ref name=Au10/> Fever and runny nose may also be present.<ref name=Au10>Template:Cite journal</ref> These symptoms may be mild, moderate, or severe.<ref name=Croup09>Template:Cite journal</ref> It often starts or is worse at night and normally lasts one to two days.<ref name=Thom2013>Template:Cite journal</ref><ref name=Au10/><ref name=Croup09/>

Croup can be caused by a number of viruses including parainfluenza and influenza virus.<ref name=Au10/> Rarely is it due to a bacterial infection.<ref name=Cherry08>Template:Cite journal</ref> Croup is typically diagnosed based on signs and symptoms after potentially more severe causes, such as epiglottitis or an airway foreign body, have been ruled out.<ref name=PedN09/> Further investigations, such as blood tests, X-rays and cultures, are usually not needed.<ref name=PedN09>Template:Cite journal</ref>

Many cases of croup are preventable by immunization for influenza and diphtheria.<ref name=Cherry08/> Most cases of croup are mild and the patient can be treated at home with supportive care. Croup is usually treated with a single dose of steroids by mouth.<ref name=Au10/><ref name="Gate2018">Template:Cite journal</ref> In more severe cases inhaled epinephrine may also be used.<ref name=Au10/><ref>Template:Cite journal</ref> Hospitalization is required in one to five percent of cases.<ref name=CMAJ2013>Template:Cite journal</ref>

Croup is a relatively common condition that affects about 15% of children at some point.<ref name=PedN09/> It most commonly occurs between six months and five years of age but may rarely be seen in children as old as fifteen.<ref name=Croup09/><ref name=PedN09/><ref name=CMAJ2013/> It is slightly more common in males than females.<ref name=CMAJ2013/> It occurs most often in autumn.<ref name=CMAJ2013/> Before vaccination, croup was frequently caused by diphtheria and was often fatal.<ref name=Cherry08/><ref>Template:Cite book</ref> This cause is now very rare in the Western world due to the success of the diphtheria vaccine.<ref name=history>Template:Cite book</ref>

Signs and symptoms

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Croup is characterized by a "barking" cough, stridor, hoarseness, and difficult breathing which usually worsens at night.<ref name=Au10/> The "barking" cough is often described as resembling the call of a sea lion.<ref name=Cherry08/> 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.<ref name=Au10/>

Other symptoms include fever, coryza (symptoms typical of the common cold), and indrawing of the chest wall–known as Hoover's sign.<ref name=Au10/><ref name=Alberta07>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Drooling or a very sick appearance can indicate other medical conditions, such as epiglottitis or tracheitis.<ref name=Alberta07/>

Causes

Croup is usually deemed to be due to a viral infection.<ref name=Au10/><ref name=PedN09/> Others use the term more broadly, to include acute laryngotracheitis (laryngitis and tracheitis together), 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.<ref name=Cherry08/>

Viral

Viral croup or acute laryngotracheitis is most commonly caused by parainfluenza virus (a member of the paramyxovirus family), primarily types 1 and 2, in 75% of cases.<ref name=Croup09/> Other viral causes include influenza A and B, measles, adenovirus and respiratory syncytial virus (RSV).<ref name=Cherry08/> 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).<ref name=Cherry08/> Treatment, and response to treatment, are also similar.<ref name=Croup09/>

Bacteria and cocci

Croup caused by a bacterial infection is rare.<ref name=":1" /> Bacterial croup may be divided into laryngeal diphtheria, bacterial tracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis.<ref name=Cherry08/> Laryngeal diphtheria is due to Corynebacterium diphtheriae while bacterial tracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis are usually due to a primary viral infection with secondary bacterial growth. The most common cocci implicated are Staphylococcus aureus and Streptococcus pneumoniae, while the most common bacteria are Haemophilus influenzae, and Moraxella catarrhalis.<ref name=Cherry08/>

Pathophysiology

The viral infection that causes croup leads to swelling of the larynx, trachea, and large bronchi<ref name=PedN09/> due to infiltration of white blood cells (especially histiocytes, lymphocytes, plasma cells, and neutrophils).<ref name=Cherry08/> Swelling produces airway obstruction which, when significant, leads to dramatically increased work of breathing and the characteristic turbulent, noisy airflow known as stridor.<ref name=PedN09/>

Diagnosis

Croup is typically diagnosed based on signs and symptoms.<ref name=PedN09/> 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.<ref name=PedN09/><ref name=Cherry08/>

A frontal X-ray of the neck is not routinely performed,<ref name=PedN09/> but if it is done, it may show a characteristic narrowing of the trachea, called the steeple sign, because of the subglottic stenosis, which resembles a steeple in shape. The steeple sign is suggestive of the diagnosis, but is absent in half of cases.<ref name=Alberta07/>

Other investigations (such as blood tests and viral culture) are discouraged, as they may cause unnecessary agitation and thus worsen the stress on the compromised airway.<ref name=PedN09/> While viral cultures, obtained via nasopharyngeal aspiration, can be used to confirm the exact cause, these are usually restricted to research settings.<ref name=Au10/> Bacterial infection should be considered if a person does not improve with standard treatment, at which point further investigations may be indicated.<ref name=Cherry08/>

Severity

Westley score: Classification of croup severity<ref name=Croup09/><ref name=Peds99/>

Feature	Number of points assigned for this feature
	0	1	2	3	4	5
Chest wall retraction	None	Mild	Moderate	Severe
Stridor	None	With agitation	At rest
Cyanosis	None				With agitation	At rest
Level of consciousness	Normal					Disoriented
Air entry	Normal	Decreased	Markedly decreased

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.<ref name=Cherry08/> It is the sum of points assigned for five factors: level of consciousness, cyanosis, stridor, air entry, and retractions.<ref name=Cherry08/> The points given for each factor is listed in the adjacent table, and the final score ranges from 0 to 17.<ref name=Peds99/>

• A total score of ≤ 2 indicates mild croup. The characteristic barking cough and hoarseness may be present, but there is no stridor at rest.<ref name=Croup09/>
• A total score of 3–5 is classified as moderate croup. It presents with easily heard stridor, but with few other signs.<ref name=Croup09/>
• A total score of 6–11 is severe croup. It also presents with obvious stridor, but also features marked chest wall indrawing.<ref name=Croup09/>
• A total score of ≥ 12 indicates impending respiratory failure. The barking cough and stridor may no longer be prominent at this stage.<ref name=Croup09/>

85% of children presenting to the emergency department have mild disease; severe croup is rare (<1%).<ref name=Croup09/>

Prevention

Croup is contagious during the first few days of the infection.<ref name=":1" /> Basic hygiene including hand washing can prevent transmission.<ref name=":1" /> There are no vaccines that have been developed to prevent croup,<ref name=":1" /> however, many cases of croup have been prevented by immunization for influenza and diphtheria.<ref name=Cherry08/> At one time, croup referred to a diphtherial disease, but with vaccination, diphtheria is now rare in the developed world.<ref name=Cherry08/>

Treatment

Most children with croup have mild symptoms and supportive care at home is effective.<ref name=":1">Template:Cite journal</ref> For children with moderate to severe croup, treatment with corticosteroids and nebulized epinephrine may be suggested. Steroids are given routinely, with epinephrine used in severe cases.<ref name=PedN09/> Children with oxygen saturation less than 92% should receive oxygen,<ref name=Cherry08/> and those with severe croup may be hospitalized for observation.<ref name=Alberta07/> In very rare severe cases of croup that result in respiratory failure, emergency intubation and ventilation may be required.<ref name=":0">Template:Cite journal</ref> With treatment, less than 0.2% of children require endotracheal intubation.<ref name="Peds99">Template:Cite journal</ref> Since croup is usually a viral disease, antibiotics are not used unless secondary bacterial infection is suspected.<ref name="Au10" /> The use of cough medicines, which usually contain dextromethorphan or guaifenesin, are also discouraged.<ref name="Au10" />

Supportive care

Supportive care for children with croup includes resting and keeping the child hydrated.<ref name=":1" /> Infections that are mild are suggested to be treated at home. Croup is contagious so washing hands is important.<ref name=":1" /> Children with croup should generally be kept as calm as possible.<ref name="PedN09" /> Over the counter medications for pain and fever may be helpful to keep the child comfortable.<ref name=":1" /> There is some evidence that cool or warm mist may be helpful, however, the effectiveness of this approach is not clear.<ref name="PedN09" /><ref name="Cherry08" /><ref name=":1" /> If the child is showing signs of distress while breathing (inspiratory stridor, working hard to breathe, blue (or blue-ish) coloured lips, or decrease in the level of alertness), immediate medical evaluation by a doctor is required.<ref name=":1" />

Steroids

Corticosteroids, such as dexamethasone and budesonide, have been shown to improve outcomes in children with all severities of croup, however, the benefits may be delayed.<ref name="Gate2018" /> Significant relief may be obtained as early as two hours after administration.<ref name=Gate2018/> While effective when given by injection, or by inhalation, giving the medication by mouth is preferred.<ref name=PedN09/> A single dose is usually all that is required, and is generally considered to be quite safe.<ref name=PedN09/> Dexamethasone at doses of 0.15, 0.3 and 0.6 mg/kg appear to be all equally effective.<ref>Template:Cite journal</ref>

Epinephrine

Moderate to severe croup (for example, in the case of severe stridor) may be improved temporarily with nebulized epinephrine.<ref name=PedN09/> While epinephrine typically produces a reduction in croup severity within 10–30 minutes, the benefits are short-lived and last for only about 2 hours.<ref name=Au10/><ref name=PedN09/> If the condition remains improved for 2–4 hours after treatment and no other complications arise, the child is typically discharged from the hospital.<ref name=Au10/><ref name=PedN09/> Epinephrine treatment is associated with potential adverse effects (usually related to the dose of epinephrine) including tachycardia, arrhythmias, and hypertension.<ref name=":0" />

Oxygen

More severe cases of croup may require treatment with oxygen. 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.<ref name="Cherry08" />

Other

While other treatments for croup have been studied, none has sufficient evidence to support its use. There is tentative evidence that breathing heliox (a mixture of helium and oxygen) to decrease the work of breathing is useful in those with severe disease, however, there is uncertainty in the effectiveness and the potential adverse effects and/or side effects are not well known.<ref name=":0" /> In cases of possible secondary bacterial infection, the antibiotics vancomycin and cefotaxime are recommended.<ref name=Cherry08/> In severe cases associated with influenza A or B infections, the antiviral neuraminidase inhibitors may be administered.<ref name=Cherry08/>

Prognosis

Viral croup is usually a self-limiting disease,<ref name=Au10/> with half of cases resolving in a day and 80% of cases in two days.<ref name=Thom2013/> It can very rarely result in death from respiratory failure and/or cardiac arrest.<ref name=Au10/> Symptoms usually improve within two days, but may last for up to seven days.<ref name=Croup09/> Other uncommon complications include bacterial tracheitis, pneumonia, and pulmonary edema.<ref name=Croup09/>

Epidemiology

Croup affects about 15% of children, and usually presents between the ages of 6 months and 5–6 years.<ref name=PedN09/><ref name=Cherry08/> It accounts for about 5% of hospital admissions in this population.<ref name=Croup09/> In rare cases, it may occur in children as young as 3 months and as old as 15 years.<ref name=Croup09/> Males are affected 50% more frequently than are females, and there is an increased prevalence in autumn.<ref name=Cherry08/>

History

The word croup comes from the Early Modern English verb croup, meaning "to cry hoarsely." The noun describing the disease originated in southeastern Scotland and became widespread after Edinburgh physician Francis Home published the 1765 treatise An Inquiry into the Nature, Cause, and Cure of the Croup.<ref>Template:Cite book</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

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.<ref name=history/><ref name="Hist2001">Template:Cite journal</ref> Viral croup was then called "faux-croup" by the French and often called "false croup" in English,<ref name=cormack>Template:Cite journal</ref><ref name=loving>Template:Cite journal</ref> as "croup" or "true croup" then most often referred to the disease caused by the diphtheria bacterium.<ref name=bennett>Template:Cite journal</ref><ref name=beard>Template:Cite book</ref> False croup has also been known as pseudo croup or spasmodic croup.<ref>Template:Cite book</ref> Croup due to diphtheria has become nearly unknown in affluent countries in modern times due to the advent of effective immunization.<ref name=history/><ref name=vanderpool>Template:Cite journal</ref>

One famous fatality of croup was Napoleon's designated heir, Napoléon Charles Bonaparte. His death in 1807 left Napoleon without an heir and contributed to his decision to divorce from his wife, the Empress Josephine de Beauharnais.<ref>Template:Cite book</ref>

Preston Brooks, a pro-slavery, pre-Civil War US congressman from South Carolina died unexpectedly from a violent attack of croup on January 27, 1857, a few weeks before the March 4 start of the new congressional term to which he had been re-elected.<ref>Template:Cite news</ref>

External links

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