Laryngotracheobronchitis, more commonly known as croup, is a respiratory condition that affects the larynx (voice box), trachea (windpipe), and bronchi. It is most often triggered by a viral infection and is characterized by a distinctive barking cough, hoarseness of the voice, and noisy breathing known as stridor. Although the illness is usually self-limiting and mild, in certain cases it can progress to severe respiratory distress, requiring urgent medical attention.
Croup is particularly common in young children between six months and three years of age, though it can occur in older children as well. Its onset is often dramatic, with symptoms worsening at night, which can be frightening for both the child and caregivers. Understanding its causes, symptoms, and treatments can make a critical difference in ensuring proper management and preventing complications.
Pathophysiology of Croup
The term laryngotracheobronchitis itself provides insight into the pathology. The suffix “-itis” refers to inflammation, while the prefix denotes the affected structures:
- Laryngo → Larynx (voice box)
- Tracheo → Trachea (windpipe)
- Bronchi → Bronchial passages
Thus, croup is the inflammation of the larynx, trachea, and bronchi, primarily due to viral infection. The parainfluenza virus is the most common causative agent, although other viruses such as influenza, adenovirus, respiratory syncytial virus (RSV), and measles virus may also be implicated.
When the infection sets in, it triggers mucosal inflammation and edema, especially around the subglottic region of the larynx. Because this part of the airway is already narrow in children, even minimal swelling can significantly obstruct airflow. This obstruction is responsible for the classic barking cough, stridor, and respiratory distress observed in affected children.
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Causes and Risk Factors
The majority of croup cases arise from viral infections, with parainfluenza virus type 1 being the leading culprit. Other causes include:
- Influenza A and B viruses
- Respiratory syncytial virus (RSV)
- Adenoviruses
- Measles virus
- Less commonly, bacterial superinfections may complicate the condition, leading to more severe presentations such as bacterial tracheitis.
Risk factors that increase susceptibility include:
- Age between 6 months and 3 years
- History of recurrent respiratory infections
- Seasonal exposure (most common during autumn and winter)
- Poorly ventilated environments with high exposure to viral transmission
Signs and Symptoms
The hallmark of croup lies in its classic triad of symptoms, often remembered as the “3 S’s”:
- Stridor – A harsh, vibrating sound heard during inspiration due to airway narrowing.
- Subglottic swelling – Causes hoarseness of the voice.
- Seal-bark cough – A distinctive barking cough resembling the sound of a seal.
Symptoms typically worsen at night and may fluctuate in severity. In many cases, children appear well during the day but develop sudden cough and noisy breathing after going to bed.
Additional features include:
- Fever (usually low-grade and fluctuating)
- Hoarseness of the voice
- Labored or noisy breathing
- Restlessness and irritability in severe cases
Croup vs Epiglottitis
Because both croup and epiglottitis present with respiratory distress, differentiating the two is crucial. Epiglottitis is a medical emergency and can be fatal if not promptly recognized.
Here is a comparison:
| Feature | Croup | Epiglottitis |
|---|---|---|
| Onset | Sudden, usually at night | Rapid, within hours |
| Fever | Fluctuating, low-grade | High |
| Cough | Present (seal-bark cough) | Absent |
| Dysphagia (difficulty swallowing) | No | Yes |
| Cause | Viral infection | Bacterial infection (e.g., Haemophilus influenzae type B) |
| Emergency status | Not typically an emergency | Always an emergency |
Understanding these differences helps clinicians and caregivers identify when urgent action is required.
Diagnosis
Croup is usually diagnosed based on clinical presentation. Investigations are rarely required, as the barking cough and stridor are distinctive. In severe or atypical cases, however, the following may be considered:
- Neck X-ray (AP view) may show the classic “steeple sign” indicating subglottic narrowing.
- Pulse oximetry can help assess oxygen saturation in cases with respiratory distress.
- Laboratory tests (such as viral cultures or PCR) are not routinely necessary but may be used in research or complicated cases.
Home Care and Self-Limiting Nature
Most cases of croup are mild and resolve on their own within a few days. Parents and caregivers can manage symptoms at home by ensuring the child remains comfortable and well-hydrated.
Helpful measures include:
- Providing humidified air through a mist humidifier or by sitting with the child in a steamy bathroom.
- Encouraging rest and fluid intake to maintain hydration and support recovery.
- Creating a calm environment to reduce agitation, as crying can worsen airway obstruction.
In most cases, croup is self-limiting and requires no hospitalization.
Medical Treatment
When symptoms are more pronounced, medical therapy may be necessary. The mainstays of treatment include:
- Corticosteroids (such as dexamethasone or prednisolone) to reduce airway inflammation.
- Racemic epinephrine delivered via nebulizer for moderate to severe croup to provide rapid relief by reducing airway swelling.
- Oxygen therapy in severe cases.
When to Seek Emergency Help
While most children with croup recover without complications, some may progress to respiratory distress. Parents should seek urgent medical help if the child develops:
- Confusion, restlessness, or extreme agitation
- Blue lips or nails indicating cyanosis
- Increased breathing effort but decreased airflow
- Retractions (visible pulling in of the chest wall with each breath)
- Nasal flaring
- Drooling or inability to swallow
These signs may indicate impending airway obstruction, requiring hospitalization and advanced airway management.
Prognosis and Outcomes
The prognosis for viral croup is generally excellent. Most children recover completely within 3 to 5 days. Severe cases requiring hospitalization are rare, and long-term complications are uncommon. However, recurrent croup can occur in susceptible children and may warrant further evaluation to exclude underlying airway anomalies or allergies.
Prevention
Since croup is caused by viruses, prevention strategies align with general respiratory infection control:
- Good hand hygiene and avoiding close contact with infected individuals
- Disinfection of commonly touched surfaces
- Ensuring children receive appropriate vaccinations, including influenza and measles vaccines
- Encouraging strong immunity through balanced nutrition, adequate rest, and physical activity
FAQs on Laryngotracheobronchitis (Croup)
Q1. What is the difference between croup and a regular cough?
Croup produces a distinct barking cough that sounds like a seal, unlike the dry or productive coughs of other respiratory illnesses.
Q2. How long does croup last in children?
Most cases resolve within 3 to 5 days, with symptoms peaking during the first two nights.
Q3. Is croup contagious?
Yes, croup is caused by viruses such as parainfluenza and can spread through respiratory droplets, coughing, or sneezing.
Q4. Can adults get croup?
Croup is far more common in children because their smaller airways are more prone to obstruction. Adults can develop similar viral infections but rarely exhibit the classic symptoms.
Q5. Does croup require antibiotics?
No. Since croup is almost always viral, antibiotics are not effective. They are only considered if a bacterial infection is suspected.
Q6. What is the “steeple sign” in croup?
It is a narrowing of the upper trachea seen on an X-ray, resembling the steeple of a church, and is a radiological sign of subglottic edema.
Q7. Can croup cause long-term breathing problems?
Most children recover fully without complications. However, recurrent episodes may suggest an underlying condition such as asthma, allergies, or airway anomalies.
