Definition and pathogenesis
False croup is acute obstructive laryngitis characterized by inflammation and edema of the laryngeal mucosa and the subglottic tissues located directly beneath the vocal cords. As a result, the lumen of the larynx and trachea narrows, obstructing airflow.
The condition is typically seen in pediatrics due to the anatomical features of a child's airways: the larynx has a funnel shape (unlike the barrel shape in adults), and the lumen of the larynx and trachea is initially narrow. Therefore, even moderate inflammation in this area quickly leads to clinically significant stenosis.
Two concepts should be distinguished:
- True croup is a consequence of diphtheritic infection, where luminal narrowing is caused by fibrinous membranes. Due to vaccination, it is rare.
- False croup is narrowing caused by edema and inflammation resulting from a viral infection. The most common pathogen is parainfluenza virus, less commonly influenza, adenovirus, rhinovirus, and coronavirus.
Since the etiology is viral, antibiotics are not indicated for false croup. This is the most common cause of acute upper airway obstruction in children aged 6 months to 6 years.
Clinical presentation
The diagnosis is clinical and is established based on the medical history and symptoms. The episode most often develops at night or early morning during the cold season against the background of an acute respiratory viral infection (ARVI).
- Symptoms of ARVI: rhinorrhea, cough, temperature (normal, low-grade, or high).
- Hoarseness is one of the initial symptoms; in non-verbal children, the character of the cry changes (rough, raspy).
- Barking cough is a rough cough resembling a dog's bark or a seal's cry.
- Inspiratory dyspnea with stridor—inspiration is specifically impaired (unlike bronchial obstruction, where expiration is impaired).
- Retraction of compliant chest areas (intercostal spaces) and cyanosis are signs of increasing severity.
On auscultation, breath sounds are unchanged: vesicular or puerile (puerile breathing is normal in young children). Radiography may reveal the steeple sign—characteristic narrowing of the subglottic space, although instrumental methods are not mandatory.
First aid prior to drug therapy
The main rule is to stay calm: the calmer the parent, the calmer the child, and the easier it is for them to breathe. For the first episode, calling an ambulance is indicated. Before the medical team arrives, non-pharmacological measures are applied:
- Air humidification and cooling: using a humidifier, opening a window, cool air. You can take the child outside or into the bathroom with running warm water.
- Reduction of body temperature in case of fever—ibuprofen or paracetamol; high temperature increases anxiety and promotes drying of the mucosa.
- Fluid replenishment: breast milk, water, diluted compote—prevents thickening of secretions in the airways.
It is strictly not recommended to use hot steam inhalations ("breathing over potatoes")—this can provoke spastic stenosis and worsen the condition.
Pharmacotherapy
Drugs of choice are glucocorticosteroids. The algorithm is step-wise: first budesonide inhalation, if ineffective—systemic dexamethasone, followed by hospitalization.
Inhalation of budesonide suspension (trade name: Pulmicort):
- Dosage: 0.5–2 mg per inhalation, independent of weight and age.
- Practical guideline: 2 ampoules of the drug into the nebulizer regardless of concentration (0.25 or 0.5 mg/ml).
- Can be repeated after 30 minutes, dividing the total dose of 2 mg into two administrations.
- A compressor or mesh nebulizer is suitable; an ultrasonic nebulizer must not be used as it destroys the drug.
Dexamethasone is used in the absence of effect or impossibility of inhalation:
- Dosage: 0.15–0.6 mg/kg orally (the contents of the ampoule can be given by mouth), intramuscularly, or intravenously.
- Practical guideline for children under 3 years: one 4 mg (1 ml) ampoule is sufficient to relieve the attack.
- The effect develops within 10–40 minutes.
An alternative is prednisolone at a dose of 1–2 mg/kg, but it is less effective.
Indications for hospitalization and intensive care
Hospitalization is necessary if glucocorticosteroid therapy is ineffective or the child's condition progressively deteriorates. Warning signs:
- Increasing cyanosis;
- Pronounced retraction of intercostal spaces and other compliant areas;
- Impairment or loss of consciousness;
- Decrease in blood oxygen saturation below 92%.
In the hospital setting, the following may be used: adrenaline inhalations, oxygen therapy, and for severe stenosis—tracheal intubation.
What should not be prescribed
In false croup, the following are not drugs of choice and are not indicated:
- Antibiotics—the etiology is viral;
- Mucolytics and expectorants—can increase sputum volume in a narrow lumen and worsen the situation;
- Hot steam inhalations—risk of spastic stenosis.
Key points
- False croup is acute obstructive laryngitis of viral etiology in children aged 6 months to 6 years, most often against the background of parainfluenza.
- Triad of symptoms: hoarseness, barking cough, inspiratory dyspnea with stridor.
- Diagnosis is clinical; auscultatory findings may remain normal (vesicular or puerile breathing).
- First aid: calm the child, humidify and cool the air, give fluids, for fever—ibuprofen or paracetamol.
- First-line drug—inhalation of budesonide 0.5–2 mg via a compressor or mesh nebulizer.
- If ineffective—dexamethasone 0.15–0.6 mg/kg orally, IM, or IV.
- Antibiotics, mucolytics, and steam inhalations are contraindicated.
- Hospitalization—in case of cyanosis, altered consciousness, SpO₂ < 92%; in the hospital, adrenaline, oxygen, and intubation are possible.