Croup for PA
Croup for the Physician Assistant Licensing Exam
Etiology
- Viral Causes:
- Croup is primarily caused by parainfluenza virus type 1, which leads to inflammation of the upper airway. Other viral causes include:
- Parainfluenza types 2 and 3
- Respiratory syncytial virus (RSV)
- Influenza A and B
- Adenovirus
- Human metapneumovirus
- Age Group:
- Croup commonly affects children between 6 months and 3 years, with peak incidence in the second year of life.
Pathophysiology
- Airway Edema:
- Viral infection causes inflammation and edema of the larynx, trachea, and bronchi, especially in the subglottic region, leading to airway narrowing.
- Increased Mucus Production:
- Cytokine release leads to increased mucus secretion and mucosal swelling, which further contributes to airway obstruction.
Clinical Features
- Prodromal Symptoms:
- Initially, croup presents with mild upper respiratory symptoms, including rhinorrhea and low-grade fever.
- Barking Cough:
- A seal-like barking cough is the hallmark feature of croup, caused by turbulent airflow through the narrowed airway.
- Stridor:
- Inspiratory stridor, especially during agitation or crying, results from partial airway obstruction.
- Hoarseness:
- Hoarseness due to laryngeal inflammation is common.
- Symptom Severity:
- Symptoms worsen at night and may range from mild (occasional barking cough) to severe (continuous stridor and respiratory distress).
Diagnosis
- Clinical Diagnosis:
- Based on characteristic symptoms, including barking cough, stridor, and hoarseness. Neck X-ray is rarely needed but may show the classic "steeple sign" (subglottic narrowing).
- Differential Diagnosis:
- Conditions to consider include epiglottitis, bacterial tracheitis, and foreign body aspiration.
Management
- Supportive Care:
- For mild cases, hydration and exposure to humidified air may help reduce symptoms. Keeping the child calm is crucial to prevent worsening of stridor.
- Glucocorticoids:
- A single dose of dexamethasone (0.6 mg/kg) is recommended for all cases to reduce airway inflammation.
- Nebulized Epinephrine:
- Used for moderate to severe croup with significant respiratory distress or stridor at rest. Patients should be monitored for rebound symptoms.
Key Points
- Croup is a viral infection, primarily caused by parainfluenza virus, leading to subglottic airway edema and narrowing.
- Symptoms include a barking cough, stridor, and hoarseness, with severity ranging from mild to severe respiratory distress.
- Diagnosis is clinical, and treatment includes supportive care and dexamethasone for all cases. Nebulized epinephrine is used for moderate to severe cases.
- Hospitalization may be required for severe cases with persistent respiratory distress or need for repeated epinephrine treatments.