Acute Respiratory Distress in Children

A key differentiator is that upper airway obstruction typically causes stridor (an inspiratory sound), while lower airway disease is characterized by wheezing (an expiratory sound).

Upper Airway Diseases

The primary sign of upper airway obstruction is stridor, a high-pitched sound caused by turbulent airflow through a narrowed larynx or trachea.

Condition	Croup (Laryngotracheobronchitis)	Epiglottitis	Bacterial Tracheitis	Foreign Body Aspiration
Patho/Etiology	Parainfluenza virus (most common). Inflammation/edema of subglottic area.	H. influenzae type b (less common with Hib vaccine). S. pyogenes, S. aureus. Inflammation/edema of supraglottic structures.	S. aureus (most common). Often a bacterial superinfection after a viral illness (e.g., croup). Thick, purulent exudates in the trachea.	Aspiration of object (e.g., peanut, coin, toy part) into the airway.
Clinical Presentation	Age: 6 mo - 3 yr. Barking "seal-like" cough, inspiratory stridor, hoarseness. Symptoms often worse at night after a viral prodrome.	Age: 2-7 yr (unvaccinated). Acute onset, high fever, dysphagia, drooling, distress ("3 D's"). Tripod position (sitting up, leaning forward), muffled "hot potato" voice. No cough.	Age: 6 mo - 6 yr. High fever, toxic appearance, inspiratory/expiratory stridor. Initial croup-like symptoms that rapidly worsen and don't respond to croup treatment. Productive cough with thick secretions.	Age: 1-3 yr. Sudden onset of choking, coughing, stridor, or wheezing. Unilateral wheezing or decreased breath sounds.
Diagnosis	Clinical diagnosis. X-ray (AP neck) shows "steeple sign" (subglottic narrowing), but not required for diagnosis.	Do NOT examine throat. Lateral neck X-ray shows "thumb sign" (enlarged epiglottis). Definitive Dx: Direct laryngoscopy in a controlled setting (OR).	X-ray may show steeple sign or subglottic narrowing with a "shaggy" tracheal border. Definitive Dx: Bronchoscopy shows purulent secretions.	History is key. Chest X-ray may show a radiopaque object or signs of air trapping (hyperinflation) on the affected side. Bronchoscopy is both diagnostic and therapeutic.
Management	Mild: Humidified air, corticosteroids (dexamethasone). Moderate/Severe: Corticosteroids + nebulized racemic epinephrine.	Emergency! Intubate in the OR. IV antibiotics (e.g., Ceftriaxone) and corticosteroids.	Airway management (intubation often required). IV antibiotics (e.g., Vancomycin + Ceftriaxone). Bronchoscopy for secretion removal.	Rigid bronchoscopy for removal of the object.

Lower Airway Diseases

Lower airway diseases involve the bronchi and bronchioles, typically presenting with wheezing, tachypnea, and increased work of breathing.

Condition	Bronchiolitis	Asthma	Pneumonia
Patho/Etiology	RSV (Respiratory Syncytial Virus) is the most common cause. Inflammation and necrosis of small airway epithelial cells leading to obstruction.	Reversible bronchoconstriction due to airway hyperresponsiveness to various triggers (allergens, viruses, cold air).	Infection of the lung parenchyma. Can be viral (RSV, influenza) or bacterial (S. pneumoniae, M. pneumoniae).
Clinical Presentation	Age: < 2 years. Preceded by URI symptoms (rhinorrhea, cough). Diffuse wheezing, crackles, tachypnea, increased work of breathing (retractions, nasal flaring).	Age: > 2 years. Recurrent episodes of wheezing, cough (often nocturnal), and dyspnea. Personal or family history of atopy (eczema, allergic rhinitis).	Can occur at any age. Fever, cough, tachypnea. Auscultation may reveal crackles, rhonchi, or decreased breath sounds over a focal area. Wheezing is less common than in bronchiolitis or asthma.
Diagnosis	Clinical diagnosis. Chest X-ray is not routinely needed but may show hyperinflation and patchy atelectasis.	History and physical exam. Pulmonary function tests (spirometry) in older children show obstructive pattern with reversibility after bronchodilator use.	Chest X-ray is key: shows lobar consolidation (bacterial), diffuse interstitial infiltrates (viral/atypical).
Management	Supportive care: Hydration, nasal suctioning, and supplemental O2 if needed. Bronchodilators and steroids are not routinely recommended.	SABA (e.g., Albuterol) for acute attacks. Inhaled corticosteroids for long-term control. Systemic steroids for exacerbations.	Bacterial: Amoxicillin (first-line). Macrolides for atypical. Viral: Supportive care. Hospitalize for respiratory distress.
Key Associations/Complications	Apnea (especially in premature infants and those <2 months). Risk factor for developing asthma later in life.	Atopic dermatitis, allergic rhinitis.	Pleural effusion, empyema, lung abscess.