2.1 Upper Airway Obstruction

2.1 Upper Airway Obstruction

Pediatric upper airway emergencies represent high-acuity scenarios in the emergency department (ED). Because young children possess unique anatomical features—such as a relatively larger tongue, a higher and more anterior larynx (C3–C4 level), a compliant and floppy epiglottis, and a funnel-shaped airway where the narrowest region is the subglottic cricoid ring—minimal mucosal edema can dramatically reduce cross-sectional airway area. According to Poiseuille's Law, resistance to airflow is inversely proportional to the fourth power of the airway radius ($R \propto 1/r^4$). In an infant, 1 mm of subglottic mucosal swelling reduces the airway cross-sectional area by over 50% and increases airway resistance by sixteen-fold, rapidly precipitating work of breathing and inspiratory stridor.

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1. Croup (Viral Laryngotracheobronchitis)

Pathophysiology & Etiology

Viral laryngotracheobronchitis (croup) is the most common cause of pediatric upper airway obstruction in children aged 6 months to 3 years, with peak incidence occurring in late autumn and winter. The primary causative pathogen is Parainfluenza virus type 1 (accounting for ~65% of cases), followed by Parainfluenza types 2 and 3, Respiratory Syncytial Virus (RSV), Adenovirus, and Influenza A/B. Viral infection leads to diffuse mucosal inflammation, edema, and cellular infiltration of the larynx, trachea, and bronchi, localized primarily at the subglottic space.

Clinical Presentation & Emergency Assessment

The classic presentation begins with a 1- to 3-day prodrome of low-grade fever, rhinorrhea, and coryza, escalating to:

• A distinctive seal-like barking cough.
• Inspiratory stridor (worsened by agitation, crying, or exertion).
• Hoarseness due to vocal cord edema.
• Signs of respiratory distress: intercostal/subcostal retractions, suprasternal notch indrawing, nasal flaring, and tachypnea.

The Westley Croup Score is the gold standard clinical tool for stratifying severity:

• Mild (Score ≤ 2): Occasional barking cough, minimal or no stridor at rest, no or mild retractions.
• Moderate (Score 3–5): Frequent barking cough, easily audible stridor at rest, noticeable intercostal and suprasternal retractions, no agitation.
• Severe (Score 6–11): Frequent barking cough, prominent inspiratory/expiratory stridor at rest, severe retractions, significant agitation or lethargy.
• Impending Respiratory Failure (Score ≥ 12): Barking cough (may be feeble), stridor at rest, severe retractions, lethargy, decreased breath sounds, cyanosis.

Anteroposterior (AP) neck radiographs—though not routinely required for diagnosis—reveal classic subglottic narrowing, known as the "steeple sign" or "pencil-point sign."

+-----------------------------------------------------------------------------------+
|                        DIAGNOSTIC COMPARISON TABLE                                |
+------------------------+-------------------+------------------+-------------------+
| Disease Entity         | Primary Site      | Radiographic     | Key Clinical      |
|                        | of Edema          | Sign             | Finding           |
+------------------------+-------------------+------------------+-------------------+
| Croup (LTB)            | Subglottic Space  | Steeple Sign     | Barking cough,    |
|                        | (Cricoid ring)    | (AP Neck X-Ray)  | hoarseness        |
+------------------------+-------------------+------------------+-------------------+
| Epiglottitis           | Supraglottic      | Thumbprint Sign  | 4 D's: Drooling,  |
|                        | Structures        | (Lat Neck X-Ray) | Dysphagia, etc.   |
+------------------------+-------------------+------------------+-------------------+
| Bacterial Tracheitis   | Tracheal Mucosa   | Irregular tracheal| Purulent secretions|
|                        | & Subglottis      | lumen / Membranes| toxic appearance  |
+------------------------+-------------------+------------------+-------------------+
| Foreign Body Aspiration| Tracheobronchial  | Radiopaque object| Sudden choking,   |
|                        | Tree              | or Air Trapping  | unilateral wheeze |
+------------------------+-------------------+------------------+-------------------+

Emergency Nursing Interventions & Pharmacology

• Mild Croup: Single dose of Dexamethasone 0.6 mg/kg PO/IM (maximum dose 16 mg). Dexamethasone reduces airway mucosal edema within 2 to 4 hours and exhibits a prolonged half-life (36–54 hours). Oral administration is preferred to minimize distress.
• Moderate-to-Severe Croup:
  • Nebulized Racemic Epinephrine (2.25%): Administer 0.5 mL in 3 mL of normal saline via nebulizer (or L-epinephrine 1:1000 at 0.5 mL/kg, max 5 mL). Epinephrine stimulates alpha-adrenergic receptors, causing subglottic mucosal arteriolar vasoconstriction and rapid decrease in airway edema within 10–30 minutes.
  • Dexamethasone 0.6 mg/kg IV/IM/PO (max 16 mg).
  • Humidified Blow-by Oxygen: Provide cool, humidified oxygen to maintain $\text{SpO}_2 \ge 92%$.
  • Observation Period: Mandatory monitoring in the ED for a minimum of 2 to 4 hours post-epinephrine administration to evaluate for rebound stridor and worsening edema as the drug effect wanes.

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2. Epiglottitis (Acute Supraglottitis)

Pathophysiology & Etiology

Epiglottitis is a rapidly progressive, life-threatening bacterial infection of the epiglottis and surrounding supraglottic structures (aryepiglottic folds, arytenoids). Before widespread administration of the Haemophilus influenzae type b (Hib) conjugate vaccine, Hib was responsible for over 90% of cases. Currently, non-vaccine strains of H. influenzae, Streptococcus pneumoniae, Group A Streptococcus, and Staphylococcus aureus (including MRSA) are the predominant pathogens.

Clinical Presentation & The 4 D's

Unlike croup, epiglottitis lacks a viral prodrome and features a fulminant onset over 4 to 12 hours, characterized by high fever ($> 38.5^\circ\text{C}$), severe sore throat, and the classic 4 D's:

1. Dysphagia (inability or severe pain when swallowing).
2. Dysphonia (muffled "hot potato" voice).
3. Drooling (due to severe painful dysphagia).
4. Distress (marked respiratory work and anxiety).

The child typically assumes the tripod position (sitting upright, leaning forward, chin extended, mouth open, arms supporting torso on knees) or sniffing position to optimize supraglottic airway diameter.

CRITICAL NURSING WARNING: Any invasive maneuver that increases agitation—such as using a tongue depressor to inspect the pharynx, obtaining an oral temp, or attempting IV cannulation before securing the airway—can trigger acute, complete laryngospasm and total airway occlusion!

Lateral neck radiographs demonstrate a markedly enlarged, swollen epiglottis protruding into the pharyngeal air space, classic for the "thumbprint sign."

Emergency Airway Management & Therapeutics

• Primary Goal: Immediate airway stabilization in a controlled environment (Operating Room).
• Interventions:
  • Keep the child calm and in the caregiver's arms.
  • Provide gentle blow-by oxygen without forcing a mask onto the face.
  • Immediately mobilize the Emergency Airway Team (Pediatric Otolaryngologist, Anesthesiologist, Emergency Physician).
  • Endotracheal intubation is performed in the OR under direct inhalation induction (Sevoflurane). Prepare endotracheal tubes (ETTs) sized 0.5 to 1.0 mm smaller than standard age-based calculations due to supraglottic edema.
  • Obtain blood cultures and IV access only after the airway is secured.
  • Administer broad-spectrum empiric IV antibiotics: Ceftriaxone 50–100 mg/kg/day IV (max 2 g/day) plus Vancomycin 15 mg/kg IV q6h for MRSA coverage.

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3. Bacterial Tracheitis (Pseudomembranous Croup)

Pathophysiology & Clinical Features

Bacterial tracheitis is an invasive, purulent bacterial infection of the subglottic trachea, frequently secondary to mucosal damage caused by an antecedent viral illness (croup, influenza, measles). The primary causative organism is Staphylococcus aureus (including MRSA), followed by Streptococcus pneumoniae, Streptococcus pyogenes, and Moraxella catarrhalis. Thick, purulent mucosal exudates and pseudomembranes form along the tracheal lumen, creating severe mechanical airway obstruction.

Clinical Signs & Diagnostic Differentiation

• Initial presentation resembles viral croup, but rapidly deteriorates with high fever, severe toxicity, and intense stridor.
• Key Diagnostic Clue: Children with bacterial tracheitis fail to respond to nebulized racemic epinephrine and dexamethasone, and produce copious, thick, purulent tracheal secretions.
• Soft tissue neck radiographs reveal an irregular, ragged tracheal mucosal contour with intraluminal pseudomembranes.

Nursing & Pharmacologic Management

• Most patients (up to 80%) require intubation for airway protection and pulmonary hygiene due to the high risk of sudden ETT occlusion from tenacious pseudomembranes.
• Frequent, gentle ETT suctioning with instillation of normal saline is critical to maintain tube patency.
• Empiric IV antibiotic therapy: Ceftriaxone 50–100 mg/kg/day IV combined with Vancomycin 15 mg/kg IV q6h or Clindamycin 10 mg/kg IV q8h.

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4. Foreign Body Aspiration (FBA)

Epidemiology & Pathophysiology

Foreign body aspiration predominantly affects toddlers aged 1 to 3 years due to developmental oral exploration, lack of molar teeth for chewing, and uncoordinated deglutition. Organic items (peanuts, popcorn, seeds, hot dog pieces) and inorganic items (coins, small toy components, batteries) are most commonly implicated. Anatomically, because the right mainstem bronchus is wider, steeper, and more direct than the left, foreign objects lodge in the right bronchial tree in over 60% of cases.

Clinical Presentation & Diagnostic Evaluation

• Triad of FBA: Sudden onset of coughing/choking, unilateral wheezing, and localized decreased breath sounds.
• Complete Airway Obstruction: Inability to speak, cough, or breathe, cyanosis, and rapid loss of consciousness.
• Partial Airway Obstruction: Persistent localized wheezing, inspiratory stridor (if lodged at the larynx/trachea), or recurrent unilateral post-obstructive pneumonia.
• Radiographic Imaging: Anteroposterior and lateral chest X-rays may show the radiopaque object. If radiolucent (e.g., food items), secondary radiologic signs include unilateral air trapping (hyperlucency and hyperinflation of the affected lung on end-expiratory views) and mediastinal shift away from the affected side.

+-----------------------------------------------------------------------------------+
|                         FOREIGN BODY MANAGEMENT ALGORITHM                         |
+-----------------------------------------------------------------------------------+
| 1. ASSESS OBSTRUCTION SEVERITY                                                    |
|    |- Ineffective Cough / Stridor / Silent Airway -> COMPLETE OBSTRUCTION          |
|    |- Forceful Cough / Able to Speak -> PARTIAL OBSTRUCTION                       |
+-----------------------------------------------------------------------------------+
| 2. IMMEDIATE BLS MANEUVERS (If Complete)                                          |
|    |- Age < 1 Year: 5 Back Blows followed by 5 Chest Thrusts                      |
|    |- Age >= 1 Year: Abdominal Thrusts (Heimlich Maneuver)                        |
|    |- Unresponsive: Begin CPR; inspect oral cavity; remove object ONLY if visible. |
+-----------------------------------------------------------------------------------+
| 3. DEFINITIVE INTERVENTION (If Partial or Post-BLS Rescue)                        |
|    |- Emergent Rigid Bronchoscopy under General Anesthesia in Operating Room      |
+-----------------------------------------------------------------------------------+

Emergency Nursing Actions

• For partial obstruction: Do not interfere with the child's spontaneous coughing efforts; keep calm, provide supplemental oxygen, and transfer immediately for rigid bronchoscopy.
• For complete obstruction: Perform age-appropriate BLS interventions immediately. Avoid blind finger sweeps, which risk pushing the object further into the larynx.

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Congenital Airway Conditions (Stenosis, Malacia, Cystic Fibrosis)

System-Focused Respiratory blueprint content includes congenital conditions such as stenosis, malacia, and cystic fibrosis—not only acquired infections and foreign bodies.

Laryngomalacia / Tracheomalacia

• Laryngomalacia is the most common congenital laryngeal anomaly: inspiratory stridor that worsens when supine or feeding, often improves prone. Most infants improve with growth; severe cases with failure to thrive or apnea need ENT evaluation.
• Tracheomalacia produces biphasic or expiratory stridor/wheeze from tracheal wall collapse; avoid forced agitation; support with positioning and oxygen; severe collapse may need specialty airway planning.

Subglottic Stenosis and Choanal Issues

• Acquired or congenital subglottic stenosis presents with biphasic stridor and may follow prolonged intubation history—do not force blind instrumentation; prepare difficult-airway resources and ENT backup.
• Choanal atresia (bilateral) is a neonatal emergency: cyclic cyanosis relieved by crying; secure oral airway and urgent specialty consultation.

Cystic Fibrosis (CF) Pulmonary Exacerbation

Children with CF may present with increased cough, hypoxia, fever, or hemoptysis. ED priorities: airway clearance support per home regimen, oxygen titration, sputum culture when indicated, CF-center notification, and cautious IV fluid/electrolyte management. Avoid assuming "simple asthma"—thick secretions and infection drive obstruction. Hemoptysis or right-heart strain signs require escalation.