Approach to stridor
I. Clinical Summary & Definition
- Stridor: Harsh, high-pitched respiratory sound caused by turbulent airflow due to partial airway obstruction.
- Key Differentiator: The presence of fever excludes non-infectious causes like Foreign Body Aspiration (unless secondary infection is present) or Angioedema.
II. Differential Diagnosis (Prioritized)
-
**Acute Laryngotracheobronchitis (Viral Croup)
- Probability: Most common cause (>80%).
- Etiology: Parainfluenza virus (Types 1, 2, 3).
- Classic presentation: Barking cough, hoarseness, low-grade fever.
-
Acute Epiglottitis (Supraglottitis):
- Probability: Rare post-HiB vaccination but a medical emergency.
- Etiology: H. influenzae type b (classic), Staph. aureus, Strep. pyogenes.
- Classic presentation: High fever, toxic look, drooling, no cough.
-
Bacterial Tracheitis:
- "Super-Croup" (Secondary bacterial infection of viral croup).
- Etiology: Staph. aureus.
- Presentation: Patient looks toxic like epiglottitis but has a cough like croup.
-
Retropharyngeal Abscess:
- Fever, stridor, difficulty swallowing, stiffness of neck.
III. Clinical Evaluation & Comparison
Distinguishing the two main causes is the primary diagnostic task.
| Feature | Viral Croup (Laryngotracheobronchitis) | Acute Epiglottitis |
|---|---|---|
| Onset | Gradual (preceded by URI/coryza) | Sudden, fulminant |
| Fever | Low to Moderate | High (>39Β°C) |
| Cough | Barking / Seal-like | Absent |
| Appearance | Non-toxic | Toxic, anxious, air hunger |
| Posture | Variable | Tripod position (sitting up, leaning forward) |
| Drooling | Absent | Present (due to dysphagia) |
| Voice | Hoarse | Muffled ("Hot potato") |
| Pathology | Subglottic edema | Supraglottic inflammation |
IV. Diagnostic Approach
1. Immediate Assessment (Pediatric Assessment Triangle)
- Assess Appearance (Tone, interactivity), Work of Breathing (Retractions), and Circulation.
- WARNING: If Epiglottitis is suspected (Drooling, Toxic, Tripod):
- Do NOT examine the throat using a tongue depressor (risk of laryngospasm).
- Do NOT upset the child (keep in parent's lap).
- Secure airway immediately in OT.
2. Physical Examination (If stable/Croup suspected)
- Evaluate respiratory distress.
- Westley Croup Score: Used to grade severity of Croup.
- Parameters: Stridor, Retractions, Air Entry, Cyanosis, Level of Consciousness.
- Score: <2 (Mild), 3β5 (Moderate), >6 (Severe).
3. Radiological Investigation
X-ray Neck (AP and Lateral views) is useful if the diagnosis is unclear.
-
Croup:
- AP View: Steeple Sign (Subglottic narrowing/tapering of the trachea).
- Lateral View: Distention of hypopharynx only.
-
Epiglottitis:
- Lateral View: Thumb Sign (Enlarged, swollen epiglottis).
- Aryepiglottic folds: Thickened.
-
Retropharyngeal Abscess:
- Lateral View: Increased prevertebral soft tissue thickness (> width of adjacent vertebral body).
4. Laboratory Investigations
- CBC:
- Croup: Lymphocytosis (Viral picture).
- Epiglottitis/Tracheitis: Neutrophilic leukocytosis with shift to left.
- Blood Culture: Indicated in Epiglottitis or Bacterial Tracheitis.
V. Management of Stridor in Children
I. Immediate Resuscitation (ABC Approach)
Stridor indicates partial airway obstruction. Management begins with assessing stability.
- Airway & Breathing:
- Assess Pediatric Assessment Triangle (PAT): Appearance, Work of Breathing, Circulation.
- "Keep the child calm": Agitation worsens obstruction. Allow child to sit in parent's lap.
- Oxygen: Administer 100% humidified
(blow-by or mask) if hypoxic. - Heliox: Helium-oxygen mixture (70:30) decreases airflow resistance (useful in temporary bridging).
- Red Flags (Impending Failure):
- Drooling, Tripod position, Silent chest, Altered sensorium.
- Action: Secure airway immediately (Intubation/Tracheostomy) in OT with ENT backup.
- Caution: Do NOT examine throat if Epiglottitis is suspected.
II. Diagnostic Evaluation (Concurrent with Stabilization)
- History:
- Acute: Croup (viral prodrome), Foreign Body (choking episode), Epiglottitis (toxic).
- Chronic: Laryngomalacia (since birth), Vascular ring.
- Examination (Level of Obstruction):
- Inspiratory: Supraglottic/Glottic (e.g., Laryngomalacia, Croup).
- Expiratory/Biphasic: Tracheal/Bronchial (e.g., Foreign body, Tracheomalacia).
- Investigations:
- X-ray Neck (Lat/AP): Steeple sign (Croup) vs Thumb sign (Epiglottitis).
- Flexible Laryngoscopy/Bronchoscopy: Definitive for structural/dynamic lesions.
III. Specific Management by Etiology
| Condition | Specific Management |
|---|---|
| Viral Croup | β’ Dexamethasone (0.15β0.6 mg/kg stat). β’ Nebulized Adrenaline (if moderate/severe). β’ Cool mist/Cold air. |
| Acute Epiglottitis | β’ Secure Airway (Intubation). β’ IV Antibiotics (Ceftriaxone). β’ Avoid throat exam/agitation. |
| Foreign Body | β’ Rigid Bronchoscopy for removal. β’ Heimlich maneuver (only if complete obstruction/choking). |
| Bacterial Tracheitis | β’ IV Antibiotics (Anti-Staph). β’ Aggressive pulmonary toilet/suctioning. β’ Intubation often required. |
| Laryngomalacia | β’ Conservative: Most resolve by 18-24 months. β’ Surgical: Supraglottoplasty (if failure to thrive/severe apnea). |
| Hypocalcemia | β’ IV Calcium Gluconate (for laryngeal tetany). |
IV. Disposition
- Discharge: Mild croup after observation.
- Admit: Moderate-severe croup, epiglottitis, or uncertain diagnosis.
- ICU: Impending respiratory failure or post-intubation.
VI. Final Diagnostic Synthesis
- If the child has a barking cough, is hoarse, and looks non-toxic: Diagnosis is Viral Croup.
- If the child is drooling, mute/muffled, and toxic: Diagnosis is Epiglottitis.
- If the child has croup symptoms but high fever and poor response to nebulized epinephrine: Suspect Bacterial Tracheitis.