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MD PEDIATRICS EXAM - MODEL ANSWER [10 Marks]

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PART 1 - DEFINITION OF STRIDOR [1 Mark]

• Inspiratory stridor - obstruction at or above the vocal cords (supraglottic/glottic)
• Expiratory stridor - lower airway (infra-glottic/tracheobronchial); presents as wheeze
• Biphasic stridor - fixed obstruction at glottic/subglottic level or tracheobronchial disease

Bailey & Love, 28th Ed.: "Stridor means noisy breathing... Inspiratory stridor is usually due to an obstruction at or above the vocal folds and is most commonly the result of an inhaled foreign body or acute infections such as epiglottitis."

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PART 2 - DIAGNOSIS [4 Marks]

Context: Sudden Onset Stridor in a 1-Year-Old

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TABLE 1: Differential Diagnosis of Acute Stridor in a 1-Year-Old

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Diagnostic Approach Flowchart

1-YEAR-OLD WITH SUDDEN ONSET STRIDOR
              |
     Is the child in DISTRESS?
    (cyanosis, silent chest, unconscious)
              |
     YES ─────────────────── NO
      |                       |
IMMEDIATE AIRWAY          Full history
MANAGEMENT                    |
(See Treatment)      ┌────────┴────────┐
                     |                 |
               Witnessed           No witnessed
               choking?            choking episode
                  |                    |
                 YES                   |
                  |                    |
        SUSPECT FOREIGN            Other features?
        BODY ASPIRATION               |
                  |          ┌────────┴──────────┐
             ↓               |                   |
      Stable? → X-ray    Barking cough       Drooling +
      chest + neck       + low fever +       toxic + high
      (AP + lateral)     URTI prodrome       fever + no cough
             |               |                   |
      Bronchoscopy        CROUP              EPIGLOTTITIS
      (diagnostic +       (viral LTB)        (EMERGENCY)
      therapeutic)

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Specific Diagnostic Steps for FBA (Most Likely at Age 1)

• Sudden choking/coughing episode (present in ~90% of cases) - often while eating or playing
• Type of object (round foods: peanut, grape, coin, toy part - peak risk at 1-2 years)
• Often unwitnessed since child is pre-verbal

• Phase of stridor (inspiratory = upper airway/laryngeal FB; expiratory wheeze = bronchial FB)
• Unilateral decreased breath sounds (right bronchus more commonly affected)
• Signs of respiratory distress: tachypnea, subcostal/intercostal retractions, SpO2

"A normal chest radiograph cannot rule out a non-radiopaque foreign body. CT scan and virtual bronchoscopy may be used to aid diagnosis in equivocal cases." - Rosen's Emergency Medicine, 10th Ed.

"The peak incidence of foreign body aspiration is between one and two years of age." - AAFP/Nelson

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PART 3 - TREATMENT [5 Marks]

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TREATMENT FLOWCHART: 1-Year-Old with Acute Stridor / Foreign Body Aspiration

ACUTE STRIDOR IN 1-YEAR-OLD
              |
    ┌─────────┴──────────┐
COMPLETE OBSTRUCTION    PARTIAL OBSTRUCTION / STABLE
(No air exchange,        (Moving air, crying,
cyanosis, silent)        tolerating position)
    |                         |
IMMEDIATE BLS:          ALLOW CHILD TO MAINTAIN
5 Back blows +          PREFERRED POSITION
5 Chest thrusts*        Do NOT agitate / lay down
(for infants <1 yr)     Do NOT blind finger sweep
5 Abdominal thrusts     Do NOT examine throat with tongue blade
(for children >1 yr)         |
    |                    Supplemental O2 (if SpO2 <94%)
No improvement               |
    |                    Stable X-ray workup
Laryngoscopy +               |
Magill forceps          RIGID BRONCHOSCOPY
    |                   (diagnostic + therapeutic)
Still no improvement         |
    |                  Successful removal
ETT to push FB         → Monitor → Discharge
into R. mainstem
(ventilate L. lung)
    |
Last resort:
Needle cricothyrotomy
(temporizing measure)

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TABLE 2: Treatment by Cause (for Sudden Onset Stridor, 1-Year-Old)

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Detailed Treatment Protocol: Foreign Body Aspiration (Primary Concern at Age 1)

• Child <1 year: 5 back blows + 5 chest thrusts (NOT Heimlich)
• Child >1 year: Heimlich maneuver (5 abdominal thrusts) if conscious
• Unconscious: Start CPR; look in mouth before breaths; remove visible object only

• Maintain SpO2 >94% with supplemental O2
• IV access; NPO
• Do NOT give sedation or paralytics if child is moving air (may convert partial to complete obstruction)
• X-rays in stable child only

• Performed under general anesthesia in operating theatre
• Allows direct visualization, grasping with optical forceps, and removal
• Success rate >95% for accessible bronchial FB
• Flexible bronchoscopy (with laryngeal mask, general anesthesia) - emerging as a safe alternative for select cases (Keil & Schwerk, Curr Opin Anaesthesiol, 2023, PMID: 36745076)
• Post-procedure: bronchodilators, antibiotics if secondary infection, chest physiotherapy

• Observe for rebound edema, post-obstructive pneumonia
• Follow-up CXR at 24-48 hours
• Discharge when SpO2 stable on room air and no respiratory distress

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Westley Croup Score (For Viral LTB)

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Steeple Sign (Croup) vs Thumb Sign (Epiglottitis)

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Key Points for Exam (Quick Recall)

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References

• Nelson's Textbook of Pediatrics, 22nd edition - Chapter on Respiratory Tract Disorders
• Piyush Gupta - Principles of Pediatric and Neonatal Emergencies
• Bailey & Love's Short Practice of Surgery, 28th Ed., Ch. 52
• Scott-Brown's Otorhinolaryngology, Vol. 2, Ch. 29
• Rosen's Emergency Medicine, 10th Ed., Ch. 162
• Keil O, Schwerk N. Foreign body aspiration in children - being safe and flexible. Curr Opin Anaesthesiol. 2023 (PMID: 36745076) - supports flexible bronchoscopy as safe alternative
• Karišik M. Foreign body aspiration and ingestion in children. Acta Clin Croat. 2023 (PMID: 38746610)