4.1 Upper Airway Obstruction

Upper vs Lower Airway Obstruction: Clinical Discrimination

Respiratory Emergencies account for about 15% of PALS content, and many items hinge on placing the problem above or below the thoracic inlet. Anatomy drives the sounds and the therapy. The upper airway (nose, pharynx, larynx, and extrathoracic trachea) is a narrow tube; small decreases in caliber produce large increases in resistance (Poiseuille’s relationship). The lower airways (intrathoracic trachea, bronchi, bronchioles) narrow further on expiration, so small-airway disease lengthens the expiratory phase.

Exam-level contrast table

Stridor is turbulent flow through a narrowed extrathoracic airway and is classically inspiratory. Wheeze is lower-airway narrowing and is classically expiratory. Real children can have mixed findings (for example anaphylaxis affecting both larynx and lower airways), but the exam expects you to pick the dominant pattern and the matching first intervention.

Severity signals that apply to any upper-airway problem

• Partial obstruction with effective cough and ability to cry/speak → support, oxygen if needed, allow the child to clear if possible.
• Ineffective cough, silent or weak cry, cyanosis, or progressive lethargy → emergency obstruction pathway (FBAO maneuvers or advanced airway support depending on cause).
• Drooling, tripod posture, and toxic appearance raise concern for severe infectious obstruction—minimize agitation and prepare for difficult airway with expert help.

Croup (Laryngotracheobronchitis)

Croup is the most common infectious upper-airway obstruction in toddlers. Viral inflammation (often parainfluenza) narrows the subglottic trachea. The classic history is a young child with a preceding upper respiratory infection who develops a barking/seal-like cough, hoarse voice, and inspiratory stridor, often worse at night.

Clinical picture on the PAT and primary assessment

• Appearance: May be anxious but usually interactive unless severe or failing.
• Work of breathing: Tachypnea, stridor, suprasternal retractions; severity tracks with stridor at rest and degree of effort.
• Circulation to skin: Usually normal early; cyanosis is late.

Severity framing used on exams:

• Mild: Barky cough, minimal or no stridor at rest, little work of breathing.
• Moderate: Stridor at rest, moderate retractions, still interactive.
• Severe: Marked stridor, severe retractions, agitation or fatigue, hypoxia—this is upper-airway obstruction with high risk of failure.
• Impending failure: Quiet breathing after severe effort, lethargy, poor air entry, bradycardia.

Management priorities (exam level)

1. Keep the child calm. Agitation worsens dynamic obstruction. Allow preferred posture; avoid forced examination of the throat if the child is severely obstructed.
2. Oxygen as needed for hypoxemia or significant distress (blow-by if a mask increases agitation).
3. Cool mist / humidified air is traditional supportive care in many protocols; it is adjunctive comfort, not a substitute for epinephrine when obstruction is significant.
4. Nebulized epinephrine (often racemic epinephrine) when there is stridor at rest or moderate-to-severe obstruction. Epinephrine reduces laryngeal mucosal edema via α-adrenergic vasoconstriction. Observe after dosing because rebound can occur as the drug wears off.
5. Corticosteroids (commonly dexamethasone in clinical practice) reduce inflammation and are standard for croup; PALS vignettes may mention steroid therapy as part of definitive medical care after acute airway support.
6. If respiratory failure develops—inadequate effort, severe hypoxia, progressive lethargy—open the airway and provide bag-mask ventilation with oxygen; prepare for advanced airway with anticipated difficulty and call for the most experienced airway clinician available.

Differentials the exam may contrast

• Foreign body: Sudden onset during eating or play, may lack viral prodrome.
• Anaphylaxis: Rapid onset with urticaria, angioedema, wheeze, hypotension.
• Epiglottitis / bacterial tracheitis: Toxic appearance, high fever, drooling (epiglottitis), or toxic child with croup-like picture that worsens—rare but high stakes; do not agitate; early airway expertise.

Do not confuse mild croup (supportive care) with severe obstruction needing nebulized epinephrine and possible assisted ventilation.

Foreign-Body Airway Obstruction (FBAO) — 2025 AHA/AAP Updates

Foreign-body aspiration is a classic sudden-onset upper-airway emergency. Suspect FBAO when a previously well child develops acute coughing, gagging, stridor, or inability to speak or cry during eating or play—especially with small objects, nuts, grapes, or hot dogs.

Responsive child: complete vs partial obstruction

2025 relief sequences (must memorize)

Infants (<1 year):

1. Deliver 5 back blows (infant face-down along forearm, head lower than chest, blows between scapulae with heel of hand).
2. Turn infant face-up and deliver 5 chest thrusts (two fingers on lower half of sternum, similar position to infant CPR compressions).
3. Repeat cycles of 5 back blows + 5 chest thrusts until the object is expelled or the infant becomes unresponsive.
4. Do not use abdominal thrusts in infants—risk of solid-organ injury.

Children (≥1 year):

1. Deliver 5 back blows (lean child forward; heel of hand between scapulae).
2. Deliver 5 abdominal thrusts (Heimlich-type: fist above navel, upward thrusts).
3. Alternate 5 back blows + 5 abdominal thrusts until the object is expelled or the child becomes unresponsive.

The 2025 emphasis on combining back blows with thrusts for children (not thrusts alone as the only remembered step) is a high-yield update relative to older single-maneuver mental models. Match the sequence to age on every vignette.

If the child becomes unresponsive

1. Start CPR immediately (begin with chest compressions as for cardiac arrest/BLS).
2. Each time the airway is opened for breaths, look in the mouth—if you see a foreign body, remove it.
3. Never perform blind finger sweeps—you may push the object deeper or cause injury.
4. Attempt ventilation when indicated by the BLS sequence; if the chest does not rise, reposition and continue CPR with checks for a visible object.
5. Activate emergency response / ALS backup early.

Link to PALS advanced care

After relief, reassess ABCs. Residual wheeze or focal findings may indicate a remaining distal foreign body needing imaging and specialty care. If obstruction cannot be relieved and the child remains critically ill, advanced airway attempts and surgical airway readiness may be required in real systems—exam focus stays on correct BLS FBAO sequence and no blind sweeps.

Anaphylaxis with Airway Involvement

Anaphylaxis is a rapid, multi-system allergic reaction that can obstruct the upper airway (laryngeal edema, tongue swelling) and constrict lower airways (bronchospasm) while causing distributive shock. Triggers include foods (peanut, tree nut, shellfish, milk), insect stings, medications, and latex.

Recognition clues

• Acute onset after exposure (minutes to a few hours).
• Skin/mucosal signs: urticaria, flushing, angioedema of lips/tongue/face.
• Respiratory: stridor, hoarseness, drooling, wheeze, dyspnea, hypoxia.
• Circulatory: tachycardia, hypotension, poor perfusion (may present as shock).
• GI: vomiting, crampy pain (supportive of multi-system involvement).

Not every case has a full rash. Airway and circulation findings alone can still be anaphylaxis when the history fits.

First-line therapy

1. Intramuscular epinephrine in the mid-outer thigh immediately—this is the definitive first-line drug. Do not delay IM epinephrine to start an IV, give antihistamines alone, or "watch the rash."
2. Position of comfort; if hypotensive, supine with legs elevated when feasible (avoid forcing flat if severe respiratory distress requires upright posture—use clinical judgment).
3. High-flow oxygen and airway support; prepare for bag-mask and difficult airway if edema progresses.
4. Rapid IV/IO access after epinephrine for fluid boluses if shock is present (isotonic crystalloid per shock algorithms).
5. Adjuncts (antihistamines, bronchodilators for wheeze, corticosteroids) are secondary—they do not replace epinephrine.
6. Observe for biphasic recurrence; prepare for repeat IM epinephrine if symptoms return.

Exam traps

• Choosing diphenhydramine or steroids as the first drug when airway/breathing/circulation are threatened.
• Confusing isolated mild urticaria with anaphylaxis—but when stridor, respiratory distress, or hypotension is present, treat as anaphylaxis.
• Forgetting that anaphylaxis can present with both upper-airway stridor and lower-airway wheeze; epinephrine still comes first.

Clinical scenario (synthesis)

A 4-year-old develops facial swelling, inspiratory stridor, and wheezing minutes after a peanut exposure. The child is anxious with retractions; SpO2 is 91% on room air. This is anaphylaxis with upper- and lower-airway involvement. Immediate action: IM epinephrine, oxygen, continuous monitoring, IV access and fluids if perfusion worsens, and readiness to support the airway. Nebulized bronchodilators may help wheeze but are not a substitute for epinephrine. If the child later becomes unresponsive with no effective breathing, treat as arrest with CPR and airway support—still remove only a visible foreign body if FBAO were the differential, but here the pathophysiology is edema, not a peanut lodged as a classic solid FB (history guides you).

Mastering upper-airway patterns—croup, FBAO, anaphylaxis—and matching each to the correct first move is core PALS respiratory content and feeds directly into the ventilation skills in Section 4.3.