Croup & Epiglottitis

Two of the most heavily-tested causes of acute upper-airway obstruction with stridor in children. The single most rewarding skill for NEET PG is the rapid bedside and radiological discrimination between viral croup (a barking, slowly-evolving, usually benign laryngotracheobronchitis) and acute epiglottitis (a fulminant, life-threatening supraglottic cellulitis). Get the "steeple vs thumb" and "dexamethasone vs secure-the-airway-first" pairs absolutely reflexive.

Definitions & classification

Stridor is a harsh, monophonic sound from turbulent airflow through a partially obstructed airway. Its timing localises the lesion:

• Inspiratory stridor → obstruction above the thoracic inlet (supraglottic/glottic) — laryngomalacia, croup, epiglottitis.
• Expiratory stridor / wheeze → intrathoracic (lower trachea, bronchi).
• Biphasic stridor → fixed lesion at the level of the glottis/subglottis (subglottic stenosis, bacterial tracheitis, foreign body at carina).

Croup (acute laryngotracheobronchitis) is inflammation centred on the subglottic region (the narrowest part of a child's airway, the cricoid ring). Because the cricoid is a complete non-distensible ring, even mild oedema markedly narrows the lumen (Poiseuille: resistance ∝ 1/r⁴).

Acute epiglottitis (supraglottitis) is bacterial cellulitis of the epiglottis and aryepiglottic folds — a supraglottic process that can occlude the airway within hours.

Type of croup	Notes
Viral croup (classic LTB)	Commonest; parainfluenza; 6 mo–3 yr; prodrome of coryza
Spasmodic (recurrent) croup	Sudden nocturnal onset, no fever, allergic/atopic basis, recurs
Bacterial tracheitis	"Membranous croup"; Staph aureus; toxic child, high fever, poor steroid response — a croup mimic that needs antibiotics + often intubation

High-yield: The narrowest part of the paediatric airway is the subglottis (cricoid ring), unlike adults where the glottis (rima glottidis) is narrowest. This is why subglottic oedema in croup is so symptomatic.

Etiology & pathophysiology

Viral croup

• Parainfluenza virus type 1 is the single most common cause (also types 2 and 3). Others: RSV, influenza A/B, adenovirus, human metapneumovirus, measles (in unimmunised).
• Peak: 6 months to 3 years, autumn/early winter, boys > girls.
• Mucosal inflammation and oedema of the subglottic larynx and trachea → luminal narrowing → inspiratory stridor + the characteristic barking ("seal-like") cough and hoarse voice (vocal cord involvement).

Acute epiglottitis

• Classic organism: Haemophilus influenzae type b (Hib). Incidence has collapsed in countries with Hib conjugate vaccine; in the post-vaccine era it is increasingly caused by Streptococcus pneumoniae, group A Streptococcus, Staph aureus, and is now relatively more common in adults / older children.
• Supraglottic cellulitis → cherry-red, swollen epiglottis → rapid mechanical obstruction; the child cannot handle secretions → drooling.

High-yield: A child with epiglottitis-like illness who is fully Hib-immunised should raise suspicion of S. pneumoniae or S. pyogenes. Always ask about/state immunisation status in stems.

Clinical features — the bedside discriminator

The exam loves the contrasting picture. Memorise it as a paired table.

Feature	Viral Croup	Acute Epiglottitis
Onset	Gradual (1–2 days), preceded by coryza	Sudden, fulminant (hours)
Age	6 mo – 3 yr	2 – 6 yr (classically); also adults
Cough	Barking / seal-like	Absent or minimal
Voice	Hoarse	Muffled / "hot-potato", no hoarseness
Stridor	Loud, inspiratory	Soft inspiratory ("quiet stridor" — ominous)
Fever	Low-grade	High (>39 °C), toxic
Drooling	Absent	Present (cannot swallow secretions)
Dysphagia	Absent	Present
Posture	Variable	Tripod / sniffing, leaning forward, neck extended
Appearance	Non-toxic, playful	Toxic, anxious, still
Cough vs ill-look	Cough prominent, child well	Child very ill, cough absent

The classic epiglottitis triad/mnemonic — the "4 Ds": Drooling, Dysphagia, Dysphonia (muffled), Distress (some add a 5th D = high-grade fever/"Dyspnoea"). The tripod position with sniffing-dog posture maximises airway calibre.

High-yield: In suspected epiglottitis, do NOT examine the throat with a tongue depressor, lay the child supine, take blood, or do anything that distresses the child — any of these can precipitate complete laryngospasm and fatal obstruction. Keep the child upright in the parent's lap.

Investigations & investigation of choice

Diagnosis is largely clinical, especially for epiglottitis where stability trumps imaging.

Croud — lateral/AP neck X-ray (only if diagnosis uncertain):

• AP neck film → "Steeple sign" (pencil-point / wine-bottle sign) = symmetrical subglottic narrowing tapering the tracheal air column. This is the classic croup radiographic sign.

Epiglottitis — lateral neck X-ray (soft tissue):

• "Thumb sign" = swollen, rounded epiglottis resembling a thumbprint.
• Other lateral-film clues: thickened aryepiglottic folds, ballooned hypopharynx, loss of the vallecula ("vallecula sign" — obliteration of the air pocket between tongue base and epiglottis).
• Imaging is optional and must never delay airway management; never send an unstable child to a remote X-ray room without airway-skilled staff.

Definitive diagnosis of epiglottitis = direct visualisation of the cherry-red, swollen epiglottis — and this should be done in a controlled environment (OT) with anaesthesia + ENT ready to secure the airway (gold standard = laryngoscopy under controlled conditions).

Sign	Disease	Film/view
Steeple sign	Croup	AP neck
Thumb sign / vallecula sign	Epiglottitis	Lateral neck
"Shaggy"/irregular tracheal membrane	Bacterial tracheitis	Lateral neck
Radiolucent/radio-opaque object	Foreign body	AP + lateral

High-yield: Steeple sign is AP view; thumb sign is lateral view. Examiners frequently swap the views to trip you up.

Severity grading — the Westley Croup Score

The Westley score quantifies croup severity (max 17). It is highly examinable for both its components and its cut-offs.

Parameter	Options (points)
Level of consciousness	Normal 0; Disoriented 5
Cyanosis	None 0; with agitation 4; at rest 5
Stridor	None 0; with agitation 1; at rest 2
Air entry	Normal 0; decreased 1; markedly decreased 2
Retractions	None 0; mild 1; moderate 2; severe 3

Interpretation: ≤2 = mild · 3–7 = moderate · 8–11 = severe · ≥12 = impending respiratory failure.

High-yield: Stridor at rest marks the transition from mild to at least moderate croup and is the threshold for considering nebulised adrenaline. Note that the score is weighted toward signs of hypoxia/effort, not the loudness of the cough.

Management

Stepwise approach to a child with stridor

Assess (do not agitate) → decide croup vs epiglottitis vs other → if toxic/drooling/quiet-stridor → treat as epiglottitis: SECURE AIRWAY FIRST → if barking cough/non-toxic → treat as croup medically.

Croup — drug of choice

1. Keep the child calm, on the parent's lap; cool humidified air has historically been used but has no proven benefit in trials (don't pick "humidified air/steam" as the best answer).
2. Corticosteroids for ALL severities — drug of choice = a single dose of oral dexamethasone 0.15–0.6 mg/kg (0.6 mg/kg most studied; even mild croup benefits). Oral = IM = nebulised budesonide in efficacy; oral dexamethasone is preferred for being cheap, single-dose, long-acting.
3. Nebulised (racemic or L-) adrenaline 0.5 mL/kg of 1:1000 (max ~5 mL) for moderate–severe croup / stridor at rest. Onset within 10–30 min; effect wanes by ~2 hours.
4. Oxygen / Heliox and observation for moderate–severe disease.
5. Intubation only for impending failure (a minority).

High-yield (rebound phenomenon): After nebulised adrenaline the child must be observed for at least 3–4 hours because of "rebound" worsening once the drug wears off. Steroid given concurrently blunts this. A child who received adrenaline should not be discharged immediately.

High-yield: Dexamethasone is the drug of choice for croup of every severity, including mild. Nebulised adrenaline is added for moderate–severe (stridor at rest), never used alone as definitive therapy.

Epiglottitis — airway first, antibiotics second

The priority is a definitive airway, NOT antibiotics.

1. Do not disturb the child. Transfer to OT/ICU; the most skilled person (anaesthetist ± ENT) performs controlled intubation under inhalational general anaesthesia, with equipment for emergency tracheostomy standing by.
2. After the airway is secured, take blood cultures and start IV antibiotics: ceftriaxone or cefotaxime (third-generation cephalosporin) for 7–10 days. Add anti-staphylococcal cover (e.g., vancomycin) if MRSA likely.
3. Chemoprophylaxis with rifampicin for close/household contacts if the case is Hib and there are unimmunised/at-risk contacts < 4 yr (or immunocompromised).

High-yield: Best initial step in suspected epiglottitis = secure the airway in a controlled setting, not "start IV ceftriaxone" and not "lateral neck X-ray." Antibiotics follow airway control.

Indications for intubation (either disease)

• Progressive/worsening obstruction despite therapy; rising PaCO₂ / falling SpO₂.
• Exhaustion, depressed consciousness, cyanosis at rest (Westley ≥8 trending up, ≥12 = impending failure).
• Epiglottitis: low threshold — most need a secured airway.

Differential diagnosis

Condition	Key distinguishing clue
Bacterial tracheitis	Toxic, high fever, thick purulent secretions, poor response to adrenaline/steroid, S. aureus; "membranous croup"
Foreign body aspiration	Sudden onset in a previously well toddler, no fever, history of choking, unilateral findings
Retropharyngeal abscess	Neck stiffness, drooling, bulging posterior pharyngeal wall, widened prevertebral soft tissue on lateral film
Peritonsillar abscess (quinsy)	Older child, trismus, uvular deviation, "hot-potato" voice
Laryngomalacia	Neonate/young infant, stridor worse supine/feeding, better prone; chronic, benign
Angioedema / anaphylaxis	Urticaria, lip/face swelling, allergen exposure, rapid
Diphtheria	Unimmunised, grey adherent pseudomembrane that bleeds on removal, bull-neck

High-yield: A "croup" that does not respond to nebulised adrenaline and dexamethasone, with a toxic high-fever child, is bacterial tracheitis until proven otherwise — needs antibiotics (anti-staph) and often intubation.

Complications

• Croup: dehydration, secondary bacterial tracheitis, rarely pneumothorax/pneumomediastinum from airway pressure, post-obstructive pulmonary oedema after relief of obstruction, hypoxic complications if obstruction severe.
• Epiglottitis: complete airway obstruction and death (the feared complication), aspiration, secondary septic foci of Hib (meningitis, septic arthritis, cellulitis, pneumonia), post-obstructive pulmonary oedema.

Prevention

• Hib conjugate vaccine has dramatically reduced epiglottitis incidence — a favourite single-best-answer for "most important factor in declining incidence."
• No specific vaccine for viral croup; influenza vaccination indirectly reduces some cases.

Recently asked / exam angle

• Image-based: AP neck film with subglottic tapering → "steeple sign → diagnosis = croup." Lateral neck film with rounded epiglottis → "thumb sign → epiglottitis."
• Drug-of-choice stems: "Best/initial drug in croup of any severity" = oral dexamethasone; "added agent for stridor at rest / severe croup" = nebulised adrenaline.
• Management-priority stems: drooling + tripod + muffled voice + high fever → "next best step" = secure airway in controlled setting (OT), NOT throat examination, NOT supine X-ray, NOT immediate IV antibiotics.
• One-liner traps: narrowest airway in children = subglottis/cricoid; commonest cause of croup = parainfluenza type 1; classic cause of epiglottitis = Hib (but think pneumococcus/GAS if immunised).
• "Do-not-do" question: what is contraindicated in epiglottitis → tongue-depressor throat exam / making the child lie down / agitating the child.
• Westley score: components and the cut-off where "stridor at rest" begins to matter.
• Mimic question: unresponsive "croup" + toxic child → bacterial tracheitis (S. aureus).
• Rebound after nebulised adrenaline → minimum 3–4 h observation before discharge.

Rapid revision

1. Narrowest part of paediatric airway = subglottis (cricoid ring); in adults = glottis.
2. Commonest cause of croup = parainfluenza virus type 1; age 6 mo–3 yr.
3. Croup = barking cough + hoarse voice + inspiratory stridor, child non-toxic.
4. Croup X-ray = steeple sign on AP view (subglottic narrowing).
5. Dexamethasone (oral, single dose) is the drug of choice for croup of ALL severities.
6. Nebulised adrenaline added for moderate–severe croup / stridor at rest; observe 3–4 h for rebound.
7. Westley score grades croup: ≤2 mild, 3–7 moderate, 8–11 severe, ≥12 impending failure.
8. Epiglottitis = Hib classically; now also pneumococcus/GAS in vaccinated populations; older children/adults.
9. Epiglottitis = 4 Ds — Drooling, Dysphagia, Dysphonia (muffled), Distress + tripod/sniffing posture, toxic, no barking cough.
10. Epiglottitis X-ray = thumb sign on lateral view; never delay airway for imaging; do not examine throat or lay child supine.
11. Epiglottitis management = secure airway first (controlled intubation in OT), then IV ceftriaxone/cefotaxime; rifampicin prophylaxis for Hib contacts.
12. Croup not responding to adrenaline + steroid in a toxic febrile child = bacterial tracheitis (S. aureus) — needs antibiotics ± intubation.