10.2 Paediatric Respiratory Distress: Croup, Bronchiolitis & Wheeze
Key Takeaways
Assessment of paediatric respiratory distress relies on work of breathing (subcostal/intercostal recession, sternal indrawing, tracheal tug, nasal flaring, grunting) and age-specific tachypnoea thresholds (<2 months: >60/min; 2–11 months: >50/min; 1–5 years: >40/min).
Croup (laryngotracheobronchitis) is predominantly caused by parainfluenza virus in children aged 6 months to 3 years; oral dexamethasone (0.15 mg/kg stat) is the definitive first-line treatment for all severities, while severe croup requires nebulised adrenaline (1:1000) under close observation.
Acute epiglottitis (Haemophilus influenzae type b) is a life-threatening airway emergency characterized by toxic appearance, high fever, tripod position, drooling, and absent cough; direct examination or throat instrumentation is strictly forbidden, requiring immediate senior anaesthetic and ENT airway control in theatre.
Bronchiolitis is primarily driven by respiratory syncytial virus (RSV) in infants under 1 year (peak 3–6 months); clinical management is purely supportive (humidified oxygen for SpO2 <92% and NG/IV fluids for feed intake <50%), with NICE explicitly recommending against bronchodilators, corticosteroids, or antibiotics.
Preschool wheeze is predominantly viral-induced wheeze (VIW) lacking interval symptoms or atopic features; acute severe wheeze is treated with titrated inhaled salbutamol via spacer (up to 10 puffs), oral prednisolone (10–20 mg), and emergency escalation to nebulised bronchodilators or IV magnesium sulphate if failing to improve.
Paediatric Respiratory Distress: Croup, Bronchiolitis & Wheeze
Respiratory tract pathology represents the leading cause of emergency paediatric presentations and acute hospital admissions in the United Kingdom. Because young children possess narrow subglottic airways, high compliance of the cartilaginous thoracic cage, and high baseline metabolic demands, respiratory distress can rapidly transition to respiratory muscle exhaustion and catastrophic respiratory failure. Differentiating upper airway obstruction (stridor) from lower airway obstruction (wheeze and crackles) is the cornerstone of clinical evaluation.
Assessment of Paediatric Respiratory Distress
Clinical evaluation must assess the work of breathing, airway patency, physiological compromise, and respiratory exhaustion.
Clinical Signs of Increased Work of Breathing
- Tachypnoea: The earliest and most reliable compensatory sign of paediatric respiratory compromise. Thresholds defined by the Advanced Paediatric Life Support (APLS) framework:
- < 2 months: > 60 breaths/minute
- 2 to 11 months: > 50 breaths/minute
- 1 to 5 years: > 40 breaths/minute
- > 5 years: > 30 breaths/minute
- Chest Wall Recession: Negative intrathoracic pressures generated against airway resistance lead to dynamic inward collapse of compliant tissues:
- Subcostal recession: Indrawing below the lower costal margin.
- Intercostal recession: Inward movement of intercostal spaces.
- Sternal indrawing: Retraction of the sternum (sign of severe distress).
- Tracheal Tug: Inferior downward displacement of the thyroid cartilage and suprasternal notch during inspiration.
- Nasal Flaring: Dilatation of the alae nasi to reduce upper airway resistance.
- Expiratory Grunting: Forced expiration against a partially closed glottis to generate physiological positive end-expiratory pressure (PEEP), preventing alveolar collapse and maintaining functional residual capacity (FRC). Grunting is an ominous red-flag sign of impending respiratory failure.
- Head Bobbing: Scalene and sternocleidomastoid contractions pulling the head forward with each breath in exhausted infants.
Upper Airway Emergencies: Croup vs Acute Epiglottitis
Upper airway obstruction produces inspiratory stridor—a harsh, high-pitched vibratory sound arising from turbulent airflow through narrowed extrathoracic airways.
| Diagnostic Feature | Croup (Laryngotracheobronchitis) | Acute Epiglottitis |
|---|---|---|
| Primary Aetiology | Parainfluenza virus (types 1, 2, and 3 account for ~75%); RSV, influenza | Haemophilus influenzae type b (Hib); Streptococcus pneumoniae; Staphylococcus aureus |
| Typical Age Range | 6 months to 3 years (peak around 1–2 years) | 2 to 7 years (unimmunised or partially immunised children) |
| Onset & Progression | Gradual onset over 1–3 days; preceded by coryzal symptoms | Hyperacute, rapid progression over hours; no prodrome |
| Toxic Appearance & Fever | Generally non-toxic; low-grade pyrexia (< 38.5°C) | Severely toxic, septic appearance; high fever (> 39.0°C) |
| Cough & Voice | Loud, barking "seal-like" cough; hoarse voice | Absent or minimal cough; muffled, soft "hot potato" voice |
| Posture & Salivation | Restless or agitated; swallowing preserved, no drooling | Sitting upright in "tripod" position, neck extended; prominent drooling (dysphagia/odynophagia) |
| Emergency Throat Exam | Safe to inspect if necessary without agitating child | STRICTLY FORBIDDEN: Do not inspect or use tongue depressor! |
Croup (Laryngotracheobronchitis) Management
Croup involves inflammatory mucosal oedema of the larynx, trachea, and subglottic space. Symptoms characteristically worsen late at night.
- Severity Stratification (Westley Score):
- Mild: Occasional barking cough, hoarseness, no stridor at rest, no or mild recession.
- Moderate: Frequent barking cough, easily audible stridor at rest, intercostal and subcostal recession, child irritable but consolable.
- Severe: Prominent inspiratory stridor at rest, sternal indrawing, marked agitation or lethargy, tachypnoea, signs of fatigue.
- Definitive Pharmacotherapy: A single oral dose of dexamethasone (0.15 mg/kg) is indicated for all severities of croup (mild, moderate, and severe). It significantly reduces hospital admissions, the need for nebulised adrenaline, and repeat presentations. If vomiting, oral prednisolone (1–2 mg/kg) or nebulised budesonide (2 mg) can be substituted.
- Severe Croup / Impending Airway Exhaustion:
- Administer nebulised adrenaline (1:1000, 0.5 mL/kg up to a maximum of 5 mL) with high-flow oxygen.
- Adrenaline acts rapidly on alpha-adrenergic receptors to induce subglottic arteriolar vasoconstriction, shrinking mucosal oedema within 10–30 minutes.
- Safety Precautions: Keep the child calm on the parent's lap; crying drastically increases turbulence and accelerates obstruction. Adrenaline has a short duration of action (~2 hours) and mucosal rebound can occur; observe continuously for at least 4 hours post-nebulisation.
Acute Epiglottitis Management
Acute epiglottitis is a medical and surgical emergency causing supraglottic cellulitis and massive oedema of the lingual surface of the epiglottis, aryepiglottic folds, and arytenoids.
- The Golden Rule: DO NOT examine the throat with a tongue depressor, attempt venepuncture, or force the child into a supine position. Any invasive agitation can trigger immediate, fatal laryngospasm and complete airway occlusion.
- Immediate Escalation: Immediately summon the most senior paediatrician, consultant anaesthetist, and senior ENT surgeon.
- Airway Control in Theatre: Transfer the child calmly in the parent's arms directly to the operating theatre for urgent endotracheal intubation under gentle inhalational anaesthesia (sevoflurane).
- Antimicrobial Therapy: Following definitive airway securing, obtain blood cultures and initiate intravenous ceftriaxone (80 mg/kg).
Lower Airway Disorders: Bronchiolitis vs Preschool Wheeze
Lower airway obstruction causes expiratory airflow limitation, resulting in prolonged expiration and wheezing (a musical, polyphonic adventitious sound).
Bronchiolitis
Bronchiolitis is an acute viral infection of the lower respiratory tract leading to inflammatory epithelial necrosis, ciliary denudation, peribronchiolar lymphocytic infiltration, and mucus plugging of the terminal bronchioles.
- Epidemiology & Aetiology: Predominantly driven by Respiratory Syncytial Virus (RSV) in > 75% of cases (others include rhinovirus and human metapneumovirus). Affects infants under 1 year of age, peaking between 3 and 6 months during winter.
- Prevention: Since September 2024 the UK offers RSV vaccination in pregnancy from 28 weeks (antibodies cross the placenta to protect the infant in the first months of life); high-risk infants (for example those born very preterm or with haemodynamically significant congenital heart disease) may also receive a monoclonal antibody (palivizumab or nirsevimab) according to Green Book criteria.
- Clinical Presentation: Commences with a 1- to 3-day viral prodrome of coryza, clear rhinorrhoea, and mild fever, progressing to a persistent dry, harsh wheezy cough, tachypnoea, chest indrawing, and feeding difficulties. Auscultation reveals bilateral fine inspiratory crackles and diffuse high-pitched expiratory wheezes across all lung zones.
- NICE NG9 Admission Criteria:
- Oxygen saturation consistently < 92% in room air.
- Inadequate fluid intake (< 50% of normal daily intake over preceding 24 hours).
- Witnessed or reported apnoea.
- Severe respiratory distress (grunting, marked chest recession, or a respiratory rate over 70/min; NICE NG9).
- High-risk co-morbidities: Prematurity (< 32 weeks), congenital heart disease, chronic lung disease of prematurity (bronchopulmonary dysplasia).
- Evidence-Based Management (Supportive Care):
- Oxygenation: Humidified supplemental oxygen via nasal prongs to maintain SpO2 ≥ 92%.
- Hydration & Nutrition: Nasogastric (NG) tube feeding if oral intake is 50% or less; intravenous isotonic fluids (0.9% saline with 5% glucose) if enteral feeding is unsafe due to respiratory distress or vomiting.
- What NOT to Prescribe (NICE Negative Guidance): Extensive clinical trials confirm that salbutamol, systemic or inhaled corticosteroids, nebulised adrenaline, montelukast, and antibiotics provide NO clinical benefit in bronchiolitis and must NOT be routinely prescribed.
Preschool Wheeze vs Paediatric Asthma
Wheezing in preschool children (< 5 years) is extremely prevalent, occurring in up to one-third of children. It is essential to differentiate viral-induced wheeze from true emerging paediatric asthma.
| Clinical Characteristic | Viral-Induced Wheeze (VIW) | Paediatric Asthma / Multi-Trigger Wheeze |
|---|---|---|
| Triggers | Exclusively viral upper respiratory tract infections | Viral infections PLUS exercise, cold dry air, animal dander, house dust mites, emotional crying |
| Interval Symptoms | Completely asymptomatic between viral colds; no cough or wheeze | Persistent interval symptoms: Nocturnal waking with cough, early morning wheeze, exercise limitation |
| Atopic Background | No personal history of eczema or allergic rhinitis; negative family history of atopy | Personal history of atopic eczema or food allergies; strong first-degree family history of asthma/atopy |
| Long-Term Prognosis | Benign natural history; typically resolves completely by age 5–6 as airway calibre enlarges | Often persists into middle childhood and adolescence; represents true chronic airway inflammation |
Acute Management of Paediatric Wheeze (BTS/SIGN & NICE Guidelines)
When a child over 1 year presents with acute wheeze, management follows a standardized, escalating protocol:
- Inhaled Beta-2 Agonist: Administer salbutamol via a metered-dose inhaler (MDI) with a volume spacer and facemask:
- Mild-to-moderate wheeze: 2 to 6 puffs.
- Severe wheeze: Up to 10 puffs (administered as 1 puff every 30–60 seconds, with the child breathing 5 normal tidal breaths per puff).
- Oral Systemic Corticosteroids: Indicated for moderate-to-severe exacerbations:
- Oral prednisolone for 3 days:
- Age < 2 years: 10 mg daily.
- Age 2 to 5 years: 20 mg daily.
- Age > 5 years: 30–40 mg daily.
- Oral prednisolone for 3 days:
- Controlled Oxygen Therapy: High-flow oxygen via Hudson mask or reservoir bag to maintain target saturation 94% to 98%.
- Second-Line Escalation (Severe / Refractory Wheeze):
- Nebulised bronchodilators: Back-to-back nebulised salbutamol (2.5 mg for < 5 years; 5 mg for ≥ 5 years) driven by oxygen, combined with nebulised ipratropium bromide (250 mcg) every 20–30 minutes for the first hour.
- Intravenous Magnesium Sulphate (40 mg/kg, max 2 g) infused over 20 minutes to achieve bronchial smooth muscle relaxation.
- Intravenous aminophylline or intravenous salbutamol in a High Dependency Unit (HDU) or Paediatric Intensive Care Unit (PICU) under continuous ECG and hemodynamic monitoring.
A 14-month-old boy is brought to the emergency department at 02:00 with sudden-onset noisy breathing and a harsh, loud cough described by his father as sounding like a barking seal. He had a mild runny nose over the previous two days. On examination, the toddler is sitting quietly on his mother's lap. He has an occasional barking cough and hoarse vocalizations. There is mild subcostal indrawing, but no stridor is audible while he rests calmly. However, when he cries during examination, a harsh inspiratory stridor becomes clearly audible. His oxygen saturation is 98% in room air and temperature is 37.8°C. What is the most appropriate first-line medical intervention?
Inhaled salbutamol 10 puffs via spacer and close observation
A single dose of oral dexamethasone (0.15 mg/kg stat)
Intravenous amoxicillin and clavulanic acid for 7 days
Immediate nebulised adrenaline (1:1000, 5 mL) with high-flow oxygen
A 4-month-old baby girl is admitted to the paediatric assessment unit with a 2-day history of clear rhinorrhoea and sneezing, followed by progressive cough, breathlessness, and poor feeding. On examination, she is tachypnoeic with a respiratory rate of 66 breaths/min, marked subcostal recession, and nasal flaring. Auscultation demonstrates widespread bilateral high-pitched expiratory wheezes accompanied by fine inspiratory crackles throughout both lung fields. Her oxygen saturation is 89% in room air, and her parents report that she has taken less than 40% of her usual formula milk over the past 24 hours. Which of the following is the most appropriate initial management?
Administer humidified oxygen via nasal cannulae to maintain SpO2 ≥ 92% and initiate nasogastric tube feeding
Start intravenous cefotaxime 50 mg/kg and oral erythromycin for atypical bacterial infection
Administer 10 puffs of inhaled salbutamol via spacer and oral prednisolone 10 mg daily for 3 days
Administer nebulised adrenaline 1:1000 and nebulised 3% hypertonic saline solution
A 3-year-old boy who has never received routine childhood vaccinations is brought to the emergency department looking extremely unwell. His parents state that he became rapidly breathless and feverish over the last 4 hours. On arrival, the child is toxic, anxious, and sitting rigidly upright on the stretcher, leaning forward with his hands on his knees. Saliva is continuously drooling from his mouth, his speech is muffled, and he produces a soft, inspiratory stridor with each breath. His temperature is 39.8°C and he has no cough. Which of the following is the most dangerous and contraindicated intervention?
Transferring the child directly to the operating theatre for inhalational induction
Summoning an on-call consultant anaesthetist and ENT surgeon to the emergency department
Calming the parents and allowing the child to remain sitting in his preferred posture
Depressing the tongue with a wooden spatula to directly inspect the posterior pharynx
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