10.2 Pediatric Respiratory & Infectious Illnesses

Pediatric Respiratory & Infectious Illnesses

Respiratory emergencies and infectious diseases account for the majority of acute pediatric admissions. Because young children possess unique anatomical, physiological, and immunological vulnerabilities, nurses must rapidly differentiate benign upper respiratory illnesses from life-threatening airway emergencies, initiate aggressive supportive care, and enforce strict transmission-based infection control.

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Pediatric Respiratory Anatomical & Physiological Peculiarities

A child's airway is not merely a miniature version of an adult airway; distinct anatomical characteristics increase susceptibility to rapid respiratory decompensation:

• Narrow Airway Caliber & Poiseuille's Law:
  • In infants, the normal subglottic airway diameter is only 4 to 5 mm (compared to 18 to 20 mm in adults).
  • According to Poiseuille's Law, resistance to laminar airflow is inversely proportional to the fourth power of the airway radius ($R \propto 1/r^4$).
  • Worked Comparison: With a 4-mm airway diameter, 1-mm circumferential edema reduces radius from 2 to 1 mm: area falls by 75% and modeled resistance rises (2/1)^4 = 16-fold. In a 20-mm-diameter adult airway, radius falls from 10 to 9 mm: area falls by 19% and resistance rises (10/9)^4, approximately 1.52-fold. These calculations illustrate why small pediatric airways are vulnerable.
• Tongue and Oropharynx Size:
  • The infant tongue is proportionately massive relative to the small oral cavity. When muscle tone decreases (e.g., during sedation, lethargy, or anesthesia), the tongue easily falls posterior against the pharyngeal wall, causing complete upper airway obstruction.
• Laryngeal Position and Funnel Configuration:
  • The pediatric larynx is situated higher and more anterior in the neck (at cervical vertebra C3–C4 in infants vs. C4–C5 in adults).
  • The narrowest anatomical portion of the pediatric airway prior to puberty (under 8 to 10 years of age) is the rigid cricoid cartilage ring (funnel-shaped airway), unlike the adult airway where the narrowest point is the vocal cords (cylindrical airway).
• Epiglottic Morphology:
  • The pediatric epiglottis is longer, narrower, less rigid, and shaped like an "omega" ($\Omega$) or "U", angled obliquely toward the posterior pharyngeal wall, making it highly vulnerable to inflammation, floppy collapse, and traumatic injury.
• Compliant Thoracic Cage & Diaphragmatic Breathing:
  • Pediatric ribs are composed of pliable cartilage and are aligned horizontally rather than obliquely downward. Intercostal muscles are underdeveloped and fatigue quickly.
  • Infants and young children rely almost exclusively on the diaphragm for tidal breathing ("abdominal breathers"). Any abdominal distension (gas, full stomach, organomegaly) impedes diaphragmatic excursion and severely compromises minute ventilation.
  • High respiratory effort causes the soft, cartilaginous chest wall to collapse inward during inspiration, producing visible substernal, subcostal, and intercostal retractions.
• Obligate Nose Breathing:
  • Infants are obligate nasal breathers until 4 to 6 months of age due to the high approximation of the soft palate and epiglottis. Nasal congestion or copious secretions can precipitate acute respiratory failure in early infancy.

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Upper Airway Infections: Croup vs. Acute Epiglottitis

Differentiating viral croup from acute bacterial epiglottitis is one of the most critical clinical distinctions in emergency pediatric nursing.

Acute Laryngotracheobronchitis (Viral Croup)

Croup is an acute viral infection characterized by mucosal inflammation and subglottic edema of the larynx, trachea, and bronchi.

• Etiology & Epidemiology: Most commonly caused by Parainfluenza viruses (types 1, 2, and 3), followed by respiratory syncytial virus (RSV), adenoviruses, and influenza. Typically affects children aged 6 months to 3 years, with peak incidence in autumn and winter.
• Clinical Presentation:
  • Onset is gradual over 2 to 3 days, typically preceded by mild upper respiratory symptoms (rhinorrhea, low-grade fever).
  • Characterized by the classic triad: (1) a barking "seal-like" brassy cough, (2) hoarseness, and (3) inspiratory stridor accompanied by varying degrees of respiratory distress (retractions, nasal flaring).
  • Symptoms characteristically worsen at night and escalate dramatically when the child becomes agitated or cries.
• Radiographic Findings: Anteroposterior (AP) soft-tissue neck radiograph reveals classic subglottic tracheal narrowing termed the "Steeple Sign" (or pencil-point sign).
• Nursing & Medical Management:
  • Environmental Support: Maintain a calm, unhurried environment. Keep the child comfortably seated on the parent's lap, as agitation increases oxygen demand and worsens subglottic narrowing.
  • Supportive Care: Keep the child calm with a caregiver in a comfortable position. Humidified mist has not been shown to improve croup severity and should not replace corticosteroids or indicated nebulized epinephrine.
  • Corticosteroid Therapy: Dexamethasone (oral or IM, 0.15 to 0.6 mg/kg, maximum 16 mg single dose) is the cornerstone of treatment for all severities of croup. Its long biological half-life (36 to 54 hours) reduces laryngeal mucosal edema within 1 to 2 hours of administration.
  • Nebulized Racemic Epinephrine: Indicated for moderate-to-severe croup manifesting with inspiratory stridor at rest, marked suprasternal/intercostal retractions, or agitation. Administered as 0.5 mL of 2.25% racemic epinephrine solution diluted in 2.5 to 3.0 mL normal saline via nebulizer. Racemic epinephrine stimulates mucosal alpha-1 adrenergic receptors, inducing rapid local precapillary vasoconstriction that dramatically shrinks subglottic edema within 10 to 30 minutes.
  • CRITICAL REBOUND SURVEILLANCE: Racemic epinephrine has a short duration of action (~2 hours). As the drug metabolizes, mucosal vasodilation may recur, precipitating rebound stridor and severe airway obstruction. Therefore, the nurse must monitor the child in the healthcare facility for a minimum of 3 to 4 hours post-nebulization before considering discharge.

Acute Epiglottitis (Supraglottitis)

Epiglottitis is a fulminant, life-threatening bacterial cellulitis of the epiglottis, aryepiglottic folds, and surrounding supraglottic structures that can progress to complete fatal airway occlusion within minutes to hours.

• Etiology: Historically caused by Haemophilus influenzae type b (Hib). Although universal Hib conjugate vaccination has drastically decreased its incidence, epiglottitis still occurs in unimmunized/undervaccinated children, or can be caused by Streptococcus pneumoniae, Staphylococcus aureus, or group A Streptococcus. Peak age is typically 2 to 7 years.
• Clinical Presentation:
  • Onset is acute, abrupt, and rapidly progressive over several hours.
  • High fever (often >39.0°C / 102.2°F), severe sore throat, toxic appearance, and marked anxiety.
  • The Classic "4 Ds" of Epiglottitis:
    1. Drooling: Copious pooling and drooling of saliva because extreme supraglottic odynophagia makes swallowing impossible.
    2. Dysphagia: Inability or severe pain upon attempting to swallow.
    3. Dysphonia: Muffled, thickened, hoarse "hot potato" speech, or complete aphonia.
    4. Distressed Inspiratory Efforts: High-pitched inspiratory stridor, tachypnea, suprasternal retractions, and cyanosis.
  • Characteristic Posture: The child assumes the Tripod Position—sitting upright, leaning forward with arms braced on the knees or bed, chin thrust forward, neck hyperextended, and mouth open with tongue protruding to mechanically maximize upper airway caliber.
• Radiographic Findings: Lateral soft-tissue neck radiograph reveals an enlarged, rounded, edematous epiglottis resembling an adult thumb, known as the "Thumbprint Sign". (Radiographs should only be obtained if the airway is stable and must NEVER delay definitive airway management).
• CRITICAL NURSING PROHIBITION: STRICTLY PROHIBITED TO VISUALIZE THE PHARYNX, INSERT A TONGUE DEPRESSOR, OR COLLECT A THROAT SWAB! Any mechanical stimulation of the hypersensitive, hyperemic epiglottis can provoke instantaneous, reflex-mediated laryngospasm and complete, irreversible airway obstruction. The nurse must also avoid taking rectal temperatures, starting IV lines, or separating the child from the parents until the airway is secured.
• Emergency Airway Protocol:
  1. Immediately activate the pediatric emergency airway response team (anesthesiology, pediatric intensivist, and otolaryngologist/ENT surgeon) with emergency intubation and tracheostomy equipment readily available.
  2. Keep the child completely calm, undisturbed, and upright on the parent's lap; administer blow-by humidified oxygen if tolerated.
  3. Transport the patient immediately to the operating room (OR) where controlled endotracheal intubation can be performed under general inhalation anesthesia by the most experienced airway specialist.
  4. Once the artificial airway is definitively established, obtain blood cultures and initiate intravenous antibiotic therapy with a third-generation cephalosporin (Ceftriaxone or Cefotaxime) plus an anti-staphylococcal agent (Vancomycin) for 7 to 10 days.

Clinical Comparison: Croup vs. Epiglottitis

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Lower Airway Disorders: Bronchiolitis & Pediatric Asthma

Acute Bronchiolitis & Respiratory Syncytial Virus (RSV)

Bronchiolitis is an acute viral lower respiratory tract infection of the small airways (bronchioles) characterized by inflammation, cellular necrosis, mucus production, and bronchospasm.

• Pathophysiology: Respiratory Syncytial Virus (RSV) causes over 80% of cases. The virus invades the ciliated epithelial cells lining the bronchioles, causing epithelial cell necrosis, peribronchiolar lymphocytic infiltration, and submucosal edema. Sloughed dead epithelial cells and excessive tenacious mucus occlude the narrow bronchiolar lumens, causing air trapping, hyperinflation, and patchy atelectasis. Peak incidence is in infants aged 2 to 6 months.
• Clinical Manifestations:
  • Begins as a mild upper respiratory illness with clear rhinorrhea, sneezing, and low-grade fever.
  • Progresses on days 3 to 5 to lower airway involvement: tachypnea (respiratory rate >60 breaths/min), wheezing, diffuse fine inspiratory crackles, intercostal/subcostal retractions, nasal flaring, and prolonged expiration.
  • Severe signs: Episodic apnea (especially in preterm infants and young neonates <2 months), grunting, cyanosis, and poor feeding due to dyspnea.
• Evidence-Based Nursing Management:
  • Supportive Airway Clearance: Frequent, gentle nasal suctioning of copious nasal secretions using a bulb syringe or olive-tip nasal aspirator, particularly prior to feeding and sleeping. Nasal suctioning dramatically reduces airway resistance in obligate nose-breathers.
  • Oxygenation: Administer humidified supplemental oxygen via nasal cannula to maintain SpO2 >=90% to 92%.
  • Hydration & Nutrition: Assess oral feeding safety. If the infant's respiratory rate exceeds 60 to 70 breaths per minute, withhold oral feeds (NPO) due to extreme risk of pulmonary aspiration; initiate intravenous crystalloid fluids or continuous nasogastric tube feeds.
  • Infection Control: Implement Contact and Droplet Precautions (private room or cohorting, gown, gloves, mask with eye protection, dedicated stethoscope). RSV survives on hard surfaces for up to 6 hours and on unwashed hands for 30 minutes.
  • RSV Immunoprophylaxis: DOH Circular 37/2026 introduces a single long-acting monoclonal antibody dose at birth during the RSV season (1 September–1 March). It is indicated if maternal RSV vaccination was not given, is unknown, or birth occurred within 14 days of vaccination. Nirsevimab is also used for eligible high-risk children aged 8–19 months entering their second season. Select the product, age eligibility and dose under the approved ADPHC protocol; this provides passive protection rather than active vaccination.

Pediatric Asthma Exacerbations

Asthma is a chronic inflammatory disorder of the airways characterized by bronchial hyperresponsiveness, reversible airway obstruction, mucosal edema, and excessive mucus plugging.

• Clinical Signs of Acute Exacerbation: Wheezing (predominantly expiratory), tachypnea, prolonged expiratory phase, dyspnea, persistent dry cough, intercostal/suprasternal retractions, and pulsus paradoxus.
• CRITICAL DANGER SIGN - THE "SILENT CHEST":
  • If an acutely tachypneic, distressed asthmatic child suddenly exhibits a diminution or complete absence of audible wheezing and breath sounds, this does NOT indicate improvement!
  • A "Silent Chest" indicates critically reduced airflow and possible impending respiratory failure. Call the emergency/PICU team; give oxygen, intensive inhaled bronchodilators and systemic corticosteroids, with IV magnesium for poor response. Prepare for expert intubation if respiratory failure progresses or persists despite optimized treatment.
• Pharmacological Management:
  • Short-Acting Beta-2 Agonists (SABA): Albuterol (Salbutamol) via metered-dose inhaler (MDI) with valved holding chamber/spacer or via nebulizer (2.5 to 5 mg every 20 minutes for 3 doses, or continuous nebulization 10 to 20 mg/hr for severe status asthmaticus).
  • Inhaled Anticholinergic: Ipratropium Bromide added to albuterol for moderate-to-severe exacerbations to produce synergistic bronchodilation.
  • Systemic Corticosteroids: Early administration of oral Prednisolone (1 to 2 mg/kg/day) or IV Methylprednisolone (1 to 2 mg/kg/day) to suppress airway inflammation and accelerate recovery.
  • Intravenous Magnesium Sulfate: 25 to 50 mg/kg (max 2 g) IV infused over 20 to 30 minutes for refractory severe status asthmaticus; relaxes bronchial smooth muscle by inhibiting calcium influx.

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Pediatric Infectious Diseases & UAE Immunization Schedule

Vaccination is the most effective public health strategy for preventing catastrophic childhood infectious diseases.

Childhood and School Immunization in Abu Dhabi

Use the current DOH/ADPHC schedule. Circular 77/2026 (14 May 2026), Appendix 1 updated April 2026, specifies the following routine schedule:

• At Birth:
  • BCG (Bacillus Calmette-Guérin): Live attenuated Mycobacterium bovis administered intradermally into the left deltoid to prevent severe tuberculous meningitis and miliary tuberculosis. A small papule appears after 2 to 4 weeks, ulcerates, and heals with a permanent flat scar.
  • Hepatitis B (HepB-1): First dose administered intramuscularly in the anterolateral thigh within 24 hours of birth.
  • RSV: A single long-acting antibody dose for eligible newborns during the season, as above; it may be given with BCG and HepB.
• 2 and 4 Months: Hexavalent DTaP-IPV-Hib-HepB, PCV20 and oral monovalent rotavirus vaccine (RV1).
• 6 Months: Hexavalent vaccine and bivalent oral polio vaccine (bOPV).
• 12 Months: MMR-1, varicella-1 and meningococcal ACWY conjugate vaccine (MCV4).
• 18 Months: DTaP-Hib-IPV booster, bOPV, MMR-2 and PCV20.
• School Schedule: Grade 1: DTaP-IPV, bOPV and varicella; complete any missing MMR doses. Grade 5: MCV4. Grade 8: HPV9 for girls and boys. Grade 11: Tdap and MCV4.

Product and Risk Distinctions: Healthy children receive PCV20 at 2, 4 and 18 months; infants born before 28 weeks and children with specified high-risk conditions receive an additional 6-month dose. ADPHC uses RV1 at 2 and 4 months; RV5 used in the private sector has doses at 2, 4 and 6 months. Follow age limits and catch-up guidance. HPV dosing depends on age at the first dose: two doses when started before 15 years; three when started at 15 or older. The Grade 5 MCV4 addition applies from the 2026–2027 school year.

Childhood Exanthems (Rash Illnesses)

1. Measles (Rubeola):

   • Transmission: Highly contagious airborne transmission via respiratory droplets that remain suspended in room air for up to 2 hours.
   • Prodrome: High fever (up to 40°C) and the classic "3 Cs": Cough, Coryza (rhinitis), and Conjunctivitis with severe photophobia.
   • Pathognomonic Enanthem: Koplik Spots—tiny, irregular, bluish-white granular spots surrounded by an erythematous base on the buccal mucosa opposite the lower molars, appearing 1 to 2 days before the skin rash.
   • Exanthem: Erythematous, confluent maculopapular rash that starts at the hairline and behind the ears, spreads cephalocaudally over the face, neck, trunk, and extremities, and fades in the same order.
   • Nursing Management: Strict Airborne Precautions in an airborne infection isolation room (AIIR) with negative pressure; healthcare workers must wear fit-tested N95 respirators. Give prescribed vitamin A using age-specific doses: 50,000 IU orally for infants <6 months, 100,000 IU at 6–11 months and 200,000 IU at >=12 months, repeated the next day. Supervised age-appropriate dosing avoids toxicity.

2. Varicella (Chickenpox):

   • Etiology: Varicella-Zoster Virus (VZV). Transmitted via airborne droplet and direct vesicular fluid contact.
   • Contagious Period: From 1 to 2 days before the rash appears until all vesicles have completely dried and crusted (typically 6 to 7 days after rash onset).
   • Exanthem Characteristics: Intensely pruritic lesions that appear in successive crops over several days, predominantly on the trunk, face, and scalp. Hallmarked by the simultaneous presence of lesions in all different stages of development: macules $\rightarrow$ papules $\rightarrow$ clear vesicles on an erythematous base ("dewdrops on a rose petal") $\rightarrow$ umbilicated pustules $\rightarrow$ dry crusts.
   • Nursing Management: Strict Airborne and Contact Precautions. Trim fingernails short and apply mitts to prevent excoriation and secondary invasive Group A Streptococcal or Staph aureus skin superinfections. Administer oral acyclovir for high-risk patients. Children must not return to school/daycare until all lesions are fully crusted.

3. Hand, Foot, and Mouth Disease (HFMD):

   • Etiology: Coxsackievirus A16 and Enterovirus 71. Transmitted via fecal-oral, droplet, and vesicular fluid contact.
   • Clinical Signs: Low-grade fever, anorexia, and painful shallow ulcerative oral lesions (herpangina) on the tongue, gums, and buccal mucosa. Accompanied by small, non-pruritic oval vesicles with an erythematous halo located on the palms of the hands, soles of the feet, and buttocks.
   • Nursing Focus: Contact precautions; hydration support with cool, non-acidic liquids; pain management with acetaminophen or ibuprofen.