Croup

Aka: Croup, Laryngo-tracheo Bronchitis, Laryngotracheal Bronchitis, Laryngotracheitis, Laryngotracheobronchitis, Laryngotracheobronchopneumonitis, Spasmodic Croup

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II. History

  1. Word "Croup" derived from Scottish for raven's "croak"

III. Epidemiology

  1. Incidence
    1. Overall Incidence: 3-6 cases per 100 children <6 years
    2. Accounts for 15% of pediatric respiratory visits to the emergency department (up to 400,000/year)
    3. Hospitalizations: 1-8% of US cases (20,000 per year)
    4. Intubation: 1-5% of cases hospitalized
  2. Boys affected more than girls by ratio of 1.5 to 1
  3. Outbreaks and epidemics occur in autumn to early winter
    1. Can occur year round sporadically
  4. Affects ages under 6 years (rarely up to 8 to 12 years)
    1. Most common cause of Stridor in children 6 months to 3 years of age
    2. Typical age 6 months to 36 months of age (peaks between 12 and 24 months)
    3. Rare before 3 months of age

IV. Pathophysiology

  1. Subglottic infection, inflammation and edema
  2. Tracheal edema at the most narrow aspect of a child's airway
  3. Subglottic area is 4 mm in a typical infant (and croup may decrease this to 2 mm area)
  4. Every mm of airway area lost results in a loss of air flow volume to the power of 4 (Poiseuille's law)

V. Causes

  1. Parainfluenza virus (50-75% of cases)
    1. Type 1 (most common type, 18% of cases)
    2. Type 2
    3. Type 3 (more common in younger children)
  2. Covid19
  3. Adenovirus
  4. Respiratory Syncytial Virus (RSV)
  5. Influenza A and Influenza B
  6. Rhinovirus
  7. Enteroviruses
  8. Human Bocavirus (spring and fall)
  9. Mycoplasma pneumoniae (uncommon)
  10. Corynebactgerium Diphtheriae (uncommon)

VI. Symptoms

  1. Low grade fever (or affebrile in some cases)
    1. High grade fever suggests other diagnosis (see differential diagnosis)
  2. Prodrome of initially mild upper respiratory symptoms or Coryza (first 1-2 days)
    1. Nasal Congestion
    2. Rhinorrhea
  3. Upper respiratory symptoms rapidly develop with abrupt onset
    1. Hoarseness
    2. Cough: "Barking" OR "seal-like"
    3. Inspiratory Stridor
    4. Expiratory Wheezing
    5. Dyspnea
  4. Symptoms worse at night
  5. Symptom duration <1 week (peaks at 2-4 days)
    1. Cough may persist up to 1 week

VII. Signs

  1. "Sound worse than they look" (Opposite of Epiglottitis)
    1. However, severe croup can cause complete airway obstruction
  2. Minimal Wheezing (Inspiratory Stridor instead)
  3. Minimal rhonchi and no rales
  4. Moderate respiratory distress
    1. Nasal flaring
    2. Respiratory retractions
    3. Inspiratory Stridor

VIII. Grading

  1. See Croup Score
  2. Croup Score 0-2: Mild Croup
    1. Occaisonal barking cough
    2. Minimal to no rest Stridor
    3. MInimal to no intercostal retractions
  3. Croup Score 3-5: Moderate Croup
    1. Frequent barking cough
    2. Audible Stridor at rest
    3. Suprasternal and Intercostal retractions
    4. Minimal to no distress or Agitation
  4. Croup Score 6-11: Severe Croup
    1. Frequent barking cough
    2. Audible Stridor at rest, and may be both inspiratory and expiratory (Biphasic Stridor)
    3. Severe intercostal retractions
    4. Siginificant distress or Agitation
  5. Croup Score 12-17: Impending Respiratory Failure
    1. Audible Stridor at rest, and may be quieter than before as the airway critically narrows
    2. Altered Level of Consciousness
    3. Cyanosis

IX. Labs

  1. Avoid labs unless diagnosis unclear
    1. Blood draws cause worsening distress and do not add to diagnosis in typical croup
  2. Complete Blood Count
    1. May show mild Leukocytosis
    2. May distinguish from the high white counts in Bacterial causes in differential diagnosis

X. Diagnosis

  1. See Croup Score
  2. Croup accounts for 99% of abrupt onset of Stridor
    1. However, consider the atypical case in the differential diagnosis as below

XI. Course

  1. Mild Cases: 85%
  2. Hospitalized: 5%
  3. Severe Cases: 1%
    1. Intubated: 0.05% of croup cases
  4. Mortality <0.5% (even for intubated patients)

XII. Differential Diagnosis (Croup is diagnosis of exclusion)

  1. See Pediatric Airway Obstruction Causes
  2. Angioedema
  3. Epiglottitis (3-12 years old)
    1. Less common in U.S. now since HaemophilusInfluenzae type B Immunization
    2. High fever, Drooling, muffled voice, Pharyngitis
    3. Cough (esp. barking cough) is more likely to be croup
  4. Bacterial Tracheitis (<6 years old)
    1. High fever with signs of toxicity and rapid decompensation
  5. Ludwig's Angina
  6. Peritonsillar Abscess
  7. Retropharyngeal Abscess
  8. Diphtheria
  9. Paraquat Poisoning (Herbicides)
  10. Smoke Inhalation
  11. Foreign Body Aspiration (esp. < 3 years old)
    1. History of Choking episode (88%)
    2. Neck XRay PA and Lateral if object is radiopaque
  12. Gastroesophageal Reflux
    1. Common cause of recurrent croup
  13. Airway lesion (Hemangioma, laryngeal mass)

XIII. Imaging

  1. Avoid imaging (as with labs) unless diagnosis is unclear
    1. Typically worsens distress and does not add to diagnosis in typical croup
    2. Avoid CT neck in children (radiation risk) unless high suspicion for lesion
  2. Lateral Neck XRay
    1. Findings suggestive of croup
      1. "Steeple" sign on PA Neck XRay (40-50% of croup cases)
      2. Narrowing of subglottic region from mucosal edema
      3. Dilated hypopharynx (most sensitive finding)
      4. Images
        1. RadCroupMedPix1246.jpgFrom MedPix with permission.
    2. Findings suggestive of alternative diagnosis
      1. Epiglottitis: Thickened epiglottis
      2. Retropharyngeal Abscess: Widening retropharyngeal soft tissue
      3. Bacterial Tracheitis: Thickened trachea
  3. Chest XRay
    1. Does not diagnose croup (will not demonstrate steeple sign)
    2. Indicated only to evaluate differential diagnosis (e.g. Pneumonia) where the diagnosis is unclear
  4. Other diagnostics
    1. Laryngoscopy
      1. May be considered (only with caution) in suspected Epiglottitis

XIV. Management: Home Therapy

  1. Maintain adequate Ambient humidity in house
  2. Cool mist may decrease subglottic edema
    1. No studies to support this
    2. May make Asthma worse due to irritation
    3. Theoretically decreases tracheal mucosal edema and secretion viscosity
    4. Options
      1. Cool-mist humidifier
      2. Cold Weather
        1. Bundle child warmly
        2. Bring outside for 15 minutes
      3. Closed bathroom with cold shower mist
  3. Maintain adequate hydration
    1. Offer child favorite drink every 10 minutes
    2. Consider crushed ice drinks or other frozen treats
  4. Corticosteroids
    1. See Dexamethasone in Croup

XV. Management: Emergency Department and Inpatient

  1. See Severe Croup management and delayed sequence protocol described below
  2. Primary tenet
    1. Do not distress a child with croup
    2. Avoid unnecessary procedures (e.g. delay Intravenous Access until stable)
    3. Position child as they are most comfortable
  3. Oxygen
    1. Target Supplemental Oxygen to >90% Oxygen Saturation
    2. Indicated for Hypoxia or moderate to severe respiratory distress
    3. Humidified oxygen offers no benefit over non-humidified oxygen in moderate croup
      1. Moore (2007) Fam Pract 24(4): 295-301 [PubMed]
    4. Blow-by oxygen is preferred to avoid distressing child
    5. Do not use heated humidification due to risk of burns
  4. Corticosteroids
    1. See Dexamethasone in Croup (includes Nebulized Budesonide in Croup)
    2. Indicated in all croup cases, regardless of severity
    3. Single dose lasts 60-72 hours and should cover the entire croup episode (typically 2-5 days)
    4. Most important single treatment in croup
      1. Has decreased croup mortality 200% from before 1990 to now (from 0.5% to 0.03%)
    5. Dexamethasone
      1. Typical dose (esp. severe cases): 0.6 mg/kg orally (maximum 10-16 mg)
      2. Dose of 0.15 to 0.3 mg/kg as effective as 0.6 mg/kg in mild to moderate cases
      3. Onset of action in 6 hours and effect lasts for 72 hours
      4. Oral is preferred over Parenteral dosing (give 1 mg/ml concentrated IV solution orally)
      5. Dexamethasone is preferred over Budesonide
  5. Nebulized racemic epinephrine
    1. Indicated in moderate to severe emergency department cases with signs of respiratory distress
      1. Alpha-Agonist effect Vasoconstricts, decreasing mucosal edema
      2. Beta agonsit effect increases Smooth Muscle relaxation as well as thinning tracheal secretions
    2. Nebulizer Dose
      1. Racemic Epinephrine 0.05 ml/kg (maximum 0.5 ml) of 2.25% in 2 ml saline via nebulizer or
      2. Standard L-Epinephrine 0.5 ml/kg (maximum 5 ml) of 1:1,000 in 2 ml saline via nebulizer
        1. As effective as Racemic Epinephrine and widely available in all ERs without special ordering
    3. Effect onset within 30 minutes and lasts up to 2 hours (some effects may persist up to 4 hours)
    4. Observe at least 2 hours after administration (some recommend 3 hours)
      1. If no recurrent Stridor, may discharge home after 2-3 hours
        1. Most croup decompensations will occur 1 to 1.5 hours after nebulized Epinephrine
      2. If Stridor recurs may give one additional Epinephrine neb and observe for additional 2-3 hours
        1. Dexamethasone may be taking effect by this time (~6 hours from dose)
        2. If no recurrent Stridor after 2-3 hours from second neb, may discharge home
      3. Admit patient if recurrent Stridor after second Epinephrine neb
        1. Some admit if Stridor after first Epinephrine neb
  6. Antibiotics
    1. Not indicated unless concurrent Bacterial Infection
  7. Helium added to Oxygen (Heliox)
    1. Not typically recommended
    2. Appears effective in small trials and my prevent intubation in borderline patients
      1. Vorwerk (2010) Cochrane Database Syst Rev (2): CD006822 [PubMed]
    3. Requires mask delivery which may upset child and result in airway closure
    4. Consider with double set-up with Anesthesia to perform gas induction if sudden decompensation occurs
  8. Intubation
    1. See protocols below
    2. Indicated less frequently now with above management
    3. Significant risk of Subglottic Stenosis
    4. Use ET Tube at least 1 size smaller than predicted

XVI. Management: Outpatient Management Indications

  1. Non-toxic appearance
  2. Well hydrated and taking oral fluids
  3. Minimal or no Stridor or retractions at rest
    1. At presentation or 3 hours after Epinephrine
  4. Reassuring respiratory Vital Signs
    1. Oxygen Saturation >94%
    2. Respiratory Rate <40 per minute
  5. Reliable parents
  6. Majority of croup patients may be discharged home
    1. However, keep a high index of suspicion for children with tenuous airways
    2. Croup can cause airway compromise that rivals Epiglottitis cases of the past

XVII. Management: Inpatient Observation Indications

  1. Persistent moderate to severe symptoms despite above management
    1. Dexamethasone 0.6 mg/kg and
    2. Epinephrine nebulizer treatment with observation for 3 hours (6 hours if a second Epinephrine given)
  2. Signs of respiratory distress or Respiratory Failure
  3. Cyanosis
  4. Tachypnea
  5. Agitation or Fatigue
  6. Stridor severity
  7. Accessory Muscle use
    1. Intercostal retractions
    2. Neck or abdominal Muscle use
  8. Rising arterial PCO2

XVIII. Management: Severe Croup

  1. Risk of peri-respiratory arrest
    1. Notify Anesthesia (may require blow-by gas induction)
    2. Notify ENT or general surgery (may require emergent surgical airway)
    3. Notify PICU
  2. Avoid upsetting child
    1. May delay Dexamethasone until airway less tenuous (consider budesonide neb)
    2. Place in position of comfort sitting in parent's lap
  3. Non-invasive strategies
    1. Administer Racemic Epinephrine neb by blow-by
      1. Consider continuous Epinephrine neb in severe cases
    2. High Flow Nasal Cannula (HHFNC)
      1. Start at 2 L/kg/min and titrate as needed
      2. High Flow Oxygen via large bore nasal canula (with prewarmed air blended with compressed oxygen)
      3. Consider Ketamine for sedation (or intranasal Versed) to allow child to tolerate
    3. Consider Bipap
      1. May be tolerated with Ketamine at dissociative dose (if IV Access available)
  4. Peri-respiratory arrest emergent airway management
    1. See Modified Delayed Sequence Intubation below
    2. Gas Induction or Ketamine IV if available
    3. Video Laryngoscopy (e.g. Glidescope)
      1. Load Elastic Bougie in mouth ready to pass through cords
  5. References
    1. Orman and Sloas in Majoewsky (2013) EM:Rap 13(2): 4-7
    2. Orman and Sloas in Herbert (2013) EM:Rap 15(6): 1-2

XIX. Management: Modified Delayed Sequence Intubation

  1. Ketamine for sedation
  2. Continuous Epinephrine neb
  3. Pre-oxygenate (and expel carbon dioxide)
    1. High Flow Nasal Cannula (HHFNC) or
    2. BiPap mask attached to Ventilator set to SIMV with pressure support
      1. Set to RR 0-2 and TV 8-10 ml/kg
      2. Set Pressure support to 10-15 cmH2O and PEEP 5 cmH2O
  4. Positive Pressure Ventilation
    1. Consider bilateral Nasal Airway trumpet (and if unconscious, Oral Airway)
    2. Consider Intubating Laryngeal Mask Airway (LMA)
      1. Provide Positive Pressure Ventilation via the LMA
    3. Bag Valve Mask with PEEP Valve
      1. Use two provider technique (Luten Walls Technique)
      2. One provider squeezes bag with prolonged inspiratory phase and shorter expiratory phase
      3. Other provider achieves mask seal drawing Mandible up and holding mask tightly against face
  5. Intubate via pediatric bronchoscope
    1. Thread an under-sized Endotracheal Tube (ET) over pediatric bronchoscope
    2. Insert pediatric bronchoscope into the intubating LMA port
    3. Push ET Tube over the top of the bronchoscope through the Vocal Cords and remove the bronchoscope
  6. References
    1. Orman and Sloas in Majoewsky (2013) EM:Rap 13(2): 4-7
    2. Orman and Sloas in Herbert (2013) EM:Rap 15(6): 1-2

XX. Management: Recurrent Croup

  1. Consider Esophageal Reflux
  2. Consider referral to pulmonology for bronchoscopy (especially age under 3 years old)
    1. Higher Incidence of findings such as Subglottic Stenosis or cyst
    2. Other risks include prior intubation, prematurity and age <3 years old

XXI. References

  1. Mehta and Eliason (2024) Crit Dec Emerg Med 38(6): 27-35
  2. Cherry (2008) N Engl J Med 358(4): 384-91 [PubMed]
  3. Folland (1997) J Postgrad Med 101(3): 271-8 [PubMed]
  4. Geelhoed (1997) Pediatr Pulmonol 23:370-374 [PubMed]
  5. Klassen (1994) N Engl J Med, 331: 285-9 [PubMed]
  6. Knutson (2004) Am Fam Physician 69(3):535-42 [PubMed]
  7. Quan (1992) Am Fam Physician 46(3): 747-55 [PubMed]
  8. Sobol (2008) Otolaryngol Clin North Am 41(3): 551-66 [PubMed]
  9. Smith (2018) Am Fam Physician 97(9): 575-80 [PubMed]
  10. Wald (2010) Pediatr Ann 39(1): 15-21 [PubMed]
  11. Zoorab (2011) Am Fam Physician 83(9): 1067-73 [PubMed]

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