Croup

Overview

Croup, medically known as laryngotracheobronchitis, affects the upper portion of the respiratory system, causing inflammation that narrows the airway. The condition gets its name from the characteristic "croupy" or barking cough that develops when air passes through the swollen and narrowed vocal cords and windpipe.

The anatomy of a child's airway makes them particularly susceptible to croup. Children have smaller airways than adults, and even minor swelling can significantly reduce airflow. The cricoid cartilage, which forms a complete ring around the airway just below the vocal cords, is the narrowest part of a child's airway. When this area becomes inflamed and swollen, it creates the classic symptoms of croup.

Croup is highly contagious and spreads through respiratory droplets when an infected person coughs or sneezes. The condition typically occurs in fall and winter months, often in epidemic patterns. Most children will experience at least one episode of croup during their early years, and some children may have recurrent episodes. The good news is that as children grow older and their airways become larger, they become less susceptible to croup.

Symptoms

Croup symptoms typically develop gradually over 1-2 days, often starting like a common cold before progressing to more distinctive respiratory symptoms. The severity can range from mild to severe, with most cases being mild to moderate.

Early Symptoms

• Nasal congestion - stuffy or runny nose
• Coryza - cold-like symptoms with nasal discharge
• Sore throat - mild throat discomfort initially
• Fever - usually low-grade, typically 100-102°F (37.8-38.9°C)
• Mild fatigue and irritability
• Decreased appetite

Characteristic Symptoms

• Barking cough: The hallmark symptom that sounds like a seal's bark
• Hoarse voice - voice changes due to vocal cord swelling
• Abnormal breathing sounds - stridor (harsh sound when breathing in)
• Inspiratory stridor - noisy breathing on inhalation
• Voice changes ranging from hoarseness to complete voice loss

Respiratory Symptoms

• Shortness of breath - difficulty breathing, especially when active
• Wheezing - high-pitched whistling sound when breathing
• Labored breathing with visible chest retractions
• Breathing that is more rapid than normal
• Difficulty breathing that worsens when lying flat
• Agitation or restlessness due to breathing difficulties

Associated Symptoms

• Vomiting - often triggered by severe coughing fits
• Pulling at ears - may indicate ear discomfort or infection
• Drooling due to difficulty swallowing
• Poor feeding in infants and young children
• Sleep disturbances due to coughing and breathing difficulties

Severity Classifications

Mild Croup

• Barking cough without stridor at rest
• Normal air entry on examination
• No or minimal chest wall retractions
• Child appears well when not coughing

Moderate Croup

• Barking cough with stridor at rest
• Some chest wall retractions
• Agitation when disturbed
• Decreased air entry but no severe distress

Severe Croup

• Barking cough with prominent stridor at rest
• Significant chest wall retractions
• Marked agitation or altered level of consciousness
• Poor air entry
• Cyanosis (blue discoloration around lips or fingernails)

Symptom Patterns

Typical Timeline

• Days 1-2: Cold-like symptoms, mild fever
• Days 2-3: Development of barking cough and hoarseness
• Days 3-4: Peak symptoms with possible stridor
• Days 4-7: Gradual improvement of symptoms

Daily Variation

• Symptoms often worse at night
• Cool night air may provide temporary relief
• Crying or agitation can worsen breathing difficulties
• Symptoms may improve during the day

Causes

Croup is primarily caused by viral infections that lead to inflammation and swelling of the upper respiratory tract, particularly around the vocal cords and windpipe. Understanding the causative agents helps in prevention and treatment approaches.

Viral Causes

Parainfluenza Viruses

• Most common cause: Accounts for 50-75% of croup cases
• Types 1-4: Type 1 most frequently associated with croup
• Seasonal pattern: Peak in fall months
• Transmission: Highly contagious through respiratory droplets

Other Viral Causes

• Respiratory Syncytial Virus (RSV):
  • Common in infants and toddlers
  • Can cause severe lower respiratory symptoms
  • Peak season: late fall through early spring
• Influenza A and B:
  • Can cause more severe croup symptoms
  • Often associated with higher fever
  • Seasonal outbreaks in winter
• Adenovirus:
  • Can cause year-round infections
  • May cause more prolonged symptoms
  • Associated with conjunctivitis
• Rhinovirus:
  • Common cold virus
  • Usually causes milder croup symptoms
  • Peak in fall and spring
• Human metapneumovirus:
  • Similar to RSV in presentation
  • More common in late winter and spring

Less Common Causes

Bacterial Causes

• Bacterial tracheitis: Secondary bacterial infection
• Staphylococcus aureus: Can cause severe complications
• Streptococcus pneumoniae: Rare but serious
• Haemophilus influenzae: Much less common since vaccination

Other Causes

• Allergic reactions: Spasmodic croup
• Gastroesophageal reflux: Irritation from stomach acid
• Inhaled irritants: Smoke, chemicals, or allergens
• Trauma: Rarely, from intubation or foreign body

Pathophysiology

Mechanism of Disease

• Viral invasion: Viruses infect epithelial cells of upper respiratory tract
• Inflammatory response: Body's immune response causes swelling
• Airway narrowing: Swelling reduces airway diameter
• Turbulent airflow: Creates characteristic sounds (stridor, barking cough)

Anatomical Factors

• Small airways: Children's airways are naturally smaller
• Cricoid ring: Narrowest part of child's airway
• Looser mucosa: More prone to swelling than adult airways
• Less cartilage support: Airways more collapsible

Transmission and Contagion

• Respiratory droplets: Primary mode of transmission
• Direct contact: Touching contaminated surfaces
• Incubation period: 1-6 days after exposure
• Contagious period: Most contagious in first 3-4 days
• Environmental factors: Crowded conditions increase spread

Risk Factors

Several factors increase a child's likelihood of developing croup. Understanding these risk factors helps parents and healthcare providers identify children who may be at higher risk and implement appropriate preventive measures.

Age-Related Factors

• Peak age group: 6 months to 6 years
  • Most common between 1-2 years of age
  • Rare in children under 6 months (maternal antibodies protective)
  • Becomes less common after age 6 (larger airways)
  • Very rare in adults due to larger airway diameter

Seasonal and Environmental Factors

• Seasonal patterns:
  • Peak incidence in fall and early winter
  • October through December highest risk
  • Corresponds with viral circulation patterns
• Environmental conditions:
  • Daycare or school attendance
  • Crowded living conditions
  • Exposure to secondhand smoke
  • Poor air quality or pollution

Individual Risk Factors

Medical History

• Previous croup episodes: Children who have had croup are more likely to have recurrent episodes
• Recurrent croup: Some children have a tendency toward multiple episodes
• Prematurity: Premature infants may have increased risk
• Chronic respiratory conditions: Asthma, bronchopulmonary dysplasia

Anatomical Factors

• Small airway diameter: Natural variation in airway size
• Airway malformations: Congenital abnormalities
• Subglottic stenosis: Narrowing below vocal cords
• Laryngomalacia: Soft laryngeal cartilage

Immunological Factors

• Immunodeficiency: Primary or secondary immune defects
• Recent illness: Weakened immune system from other infections
• Lack of previous exposure: First-time exposure to certain viruses
• Nutritional status: Malnutrition affecting immune function

Family and Genetic Factors

• Family history: Siblings or parents with history of croup
• Genetic predisposition: Some families show clustering of cases
• Atopic conditions: Family history of allergies or asthma
• Airway reactivity: Inherited tendency toward airway inflammation

Behavioral and Social Factors

• Daycare attendance: Increased viral exposure
• Large family size: More opportunities for viral transmission
• Poor hand hygiene: Inadequate infection prevention
• Close contact with sick individuals: Family members or caregivers with respiratory infections

Geographic and Demographic Factors

• Geographic location: Some regions have higher incidence
• Population density: Urban areas with higher transmission rates
• Socioeconomic factors: Overcrowding, limited healthcare access
• Climate factors: Dry air may increase susceptibility

Protective Factors

• Breastfeeding: Provides passive immunity in infants
• Good hygiene practices: Reduces viral transmission
• Vaccination: Up-to-date immunizations reduce secondary complications
• Smoke-free environment: Reduces airway irritation
• Good nutrition: Supports immune system function

Diagnosis

Croup is primarily diagnosed based on clinical presentation and characteristic symptoms. The diagnosis is usually straightforward when the classic barking cough and stridor are present, but healthcare providers may need to differentiate croup from other respiratory conditions.

Clinical Assessment

History Taking

• Symptom onset: Gradual onset over 1-2 days
• Preceding illness: Recent cold-like symptoms
• Cough characteristics: Distinctive barking quality
• Voice changes: Hoarseness or voice loss
• Breathing difficulties: Stridor, increased work of breathing
• Fever pattern: Usually low-grade
• Previous episodes: History of recurrent croup
• Recent exposures: Sick contacts, daycare attendance

Physical Examination

General Assessment

• Appearance: Level of distress, alertness, color
• Vital signs: Temperature, heart rate, respiratory rate, oxygen saturation
• Growth parameters: Weight, especially if poor feeding
• Hydration status: Signs of dehydration from poor intake

Respiratory Examination

• Inspection:
  • Chest wall retractions (suprasternal, subcostal, intercostal)
  • Use of accessory muscles
  • Cyanosis (central or peripheral)
  • Nasal flaring
• Auscultation:
  • Stridor (inspiratory, expiratory, or biphasic)
  • Air entry and quality of breath sounds
  • Wheezing or other adventitious sounds
  • Areas of decreased breath sounds
• Voice assessment:
  • Quality of voice (hoarse, muffled, or normal)
  • Ability to speak or cry
  • Changes with positioning

Other Systems

• Head and neck: Lymphadenopathy, throat examination (if cooperative)
• Cardiovascular: Heart sounds, signs of cor pulmonale
• Neurological: Level of consciousness, agitation
• Skin: Color, perfusion, rash

Severity Assessment

Croup Scoring Systems

• Westley Croup Score:
  • Stridor (0-2 points)
  • Retractions (0-3 points)
  • Air entry (0-2 points)
  • Cyanosis (0-4 points)
  • Level of consciousness (0-5 points)
  • Total score: 0-17 (mild: 0-2, moderate: 3-7, severe: 8-11, impending failure: >12)

Clinical Severity Indicators

• Mild croup: Barking cough, no stridor at rest, normal air entry
• Moderate croup: Stridor at rest, some retractions, good air entry
• Severe croup: Prominent stridor, significant retractions, poor air entry
• Impending respiratory failure: Agitation, cyanosis, poor air entry, fatigue

Diagnostic Testing

Laboratory Tests

• Usually not required: Diagnosis is primarily clinical
• Complete blood count: May show viral pattern (lymphocytosis)
• Inflammatory markers: Usually normal in viral croup
• Viral testing: Rarely needed, may be done for epidemiological purposes

Imaging Studies

• Chest X-ray:
  • Usually not necessary for typical croup
  • May show "steeple sign" (narrowed airway)
  • Helps rule out pneumonia or foreign body
  • Consider if atypical presentation
• Neck X-ray:
  • Rarely indicated
  • May show subglottic narrowing
  • Can help differentiate from epiglottitis

Differential Diagnosis

Conditions to Consider

• Epiglottitis:
  • More severe, drooling, muffled voice
  • High fever, toxic appearance
  • Rare since Hib vaccination
• Bacterial tracheitis:
  • High fever, toxic appearance
  • Purulent secretions
  • More severe respiratory distress
• Foreign body aspiration:
  • Sudden onset, choking episode
  • Unilateral findings
  • No fever or viral prodrome
• Asthma exacerbation:
  • Expiratory wheeze predominant
  • History of asthma
  • Responds to bronchodilators
• Allergic reaction:
  • Sudden onset after exposure
  • Other allergic symptoms
  • May have urticaria or swelling

When to Investigate Further

• Atypical presentation or course
• Failure to respond to standard treatment
• Recurrent episodes (consider underlying airway abnormality)
• Very young infant (under 6 months)
• Signs suggesting bacterial infection
• Concern for foreign body or other complications

Treatment Options

Treatment of croup focuses on reducing airway inflammation, improving breathing, and providing supportive care. The approach varies based on severity, with most mild cases managed at home and more severe cases requiring medical intervention.

Home Management (Mild Croup)

Environmental Measures

• Cool mist therapy:
  • Use a cool mist humidifier in child's room
  • Sit with child in steamy bathroom
  • Go outside in cool night air (brief exposure)
  • Avoid hot steam (can worsen swelling)
• Positioning:
  • Keep child upright or in comfortable position
  • Avoid forcing child to lie flat
  • Hold and comfort to reduce anxiety

Supportive Care

• Hydration:
  • Encourage frequent small sips of fluids
  • Offer child's preferred drinks
  • Ice chips or popsicles may be soothing
  • Monitor for signs of dehydration
• Comfort measures:
  • Keep child calm and comfortable
  • Minimize crying and agitation
  • Provide quiet activities
  • Maintain normal sleep routines when possible

Fever Management

• Acetaminophen or ibuprofen: For comfort if fever present
• Appropriate dosing: Based on child's weight
• Temperature monitoring: Regular checks
• Avoid aspirin: Risk of Reye's syndrome

Medical Treatment

Corticosteroids

• Dexamethasone:
  • Single dose: 0.15-0.6 mg/kg (maximum 10 mg)
  • Oral, intramuscular, or intravenous routes
  • Reduces airway inflammation
  • Benefits seen within 2-4 hours
  • Effects last 24-72 hours
• Prednisolone:
  • Alternative to dexamethasone
  • Dose: 1-2 mg/kg
  • May require multiple doses
• Budesonide:
  • Nebulized corticosteroid
  • Dose: 2 mg nebulized
  • Alternative when oral route not possible

Nebulized Epinephrine

• Indications:
  • Moderate to severe croup
  • Significant stridor at rest
  • Marked retractions
  • Respiratory distress
• Mechanism:
  • Alpha-adrenergic vasoconstriction
  • Reduces airway edema
  • Rapid but temporary effect
• Administration:
  • Racemic epinephrine: 0.25-0.5 mL of 2.25% solution
  • L-epinephrine: 0.5 mL/kg (max 5 mL) of 1:1000 solution
  • Delivered via nebulizer with oxygen
• Monitoring:
  • Observe for 2-4 hours after treatment
  • Watch for rebound symptoms
  • May repeat if needed

Hospital Management

Indications for Hospitalization

• Moderate to severe croup
• Stridor at rest
• Significant respiratory distress
• Need for epinephrine treatment
• Inability to maintain oral intake
• Concern for other complications
• Inadequate home support or follow-up

Inpatient Care

• Monitoring:
  • Continuous pulse oximetry
  • Regular assessment of respiratory status
  • Intake and output monitoring
  • Serial croup scores
• Oxygen therapy:
  • Humidified oxygen as needed
  • Avoid high flow rates that may increase agitation
  • Monitor oxygen saturation
• IV fluids:
  • If unable to maintain oral intake
  • Careful monitoring to avoid fluid overload
  • Maintenance rate initially

Severe Croup and Respiratory Failure

ICU Management

• Intubation considerations:
  • Last resort due to airway swelling
  • Use smaller endotracheal tube
  • Experienced pediatric anesthesiologist preferred
  • Prepare for difficult airway
• Alternative airway management:
  • Heliox (helium-oxygen mixture)
  • Continuous positive airway pressure (CPAP)
  • High-flow nasal cannula

Treatment Considerations

What NOT to Do

• Avoid throat examination: May precipitate complete obstruction
• No cough suppressants: Cough helps clear secretions
• Avoid sedatives: May mask respiratory distress
• No antibiotics: Viral infection, antibiotics not helpful
• Avoid agitation: Crying worsens symptoms

Special Populations

• Infants under 6 months: Lower threshold for hospitalization
• Immunocompromised children: Consider bacterial complications
• Children with airway abnormalities: Higher risk of complications
• Recurrent croup: Consider underlying causes

Follow-up Care

• Outpatient follow-up: 24-48 hours for moderate cases
• Return precautions: Worsening breathing, high fever, poor intake
• Activity restrictions: Limit strenuous activity until recovered
• School/daycare: Can return when fever-free and well

Prevention

While croup cannot be completely prevented due to its viral nature, several strategies can reduce the risk of infection and severity of symptoms. Prevention focuses on reducing viral transmission and maintaining good respiratory health.

Infection Prevention

Hygiene Measures

• Hand washing:
  • Frequent handwashing with soap and water
  • Alcohol-based hand sanitizer when soap unavailable
  • Teach children proper handwashing technique
  • Wash hands before eating and after coughing/sneezing
• Respiratory etiquette:
  • Cover cough and sneeze with elbow or tissue
  • Dispose of tissues immediately
  • Avoid touching face with unwashed hands
  • Teach children these habits early

Avoiding Exposure

• Limit contact with sick individuals:
  • Keep children away from people with respiratory symptoms
  • Avoid crowded places during peak viral seasons
  • Consider keeping child home from daycare during outbreaks
• Sick day policies:
  • Keep sick children home from school/daycare
  • Wait until fever-free for 24 hours before returning
  • Respect others by not exposing them to illness

Environmental Measures

Indoor Air Quality

• Smoke-free environment:
  • Eliminate tobacco smoke exposure
  • Avoid other air pollutants and irritants
  • Use air purifiers if needed
  • Ensure adequate ventilation
• Humidity control:
  • Maintain appropriate humidity levels (30-50%)
  • Use humidifiers during dry seasons
  • Avoid overly dry indoor air

Cleaning and Disinfection

• Surface cleaning:
  • Regular cleaning of frequently touched surfaces
  • Disinfect toys, doorknobs, light switches
  • Pay attention to shared items
• Personal items:
  • Avoid sharing cups, utensils, or personal items
  • Regular washing of bedding and clothing
  • Clean and disinfect humidifiers regularly

Health Maintenance

Immunizations

• Routine vaccinations:
  • Keep all vaccinations up to date
  • Annual influenza vaccine
  • Prevents secondary complications
• Family immunizations:
  • Ensure all family members are vaccinated
  • Protect vulnerable children through herd immunity

General Health

• Nutrition:
  • Balanced diet to support immune system
  • Adequate vitamin D and other nutrients
  • Encourage fruits and vegetables
• Sleep:
  • Ensure adequate sleep for age
  • Maintain regular sleep schedules
  • Good sleep supports immune function
• Physical activity:
  • Regular age-appropriate exercise
  • Outdoor activities when possible
  • Builds overall health and immunity

Special Considerations

High-Risk Children

• Children with recurrent croup:
  • Extra vigilance during viral seasons
  • Consider keeping rescue medications available
  • Develop action plan with healthcare provider
• Children with chronic conditions:
  • Asthma, airway abnormalities
  • More aggressive prevention measures
  • Close communication with healthcare team

Seasonal Preparation

• Fall/winter readiness:
  • Prepare for increased viral circulation
  • Have humidifier ready
  • Know when to seek medical care
  • Emergency contacts and plans

Family Education

Recognition and Early Action

• Symptom recognition:
  • Teach parents to recognize early croup symptoms
  • Know when to implement home measures
  • Understand warning signs requiring medical attention
• Action plans:
  • Written instructions for home management
  • Emergency contact information
  • Clear criteria for seeking medical care

Community Awareness

• Educate other caregivers (grandparents, babysitters)
• Share information with daycare providers
• Promote community hygiene practices
• Support public health measures during outbreaks

When to See a Doctor

Seek emergency medical attention immediately for:

• Severe shortness of breath or difficulty breathing at rest
• Stridor (harsh breathing sounds) heard without a stethoscope
• Significant chest wall retractions (skin pulling in around ribs)
• Blue discoloration around lips, nose, or fingernails (cyanosis)
• Child appears very ill, agitated, or unusually drowsy
• Difficulty swallowing or excessive drooling
• High fever (over 103°F/39.4°C) with breathing difficulties

Contact your healthcare provider promptly for:

• First episode of characteristic barking cough
• Hoarse voice with abnormal breathing sounds
• Fever lasting more than 3-4 days
• Symptoms worsening after initial improvement
• Difficulty eating or drinking due to breathing problems
• Persistent vomiting preventing fluid intake
• Child under 6 months with croup symptoms

Consider medical evaluation for:

• Cough that sounds like a seal's bark
• Wheezing or noisy breathing when calm
• Symptoms not improving after 2-3 days of home care
• Recurrent episodes of croup
• Pulling at ears with other croup symptoms
• Concerns about child's breathing or general condition

Call 911 if:

• Child stops breathing or has periods of not breathing
• Child becomes unconscious or extremely lethargic
• Severe respiratory distress with inability to speak or cry
• You are concerned about your child's immediate safety

Related Conditions

• Epiglottitis
• Bacterial Tracheitis
• Asthma
• Bronchiolitis
• Pneumonia
• Upper Respiratory Infection

References

1. Petrocheilou A, Tanou K, Kalampokas E, et al. Viral croup: diagnosis and a treatment algorithm. Pediatr Pulmonol. 2014;49(5):421-429.
2. Bjornson C, Russell K, Vandermeer B, et al. Nebulized epinephrine for croup in children. Cochrane Database Syst Rev. 2013;(10):CD006619.
3. Russell KF, Liang Y, O'Gorman K, et al. Glucocorticoids for croup. Cochrane Database Syst Rev. 2011;(1):CD001955.
4. Zoorob R, Sidani M, Murray J. Croup: an overview. Am Fam Physician. 2011;83(9):1067-1073.
5. Sizar O, Carr B. Croup. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023.