LARYNGOTRACHEOBRONCHITIS

LARYNGOTRACHEOBRONCHITIS - Garreth C. Biegun, MD; Frank J. Domino, MD
BASICS
DESCRIPTION
Subacute viral illness characterized by barking cough, stridor, and fever
• Most common cause of upper airway obstruction or stridor in children
• Spasmodic croup: Non-infectious form
- Croupy cough with sudden night-time onset
- No fever or radiographic changes
- In spectrum, must be initially treated as croup
- Usually self-limited and resolves with mist therapy at home
- May recur in same night or within 2-3 nights
• System(s) Affected: Pulmonary
• Synonym(s): Croup; Infectious croup; Viral croup; LTB
EPIDEMIOLOGY
• Predominant age
- Common 6 months to 3 years
- Most common in 2nd year of life
- Rare >6 years
• Predominant sex: Male > Female (1.4:1)
• Timing
- Follows parainfluenza type 1
- Any time of year possible but most common in late summer and early fall
Incidence
• 6 cases of croup per 100 children
• 1.5-6% require hospitalization
• 1-5% of those require intubation
• Decreasing incidence in US
RISK FACTORS
• Past history of croup
• Recurrent upper respiratory infections
Genetics
Unknown
PATHOPHYSIOLOGY
• Small children have a small airway with more compliant walls.
• The subglottic region/larynx is entirely encircled by the cricoid cartilage.
• Inflammatory edema and subglottic mucous production decrease airway radius.
• Negative pressure inspiration pulls airway walls closer together.
• Small decrease in airway radius leads to significant decrease of air flow area.
ETIOLOGY
• Parainfluenza virus
- Most common pathogen ~75% of cases of croup
- Type 1 is most common, causes 18% of all cases of croup
- Type 2, 3, and 4 are also common.
- Type 3 may cause a particularly severe illness.
• Paramyxovirus
• Influenza virus type A or B
• Respiratory syncytial virus
• Other viruses
- Adenovirus
- Rhinovirus
- Enterovirus
- Coxsackievirus
- Echovirus
- Reovirus
- Measles virus
• Haemophilus influenza type B
- Now rare with routine immunization
• Mycoplasma pneumoniae: New and rare cause
ASSOCIATED CONDITIONS
If recurrent (>2 episodes in a year) or in 1st 90 days of life, consider host factors
• Underlying anatomic abnormality (e.g., subglottic stenosis)
• Foreign body
• Paradoxical vocal cord dysfunction
• GERD
• Prolonged neonatal intubation


DIAGNOSIS
• This is a clinical diagnosis; labs and imaging serve only ancillary purposes.
• Westley Croup Scale: 2 mild; 3-7 moderate;  8 severe
- Level of consciousness: Normal, including sleep = 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
SIGNS AND SYMPTOMS
• Barking, spasmodic cough
• Biphasic stridor
• Low-grade to moderate fever
• Upper respiratory infection prodrome lasting 1-7 days
• Hypoxia/cyanosis
• Fatigue
• Non-toxic-appearing child
• Normal voice, no drooling
• No change in stridor with positioning
• Nontender larynx
• Inflamed subglottic region
• Normal-appearing supraglottic region
History
• 2-3 days nonspecific prodromal syndrome
• Low-grade fever, coryza, rhinorrhea
• Lack of prodrome indicates spasmodic croup
Physical Exam
• Overall appearance: Child comfortable or struggling?
• Work of breathing: Labored or comfortable?
• Sound of breathing and voice: Hoarse, stridor, inspiratory wheezing, short sentences?
• Observed/subjective tidal volume: Sufficient for child size?
TESTS
Lab
• No laboratory abnormality is diagnostic.
• WBC may be low, normal, or elevated.
• Lymphocytosis expected but not required.
• Rapid antigen or viral culture tests are available in some centers.
- Guide isolation precautions not management
• Pulse oximetry often is normal because there is no disturbance of alveolar gas exchange.
Imaging
• Posteroanterior and lateral neck films show funnel-shaped subglottic region with normal epiglottis  "steeple," "hour glass," or"pencil point" sign (present in 40-60% of children with laryngotracheobronchitis).
• CT may be more sensitive for defining etiology of obstruction in a confusing clinical picture.
• Patient should be monitored during imaging  progression of airway obstruction may be rapid.
Pathological Findings
• Inflammatory reaction of respiratory mucosa
• Loss of epithelial cells
• Thick mucoid secretions
DIFFERENTIAL DIAGNOSIS
• Epiglottitiscurrently rare
• Foreign body aspiration
• Subglottic stenosis (congenital or acquired)
• Bacterial tracheitis
• Simple upper respiratory infection
• Subglottic hemangioma
• Retropharyngeal or peritonsillar abscess
• Trauma
• Allergic reaction (acute angioneurotic edema)
TREATMENT
STABILIZATION
• Outpatient care in mild cases
• Intensive care unit (ICU) for patients with tachypnea, tachycardia, hypoxia, cyanosis, reactions, pneumonia, or CHF
• In most cases, ED observation after medical management is sufficient.
GENERAL MEASURES
• Minimize labs, imaging, and other procedures that upset the child; agitation that worsens tachypnea is more detrimental than accepting a clinical diagnosis.
• Frequent checks are more sensitive to worsening disease than pulse-oximetry.
• IV fluids
• ECG monitoring and pulse oximetry
Diet
• NPO and IV fluids for severe cases
• Frequent small feedings with increased fluids for mild cases
Activity
Must keep patient quiet; crying may exacerbate symptoms
SPECIAL THERAPY
Complementary and Alternative Medicine
Mist therapy not proven to work but may be beneficial. Cool temperature misters are preferable to high temperature (e.g., tea kettles).
• Some children respond well to cold dry air
• Avoids the risk of burns
MEDICATION (DRUGS)
First Line
• Immediate: Racemic or L-epinephrine (Vaponefrin): 0.05 mL/kg/dose (max 0.5 mL) of 2.25% racemic epinephrine delivered in 3 mL of normal saline nebulized (1)[A], (2)[B]
- Onset in 10-30 minutes, duration ~2 hours
- Repeat as necessary if side-effects tolerated
• Dexamethasone 0.15-0.6 mg/kg once IM/PO have proven equal efficacy. (3)[A]
- Nebulized Budesonide also proven effective (4)[B]
• Antibiotics NOT indicated in this viral illness
- Antecedent or subsequent bacterial infection is uncommon.
• Oxygen as needed
• Contraindications
- Refer to the manufacturer's literature.
• Precautions
- Avoid oversedation.
• Significant possible interactions
- Refer to the manufacturer's literature.
Second Line
Amantadine for influenza A: 100 mg PO b.i.d. for 3-5 days
SURGERY
• Intubation required in 1-6% for 3-5 days; use smallest tube possible
- After trial of medical management, intubation is for fatigue due to work of breathing or beginning total obstruction; not secondary to low oxygen saturation
- Direct laryngoscopy if child is not in acute distress
- Fiberoptic laryngoscopy is the procedure of choice when available.
• Tracheotomyrarely
FOLLOW-UP
DISPOSITION
Most patients will be seen in ED or PCP office setting. Some will be overnight by telephone.
Admission Criteria
Minor cases need no visit to hospital or PCP.
• No stridor at rest, no difficulty breathing
• Child able to tolerate PO liquids
• No underlying medical condition
• Caretakers able to assess changes to clinical picture and re-access medical care
Discharge Criteria
Patients who maintain a good response to medical therapy for 3-4 hours (after epi dose) may be safely discharged as long as they have reliable caretakers and good access to medical services if symptoms return. (5)[C]
PROGNOSIS
• Up to 1/3 of patients will have recurrence.
• If required, intubation is maintained for 3-5 days.
• If required, tracheotomy is maintained for 3-7 days.
• Recovery is usually full and without lasting effects.
COMPLICATIONS
• Rare
• Subglottic stenosis in intubated patients
• Bacterial tracheitis
• Cardiopulmonary arrest
• Pneumonia
PATIENT MONITORING
Severe cases require ICU care with respiratory monitoring for hypoxemia and hypercapnia.
REFERENCES
1. Westley CR, Cotton EK, Brooks JG. Nebulized racemic epinephrine by IPPB for the treatment of croup: A double-blind study. Am J Dis Child. 1978;132(5):484-487.
2. Wasiman Y, et al. Prospective randomized double-blind study comparing L-epinephrine and racemic epinephrine aerosols in the treatment of laryngotracheitis (croup). Pediatrics. 1992;89(2):302-306.
3. Geelhoed GC, Turner J, MacDonald WB. Efficacy of a small single dose of oral dexamethasone for outpatient croup: A double-blind placebo controlled cinical trial. Br Med J. 1996;313(7050):140-142.
4. Cetinkaya F, Tufekci BS, Kutluk G. A comparison of nebulized budesonide, and intramuscular, and oral dexamethasone for treatment of croup. Int J Pediatr Otorhinolaryngol. 2004;68(4):453-456.
5. Klassen TP. Croup: A current perspective. Pediatr Clin North Am. 1999;46:1167-1178.
MISCELLANEOUS
See also: Bronchiolitis; Common cold; Epiglottitis; tracheitis, bacterial