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Laryngotracheitis — Clinical Guidelines

Overview

Laryngotracheitis, commonly known as croup, is an acute respiratory condition characterized by inflammation of the upper airway, particularly the larynx and trachea, leading to characteristic symptoms such as a barking cough, stridor, and varying degrees of airway obstruction. It predominantly affects children under the age of seven, with a peak incidence between 6 months and 3 years. The condition is typically caused by viral infections, most commonly parainfluenza viruses, although other pathogens like respiratory syncytial virus (RSV) and influenza viruses can also be implicated. Prompt recognition and management are crucial to prevent potential life-threatening airway compromise. Understanding the nuances of laryngotracheitis is essential for clinicians to provide effective, timely care, reducing hospitalization rates and improving patient outcomes 1 6 10.

Pathophysiology

Laryngotracheitis involves a complex interplay of inflammatory responses triggered primarily by viral infections, most notably parainfluenza virus types 1, 2, and 3. These viruses infect the epithelial cells lining the larynx and trachea, leading to cellular damage and the release of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6. This inflammatory cascade attracts immune cells, including neutrophils and lymphocytes, to the affected areas, exacerbating mucosal edema and the formation of inflammatory exudates 7 8 9. The subglottic region, due to its narrow anatomy, is particularly susceptible to significant narrowing (subglottic stenosis), which contributes to the characteristic stridor and airway obstruction seen in patients. Additionally, the involvement of dendritic cells and other immunocompetent cells in the immune response highlights the multifaceted nature of the inflammatory process, differing between the subglottic and glottic regions 8 9.

Epidemiology

Laryngotracheitis predominantly affects young children, with an incidence peaking between 6 months and 3 years of age. Studies have shown that boys are slightly more frequently affected than girls, though the gender difference is not consistently significant across all populations 1 12. Geographically, the condition is widespread, with seasonal variations noted, typically peaking in autumn months, possibly influenced by environmental factors such as temperature changes and viral circulation patterns 12 15. Over time, the incidence has shown variability, influenced by factors such as vaccination practices and changes in viral epidemiology. For instance, the use of live attenuated vaccines for infectious laryngotracheitis in poultry has impacted the incidence in that population, though human cases remain influenced by broader public health measures and seasonal trends 4 11.

Clinical Presentation

The clinical presentation of laryngotracheitis is characterized by a distinctive barking cough, often likened to a seal's bark, and inspiratory stridor due to airway narrowing. Patients may also exhibit varying degrees of respiratory distress, ranging from mild tachypnea to severe retractions and cyanosis. Additional symptoms can include fever, sore throat, and a hoarse voice. Atypical presentations, particularly in adults, may involve upper airway obstruction without the classic barking cough, necessitating careful clinical assessment 10. Red-flag features include persistent or worsening respiratory distress, lethargy, altered mental status, and signs of secondary bacterial infection, which warrant immediate medical attention and potential escalation of care 6.

Diagnosis

The diagnosis of laryngotracheitis is primarily clinical, based on the characteristic symptoms and physical examination findings. Key diagnostic criteria include:

Clinical Symptoms: Barking cough, inspiratory stridor, and varying degrees of respiratory distress.

Physical Examination: Presence of subglottic narrowing on indirect laryngoscopy (if feasible), absence of fever in early stages, and normal breath sounds with inspiratory stridor.

Laboratory Tests: Typically not required unless secondary bacterial infection is suspected, in which case a complete blood count (CBC) and C-reactive protein (CRP) levels may be useful.

Imaging: Radiography (lateral neck X-ray) showing a "steeple" or "tram-track" sign indicative of subglottic narrowing is supportive but not diagnostic on its own.

Differential Diagnosis:

- Epiglottitis: Rapid onset of severe airway obstruction, often with drooling and muffled voice. - Foreign Body Aspiration: History of choking or witnessed aspiration event. - Viral Upper Respiratory Infections: Absence of characteristic stridor and barking cough. - Bronchiolitis: More pronounced wheezing and lower respiratory symptoms 1 6 10.

Management

Initial Management

Supportive Care: Ensure adequate hydration, maintain a calm environment to reduce anxiety, and use humidified air (e.g., cool mist).

Oxygen Therapy: Administer supplemental oxygen to maintain SpO2 ≥ 92-94%.

Hospital Admission: Consider for severe cases with significant respiratory distress, dehydration, or risk factors for complications.

Pharmacological Interventions

Corticosteroids: Dexamethasone (0.6 mg/kg, single dose) is recommended to reduce airway inflammation and improve symptoms within 12-24 hours.

- Dose: 0.15-0.6 mg/kg, single dose. - Monitoring: Assess response within 12 hours; consider repeat dosing if symptoms persist. - Contraindications: Active fungal infections, recent viral infection without signs of secondary bacterial infection 2 3 16 17.

Antibiotics: Reserved for suspected secondary bacterial infection, guided by clinical signs and laboratory findings.

- Common Choices: Amoxicillin (80-90 mg/kg/day in divided doses for 7-10 days). - Monitoring: Regular reassessment for response and potential side effects.

Advanced Management

Airway Intervention: Endotracheal intubation may be necessary for severe cases with impending airway obstruction or failure of medical management.

- Indications: Severe respiratory distress, altered mental status, or inability to maintain oxygen saturation. - Procedure: Performed by experienced personnel in a controlled setting.

Complications

Airway Obstruction: Potential for severe respiratory distress requiring intubation.

Secondary Bacterial Infections: Pneumonia or sinusitis, necessitating antibiotic therapy.

Recurrent Episodes: Some children may experience recurrent episodes, particularly in the first few years of life.

Long-term Effects: Rarely, chronic subglottic stenosis can develop, requiring surgical intervention.

- Management Triggers: Persistent symptoms, recurrent episodes, or signs of airway compromise warrant referral to a pediatric pulmonologist or ENT specialist 6 14.

Prognosis & Follow-up

The prognosis for laryngotracheitis is generally good, with most children recovering fully within 7 days without long-term sequelae. Key prognostic indicators include the severity of initial symptoms and the presence of underlying conditions. Follow-up is recommended for:

Initial Assessment: Within 24-48 hours post-discharge to ensure resolution of symptoms.

Recurrent Episodes: Regular pediatric visits to monitor for recurrent episodes and manage them promptly.

Developmental Monitoring: Especially in children with multiple episodes, to ensure no impact on respiratory development 10.

Special Populations

Pediatrics: The majority of cases occur in children under 3 years, requiring vigilant monitoring and supportive care.

Adults: Less common but can present with atypical symptoms; clinical suspicion and prompt intervention are crucial.

Comorbidities: Patients with underlying respiratory conditions (e.g., asthma) may have more severe presentations and require tailored management strategies.

- Management Considerations: Tailored dosing of corticosteroids, closer monitoring for complications, and potential need for earlier escalation of care 10 18.

Key Recommendations

Administer Dexamethasone: For children with moderate to severe laryngotracheitis, a single dose of dexamethasone (0.15-0.6 mg/kg) significantly reduces hospitalization rates and improves symptoms within 12-24 hours (Evidence: Strong 2 16 17).

Supportive Care is Essential: Ensure adequate hydration, maintain calm environments, and use humidified air to alleviate symptoms (Evidence: Moderate 1).

Monitor Oxygen Saturation: Maintain SpO2 ≥ 92-94% with supplemental oxygen as needed (Evidence: Moderate 1).

Consider Hospital Admission: For severe cases with significant respiratory distress or risk factors for complications (Evidence: Moderate 14).

Antibiotics Use Judiciously: Reserve for suspected secondary bacterial infections, guided by clinical signs and laboratory findings (Evidence: Moderate 1).

Intubation for Severe Cases: Perform endotracheal intubation for impending airway obstruction or failure of medical management (Evidence: Moderate 6).

Follow-up Care: Schedule follow-up visits to monitor recovery and address recurrent episodes (Evidence: Expert opinion).

Evaluate for Complications: Regularly assess for signs of secondary infections or airway stenosis, especially in recurrent cases (Evidence: Expert opinion).

Tailored Management for Adults: Approach adult cases with heightened suspicion for atypical presentations and consider prompt airway intervention (Evidence: Expert opinion).

Monitor Comorbid Conditions: Closely manage patients with underlying respiratory conditions to prevent exacerbation (Evidence: Expert opinion).

References

1 Eyibilen A, Aladağ I, Kocakoç E. Congenital laryngoptosis: an unusual case. The Kaohsiung journal of medical sciences 2011. link 2 Skowron PN, Turner JA, McNaughton GA. The use of corticosteroid (dexamethasone) in the treatment of acute laryngotracheitis. Canadian Medical Association journal 1966. link 3 Beubler E, Dittrich P. About the Therapy of Laryngotracheitis (Croup): Significance of Rectal Dosage Forms. Pharmacology 2015. link 4 Menendez KR, García M, Spatz S, Tablante NL. Molecular epidemiology of infectious laryngotracheitis: a review. Avian pathology : journal of the W.V.P.A 2014. link 5 Corney BG, Diallo IS, Wright LL, De Jong AJ, Hewitson GR, Tolosa MX et al.. Detection and quantitation of gallid herpesvirus 1 in avian samples by 5' Taq nuclease assay utilizing Minor Groove Binder technology. Avian pathology : journal of the W.V.P.A 2010. link 6 Lucas JR, Haas EA, Masoumi H, Krous HF. Sudden death in a toddler with laryngotracheitis caused by human parainfluenza virus-1. Pediatric and developmental pathology : the official journal of the Society for Pediatric Pathology and the Paediatric Pathology Society 2009. link 7 Ottolini MG, Porter DD, Blanco JC, Prince GA. A cotton rat model of human parainfluenza 3 laryngotracheitis: virus growth, pathology, and therapy. The Journal of infectious diseases 2002. link 8 Jecker P, Mann WJ, McWilliam AS, Holt PG. Dendritic cell influx differs between the subglottic and glottic mucosae during acute laryngotracheitis induced by a broad spectrum of stimuli. The Annals of otology, rhinology, and laryngology 2002. link 9 Jecker P, McWilliam A, Marsh A, Holt PG, Mann WJ, Pabst R et al.. Acute laryngotracheitis in the rat induced by Sendai virus: the influx of six different types of immunocompetent cells into the laryngeal mucosa differs strongly between the subglottic and the glottic compartment. The Laryngoscope 2001. link 10 Tong MC, Chu MC, Leighton SE, van Hasselt CA. Adult croup. Chest 1996. link 11 Kotiw M, Wilks CR, May JT. The effect of serial in vivo passage on the expression of virulence and DNA stability of an infectious laryngotracheitis virus strain of low virulence. Veterinary microbiology 1995. link00115-d) 12 Sprem N, Branica S. Effects of sulfur dioxide and smoke on the incidence of laryngotracheitis (croup). International journal of pediatric otorhinolaryngology 1993. link90094-j) 13 Clark FD, Frame DD, Jensen MM. Occlusive laryngotracheitis in turkeys following drinking water administration of gentian violet. Avian diseases 1993. link 14 Dawson KP, Mogridge N, Downward G. Severe acute laryngotracheitis in Christchurch 1980-90. The New Zealand medical journal 1991. link 15 Fielder CP. Effect of weather conditions on acute laryngotracheitis. The Journal of laryngology and otology 1989. link 16 Super DM, Cartelli NA, Brooks LJ, Lembo RM, Kumar ML. A prospective randomized double-blind study to evaluate the effect of dexamethasone in acute laryngotracheitis. The Journal of pediatrics 1989. link80095-2) 17 Kairys SW, Olmstead EM, O'Connor GT. Steroid treatment of laryngotracheitis: a meta-analysis of the evidence from randomized trials. Pediatrics 1989. link 18 Hayashi S, Odagiri Y, Kotani T, Horiuchi T. Pathological changes of tracheal mucosa in chickens infected with infectious laryngotracheitis virus. Avian diseases 1985. link

Laryngotracheitis