Parainfluenza virus accounts for two-thirds of the cases, with less common causes including respiratory syncytial virus, influenza, rhinovirus, adenovirus, enterovirus and rarely measles virus or HSV (Table 11.1) [2].

Croup mainly affects patients aged 6 months to 3 years, with a peak incidence in the second year of life [3]. It occurs more commonly in males, with a male to female preponderance of 1.4/1 [3]. Patients most often develop croup in the fall or early winter.

Viral croup has an incubation period of 2–6 days and typically starts with a prodrome of rhinorrhea, congestion, and low grade fever [3]. Following the prodrome, patients develop the characteristic symptoms of barky cough, hoarseness, and inspiratory stridor. The cough usually resolves after 3 days.

The diagnosis of croup is typically made based on the history and physical exam, however, an anterior-posterior (AP) and lateral radiograph of the neck may help confirm the diagnosis. The typical finding on AP imaging of the neck is the “steeple sign” which occurs secondary to the subglottic edema [4]. The radiographic findings are neither sensitive nor specific, making clinical history the most reliable diagnostic tool [5].

Treatment of viral laryngotracheobronchitis varies depending on the severity of the infection. Patients with a mild episode of croup are typically treated with a single dose of intramuscular (IM) or oral corticosteroids, usually dexamethasone [0.6 mg/kg (maximum dose of 10 mg)], or inhaled budesonide (2 mg) prior to discharge home. However, should a child present with more significant symptoms, they may be admitted for observation and treated with fluids, intravenous corticosteroids, nebulized racemic epinephrine (2.25 %; 0.5 mL in 2.5 mL of saline), and oxygen supplementation if the O₂ saturation is <92 %. Nebulized racemic epinephrine can be repeated every 15–20 min if indicated, but the clinical effect only lasts 1–2 h, so children should be carefully observed for symptom return.

The benefits of corticosteroids in the treatment of viral laryngotracheitis has been established in multiple randomized placebo controlled trials demonstrating a variety of benefits including an improvement in croup scores, decreased rates of return to the emergency department (ED) or health care provider, decreased rates of hospitalization, decreased length of hospital stays, and decreased need for respiratory support [6–9]. The majority of patients will respond to treatment within the first 6–12 h [9].

In the most severe cases of croup, patients may require direct laryngoscopy, bronchoscopy and intubation, although this is typically avoided as the endotracheal tube can contribute to the development of subglottic stenosis. Children with a history of multiple episodes of croup or who are under 6 months of age at the time of their first episode should undergo elective laryngoscopy and bronchoscopy when they are healthy to evaluate for a concomitant subglottic disease process (Fig. 11.1).

In the post-vaccination era the bacteriology of epiglottitis has changed. Although Haemophilus influenzae type b continues to be the most commonly implicated organism, other organisms are now increasingly found. There have been reports of β-hemolytic streptococci, Staphylococcus aureus, pneumococcus, nontypable Haemophilus influenzae, H. parainfluenzae, and Klebsiella species (Table 11.1) [10].

Epiglottitis has historically been one of the most devastating pediatric bacterial laryngeal infections. It most commonly affects children between 2 and 7 years of age [5]. Prior to the introduction of the polysaccharide vaccine to Haemophilus influenzae type b in 1985, epiglottitis was routinely encountered in the pediatric setting. Rates in the pre-vaccination era were reportedly between 4.9 and 6.1 cases per 100,000 children per year. These rates have dropped dramatically, and are now reported between 0.02 and 0.3 cases per 100,000 children per year [11]. Indeed, epiglottitis has become almost exclusively a condition of adults, and is often referred to as supraglottitis; however, diligence to identify epiglottitis in children remains necessary due to the potentially fatal outcomes. Contributing factors for continued H. influenzae type b infection are susceptibility of children under the age of 1 who have not completed their vaccination schedule, the increasing frequency of vaccination deferment, and the imperfect rate of immunity conferred by the vaccine.

The classic teaching is that a child will present toxic appearing, assuming the tripod position (sitting upright, with the chin tilted upwards, and bracing themselves with an outstretched arm). There is typically a history of fever, severe odynophagia, drooling, and muffled speech. Inspiratory stridor is present at times, and signals almost complete airway obstruction. These symptoms tend to develop rapidly over the course of hours.

The diagnosis of epiglottitis is accomplished through history and a non-invasive clinical examination. The patients, having a combination of airway swelling and significant pooling of secretions, can be easily be pushed into airway collapse or laryngospasm. Anxiety provoking maneuvers should be avoided, including intraoral examination to reduce patient anxiety.