Croup versus epiglottitis

Published on 07/02/2015 by admin

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CHAPTER 205

Croup versus epiglottitis

Peter Radell, MD, PhD and Sten Lindahl, MD, PhD, FRAC

Respiratory distress is one of the most common presenting symptoms among pediatric patients emergency departments and one of the most common reasons for admission to general pediatric intensive care units. Both acute epiglottitis (supraglottic inflammation) and croup (laryngotracheobronchitis or spasmodic croup, subglottic inflammation) present with evidence of airway obstruction. In 80% of all pediatric patients with acquired stridor, infection is the cause. Of these, 90% are due to laryngotracheobronchitis, and a minority are cases of epiglottitis. Other causes of respiratory distress, such as a foreign body, subglottic stenosis, bacterial tracheitis, and retropharyngeal abscess, also must be considered in the differential diagnosis.

Vaccination against Haemophilus influenzae has resulted in a dramatic reduction in the incidence of epiglottitis in children since the late 1980s. The incidence in adults has been less affected, and the prevalence of other bacterial infections—e.g. Staphylococcus, Streptococcus, Klebsiella, Pseudomonas—has increased relatively.

Because of the possibility of rapid clinical progression to complete obstruction, acute epiglottitis requires early and prompt intervention. To provide the appropriate therapeutic interventions, one must be able to differentiate between acute epiglottitis and laryngotracheobronchitis. Table 205-1 compares these two causes of severe stridor.

Table 205-1

Acute Epiglottitis Versus Croup

Clinical Feature	Acute Epiglottitis	Croup
Age (years)	3-7	0.5-5
Family history	No	Yes
Prodrome	Usually none ± dysphagia	Usually URI
Onset	Abrupt (6-24 h)	Gradual (days)
Clinical course	Rapid, may progress to cardiorespiratory arrest	Usually self-limited
Signs and symptoms
Temperature (° C)	38-40	38
Hoarseness	No	Yes
Dysphagia	Yes	No
Dyspnea	Severe	No
Inspiratory stridor	Yes	Yes
Appearance	Toxic, anxious, sitting upright, leaning forward, mouth open, exaggerated sniffing position	Nontoxic
Oral cavity	Pharyngitis with excessive salivation	Minimal pharyngitis
Epiglottis	Cherry red, edematous	Normal
Radiographic studies
Neck	Enlarged epiglottis(thumb sign)	Narrow epiglottis
Anteroposterior	Tracheal narrowing	Subglottic narrowing (steeple sign)
Laboratory studies
WBC count	Marked elevation with left shift	Variable
Bacteriology	Haemophilus influenzae type b, Staphylococcus, Streptococcus	Viral etiology, parainfluenza usually

URI, Upper respiratory infection; WBC, white blood cell.

Management

Croup

The treatment of croup varies according to the severity of the illness. In mild cases, conservative measures—such as humidification of air, fever control, and hydration—are usually effective. The cause is usually viral—most commonly parainfluenza viruses, influenza A and B viruses, and respiratory syncytial virus. Radiography can be performed to exclude other diagnoses, such as a foreign body, and may show the classic “steeple sign” characteristic of croup. In patients who are nontoxic and and whose condition is stable, it is increasingly common that flexible endoscopy of supraglottic structures is carried out to eliminate other diagnoses in the differential diagnosis of croup. In more severe cases, racemic epinephrine inhalations delivered by intermittent positive-pressure breathing or a simple nebulizer mask produce improvement and decrease the rate of hospital admission. L-Isomer epinephrine can be used with equal efficacy. Racemic epinephrine, 0.2 to 0.5 mL mixed in 2 to 3 mL of normal saline, can be administered over 15 to 20 min. The use of epinephrine requires subsequent observation to exclude rebound worsening when positive effects abate after 2 to 3 h, although mandatory admission does not seem necessary if observation for 3 to 6 h is carried out and reliable supervision is ensured.

If no improvement is seen after inhalation treatment, reconsider the diagnosis (e.g., bacterial tracheitis). Some patients require more than a single treatment, however. The use of steroid therapy has been controversial, but increasing evidence indicates benefit in terms of hospital admission and need for intubation. Dexamethasone, 0.6 mg/kg, can be administered orally, intramuscularly, or parenterally with equal efficacy. The use of He₂/O₂ (Heliox) has increased because the low density of He₂ attenuates the effects of turbulent flow in the airways. Mixtures of 70:30 or possibly 60:40 He₂:O₂ are needed to achieve an effect, making Heliox inappropriate for use in patients with significant O₂ requirements. In rare cases (less than 3%) of laryngotracheobronchitis, humidification, epinephrine, steroids, and Heliox are insufficient, and intubation or tracheostomy becomes necessary. Antibiotics are needed only if a secondary bacterial infection develops.

In cases with a more toxic presentation (see Table 205-1) or imminent respiratory collapse, a diagnosis of epiglottitis (supraglottitis) must be suspected. Consider the four “Ds” of epiglottitis—drooling, dysphagia, dysphonia, and dyspnea. The child with acute epiglottitis should be disturbed as little as possible (e.g. by radiography examinations or phlebotomy). Transport the child to the operating room in the sitting position with airway equipment readily available for possible ventilatory support. Do not attempt to visualize the pharynx, which may cause acute obstruction. The operating room should be set up for direct laryngoscopy, emergency bronchoscopy, and possible tracheostomy. Monitoring should include blood pressure, electrocardiography, precordial stethoscope, and pulse oximetry. Induction of anesthesia with O₂ and an inhalation anesthetic agent (sevoflurane or halothane, if it is available), with the child seated, should be performed. Because of the unpredictable variation in the amount of edema, and the potential anatomic distortion and difficulty with ventilation, the use of neuromuscular blocking agents and barbiturates should be avoided.

When anesthesia is induced, the child should be gently laid down. Assisted ventilation may be needed. Intravenous access should be obtained, and atropine, 0.02 mg/kg, should be intravenously administered to attenuate reflex bradycardia, and lidocaine, 1 mg/kg, is given to minimize the risk of coughing and laryngospasm. The use of racemic epinephrine, which may precipitate complete airway obstruction, should be avoided. Laryngoscopy should be performed and the trachea intubated orally with a tube that is 0.5 to 1.0 mm smaller than predicted for age. Once the child is anesthetized and well oxygenated, the oral tracheal tube can be replaced with a nasotracheal tube (again, 0.5 to 1.0 mm smaller than predicted for age). A chest radiograph should be obtained to confirm tube placement and to identify any infiltrate or atelectasis. After the airway is secured in the operating room, admission to an intensive care unit is essential. Intravenous sedation and restraints help prevent accidental extubation. Inspired gases should be humidified and the nasotracheal tube regularly suctioned. Extubation should be considered when pyrexia has resolved (usually within 12 to 36 h) and an air leak has developed around the tracheal tube.

Because the cause of epiglottitis is often uncertain, a broad-spectrum cephalosporin, such as cefotaxime (200 μg·kg⁻¹·day⁻¹), is initiated after blood and epiglottic cultures have been obtained. The use of corticosteroids has not been shown to be beneficial.