viral laryngotracheitis

7/26/2019 Viral Laryngotracheitis

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Viral Laryngotracheitis (Croup)

Acute laryngotracheitis (viral croup) is the most common infectious cause of acute upper airway obstruction in

pediatrics, causing 90% of cases. The disease is usually benign and self-limited. Children in the 1-2-year-old age group

are most commonly affected, and the male-to-female ratio is 2:1. Viral croup affects 3-5% of all children each year.

Although croup is most common from the late fall to early spring, cases have been reported throughout the year.

I. Clinical Evaluation of Upper Airway Obstruction and Stridor

A. Stridor is the most common presenting feature of all causes of acute upper airway obstruction. It is a harsh

sound that results from air movement through a partially obstructed upper airway.

1. Supraglottic disorders, such as epiglottitis, cause quiet, wet stridor, a muffled voice, dysphagia and a

preference for sitting upright.

2. Subglottic lesions, such as croup, cause loud stridor accompanied by a hoarse voice and barky cough.

B. Patient Age

1. Upper airway obstruction in school age and older children tends to be caused by severe tonsillitis or

peritonsillar abscesses.

2. From infancy to 2 years of age, viral croup and retropharyngeal abscess are the most common causes.

3. Between three to six years of age, epiglottitis peaks.

C. Mode of Onset

1. Gradual onset of symptoms, usually preceded by upper respiratory infection symptoms, suggests viral

croup, severe tonsillitis or retropharyngeal abscess.

2. Very acute onset of symptoms suggests epiglottitis.

3. A history of a choking episode or intermittent respiratory distress may represent a foreign body inhalation.

4. Facial edema and urticaria suggests angioedema.

D. Emergency Management of Upper Airway Obstruction

1. Maintaining an adequate airway takes precedence over other diagnostic or therapeutic interventions.

2. If a supraglottic disorder is suspected, a person skilled at intubation must accompany the child at all

times.

3. Patients with suspected supraglottic pathology, severe respiratory distress from an obstruction, or

suspected foreign body inhalation should be taken to the operating room for direct visualization and

possible intubation.

4. Those patients who are not suspected of having epiglottitis, but who have only mild or moderate

respiratory distress can be managed in the emergency room.




Causes of Upper Airway Obstruction in Children

Supraglottic Infectious DisordersEpiglottitisPeritonsillar abscessRetropharyngeal abscessSevere tonsillitis

Subglottic Infectious DisordersCroup (viral laryngotracheitis)Spasmodic croupBacterial tracheitis

Non-Infectious Causes AngioedemaForeign body aspirationCongenital obstructionNeoplasmsExternal trauma to neck

Causes of Upper Airway Obstruction in Children

Epiglottitis Laryngotracheo-

bronchitis (Croup)

Bacterial Tracheitis Foreign Body Aspiration

History

Incidence in children

presenting with

stridor

8% 88% 2% 2%

Onset Rapid, 4-12 hours Prodrome, 1-7 days Prodrome, 3 days, then

10 hours

Acute or chronic

Age 1-6 years 3 mo-3 years 3 mo-2 years Any

Season None October-May None None

Etiology Haemophilus

influenza

Parainfluenza viruses Staphylococcus Many

Pathology Inflammatory edema

of epiglottis and

supraglottis

Edema and inflammation of

trachea and bronchial tree

Tracheal bronchial

edema, necrotic debris

Localized tracheitis

Signs and Symptoms

Dysphagia Yes No No Rare

Difficulty swallowing Yes No Rare No

Drooling Yes No Rare No

Stridor Inspiratory Inspiratory and expiratory Inspiratory Variable

Voice Muffled Hoarse Normal Variable




Cough No Barking Variable Yes

Temperature Markedly elevated Minimally elevated Moderate Normal

Heart rate Increased early Increased late Proportional to fever Normal

Position Erect, anxious, "air hungry,” supine

position exacerbates

No effect on airwayobstruction

No effect No effect

Respiratory rate Increased early Increased late Normal Increased if bronchial

obstruction present

Differentiation of Epiglottitis from Viral Laryngotracheitis

Clinical Feature Epiglottitis Viral Croup

Retractions present present

Wheezing absent occasionally present

Cyanosis present present in severe cases"Toxicity" present absent

Preference for sitting yes no

II. Epidemiology and Etiology of Viral Laryngotracheitis (Croup)

A. Parainfluenza virus type 1 causes 40% of all cases of laryngotracheitis. Parainfluenza type 3, respiratory

syncytial virus (RSV), parainfluenza type 2, and rhinovirus may also cause croup.

B. RSV commonly affects infants younger than 12 months of age, causing wheezing and stridor. Influenza viruses

A and B and mycoplasma have been implicated in patients older than 5 years.

III. Clinical Manifestations

A. Viral croup begins gradually with a 1-2 day prodrome resembling an upper respiratory infection. Subglottic

edema and inflammation of the larynx, trachea, and bronchi eventually develop. Involvement of thesestructures narrows the airway and produces stridor, barky cough, and hoarseness.

B. Low-grade fever, and nocturnal exacerbation of cough are common findings. As airway obstruction increases

retractions develop. Diminished air exchange leads to restlessness, anxiety, tachycardia, and tachypnea.

C. Cyanosis is a late sign; it may not occur until the PO2 drops to less than 40 mm Hg.

D. Severe obstruction leads to respiratory muscle exhaustion, hypoxemia, carbon dioxide accumulation, and

respiratory acidosis. Stridor becomes less apparent as muscle fatigue worsens.

E. Ten percent of croup patients have severe respiratory compromise requiring hospital admission, and 3% of

those children need airway support.

IV. Laboratory Evaluation

A. The diagnosis of viral croup is based primarily on the history and clinical findings. Laboratory evaluation

provides minimal diagnostic information.B. When the diagnosis is uncertain or the patient requires hospitalization, x-rays can be helpful. The

posteroanterior neck radiograph of a patient with viral croup shows symmetrical narrowing of the subglottic

space (the classic “steeple sign”). Radiographs are unreliable in assessing the severity of illness.

C. The differential diagnosis of viral croup (89% of cases of stridor) requires definitive exclusion of epiglottitis (8%

of cases) as a possible cause of obstruction. Other diagnostic considerations include spasmodic croup,

bacterial tracheitis, foreign body aspiration, and angioedema.




V. Inpatient Treatment of Laryngotracheitis

A. The majority of patients who have croup do not require hospitalization, but careful assessment is required to

detect the 10% who do, and especially those who need intubation.

B. Indications for Hospitalization

1. Dusky, or cyanotic skin color;

2. Decreased air entry on auscultation;

3. Severe stridor;

4. Significant retractions;

5. Agitation, restlessness, or obtundation.

C. Signs that indicate the need for an artificial airway include decreased respiratory effort and stridor, decreased

level of consciousness, and failure to respond to therapy. Pulse oximetry may aid in assessing the severity

of respiratory compromise.

D. All patients suspected of having viral croup should be given humidified-air through the use of vaporizers or

masks. Hypoxic or cyanotic patients require oxygen via mask and may require intubation.

E. Oral hydration is essential to help loosen inspissated secretions; however, intravenous hydration may become

necessary in the very ill child.

F. Racemic epinephrine has alpha-adrenergic properties which cause local vasoconstriction, decreasing

subglottic inflammation and edema. The severity of airway obstruction often improves acutely.

1. Racemic epinephrine is administered as 0.5 mL of a 2.25% solution, diluted with 3.5 mL of saline (1:8)

by nebulization. It is given every 20-30 minutes for the patient with severe croup, and it is every 4-6 hours

for the patient with moderate croup.

2. Indications for racemic epinephrine include severe croup, moderate croup, or stridor at rest.

3. The patient who receives racemic epinephrine should be admitted to the hospital because epinephrine’s

effects are short-lived and a rebound obstruction may occur.

4. Children with Tetralogy of Fallot or other forms of ventricular muscle outflow obstruction should not

receive racemic epinephrine because it can cause a sudden decrease in cardiac output.

G. Corticosteroids reduce subglottic edema and inflammation, capillary permeability, and lymphoid swelling.

1. Dexamethasone (0.6 mg/kg IM) given one time early in the course of croup results in a shorter hospital

stay and reduces cough and dyspnea.

2. The need for intubation is reduced from 1.2% to 0.1%. Patients who do not require hospitalization should

not receive steroids.

H. Acetaminophen decreases fever and oxygen consumption in the febrile patient with croup.




VI. Management of Airway Obstruction

Management of Imminent Airway Obstruction

1. Take no laboratory tests, including blood gases; no radiography; no intravenouslines.

2. Administer oxygen facially, 2-4 L/min. Keep child with parents.3. Attempt trial of racemic epinephrine

4. If response is dramatic, severe croup is likely

5. Assemble bedside supplies: - Cardiopulmonary resuscitation equipment - Resuscitation bag; appropriate size mask - 14-gauge angiocatheter - Intubation equipment

6. Notify:

- Otolaryngology (come to bedside)

- Anesthesia (prepare operating room; come to bedside)

- Intensive care unit for bed availability.

7. Escort patient to operating room with parents holding child

8. Administer anesthesia to patient while in parents' arms; begin intravenous

administration of fluids9. Inspect throat by direct laryngoscopy

10. Conduct bronchoscopy if indicated

11. Intubate; change to nasotracheal tube

12. Obtain cultures of blood, epiglottis

13. Employ restraints and sedation

A. If obstruction occurs abruptly and personnel skilled in intubation are not yet available, bag and mask

ventilation is vastly superior to unskilled attempts at intubation. Cricothyrotomy or tracheotomy should be

reserved for the most dire circumstance to prevent cardiopulmonary arrest and death.

B. An endotracheal tube 1-2 mm smaller than that normally recommended for the patient's age should be

used. Intubation should be undertaken in the operating room after induction with inhalation agents when

possible.

VII. Outpatient Treatment of Laryngotracheitis

A. Patients with mild viral croup usually are not admitted to the hospital and can be treated safely at home.

B. Vaporizers, oral fluids, and antipyretics are the mainstays of home therapy.

C. Parents should be instructed to watch the child closely and return to the ER if there is increasing stridor,

retractions, anxiety, or decreased oral intake.

D. The prognosis for croup is good; however, a subset of children who have croup will later be identified as

having bronchial reactivity following infection.

viral laryngotracheitis

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