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Stridor
Theresa Laguna, MD, MSCS
Stridor is a vibratory noise caused by turbulent air flow and
airway obstruction. Stridor can be heard on inspiration
(extrathoracic obstruction), expiration (intrathoracic obstruction), or during both phases of the respiratory cycle
(fixed obstruction) depending on the location of the lesion.
Stridor can be classified as acute, chronic, or recurrent in
nature.
CAUSATIVE FACTORS
Inflammation, edema, compression, or intraluminal obstruction of the respiratory tract above the larynx (uvula,
epiglottis, and arytenoid cartilages), at the level of the larynx (false cords, vocal cords, and arytenoepiglottic folds),
or in the trachea causes narrowing of the airway and signs
of airway obstruction. 1. Infection is a main cause of acute
stridor in children. Croup is the most common cause of
acute inspiratory stridor in children between 6 months and
3 years of age. Croup is a clinical respiratory syndrome
characterized by the sudden onset of a barky cough, respiratory distress, and inspiratory stridor usually secondary to
viral pathogens, most commonly parainfluenza types 1 and
3, respiratory syncytial virus, influenza virus, adenovirus
or human metapneumovirus. In unimmunized children,
laryngeal diphtheria and measles are important infectious
causative factors of croup to consider. Spasmodic croup is
similar to viral croup; however, its symptoms usually occur
without a viral prodrome and tend to be more short-lived.
A rare cause of inspiratory stridor, epiglottitis, is usually
caused by Haemophilus influenzae type b, although Streptococcus pneumoniae and Streptococcus pyogenes can
rarely cause acute epiglottitis. Immunization against H.
influenzae type b has dramatically decreased the cases of
epiglottitis seen in the United States. Bacterial tracheitis,
either caused by Staphylococcus aureus, S. pneumoniae,
H. influenzae or influenza viruses has emerged as a leading
cause of life-threatening airway infection in children, surpassing epiglottis and viral croup. 2. Acute stridor can also
be secondary to noninfectious causes. Etiologies to consider include angioedema, foreign body aspiration, peritonsillar abscess, retropharyngeal abscess, and trauma.
3. Recurrent or chronic stridor can be caused by intrinsic
lesions such as laryngomalacia, tracheomalacia, masses and
foreign bodies, or extrinsic lesions such as vascular rings or
slings.
MEDICAL MANAGEMENT
AND APPROACH
A. In the patient’s history, ask the following questions:
When did the stridor begin? Does the child have symptoms of an upper respiratory infection or cold, such as
coughing or rhinitis? When did the cold symptoms
404
begin? Is it difficult for the child to breathe? Is there
fast breathing? Did the child recently choke on something and have difficulty breathing or turn blue? Does
the child have a sore throat, hoarseness, or a change in
voice? Can the child swallow? Is there drooling or
fever?
B. In the physical examination, count the respiratory rate,
note the heart rate, and assess the oxygen saturation for
signs of impending respiratory failure. Listen for stridor at rest when the child is calm or an increase in
stridor during crying or coughing. Note the phase of
the breathing cycle that stridor is heard (during inspiration, expiration, or both). Most cases of acute stridor
are inspiratory in nature. Listen for hoarseness, a barky
cough, or a muffled voice. Look for retractions, cyanosis, extreme anxiety or confusion, restlessness, drooling, or a sniffing-type posture. With a stethoscope, note
air exchange, wheezing, and rales. Determine whether
the stridor is acute or chronic.
C. Angioedema usually presents with facial swelling, urticaria, and a history of similar allergic reactions. Foreign body aspiration can cause stridor, asymmetric
breath sounds, or wheezing. The onset is sudden, and
upper respiratory infection symptoms and fever are not
usually present. An ingested foreign body can rarely
lodge in the esophagus and cause upper airway obstruction. A forced expiratory chest film may demonstrate air trapping and possibly a shift of the mediastinum. Bronchoscopy is diagnostic and therapeutic, and
should be performed if foreign body is suspected. Assess carefully for tonsillitis or peritonsillar abscess.
D. Assess the degree of respiratory distress and determine
whether it is mild/moderate, severe, or very severe
(Table 1). Antibiotics play no role in uncomplicated
viral croup. Early corticosteroid treatment appears to
modify the course of even mild/moderate viral croup
and should be used to reduce the progression of the
inflammation and to prevent return for care and/or
hospitalization. Corticosteroids may be given orally,
intramuscularly, or parenterally. Nebulized corticosteroids may be useful, although oral or intramuscular
routes are preferred.
E. Encourage parents to give fluids to the child with uncomplicated, mild/severe viral croup. Instruct the parents to
call or seek medical care if the child develops stridor at
rest, has evidence of respiratory distress (retractions), or
becomes too ill to drink. Children with croup whose stridor resolves after treatment with nebulized racemic epinephrine in an ambulatory setting should be observed for
at least 3 hours before returning home because stridor
and respiratory distress frequently recur.
F. When stridor is moderate to severe and does not respond
to traditional therapy, hospitalization in a pediatric ward
or pediatric intensive care unit (ICU) should be considered. If acute epiglottitis is suspected, it should be
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Patient with STRIDOR
A
History
B
Physical exam
C
Identify:
Impending respiratory failure
Angioedema
Aspiration/foreign body ingestion
Tonsillitis/peritonsillar abscess
Assess pattern
Recurrent/chronic stridor
Acute stridor
D
Assess degree of
respiratory distress
(Table 1)
Consult:
Pulmonologist or
otolaryngologist
for laryngoscopy
or bronchoscopy
Consider airway
visualization
Mild-moderate
Severe
Very severe
Treat:
Racemic epinephrine
Corticosteroids
E
Consider discharge
Hospitalize, consider
after ≥3 hrs of
pediatric ICU admission
observation after last
F
racemic epi nebulizer
Consider airway
visualization
(Table 2)
(Cont’d on p 407)
considered an airway emergency and airway visualization
should be considered (Figure 1). It is important to assess
the risk for acute airway obstruction before attempting
to visualize the epiglottis in any patient suspected of
having acute epiglottitis to allow for adequate preparation (Table 2). When there is severe distress, inspection
of the epiglottis should be done in the operating room by
an anesthesiologist whenever possible, with an otolaryngologist or pediatric surgeon available for emergency
intubation and/or tracheostomy. In visualizing the epiglottis, it is important to have oxygen, a self-inflating
Ambu bag, a laryngoscope, and an appropriately sized
endotracheal tube (0.5–1 mm less than expected for the
child’s age) available in case the examination precipitates
acute upper airway obstruction. Never force a distressed
sitting child to lie down. This may compromise the airway and cause immediate obstruction. Lateral neck
radiographs should not be taken initially in patients at
high risk for acute epiglottitis because of the danger of
acute obstruction in the radiology department and the
delay in diagnosis and treatment while waiting for the
film. The value of lateral neck films as an alternative to
direct visualization in cases with a moderate risk for epiglottitis is controversial.
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G. Suspect bacterial tracheitis when croup is complicated
by high fever, purulent tracheal secretions, and increasing respiratory distress. This may be the presenting
pattern (resembling epiglottitis), or it may present after
several days of stridor (secondary bacterial tracheitis).
Endotracheal intubation is often necessary. Tracheal
secretions should be cultured to allow for appropriate
antibiotic therapy. Abundant purulent secretions and
pseudomembrane formation require aggressive pulmonary toilet.
H. In hospitalized children, manage respiratory distress
and stridor associated with viral croup with racemic epinephrine and corticosteroids. Corticosteroid treatment
shortens the hospital stay. Although humidified mist
therapy is used routinely in many centers, its efficacy has
not been documented, and tents are a barrier to observation. Viral croup rarely requires endotracheal intubation, although extreme vigilance is required. Heliox
(70% helium and 30% oxygen) may prevent intubation
in severe cases, although there is not enough evidence to
recommend its regular use. Ribavirin therapy is not indicated for viral croup. Always continue to reassess the
patient if incomplete response to therapy for secondary
infections such as bacterial tracheitis.
I. Manage acute epiglottitis with intubation in a controlled
setting because of the high risk for acute airway obstruction. Initiate antibiotic therapy with an appropriate cephalosporin antibiotic (Table 3). Blood cultures will be positive
in more than 50% of the cases caused by H. influenzae
type b. Identify extraepiglottic foci of infections, such as
pneumonia, septic arthritis, pericarditis, and meningitis.
Consider bacterial pathogens other than H. influenzae in a
child immunized against H. influenzae type b.
J. Causes of stridor identified by direct laryngoscopy or
bronchoscopy include laryngomalacia, laryngeal web,
laryngeal papilloma, redundant folds in the glottic
area, and supraglottic masses. Diagnoses associated
with pharyngeal or retropharyngeal masses include
enlarged adenoids; abscess or cellulitis; benign neoplasms, such as cystic hygroma, hemangioma, goiter,
and neurofibroma; and malignant neoplasms, such
as neuroblastoma, lymphoma, and histiocytoma.
Bronchoscopy can further identify tracheomalacia
and/or tracheal compression from a variety of lesions
including vascular malformations. Esophagram or
barium swallow can also aid in the diagnosis of intrathoracic lesions, which often are characterized by
expiratory or fixed stridor.
K. Discharge children from the hospital when stridor at
rest and respiratory distress has resolved and they no
longer need oxygen. They should be afebrile, eating
well, and appropriately active. Schedule a follow-up
visit 24 to 48 hours after discharge. Consider a visiting
nurse referral. Instruct the parents to call the physician
immediately if stridor or signs of respiratory distress
(fast breathing or chest indrawing) return.
(Continued on page 408)
Table 1. Degree of Respiratory Distress
Mild/Moderate
Severe
Volume status
Intermittent stridor with crying and/or
coughing, no audible stridor at rest
Good air exchange with minimal or no
retractions
No signs of dehydration
Ability to take PO
Mental status
Able to drink without drooling
Normal mental status
Stridor at rest, often both inspiratory and
expiratory
Decreased air entry with marked retractions
Signs of dehydration including increased
heart rate and decreased urine output
Impaired ability to drink
Altered mental status
Oxygen saturation
Normal
Normal or slightly decreased
Stridor
Air exchange
Very Severe
Stridor at rest, cyanosis
Minimal air exchange with severe retractions
Signs of dehydration including increased
heart rate and decreased urine output
Inability to drink
Agitation and anxiety secondary to air
hunger, or lethargic
Hypoxemic
Table 2. Risk for Acute Airway Obstruction and Guidelines for Visualization of the Epiglottis in Children
with Stridor and Suspected Epiglottitis
Risk for Acute
Obstruction
High
Moderate
Low
Minimal
Clinical Manifestations
Location and Personnel for Visualization
Drooling, muffled voice, severe sore throat, sniffing posture,
high fever, dehydration, anxiety, toxicity, no URI or cough
Stridor (intermittent or constant) with minimal URI signs,
high fever, age .5 years old without other signs of
epiglottitis
Stridor at rest associated with URI symptoms for 3–4 days,
low-grade fever
Operating room with airway specialist (anesthesia,
otolaryngologist, pulmonologist) and surgeons
Emergency department with airway specialist
Intermittent stridor with 2–4 days of URI, low-grade to
absent fever, no toxicity, no respiratory distress
Visualization usually not necessary; if done in
emergency department or in patient ward, have
physician present experienced with pediatric
resuscitation
Visualization not necessary
URI, upper respiratory infection.
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