Stridor is a high-pitched respiratory sound caused by abnormal airflow in the upper airways. It can be caused by congenital anomalies or infections and can present in patients of any age. The document discusses the relevant anatomy, pathophysiology, types, causes, signs, symptoms, and management of stridor. Inspiratory stridor typically suggests an extrathoracic cause while expiratory stridor suggests an intrathoracic cause. Rapid assessment and intervention is important to address potential airway compromise, along with investigations like laryngoscopy to identify the specific cause and guide appropriate medical or surgical treatment.

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Management of Stridor
• Name and Affiliation of Presenter: Dr. Rupa Mehta
MS DNB MNAMS, Additional Professor, AIIMS-RAIPUR
• Name and Affiliation of Reviewer(s): Prof. (Dr) Nitin M Nagarkar
Director and CEO, Head of Department ENT, AIIMS-RAIPUR

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Specific Learning Objectives
Understand & learn the physics
& pathogenesis of stridor
Learn the various causes of stridor
Learn how to diagnose and
manage stridor in primary care
and seek specialist care

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Management of stridor
Subsection
Relevant Anatomy &
pathophysiology
Types & causes of stridor
Investigation & initial management
of stridor
Treatment of stridor

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Introduction
What is stridor?
• Stridor is a variable, high-pitched respiratory sound that can be assessed during breathing.
• It is produced by abnormal flow of air in airways, usually upper airways, & is most prominently
heard during inspiration.
• However, it can also be present during both inspiration & expiration.
• Stridor can be due to congenital malformations & anomalies as well as in acute phase from
life-threatening obstruction or infection.

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Relevant anatomy
• extrathoracic region includes
1) supraglottic area consisting of
nasopharynx, epiglottis, larynx,
aryepiglottic folds, & false vocal cords,
2) glottic and subglottic area consisting
of trachea prior to entering thoracic
cavity.
• intrathoracic region includes
o airways that reside in thoracic cavity
Inspiratory stridor tends to suggest
extrathoracic pathology, while expiratory
stridor suggests intrathoracic
pathology. Biphasic stridor is usually due to
a fixed obstruction such as a foreign body ,
laryngeal web

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Why is it caused ?
• 2 principles:
• 1-Poiseuille’s Equation, resistance is inversely proportional to radius to the fourth
power (r4)
o Pediatric airways are narrower, producing a higher resistance in pediatric airway,
& any further narrowing from a disease can significantly lead to airway obstruction

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• 2-Bernoulli effect -fast moving air will have less pressure following it
than slow moving air
• As one inhales , pressure in trachea decreases compared to
atmospheric pressure In stridor caused by extrathoracic
pathology, Bernoulli effect results in a drop in airway pressure
beyond obstruction, leading to collapse of airway walls & an
increase in obstruction
o This collapse limits the airflow & causes increased turbulence &
vibration of the airway walls generating characteristic sound of
stridor
• Bernoulli effect occurs in intrathoracic obstruction with forced
expiration. In intrathoracic obstruction pleural pressure is in play
• Biphasic stridor usually occurs due to a fixed obstruction from a
mass or foreign body & is not dictated by Bernoulli effect.

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Stridor can present as
Acute or Chronic Stridor
Congenital (present from birth) Stridor or Acquired Stridor
Can present in all age groups – paeditric population is more affected
Causes are different in paediatric and adult population

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acute chronic
Newborn Congenital Subglottic haemangioma Laryngomalacia
Presents shortly after birth
Tracheomalacia
Present in the first few weeks
Subglottic stenosis
Vascular ring
Children Infectious
Croup
Common under 3 years
Epiglottitis
May occur at any age and
more common in young
adults
Retropharynge al abscess
under 4 years
Bacterial tracheitis
Peritonsillar abscess
Non-infectious
Anaphylaxis
Foreign body
Burns
Adults Anaphylaxis Tumor
Recurrent respiratory papillamatosis
Hypocalcemic laryngeal spasm
Vocal cord paralysis
What are the causes of stridor?

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Inspiratory vs Expiratory Stridor
• An obstruction in extrathoracic region causes inspiratory stridor. During inspiration,
intratracheal pressure falls below atmospheric pressure, causing collapse of airway.
• An obstruction in intrathoracic region causes expiratory stridor. During expiration,
increased pleural pressure compresses airway causing a decrease in airway size at
site of the intrathoracic obstruction.

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How does a patient with stridor present?
Symptoms
• Noisy breathing
• Difficulty in breathing
• Effortful breathing
• Shallow breathing
• Laboured breathing
• fatigue
• Voice change
• Drooling
• Uneasiness
• Neck swelling
• Systemic symptoms
• Dysphagia
• Allergy history
• history of Foreign body ingestion

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What signs to look for?
Examination should focus on identifying features & severity of airway compromise &
potential underlying causes of stridor.
• Tachypnoea
• tachycardia
• Cyanosis
• Use of accessory muscles of respiration
• Clubbing
• tracheal tug
• sub-costal retraction
• intercostal recession
• Swelling neck
• Swelling tongue/floor of mouth
• sit forward, neck extended with their arms by their side to aid in breathing(tripod position)
• Restricted neck movements
• Trismus
• rashes

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How to manage a patient with stridor?
• Stridor warrants a rapid A-E assessment, primarily
focusing on assessment of airway
o Airway
o Breathing
o Circulation
o Disability
o Exposure
• Check vitals- pulse , BP, SpO2, respiratory rate,
consciousness level
• Local head & neck & chest examination
Specialists should be
involved early in the
management of stridor
including ENT and criti
cal care staff

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Investigations
• Flexible /rigid videolaryngoscopy
• bronchoscopy
• Xray Chest , Xray STN
• CT neck
• Blood investigations
• Simultaneously the following measures should be done depending on the patient’s condition
• Sit patient upright
• High flow O2
• Nebulised adrenaline: assess response & repeat if necessary
• IV steroids
• IV broad-spectrum antibiotics:)
Rapid intervention should proceed diagnostic work up in the ill-appearing patient

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Treatment
• Securing & establishing Airway- intubation / tracheostomy
• Depending on the cause – medical / surgical management

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Take home points…...
• The diffential diagnosis of stridor can be narrowed down based on the timing of stridor
(inspiratory/expiratory/biphasixc), age & presentation.
• Monitor for rapid deterioration due to respiratory failure
• Rapid intervention should proceed diagnostic work up in the sick patient
• Intubation for ill-appearing patients should be performed by trained team ( ENT &
anesthesia )
• A small ETT should be kept ready for smaller than anticipated airway due to edema
• A clinician with suitable airway equipment should accompany stable patients to
radiology in case of deterioration.

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References/Sources
Diseases of Ear, Nose & Throat and Head & Neck
Surgery, 8e & Manual of Clinical Cases in Ear, Nose and
Throat, 2e Paperback – 1 January 2021 PL Dhingra
CURRENT Diagnosis & Treatment Otolaryngology--Head
and Neck Surgery, Fourth Edition
by Anil Lalwani 2019

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Thank You
!