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Stridor

Stridor Dr Rahul Bagla ENT Textbook

Stridor

Stridor represents a form of noisy respiration that arises due to turbulent airflow through narrowed airway passages. The sound is often alarming and may be audible during inspiration, expiration, or throughout both phases of breathing. In clinical settings, any partial obstruction of a respiratory passage leads to characteristic sounds, commonly categorised as stertor or stridor. Understanding the fundamental difference between these sounds significantly aids the diagnostic process.

Stertor, derived from the Latin term meaning “to snore,” is defined as a low-pitched respiratory sound. It typically originates from the structures located above the larynx. Relaxed nasopharyngeal, pharyngeal, or laryngeal tissues cause this noise. Unlike stridor, stertor occurs solely during inspiration. Conditions like nasal congestion or enlarged adenoids commonly trigger stertor in children.

Stridor is a harsh, vibratory sound produced by turbulent airflow through obstructed segments of the larynx, trachea, or bronchi. It can be heard in inspiration, expiration, or throughout both phases of breathing. Importantly, the nature of stridor—whether inspiratory, biphasic, or expiratory—points toward the anatomical location of airway obstruction and underlying pathology.

  1. Inspiratory stridor, often low-pitched, typically arises from supraglottic structures, such as in laryngomalacia or retropharyngeal abscess.
  2. Biphasic stridor arises from glottic or subglottic structures, such as in laryngeal papillomas, vocal cord paralysis, or subglottic stenosis.
  3. Expiratory stridor, in contrast, is high-pitched, typically arises from the lower respiratory tract, including the trachea or bronchi, such as in bronchial foreign body, and tracheal stenosis.

Stridor and stertor frequently coexist with other respiratory symptoms. Accompanying symptoms, including dyspnoea, persistent cough, hoarseness of voice, and difficulty in swallowing (dysphagia), exacerbate patient distress. Consequently, clinicians undertake comprehensive evaluations to ascertain the obstruction’s aetiology. By addressing these manifestations holistically, healthcare providers optimise patient outcomes. Therefore, stridor warrants urgent investigation to avert respiratory compromise.

Causes of Stridor

  1. Congenital Causes. Congenital anomalies often underlie stridor in neonates and infants. Nasal causes include choanal atresia, deviated septum, or alar collapse. In addition, craniofacial abnormalities, such as those seen in Pierre Robin syndrome or Apert syndrome, contribute significantly. Macroglossia, an abnormally large tongue, observed in conditions like Down syndrome and Beckwith-Wiedemann syndrome, can obstruct the airway and produce stridor. Furthermore, congenital laryngeal abnormalities—laryngomalacia, laryngeal webs, laryngeal cysts, clefts, and vocal cord paralysis—are leading causes. Subglottic and tracheal stenosis, along with tracheomalacia, round out the list of common congenital contributors.
  2. Acquired Causes. Acquired causes of stridor differ between children and adults. In children, acute causes include foreign body aspiration, airway burns, bacterial tracheitis, epiglottitis, anaphylaxis, croup, peritonsillar abscess, and retropharyngeal abscess. Chronic causes encompass vocal cord paralysis, laryngeal spasm, and tumours. In adults, acute conditions like croup, allergic reactions, angioneurotic oedema, laryngeal trauma, tumours, and Ludwig’s angina are predominant. Identifying the specific cause is crucial for effective management and favourable outcomes.

History Taking in Stridulous Patients

  1. A meticulous history remains the cornerstone of evaluating a patient presenting with stridor. Firstly, the physician must ascertain whether the airway obstruction is acute or chronic. Acute obstruction, developing within minutes to hours, commonly results from inhaled foreign bodies, laryngeal oedema, or trauma. On the other hand, chronic airway obstruction evolves over weeks or months, often indicating neoplastic growths.
  2. The age of onset provides important diagnostic hints. Although congenital causes usually present at birth, some cases become apparent only during the first respiratory infection. In adults, new-onset stridor warrants an urgent evaluation for malignancies, neurological disorders, or psychological causes.
  3. Characterisation of the stridor or stertor sound further aids diagnosis. Descriptions such as whistling, croaking, rattling, or snoring help localise the obstruction. The severity of the stridor, gauged by how far it can be heard and the presence of laboured breathing or cyanosis, also requires careful documentation.
  4. Additionally, variations in noise with position, crying, activity, or feeding should be elicited. For example, in laryngomalacia, prone positioning often alleviates stridor. Furthermore, understanding the relationship of stridor to feeding provides critical clues. Aspiration during feeding suggests laryngeal paralysis, oesophageal atresia, or vascular anomalies. A thorough past history, including cardiovascular, respiratory, neurological diseases, and trauma to the neck or face, is indispensable.

Physical Examination of Stridulous Patients

  1. During physical examination, attention should be directed toward chest movements and the presence of respiratory distress signs such as pectus excavatum, intercostal, substernal, or suprasternal retractions. Identifying whether stridor is inspiratory, expiratory, or biphasic narrows the differential diagnosis significantly.
  2. The associated characteristics of the stridor offer further diagnostic clarity. A snoring or snorting sound points to nasal or nasopharyngeal obstruction. Gurgling noises combined with a muffled voice suggest a pharyngeal cause. Hoarseness or an altered cry usually indicates laryngeal involvement. In contrast, an expiratory wheeze points to bronchial obstruction.
  3. Associated fever raises suspicion for infections like acute laryngitis, epiglottitis, laryngotracheobronchitis, or diphtheria. Observing the extension of the neck during breathing, particularly in laryngomalacia, provides further clues. Positional changes, such as improvement in prone posture in macroglossia and laryngomalacia, should be noted. Additionally, flaring of nostrils, tachypnoea, tachycardia, and cyanosis are vital signs that indicate severe airway compromise.
  4. A detailed examination of the nasal cavity is necessary to rule out causes like deviated nasal septum, septal hematoma, or choanal atresia. Choanal atresia can be diagnosed if an infant’s feeding tube cannot be passed through both nasal passages. Oral cavity and oropharyngeal inspection for tonsillar hypertrophy, peritonsillar abscess, or retropharyngeal masses is also mandatory.

Investigations in Stridor

  1. Investigations aim to identify the underlying pathology promptly. Arterial blood gases and complete blood counts provide initial insights into respiratory status and infection markers.
  2. Radiological studies remain pivotal. A lateral X-ray of the neck can reveal increased prevertebral soft tissue thickness, suggesting a retropharyngeal abscess. Normally, this thickness should not exceed 6 mm at the C2 level or 22 mm at C6. The anteroposterior view of the neck helps diagnose croup through the characteristic “steeple sign.” Chest X-rays are essential for detecting foreign body aspirations; however, a negative film does not exclude the diagnosis.
  3. When conventional imaging is inconclusive, computed tomography (CT) of the neck and chest provides detailed visualisation of airway lesions. Endoscopic evaluation, including flexible fibreoptic laryngoscopy and direct micro laryngoscopy with bronchoscopy, offers direct airway visualisation, crucial for a definitive diagnosis. These procedures allow the collection of secretions for culture, the removal of foreign bodies, and the assessment of congenital or acquired anomalies.

Treatment of Stridor

Management of Acute Airway Obstruction

  1. The initial management of acute airway obstruction focuses on securing the airway urgently. Administration of 100% oxygen via a face mask is the first critical step. If laryngeal oedema is present, nebulised racemic adrenaline provides rapid relief. Intravenous corticosteroids help reduce inflammation and airway swelling.
  2. A trial with heliox, a low-density gas mixture containing 21% oxygen and 79% helium, often alleviates symptoms. Heliox, being three times less dense than air, improves airflow through narrowed airways. Also, the carbon dioxide gas diffuses four times faster in heliox than through air, so this helps in faster removal of carbon dioxide, enhancing overall gas exchange.
  3. If conservative measures fail, definitive airway management becomes necessary. Endotracheal intubation, either directly or using fiberoptic guidance, is usually the first option. In extreme emergencies, cricothyrotomy or tracheostomy may be life-saving interventions.

Management of Chronic Airway Obstruction

  1. For chronic upper airway obstruction, awake fiberoptic intubation (AFOI) has become the gold standard. A flexible laryngoscope is introduced through the nose or mouth, over which the endotracheal tube is advanced into the trachea. This technique allows continuous monitoring of airway patency during intubation.
  2. Lower airway obstructions often necessitate rigid ventilating bronchoscopy. This method not only diagnoses airway lesions but also enables therapeutic interventions. Techniques such as LASER or coblation excision of tumours, and insertion of tracheobronchial stents are commonly employed. Complex lesions at the carina may require advanced measures like jet ventilation or even cardiopulmonary bypass.

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Stridor Meaning Causes Best Lecture Notes Dr Rahul Bagla ENT Textbook

Reference Textbooks.

  • Scott-Brown, Textbook of Otorhinolaryngology-Head and Neck Surgery.
  • Cummings, Otolaryngology-Head and Neck Surgery.
  • Stell and Maran’s, Textbook of Head and Neck Surgery and Oncology.
  • Ballenger’s, Otorhinolaryngology Head And Neck Surgery
  • Susan Standring, Gray’s Anatomy.
  • Frank H. Netter, Atlas of Human Anatomy.
  • B.D. Chaurasiya, Human Anatomy.
  • P L Dhingra, Textbook of Diseases of Ear, Nose and Throat.
  • Hazarika P, Textbook of Ear Nose Throat And Head Neck Surgery Clinical Practical.
  • Mohan Bansal, Textbook of Diseases of Ear, Nose and Throat Head and Neck Surgery.
  • Hans Behrbohm, Textbook of Ear, Nose, and Throat Diseases With Head and Neck Surgery.
  • Logan Turner, Textbook of Diseases of The Nose, Throat and Ear Head And Neck Surgery.
  • Arnold, U. Ganzer, Textbook of  Otorhinolaryngology, Head and Neck Surgery.
  • Ganong’s Review of Medical Physiology.
  • Guyton & Hall Textbook of Medical Physiology.

Author:

Dr. Rahul Bagla ENT Textbook

Dr. Rahul Bagla
MBBS (MAMC, Delhi) MS ENT (UCMS, Delhi)
Fellow Rhinoplasty & Facial Plastic Surgery.
Renowned Teaching Faculty
Mail: msrahulbagla@gmail.com
India

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