ENT (Otorhinolaryngology) · MU Sofia

35. Inspiratory dyspnea.

Explains inspiratory dyspnoea as laboured inhalation caused by upper airway narrowing, with stridor as its hallmark. It lists congenital, infectious, traumatic, neoplastic, neurological and allergic causes, then a four-stage classification of airway obstruction. The note also covers clinical signs, endoscopic and imaging investigations such as the thumb and steeple signs, emergency and surgical treatment, complications, and how it differs from expiratory, mixed and cardiac dyspnoea.

Inside: 1 section · 16 flashcards · 3 min

Topic 35 of 52 in the MU Sofia syllabus for ENT (Otorhinolaryngology) (Medicine, Year 4). The free AceMed note covers it in 1 section, about 493 words (3 min of reading), with 16 flashcards.

In this note

  1. Inspiratory Dyspnea

Inspiratory Dyspnea

1. Definition: Inspiratory dyspnea is a type of breathing difficulty characterized by laboured inhalation. It occurs when the airway diameter narrows and airflow resistance increases during inspiration, typically due to an upper airway obstruction- larynx or trachea. It is commonly associated with inspiratory stridor.

2. Etiopathogenesis

  • Congenital: Laryngomalacia (most common in infants), subglottic stenosis, web.
  • Inflammatory/Infectious: Epiglottitis, Laryngotracheobronchitis (Croup), peritonsillar or retropharyngeal abscess, diphtheria.
  • Traumatic: Foreign body aspiration, laryngeal fractures, post-intubation edema.
  • Neoplastic: Laryngeal papillomatosis (benign), Squamous cell carcinoma (malignant).
  • Neurological: Bilateral vocal cord paralysis (eg, post-thyroidectomy).
  • Allergic: Angioedema (Quincke's edema).

During inspiration:

Negative pressure is created inside the airway.

If the airway is narrowed, this negative pressure causes further collapse.

Airflow becomes turbulent → produces stridor.

👉 Therefore, inspiratory dyspnea indicates upper airway obstruction

3. Classification of Airway Obstruction

  • Stage I (Compensated): Dyspnea occurs only during physical exertion. Patient anxious but stable Oxygenation adequate
  • Stage II (Partial Decompensation): Dyspnea at rest; use of accessory muscles begins.
  • Stage III (Decompensated): Severe dyspnea, marked stridor, suprasternal and intercostal retractions, anxiety, and cyanosis.
  • Stage IV (Asphyxia): Terminal stage; bradycardia, gasping, loss of consciousness, and respiratory arrest.

4. Clinical Picture

The hallmark of inspiratory dyspnea is Stridor —a high-pitched, musical sound produced by turbulent airflow through a narrowed upper airway.

  • Signs of Respiratory Distress:
  • Tachypnea: Increased respiratory rate.
  • Difficulty breathing, especially during inspiration
  • Retractions: Indrawing of the suprasternal notch, intercostal spaces, and epigastrium.
  • Nasal Flaring: Common in pediatric patients.
  • Posture: Patients may lean forward (tripod position) to maximize airway diameter (especially in epiglottitis).
  • Voice Changes: Hoarseness (laryngeal origin) or "muffled" voice (supraglottic/pharyngeal origin).
  • Cyanosis (late sign)

5. Paraclinical and Radiological Examinations

Clinical.- Observe breathing pattern

  • Endoscopy: Flexible fiberoptic laryngoscopy is the gold standard for visualising the site of obstruction.
  • Pulmonary function tests (after acute phase): Flattened inspiratory loop → extrathoracic obstruction
  • Imaging:
  • Lateral Neck X-ray: To look for the "Thumb sign" (epiglottitis) or retropharyngeal thickening.
  • AP Neck X-ray: To look for the "Steeple sign" (subglottic narrowing in Croup).
  • CT/MRI: For chronic cases or suspected neoplasms to assess tumor extent.
  • Laboratory: Arterial Blood Gas (ABG) (hypoxia and hypercapnia).

6. Treatment Options

  • Emergency Management:
  • Oxygen therapy: High-flow O2 (or Heliox to reduce turbulence).
  • Corticosteroids: IV Dexamethasone to reduce mucosal edema.
  • Adrenaline: Nebulized racemic epinephrine for temporary shrinkage of mucosa.
  • Surgical Intervention:
  • Endotracheal Intubation: Difficult in cases of anatomical distortion.
  • Tracheostomy: Indicated if intubation fails or for long-term airway management.

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