Key Takeaways
- The upper airway includes the nose, mouth, pharynx (nasopharynx, oropharynx, laryngopharynx), and larynx
- The lower airway begins at the trachea and includes the mainstem bronchi, lobar bronchi, segmental bronchi, bronchioles, and alveoli
- The right mainstem bronchus is shorter, wider, and more vertical than the left, making it the most common site for aspiration and right mainstem intubation
- The epiglottis covers the glottic opening during swallowing to prevent aspiration
- The cricoid cartilage is the only complete cartilage ring in the airway and is the narrowest point in pediatric airways
- Signs of respiratory distress include tachypnea, accessory muscle use, nasal flaring, retractions, diaphoresis, and inability to speak in full sentences
- Signs of impending respiratory failure include altered mental status, paradoxical breathing, bradycardia, central cyanosis, and exhaustion
- The Mallampati score (I-IV) predicts difficulty of intubation based on visualization of pharyngeal structures
Airway Anatomy & Assessment
A thorough understanding of airway anatomy is essential for every respiratory therapist. The airway is divided into upper and lower segments, each with distinct structures and clinical considerations. The TMC exam extensively tests your knowledge of airway anatomy, assessment of respiratory distress, and recognition of conditions requiring urgent intervention.
Upper Airway Anatomy
The upper airway extends from the nose and mouth to the larynx and serves to warm, filter, and humidify inspired air.
| Structure | Key Features | Clinical Significance |
|---|---|---|
| Nasal cavity | Turbinates warm and humidify air; mucous membranes trap particles | Nasal intubation route; epistaxis risk |
| Oral cavity | Contains tongue (most common cause of upper airway obstruction) | OPA placement; suctioning access |
| Nasopharynx | Superior portion; adenoids located here | NPA placement route |
| Oropharynx | Behind the mouth; contains base of tongue | Most common obstruction site in unconscious patients |
| Laryngopharynx | Divides into trachea (anterior) and esophagus (posterior) | Aspiration risk zone |
| Epiglottis | Leaf-shaped cartilage; covers glottis during swallowing | Epiglottitis = medical emergency |
| Larynx | Contains vocal cords; thyroid and cricoid cartilages | Landmark for cricothyrotomy; voice production |
| Glottis | Space between the vocal cords | Narrowest point in adult airway |
Lower Airway Anatomy
The lower airway begins at the trachea and conducts air to the alveoli for gas exchange.
| Structure | Key Features | Clinical Significance |
|---|---|---|
| Trachea | 10-12 cm long; C-shaped cartilage rings | ET tube placement; suctioning depth |
| Carina | Bifurcation of trachea into left and right mainstem bronchi | ET tube tip should be 3-5 cm above carina |
| Right mainstem bronchus | Shorter, wider, more vertical (25-degree angle) | Most common aspiration site; right mainstem intubation |
| Left mainstem bronchus | Longer, narrower, more horizontal (45-degree angle) | Less common intubation/aspiration site |
| Bronchioles | Small airways without cartilage; smooth muscle walls | Bronchospasm site (asthma, COPD) |
| Terminal bronchioles | Last conducting airway generation | End of dead space ventilation |
| Alveoli | ~300 million; site of gas exchange | Type I cells: gas exchange; Type II cells: surfactant production |
Assessment of Respiratory Distress vs. Failure
Distinguishing between respiratory distress and impending respiratory failure is critical for determining intervention urgency.
Signs of Respiratory Distress (the patient is compensating):
- Tachypnea (RR > 20 in adults)
- Accessory muscle use (sternocleidomastoid, scalene, intercostal)
- Nasal flaring
- Intercostal and suprasternal retractions
- Diaphoresis
- Inability to speak in full sentences
- Tachycardia
- Agitation and anxiety
- Tripod positioning (sitting upright, leaning forward, arms braced)
Signs of Impending Respiratory Failure (decompensation):
- Altered mental status (confusion, somnolence, unresponsiveness)
- Paradoxical breathing (abdomen rises while chest falls during inspiration)
- Bradycardia (ominous sign in respiratory distress)
- Central cyanosis (lips, mucous membranes)
- Exhaustion, unable to maintain respiratory effort
- Bradypnea or apnea
- Silent chest (no air movement despite respiratory effort)
Mallampati Classification
The Mallampati score predicts intubation difficulty based on pharyngeal visualization:
| Class | Visualization | Intubation Difficulty |
|---|---|---|
| Class I | Soft palate, fauces, uvula, anterior and posterior pillars visible | Easy intubation expected |
| Class II | Soft palate, fauces, uvula visible | Usually straightforward |
| Class III | Soft palate, base of uvula visible | Potentially difficult |
| Class IV | Only hard palate visible | Difficult intubation expected |
A patient is found unresponsive. What is the MOST common cause of upper airway obstruction?
The right mainstem bronchus is the most common site for aspiration because it is:
Which of the following is a sign of impending respiratory FAILURE rather than respiratory distress?
The _____ cartilage is the only complete cartilage ring in the airway and serves as a landmark for cricothyrotomy.
Type your answer below