Guedel Airway (Oropharyngeal Airway) — Exam Notes

1. Basics

2. Indications

• Unconscious patient with upper airway obstruction from a relaxed tongue/soft palate (GCS low, no gag reflex)
• Adjunct during bag-valve-mask ventilation to maintain patency
• Spontaneously breathing, deeply obtunded patients with no gag reflex
• Bite block during seizures or to protect an ET tube/bite injury

3. Contraindications

• Conscious patient or any patient with an intact gag reflex (will trigger vomiting/laryngospasm)

• Oral trauma
• Trismus / restricted mouth opening
• Recent oral surgery, loose or broken teeth
• Active seizure (relative - risk of dental/oral injury during insertion)
• Foreign body airway obstruction

4. Sizing

• Corner of the mouth to the earlobe (tragus), or
• Corner of the mouth to the angle of the mandible

• Too small: fails to displace tongue, can push tongue further back and worsen obstruction
• Too large: tip can press on the epiglottis, causing laryngospasm or obstructing the larynx directly

5. Insertion Technique (adults)

1. Measure and select correct size.
2. Open the mouth with thumb-and-index-finger scissor technique.
3. Insert the airway inverted (concave side up, tip pointing toward the hard palate).
4. Once the tip reaches the soft palate/back of the mouth, rotate 180° so the curve follows the tongue, seating the distal end in the hypopharynx. Pulling the jaw forward during passage helps.

1. Open the mouth widely, depress the tongue with a tongue blade/laryngoscope blade.
2. Advance the airway directly along the tongue's curve into the oropharynx - no rotation needed. (This is the preferred method in pediatric patients because rotation can injure the soft palate/tonsillar pillars.)

6. Complications

• Induces gagging/vomiting and aspiration if gag reflex present
• Can worsen obstruction if malpositioned (tongue pushed backward)
• Laryngospasm if oversized
• Dental/oral soft tissue trauma (e.g., case reports of fractured teeth during Guedel airway use)
• Does not protect against aspiration (unlike a cuffed ET tube) - Bailey and Love's Short Practice of Surgery, 28e

7. OPA vs NPA (common exam comparison)

8. Key exam one-liners

• "If the patient can cough or gag, don't put in an oral airway - use an NPA."
• Guedel airway "holds the tongue forward but does not prevent aspiration" - useful for short-term BVM ventilation, not definitive airway protection.
• Always pair with jaw thrust/head-tilt-chin-lift and have suction ready (risk of inducing vomiting).

Nasopharyngeal Airway (NPA) — Parts of the Device (Practical Exam)

Parts of the NPA

• The wide, funnel-shaped end that sits outside the nostril.
• Function: prevents the entire tube from being swallowed/inhaled into the nasal passage; also allows air entry/exit and can be used to attach a bag-valve mask connector in some designs.
• Some devices have an adjustable flange that can be repositioned along the shaft to fix the insertion depth.

• Soft rubber or PVC/silicone tube, anatomically curved to follow the floor of the nasal cavity and posterior nasopharynx.
• Hollow lumen throughout, allowing airflow and, if needed, passage of a suction catheter.
• Marked with the size (in French gauge or internal diameter, mm) printed on the flange or shaft.

• The leading end is cut at an angle (bevel).
• Convention: the bevel opening faces the nasal septum during insertion, with the pointed heel of the bevel facing laterally (toward the turbinates) - this minimizes trauma/epistaxis from the turbinates and septum.
• The tip should ultimately rest just behind the base of the tongue/above the epiglottis, roughly at the level of the tip of the uvula, without stimulating the gag reflex.

• A pin placed transversely through the shaft just proximal to the flange.
• Purpose: prevents the airway from slipping further into the nose and disappearing into the nasopharynx/being aspirated - a classic exam point (older rubber trumpets lacked a fixed flange, so the pin was mandatory safety equipment).

• Printed size in French (Fr) gauge and corresponding internal diameter (mm). Common exam-quoted sizes:

Quick functional summary (how to present in the exam)

Sizing method (often asked alongside parts)

Contrast with OPA (frequently paired practical station)

Oropharyngeal Airway (Guedel Airway) - Parts

1. Flange - the wide flat end that sits at the lips/teeth; limits depth of insertion
2. Reinforced bite block - hard, kink-resistant segment just behind the flange; prevents occlusion of the air channel if the patient bites down
3. Curved body (rigid, kink-resistant) - anatomically curved to push the tongue forward and keep the epiglottis off the posterior pharyngeal wall
4. Tapered tip/edges - reduces oropharyngeal mucosal trauma on insertion
5. Colour-coded sizing - each size (e.g. Guedel No. 3/4/5) has a distinct flange colour for quick identification
6. Central channel - hollow lumen running the length of the device for airflow and suction catheter passage

Nasopharyngeal Airway (Nasal Trumpet) - Parts

1. Flange - wide proximal end that rests against the nostril; limits depth of insertion (in older rubber trumpets, a safety pin was added just behind this instead of/alongside a fixed flange)
2. Body/shaft with anatomical curvature - soft, non-latex PVC or silicone; follows the natural curve of the nasal floor and nasopharynx
3. Internal striations (device-specific feature) - ridges inside the lumen that help a suction catheter pass through more easily
4. Bevelled tip - angled distal opening; faces the nasal septum on insertion to reduce turbinate trauma and epistaxis
5. Size marking on flange - internal diameter in mm (e.g. "7.5 mm") printed directly on the flange

Side-by-side exam summary

Nasal Cannula (Nasal Prongs) - Parts

Parts of a standard (low-flow) nasal cannula

1. Two soft nasal prongs - short, curved or straight soft plastic projections that sit just inside the nostrils (should not occlude more than ~50% of the nares); curved prongs point posteriorly toward the nasopharynx to reduce mucosal irritation
2. Y-junction/bifurcation - the point where the single supply tube splits into the two prongs
3. Flexible tubing (limbs) - light, soft tubing that loops over/behind the ears (or is held by an elastic headband in infants) to secure the device on the face
4. Sliding adjuster - a small plastic ring under the chin that cinches the tubing snug against the face for a secure fit
5. Connector/supply tube - the single length of tubing (commonly 7 feet in adults) that runs from the Y-junction to the oxygen source
6. Universal connector/nipple adapter - the end that attaches to the oxygen flowmeter (wall oxygen outlet, cylinder regulator, or oxygen concentrator)

High-Flow Nasal Cannula (HFNC) - additional components (common exam add-on)

1. Wide-bore nasal prongs - larger diameter prongs than standard NC to tolerate high flows without excessive noise/discomfort
2. Heated humidifier chamber - saturates the gas at 31-37°C to prevent mucosal drying at high flows
3. Heated inspiratory tubing (single-limb circuit) - contains heater wires within the tubing wall to minimize condensation ("rainout")
4. Air-oxygen blender - allows independent titration of FiO2 from 21% to 100% regardless of flow rate
5. Flow generator/flowmeter - delivers flows up to 60 L/min

Quick comparison across the three devices you've covered