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HLT-RESP80-05 · Lesson 4 · 32 clock hours · demo

Supraglottic Airway Devices

Objective. Students will insert a laryngeal mask airway (LMA) and at least one other supraglottic device on an airway trainer, confirming placement by ventilation compliance and auscultation.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

What Are Supraglottic Airway Devices?

Supraglottic airway devices (SGAs) sit above the glottis and create a seal around or near the laryngeal inlet. They are used when bag-valve-mask (BVM) ventilation alone is inadequate and when endotracheal intubation is not immediately possible or appropriate. In respiratory therapy practice, SGAs appear in emergency airway rescue, procedural sedation support, and intraoperative settings. Understanding their mechanics, correct sizing, insertion technique, and limitations is essential before using them on real patients.

Types of Supraglottic Devices

Laryngeal Mask Airway (LMA) — The LMA is the most widely studied SGA. A flexible tube connects to an elliptical, inflatable cuff that seats against the perilaryngeal tissues, forming a low-pressure seal over the laryngeal opening. Classic LMAs are reusable; disposable versions are also common. The LMA does not protect against aspiration, because it does not pass through the vocal cords.

King LT (Laryngeal Tube) — The King LT is a single-use, dual-cuff device. It is inserted blindly into the esophagus; one cuff seals the esophagus and a second cuff seals the oropharynx. Ventilation occurs through side ports positioned at the laryngeal level. A single inflation port inflates both cuffs simultaneously.

i-gel — The i-gel uses a soft, non-inflatable thermoplastic cuff that conforms to perilaryngeal anatomy by body heat. No syringe is needed for cuff inflation. It also incorporates a gastric channel that allows passage of a suction catheter to decompress the stomach.

Sizing

Choosing the correct size prevents seal failure and airway trauma. Manufacturer charts match device size to patient weight or age. For LMAs, common adult sizes are 3 (small adult), 4 (adult), and 5 (large adult). Pediatric sizes are based on weight in kilograms. Never estimate by eye alone — consult the sizing guide printed on the device packaging or the clinical reference posted in your skills lab.

Inserting an LMA: Step-by-Step

1. Select and inspect the device. Choose the correct size; check the cuff for leaks by inflating and watching for symmetry, then fully deflate it before insertion.

2. Position the patient. Place the patient (or trainer) in the sniffing position — head extended, neck slightly flexed — unless a cervical spine injury is suspected.

3. Lubricate the posterior surface of the cuff with a water-soluble lubricant. Do not lubricate the anterior (grill) surface; lubricant entering the airway risks aspiration and laryngospasm.

4. Open the mouth. Use a scissor technique or jaw thrust. The device requires adequate mouth opening (typically ≥ 2 cm; check the manufacturer recommendation).

5. Insert the device. Hold the LMA like a pen at the tube-cuff junction. Press the deflated cuff tip against the hard palate and advance it in a smooth arc following the palatal curve, using your index finger as a guide, until firm resistance is felt.

6. Inflate the cuff. Use the correct volume of air as specified for the size (listed on the device label). Do not over-inflate; excessive pressure reduces seal quality and increases mucosal injury risk.

7. Connect the BVM and ventilate. Observe chest rise and deliver two test breaths.

8. Confirm placement. Auscultate the bilateral lung fields for equal breath sounds and over the epigastrium to rule out gastric ventilation. Observe end-tidal CO₂ waveform if capnography is available.

9. Secure the device. Tape or tie the tube to prevent displacement.

Confirming Ventilation Adequacy

Placement confirmation relies on multiple methods used together:

Troubleshooting and Device Selection

If mouth opening is limited (e.g., trismus, clenched teeth), standard LMA insertion may be impossible because it requires a two-finger mouth opening. In that scenario, consider a smaller LMA size if any opening exists, or switch to a device with a smaller profile. The i-gel and King LT can sometimes be inserted with less mouth opening than a standard LMA. Document your clinical reasoning: note the observed limitation, the device you selected, and the outcome.

If a seal leak is evident after correct cuff inflation, reassess positioning and device size before adding more cuff air. Avoid exceeding the maximum cuff volume listed on the device.

Safety and Scope of Practice

Key terms10

Supraglottic airway device (SGA)Any airway adjunct that seats above the vocal cords to facilitate ventilation without passing through the glottis.
Laryngeal mask airway (LMA)An SGA with an inflatable elliptical cuff that seals around the laryngeal inlet, allowing positive-pressure ventilation without endotracheal intubation.
King LT (Laryngeal Tube)A single-use, dual-cuff SGA inserted into the esophagus; ventilation occurs through side ports positioned at the laryngeal level.
i-gelAn SGA with a soft, non-inflatable thermoplastic cuff that conforms to perilaryngeal anatomy by body heat; includes a gastric channel.
Perilaryngeal sealThe low-pressure contact between an SGA cuff and the tissues surrounding the laryngeal opening, enabling ventilation.
Cuff inflation volumeThe amount of air (in mL) specified by the manufacturer for each device size; exceeding it increases mucosal injury risk and may worsen the seal.
End-tidal CO₂ (ETCO₂)The concentration of carbon dioxide measured at the end of exhalation; a sustained normal capnography waveform is the gold-standard confirmation of effective ventilation.
Aspiration riskThe danger of stomach contents entering the airway; SGAs do not fully protect against aspiration because they do not pass through the vocal cords.
Sniffing positionHead extension combined with slight neck flexion that aligns the oral, pharyngeal, and laryngeal axes to facilitate airway device insertion.
TrismusInvoluntary clenching or reduced opening of the jaw that limits access for airway device insertion.
In class: Watch instructor demonstrate LMA insertion technique, cuff inflation, and confirmation steps on the airway trainer, taking structured notes on each step. · In pairs, take turns inserting LMAs on the trainer; rotate through sizes for adult and large-child trainers and self-evaluate against a printed step checklist after each attempt. · Participate in a scenario in which the manikin's 'teeth' are clenched (simulating limited mouth opening); troubleshoot device selection, switching to an alternative supraglottic device and documenting the clinical rationale.
Materials: Airway trainer (adult/pediatric), LMA devices (assorted sizes), King LT or i-gel as available, 10 mL syringe, stethoscope, BVM, step checklists, lubricant, gloves
Check: Instructor-observed insertion checklist on the airway trainer: student completes all required steps without critical error and confirms ventilation adequacy on two consecutive insertions; pass = zero critical errors.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Airway Management
1. Which of the following best describes the primary difference between a laryngeal mask airway and an endotracheal tube?
Airway Management
2. A respiratory therapist inserts an LMA in an adult patient during an emergency. After inflating the cuff, she squeezes the BVM and hears loud gurgling over the epigastrium with minimal chest rise. What is the most appropriate immediate action?
Airway Management
3. When selecting an LMA size for an adult patient, the therapist should primarily consult:
Airway Management
4. During a skills lab scenario, the manikin's jaw is locked in near-closed position simulating trismus. The student is unable to insert an LMA. Which action is most appropriate?
Patient Assessment and Monitoring
5. The gold-standard method for confirming adequate ventilation through a supraglottic airway device is:
Airway Management
6. Which surface of the LMA cuff should be lubricated before insertion?
Airway Management
7. A student inflates an LMA cuff beyond the maximum volume listed on the device label. What is the most likely consequence?
Airway Management
8. A respiratory therapy student is practicing LMA insertion on an airway trainer. After a successful insertion, the instructor asks why the step checklist requires that a fully deflated cuff be confirmed before insertion. The best answer is:
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