Supraglottic airway devices

What is a supraglottic airway device?

A SAD is an airway device that sits above the vocal cords (in the pharynx) to allow ventilation without passing a tube through the cords.
Common uses: routine airway for short/moderate cases, hands-free ventilation, and rescue airway when face-mask ventilation is difficult.
Key limitation: it does not fully protect against aspiration (stomach contents entering the lungs).

Common types you’ll meet

First-generation SADs: basic airway seal (e.g., classic LMA-style).
Second-generation SADs: improved seal + gastric drainage channel (allows passage of a gastric tube) and often better protection against regurgitation (not absolute).
Cuffed vs cuffless: most are cuffed (inflate to seal); some are cuffless and rely on shape to seal.
Reusable vs single-use: follow local policy for cleaning, checks, and maximum uses.

When SADs are a good choice

Elective, fasted patients with low aspiration risk.
Short procedures, day-case surgery, and cases where tracheal intubation is not required.
As a rescue device for ventilation (e.g., after failed mask ventilation or as part of difficult airway algorithms).
When you want less haemodynamic response and less sore throat than tracheal intubation (often, but not guaranteed).

When to be cautious or avoid

High aspiration risk: not fasted, bowel obstruction, active reflux/hiatus hernia with symptoms, pregnancy (especially 2nd/3rd trimester), emergency surgery, upper GI bleeding.
Need for high airway pressures: severe obesity, poor lung compliance, laparoscopic surgery (especially steep Trendelenburg), bronchospasm, restrictive lung disease.
Airway obstruction below the cords (SAD won’t bypass it).
Limited mouth opening or major upper airway pathology/trauma may make insertion difficult.

Sizing and basic setup

Choose size mainly by patient weight (check the device packaging chart; if between sizes, follow local guidance and clinical judgement).
Check the device before use: integrity, cuff inflation/deflation (if cuffed), and that connectors are secure.
Lubricate the back/sides of the cuff (avoid excess lubricant near the bowl/opening to reduce risk of airway obstruction).
Have suction ready and a plan B (mask ventilation, different size/device, intubation equipment).

Insertion: a safe, simple approach

Ensure adequate depth of anaesthesia before insertion (jaw relaxed, no coughing/straining).
Position: usually ‘sniffing’ position; in obese patients, consider head-up and ramping (ear-to-sternal notch alignment).
Insert along the hard palate and posterior pharynx with a smooth, controlled movement; don’t force against resistance.
If using a cuffed device: inflate cuff to the minimum volume needed to seal; aim for cuff pressure ≤ 60 cmH2O if you have a manometer.
Confirm ventilation: chest rise, capnography waveform, bilateral breath sounds, and stable oxygen saturation.

How to tell it’s working (and how well)

Capnography: persistent waveform is essential (do not rely on chest movement alone).
Oropharyngeal leak pressure (OLP): close APL valve gradually and listen for leak; higher OLP generally means a better seal (use local practice).
Ventilation pressures: if you need high peak pressures to ventilate, a SAD may leak or insufflate the stomach—reassess.
Gastric drainage (second-generation): pass a gastric tube if indicated and if trained; it should pass easily if the device is well positioned.

Troubleshooting: common first-time problems

No capnography / no ventilation: check circuit/oxygen, ensure adequate depth, reposition head/neck, gently adjust device depth, try jaw thrust, consider re-insertion.
Leak around device: check depth and head position, adjust cuff volume/pressure, consider upsizing, switch to a second-generation device, or proceed to intubation if ventilation inadequate.
High airway pressures: check for bronchospasm, inadequate anaesthesia, obstruction (bite), malposition; consider intubation if pressures remain high.
Gastric insufflation (epigastric sounds, rising airway pressure): reduce ventilation pressure, improve seal, consider second-generation with drainage, and reassess aspiration risk.

Ventilation strategy with a SAD

Aim for gentle ventilation: lowest pressure that achieves adequate tidal volumes and normal capnography.
Pressure-controlled ventilation often reduces peak pressures and leak compared with volume control (follow local practice).
Avoid excessive PEEP if it worsens leak; balance oxygenation needs with seal quality.
If you cannot ventilate adequately at safe pressures, escalate early (change device, intubate, call for help).

Removal and post-op considerations

Remove when the patient is either deeply anaesthetised or fully awake (local practice); avoid the ‘in-between’ stage where coughing/laryngospasm is more likely.
Suction the mouth/pharynx before removal if needed (gentle, under vision if possible).
Check for blood on the device (may indicate trauma) and ask about sore throat, hoarseness, or jaw pain.
Document: device type/size, number of attempts, cuff pressure (if measured), ease of ventilation, and any complications.

What’s the main difference between a SAD and a tracheal tube?

SAD sits above the vocal cords and is quicker/less invasive, but offers less protection from aspiration than a cuffed tracheal tube.

First-generation vs second-generation SADs?

– First-gen: basic seal – Second-gen: better seal + gastric drainage channel (and often higher leak pressures) – Second-gen is usually preferred when aspiration risk is a concern (but risk is not eliminated).

How do I confirm a SAD is correctly placed?

– Continuous capnography waveform – Chest rise and bilateral breath sounds – No significant leak at expected ventilation pressures – Stable oxygen saturation

What cuff pressure should I aim for (cuffed devices)?

Use the minimum volume to achieve an effective seal; if measured, aim for cuff pressure ≤ 60 cmH2O to reduce mucosal pressure and sore throat risk.

What should I do if there’s an audible leak?

– Reposition head/neck – Gently adjust device depth – Check/adjust cuff volume and measure cuff pressure if possible – Consider a larger size or a second-generation device – If ventilation is inadequate: escalate (call for help, consider intubation)

Can I use a SAD for laparoscopic surgery?

Sometimes, in carefully selected patients with a second-generation SAD and good seal. If high pressures are needed or aspiration risk is significant, intubation is usually safer.

What’s the role of a SAD in a difficult airway?

A SAD is a common rescue device to restore oxygenation/ventilation. If it works, it can be a bridge to waking the patient, intubation via the SAD (with appropriate equipment/skills), or proceeding with surgery if safe.

When should I pass a gastric tube?

If using a second-generation SAD with a drainage channel and it’s indicated (e.g., to decompress stomach, reduce regurgitation risk). It should pass easily—if it doesn’t, reassess position.

Deep vs awake removal—what’s safer?

– Deep removal: may reduce coughing but needs careful monitoring and airway support – Awake removal: airway reflexes intact but may cough Choose based on patient, surgery, and local practice; avoid removal during light anaesthesia.