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Laryngeal Mask Airway

General Surgery · Final Professional

Definition

The laryngeal mask airway (LMA) is a supraglottic airway device — a tube with an inflatable elliptical cuff that sits over the laryngeal inlet, forming a seal around it without entering the trachea. It provides a hands-free airway that is intermediate between a face mask and a tracheal tube, and is widely used for suitable elective cases and as a rescue device.

Uses & Advantages

The LMA is used for spontaneously breathing patients undergoing shorter, lower-risk surgery, and is a key rescue airway in the difficult/failed intubation algorithm. Advantages: it is easy to insert (no laryngoscopy or muscle relaxant needed), causes less airway stimulation and post-operative sore throat than a tracheal tube, and frees the anaesthetist’s hands.

DANGER / REMEMBER

The LMA does not reliably protect against aspiration of gastric contents, so it is avoided where aspiration risk is high (full stomach, emergency, pregnancy, significant reflux) — those patients need a cuffed tracheal tube. Some ‘second-generation’ LMAs with a drain tube offer better protection but still less than intubation.

Insertion & Limitations

The LMA is inserted blindly by advancing it along the hard palate until resistance is felt as the cuff seats in the hypopharynx, after which the cuff is inflated to form a seal; correct placement gives a clear airway with a good capnograph trace and no leak at normal pressures. Its limitations follow from the fact that it sits above, rather than within, the larynx: it seals only up to modest airway pressures, so it is less suitable for patients needing high ventilating pressures, and it leaves the trachea unprotected, which is the reason it is avoided when the stomach may be full.

CLINICAL PEARL

The LMA’s strength and weakness are the same fact — it sits over the larynx, not in the trachea: easy and atraumatic to place, but not a reliable guard against aspiration, so it is avoided in the full-stomach patient.

DANGER / REMEMBER

Complications of the LMA include an inadequate seal with leak or gastric insufflation, displacement or laryngospasm on insertion if anaesthesia is too light, and — most importantly — regurgitation and aspiration, which is why patient selection (elective, fasted, low reflux risk) is central to its safe use.

Contraindicated where aspiration risk is high.

KEY POINT

Key points TO remember

LMA = supraglottic airway; inflatable cuff seals over the larynx without entering the trachea.
Used for spontaneously breathing, lower-risk surgery and as a rescue airway.
Advantages: easy insertion (no laryngoscopy/relaxant), less stimulation and sore throat, hands-free.
Does not reliably prevent aspiration — avoid in full-stomach/high aspiration-risk patients.

EXAM TIP

Sources: Morgan & Mikhail’s Clinical Anesthesiology; Miller’s Anesthesia; Ajay Yadav’s Short Textbook of Anaesthesia.

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