Laryngeal Mask Airway
Key Points
- A laryngeal mask airway (LMA) is a supraglottic airway device that sits above the vocal cords, abutting the laryngeal inlet.
- LMAs are inserted through the mouth into the pharynx and secured with a low-pressure inflated cuff — no direct laryngoscopy or endotracheal tube placement is required.
- Primary indications: short or low-risk anesthetic cases, prehospital emergency airway, and cardiac arrest when endotracheal intubation is unavailable or not feasible.
- LMAs do not protect against aspiration as effectively as endotracheal tubes and are contraindicated in patients at high aspiration risk.
- Proper size selection and correct placement (black midline line at upper lip) are essential to maintain an adequate seal.
Pathophysiology
Airway adjuncts are used to maintain an open upper airway, relieve obstruction, or ventilate a patient when mask ventilation is difficult. The LMA is a supraglottic device: it sits in the hypopharynx above the vocal cords and forms a low-pressure seal around the laryngeal inlet, enabling ventilation without directly entering the trachea.
Unlike an oropharyngeal airway (OPA) or nasopharyngeal airway (NPA), the LMA provides a more secure airway than bag-mask ventilation but does not offer the complete airway protection of an endotracheal tube.
Airway Adjunct Comparison
| Device | Placement | Gag Reflex Tolerance | Aspiration Protection |
|---|---|---|---|
| OPA | Oropharynx, above tongue | Contraindicated with intact gag | None |
| NPA | Nasal passageway to nasopharynx | Can be used with intact gag reflex | None |
| LMA | Pharynx, abutting laryngeal inlet | Requires sedation or unconsciousness | Partial (low-pressure seal) |
| ETT | Trachea, below vocal cords | Requires sedation + paralysis | Full (cuff above carina) |
Nursing Assessment
NCLEX Focus
Know when an LMA is the appropriate choice versus endotracheal intubation — the LMA is suitable for short elective procedures and emergencies but not for patients with full stomach, obesity with high aspiration risk, or when a secure airway is required.
- Assess the patient’s aspiration risk, gag reflex status, and depth of sedation or unconsciousness before LMA placement.
- Confirm correct LMA size is selected based on patient weight and anatomy.
- After placement, monitor for adequacy of ventilation: chest rise, breath sounds bilaterally, oxygen saturation, and end-tidal CO₂ monitoring.
- Verify correct position by confirming the black midline line on the posterior of the LMA tube is aligned at the patient’s upper lip.
- Assess for signs of improper placement: inadequate chest rise, air leak, regurgitation, or decreasing oxygen saturation.
Nursing Interventions
Insertion assistance and monitoring:
- Lubricate the LMA with a water-soluble gel prior to insertion to reduce trauma.
- Support the airway provider during insertion: open the patient’s mouth, provide suction if needed.
- After insertion, inflate the mask cuff to achieve a low-pressure seal around the laryngeal inlet.
- Monitor continuously for ventilation effectiveness and cuff pressure; over-inflation can cause mucosal injury.
Intraoperative and emergency care:
- Maintain the patient’s position to prevent LMA displacement — excessive head movement can dislodge the device.
- Monitor and record oxygen saturation, end-tidal CO₂, and airway pressure continuously.
- Anticipate conversion to endotracheal intubation if the LMA fails to provide adequate ventilation or if aspiration risk increases.
- For cardiac arrest settings, ensure the LMA is used as a temporizing measure until more definitive airway management is established.
Removal (extubation):
- Remove the LMA when the patient demonstrates return of airway protective reflexes (swallowing, coughing) and adequate spontaneous ventilation.
- Deflate the cuff fully before removal.
- Assess for stridor, hoarseness, or respiratory distress after removal.
Aspiration Risk
The LMA does not protect the airway from aspiration as completely as an endotracheal tube. Patients with a full stomach, significant gastroesophageal reflux, obesity, or emergency presentations who may have undigested food are at higher aspiration risk — endotracheal intubation is preferred in these scenarios.
Related Concepts
- respiratory-system — Anatomy of the upper airway structures relevant to LMA placement.
- perioperative-surgical-classification-anesthesia-and-innovation — Context of LMA use within anesthesia types and surgical risk stratification.
- intraoperative-sterile-safety-and-complication-prevention — Intraoperative airway management and nurse role during surgery.
- postoperative-pacu-priorities-and-complication-surveillance — Monitoring respiratory status in post-anesthesia care after LMA removal.
- choking-maneuver-and-airway-clearance — Complementary airway management content for obstruction emergencies.
Self-Check
- How does an LMA differ from an endotracheal tube in terms of placement location and aspiration protection?
- What clinical sign confirms correct LMA position after insertion?
- In which patient population or clinical situation should an LMA be avoided in favor of endotracheal intubation?