Types of Laryngeal Mask Airways (LMAs)
Classification by Generation
LMAs are fundamentally divided into first-generation and second-generation devices, with second-generation devices strongly preferred in critical care and emergency settings due to superior oropharyngeal seal pressures and gastric drainage capabilities. 1
First-Generation LMAs
- Classic LMA (cLMA): The original device invented by Dr. Archie Brain in 1983, consisting of a silicone rubber tube connected to a miniature silicone mask with an inflatable elliptical cuff 2, 3
- LMA-Unique: A single-use PVC version of the classic LMA with similar clinical performance, requiring less cuff inflation volume 4
- These devices lack gastric drainage channels and have lower oropharyngeal seal pressures, making them less suitable for critical situations 1
Second-Generation LMAs
Second-generation supraglottic airways are mandatory for critical care due to their higher oropharyngeal seal pressures and reduced risk of gastric inflation. 1
- ProSeal LMA (PLMA): Offers the highest oropharyngeal seal pressure among second-generation devices and includes a gastric drainage tube for enhanced airway separation 2, 1
- LMA Supreme: Provides high seal pressure (second to ProSeal) with integrated gastric access and a rigid curved airway tube 1
- i-gel: A cuffless supraglottic airway with anatomical design, offering good seal pressure (third among second-generation devices) 1
Specialized LMA Types
Intubating LMAs
- LMA Fastrach (Intubating LMA): Specifically designed to facilitate blind or fiberoptic-guided tracheal intubation, with a rigid curved shaft and epiglottic elevating bar 5, 6
- LMA CTrach: Features integrated video capability for visualized intubation through the device, showing reduced cervical spine movement compared to direct laryngoscopy 6
- These devices allow passage of a 6.0-mm internal diameter endotracheal tube over an intubating stylet or pediatric fiberoptic bronchoscope 3
Clinical Context for Device Selection
Critical Care and Emergency Settings
For airway rescue in critically ill adults and emergency situations, use second-generation supraglottic airways (ProSeal LMA, LMA Supreme, or i-gel), with ProSeal offering the highest seal pressure. 1
- Device-specific training is essential and should receive the same emphasis as tracheal intubation training 1
- Limit insertion attempts to one optimal attempt or maximum three attempts before declaring failure 1
- Never apply cricoid pressure during insertion as it impairs placement and ventilation 1
Cardiac Arrest
- The American Heart Association recommends supraglottic airways like LMAs as reasonable alternatives to bag-mask ventilation and endotracheal intubation during CPR, particularly in out-of-hospital settings with low intubation success rates 7, 8
- Either first or second-generation devices may be used, though second-generation devices are preferable when available 1
Cervical Spine Injury
- No specific LMA type is clearly superior for reducing cervical spine movement or achieving successful intubation 6
- Clinicians should use devices familiar to them rather than selecting based solely on cervical spine considerations 6
- Second-generation SADs should be considered in preference to first-generation devices even in this context 6
Key Clinical Considerations
Contraindications
- All LMA types are contraindicated when patients are at risk for pulmonary aspiration (full stomach, emergency cases) 3, 9
- LMAs do not guarantee protection against aspiration and are not substitutes for properly placed endotracheal tubes in high-risk situations 3, 9
Advantages Over Face Mask
- Better airway control with minimal gas leakage 9
- Frees the anaesthetist's hands as no mandibular support is needed 9
- Less hemodynamically stressful than endotracheal intubation 3
- Secure airway during patient transport 9