What are supraglottic airway generations?

Supraglottic Airway Generations

Supraglottic airway devices are classified into first-generation and second-generation devices based on design features that enhance safety and functionality, with second-generation devices incorporating gastric drainage channels, higher oropharyngeal seal pressures, and improved aspiration protection. 1

First-Generation Supraglottic Airways

First-generation devices represent the original supraglottic airway designs that revolutionized airway management starting in the 1980s. 2, 3

Key characteristics of first-generation devices:

• Simple perilaryngeal seal without gastric access - These devices rely solely on an inflatable cuff to create a seal around the laryngeal inlet without any mechanism for gastric decompression. 1
• Lower oropharyngeal seal pressures - First-generation devices typically achieve seal pressures below 30 cm H₂O, limiting their ability to provide reliable positive-pressure ventilation. 4
• Classic LMA as the prototype - Brain's original Laryngeal Mask Airway (cLMA) from 1983 achieved 99.8% success rates and was used in almost one-third of cases by 1993, establishing the foundation for all subsequent supraglottic devices. 2, 5
• No integrated aspiration protection - These devices lack features to manage regurgitated gastric contents, making them unsuitable for patients with aspiration risk. 4

Clinical limitations requiring evolution:

• Inadequate for aspiration-risk patients - First-generation devices should never be used in patients at risk for aspiration due to insufficient airway protection. 4
• Limited positive-pressure ventilation capability - Lower seal pressures restrict their use in patients requiring higher airway pressures. 1

Second-Generation Supraglottic Airways

Second-generation devices incorporate multiple design improvements that address the limitations of first-generation devices and expand clinical applications. 1, 6

Defining features of second-generation devices:

• Gastric drainage channels - These devices include dedicated tubes or channels that allow passage of gastric tubes for decompression and drainage of regurgitated contents, providing enhanced separation of respiratory and gastrointestinal tracts. 2, 5
• Higher oropharyngeal seal pressures - Second-generation devices achieve seal pressures greater than 30 cm H₂O, enabling more reliable positive-pressure ventilation. 4, 1
• Integrated bite blocks - Built-in bite blocks prevent airway occlusion from patient biting. 1
• Enhanced aspiration protection - Design features including gastric drainage compartments reduce aspiration risk, though not to the level of endotracheal intubation. 4, 5

Specific second-generation device examples:

• LMA ProSeal - Offers the highest oropharyngeal seal pressure among second-generation devices and includes a gastric drainage tube for enhanced airway-gastrointestinal separation. 5
• LMA Fastrach - Specifically designed with a rigid curved shaft and epiglottic elevating bar to facilitate blind or fiberoptic-guided tracheal intubation. 5
• LMA CTrach - Features integrated video capability for visualized intubation through the device, showing reduced cervical spine movement compared to direct laryngoscopy. 5

Clinical Impact of Generational Evolution

Second-generation devices are strongly preferred in critical care and emergency settings due to superior performance characteristics and safety profile. 5

Evidence of clinical superiority:

• Immediate rescue device status - Second-generation supraglottic airways are the preferred initial rescue device after failed intubation in critically ill patients, even those with high aspiration risk. 4
• Equivalent outcomes to endotracheal intubation in high-skill settings - When endotracheal intubation success rates exceed 90%, second-generation supraglottic airways demonstrate equivalent survival and neurological outcomes. 4, 7
• Superior outcomes in low-skill settings - When endotracheal intubation success rates fall below 70%, second-generation supraglottic airways show superior survival to discharge (RR 1.34) and neurologically favorable survival (RR 1.42). 7

Widespread adoption trajectory:

• By 2011, supraglottic airway devices were used in 56.2% of general anesthetics, demonstrating their transformation from novel devices to mainstream airway management tools. 2, 5
• The American Heart Association recommends supraglottic airways as reasonable alternatives to both bag-mask ventilation and endotracheal intubation during cardiac arrest, particularly in settings with low intubation success rates. 2, 5, 7

Critical Practice Points

Device selection algorithm:

• Never use first-generation devices in aspiration-risk patients - They lack adequate seal pressure and aspiration protection features necessary for safe management. 4
• Ensure proper device characteristics - Use only devices with oropharyngeal seal pressure greater than 30 cm H₂O and ensure proper placement without excessive attempts. 4
• Device-specific training is essential - Training should receive the same emphasis as tracheal intubation training, as successful use requires familiarity with each device's particular strengths and limitations. 5, 3