The case for a 3rd generation supraglottic airway device facilitating direct vision placement

Abstract

Although 1st and 2nd generation supraglottic airway devices (SADs) have many desirable features, they are nevertheless inserted in a similar 'blind' way as their 1st generation predecessors. Clinicians mostly still rely entirely on subjective indirect assessments to estimate correct placement which supposedly ensures a tight seal. Malpositioning and potential airway compromise occurs in more than half of placements. Vision-guided insertion can improve placement. In this article we propose the development of a 3rd generation supraglottic airway device, equipped with cameras and fiberoptic illumination, to visualise insertion of the device, enable immediate manoeuvres to optimise SAD position, verify whether correct 1st and 2nd seals are achieved and check whether size selected is appropriate. We do not provide technical details of such a '3rd generation' device, but rather present a theoretical analysis of its desirable properties, which are essential to overcome the remaining limitations of current 1st and 2nd generation devices. We also recommend that this further milestone improvement, i.e. ability to place the SAD accurately under direct vision, be eligible for the moniker '3rd generation'. Blind insertion of SADs should become the exception and we anticipate, as in other domains such as central venous cannulation and nerve block insertions, vision-guided placement becoming the gold standard.

Features of new vision-incorporated third-generation video laryngeal mask airways

“…All SADs currently have one thing in common: they are inserted blindly, based on an educated guess regarding their correct placement, appropriate size and insertion depth which rely on commonly-used, often-inaccurate indirect assessment and clinical tests [3]. SADs have proved to be forgiving devices despite common non-perfect placement but, occasionally, result in more serious misadventure and poor clinical outcome.…”

“…Numerous studies have consistently shown that 50-80% of all blindly-inserted 1st and 2nd generation devices SADs (irrespective of type, brand, size and cuffed or non-cuffed design) are placed sub-optimally in the hypopharynx [3,9,10]. There is overwhelming evidence of suboptimal positioning demonstrated by clinical observation [11][12][13], radiographic imaging (CT-scan, MRI, X-rays), fibreoptic studies and ultrasound [14][15][16][17][18][19][20].…”

“…There is overwhelming evidence of suboptimal positioning demonstrated by clinical observation [11][12][13], radiographic imaging (CT-scan, MRI, X-rays), fibreoptic studies and ultrasound [14][15][16][17][18][19][20]. Suboptimal positioning, potentially, may compromise safety which includes: (a) epiglottis downfolding within the bowl of the device (up to 80% of cases); (b) epiglottis folding double; (c) floppy distal cuff folding backwards, not positioned across the entrance of the oesophagus; (d) distal cuff touching the vocal cords; (e) cuff folding (especially in PVC material cuffs) potentially creating gaps and airway leaks; (f) incorrect insertion depth of SAD; and g) use of an incorrect size or incorrect cuff inflation [3,9,10]. Sub-optimally placed SADs may result in potentially poor airway seal, airway leak and obstruction, 'loss' of airway and potential for regurgitation, gastric aspiration or airway trauma.…”

“…The SAD now commands a larger global market share than tracheal tubes (TTs) and is considered easier to insert with less complications. Indications for perioperative uses of SAD/LMA have significantly increased to include pre-hospital, emergency, obstetric and intensive care applications [3]. SAD has now an established role in the difficult airway algorithms and resuscitation guidelines as a rescue airway device to 'buy time' or as a device that acts as a conduit in guiding the TT into the trachea [4,5].…”

Time to consider supraglottic airway device oropharyngeal leak pressure measurement more objectively

“…Comparing the results of insertion of LMA‐Protector ™ and the LMA‐Supreme ™ using the novel vision‐guided (videolaryngoscope) insertion technique, improved incorrect blind insertions from 50% to 80% malpositions to a near optimal (95% correctly positioned SADs) fibreoptic‐controlled position of both devices 24 . The proposed third generation SAD vision‐guided approach, 17 is expected to be a viable and more objective alternative. In the foreseeable future with technological solutions, videolaryngoscopes may be replaced by inbuilt cameras/LEDS, implanted on the SAD wall.…”