Virtual Disaster Medicine

Training Center (VDMTC)

Module 14

Advanced Airway Techniques

Part 2 - New Generation Supraglottic Ventilatory Devices

Classification of Supraglottic Ventilatory Devices

CUFFED PERIPHARYNGEAL SEALERS - LARYNGOSEAL^TM

History

In 2005, Nellcor introduced the new LaryngoSeal™ laryngeal mask (LSLM) in response to requests by anesthesia providers who enjoy the benefits of laryngeal masks but want a cost-effective, disposable alternative that would allow improved sealing effectiveness and ease of placement.  The LSLM is currently available in the UK.  In the US, it is presently only available on a limited basis, yet it is expected to be available nationwide in early 2006.  LSLM patent applications are still pending.

Device Description

The LSLM is a convenient, single-use alternative to a reusable laryngeal mask (Figure 4).  It is manufactured from medical grade PVC for oral insertion only and contains Di(2-ethylhexyl)phthalate (DEHP).  Available in 8 sizes to fit neonates through adults (Table 6), the LSLM includes innovative design features that set it apart from other single-use laryngeal masks on the market, including a reinforced tip to aid with insertion and an inflation line integrated into the wall of the tube, which keeps the line secure and conveniently located.

Table 6 - LaryngoSeal sizing chart and maximum cuff volume (used with permission from Tyco Healthcare).

Insertion Technique & Device Removal

Prior to use, remove and discard the vent cap.  Check the integrity of the cuff and inflation system prior to insertion by completely deflating and reinflating the cuff with the maximum recommended volume of air.  Then in a similar fashion to the LMA, fully deflate the cuff prior to insertion by pressing the hollow side down onto a sterile flat surface during deflation and pressing down on a point near the tip with the two fingers.  The deflated cuff must be wrinkle free; if not, inflate and deflate the cuff again.  Apply sterile, water-based lubricant to the posterior surface of the LSLM just prior to insertion.

Place the patient’s head in the intubating position-neck flexed and the head extended.  In paralyzed patients, the triple airway maneuver (mouth opening, head extended, jaw thrust) decreases the incidence of epiglottic downfolding and should be performed, unless contraindicated.  Insert the LSLM into the palatopharyngeal curve and advance the mask into the oropharynx along the posterior pharyngeal wall.  As with other laryngeal masks, the twist technique is not recommended when inserting the device.  Continue pushing the LSLM, but do not use force.  When the mask is fully inserted into the hypopharynx, resistance should be felt.  The reference line on the LSLM tube must be aligned with the nasal septum and/or upper lip to confirm correct orientation of the device.  Inflate the cuff with air until a proper seal is obtained, equivalent to intracuff pressure around 60 cm H₂O.  Frequently, only half of the maximum cuff volume is sufficient to achieve a seal.  Connect the breathing system, taking care not to displace the mask, and assess adequacy of ventilation.  If adequate ventilation is not obtained, remove the LSLM and reinsert.  The cuff should be prepared before each insertion attempt by repeating the “prior to use” steps.  Insert a bite block alongside the tube and secure it to the LarygoSeal mask and the patient’s face with adhesive tape.

The LSLM should be removed only after the patient’s protective reflexes have returned.  Fully deflate the cuff and remove the LSLM.  It should be disposed in a safe manner according to local guidelines for disposal of contaminated medical waste, as other disposable SGAs.

Indications and Advantages

The LSLM may be used, by properly trained personnel, for: 1) airway management in patients for whom ventilation can be safely maintained through a facemask (with the exception of patient with orophayngeal pathology or abnormal anatomy); 2) known or apparent difficult airway management.  The LSLM may be used with unconscious patients at risk of airway obstruction who may need ventilatory support when endotracheal intubation is unavailable or unattainable.  It is the responsibility of properly trained personnel to balance the risk of pulmonary aspiration against the benefits of obtaining an adequate airway and oxygenation.

The LSLM is available in eight sizes to fit neonates through adults, and its convenient single-use feature eliminates the challenges of reusable masks, such as sterilization, tracking, loss, and damage.  It has a reinforced tip which aids with insertion and its cuff inflates from the distal tip.  The inflation line is integrated into the wall of the tube, which keeps the line secure and conveniently located.  Unique aperture design allows easy passage of bronchoscopes and suction catheters.

Disadvantages

The LSLM is recommended for use only in fasted patients.  It does not provide absolute protection against aspiration of gastric contents and should not be used in patients at increased risk of pulmonary aspiration of gastric contents or cannot prevent or treat airway obstruction at or beyond the glottis when tracheal intubation is indicated.

The LSLM is contraindicated in procedures that involve the use of laser or an electrosurgical active electrode in the immediate area of the device.  Contact of the beam or electrode with the LSLM, especially in the presence of oxygen-enriched and nitrous oxide mixtures, could result in the rapid combustion of the tube and harmful thermal effects and emission of corrosive and toxic combustion products.  The LSLM is contraindicated for use with patients requiring ventilation pressures >20 cm H₂O.  The LSLM should be used with caution in patients with diseases of the mouth and pharynx, including, previous radiotherapy.

Comparison to Face Mask Ventilation and Tracheal Intubation

Once in place, the LSLM provides a more secure airway than a face mask, eliminating the need to support the patient’s chin and allowing hands-free airway management.  As with other laryngeal masks, it can be inserted blindly, without the need for a laryngoscope to aid in placement.  Also, insertion of the LSLM may be less traumatic than the performance of direct laryngoscopy and endotracheal intubation.

Guide to Endotracheal Intubation

If intubation becomes necessary or desired, the LSLM will accommodate ETs ≤7.5 mm ET.

Medical Literature

Medical literature on the use of the LSLM is presently very limited.  Maino et al.⁷⁵ compared cuff pressures in various pediatric sized SGA devices (cLMA, uLMA, pLMA, SSLM, and LSLM) when the cuff was filled with the maximum recommended volume.  Maximum cuff volumes hyperinflated the cuff of all devices except a pLMA size >2 and SSLM sizes 1.5 and 2 (Table 7).  The LSLM pressure exceeded 120 cm H₂O.  Thus, recommendations were made to inflate the cuff with the minimum volume of air required to form an effective seal.  Further, the use of a manometer is recommended to avoid cuff hyperinflation.

Table 7 - LMA cuff pressures (cm H₂O) after filling completely emptied cuff with recommended volume of air (Maino: Euro J Anaesthesiol 2005; 22: a-572).

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