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Extraglottic devices for emergency airway management in adults

Extraglottic devices for emergency airway management in adults
Literature review current through: Jan 2024.
This topic last updated: Oct 24, 2022.

INTRODUCTION — Extraglottic airway devices are used to establish an airway for oxygenation and ventilation without entering the trachea. They are important tools for airway management and are used frequently in the prehospital environment, emergency department, operating room, and other settings. They can be primary airway devices, such as during cardiopulmonary resuscitation, or rescue devices for failed airways.

This topic reviews the types of extraglottic devices (EGDs) commonly found in emergency settings, how to place them and use them for intubation, and their appropriate role in emergency airway management. Other devices used for emergency airway management, approaches to emergency airway management in various clinical settings, and the use of EGDs in the operating room are discussed separately. (See "Approach to the difficult airway in adults for emergency medicine and critical care" and "The difficult pediatric airway for emergency medicine" and "Approach to the failed airway in adults for emergency medicine and critical care" and "Devices for difficult airway management in adults for emergency medicine and critical care" and "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults".)  

EXTRAGLOTTIC AIRWAY DEVICES

General indications and contraindications — EGDs provide an airway for oxygenation and ventilation without entering the trachea. They are important tools for emergency airway management and may be used as either primary or rescue devices, although they do not provide a definitive airway that protects the trachea from obstruction or aspiration.

Indications for placing an EGD include the need for oxygenation and ventilation. Contraindications include the following:

Presence of a gag reflex (risk of vomiting and aspiration)

Trauma or disease of the oropharynx or proximal esophagus (risk of mucosal perforation), such as caustic ingestion, or known esophageal varices (risk of perforation or airway hemorrhage)

Airway obstruction by a foreign body (risk of pushing a supraglottic foreign body into the trachea)

Types of devices and their features — The ideal EGD should be easy to place, provide effective oxygenation and ventilation, and allow the clinician to perform gastric decompression and tracheal intubation. Few EGDs satisfy all these criteria. A table summarizing the basic features of several common EGDs, including their location relative to the glottis and suitability for blind intubation, is provided (table 1). Each of the devices listed is highly effective for providing oxygenation and ventilation [1-16].

Several EGD classification schemes have been proposed. The simplest is based on the location of the EGD within the airway and includes supraglottic and retroglottic airway devices:

Supraglottic devices are laryngeal masks that seal around the glottic inlet and remain superior to the larynx (figure 1). Examples of laryngeal masks can be found in the following photographs (picture 1 and picture 2).

Retroglottic devices are laryngeal tubes that terminate in the upper esophagus – posterior to the glottis – and have two balloon cuffs, one pharyngeal and one esophageal, with ventilation fenestrations in between that align with the glottic opening (figure 2). An example of a laryngeal tube can be found in the following photograph (picture 3).

Other classification schemes are based on the presence of clinically important features. One such scheme divides EGDs into first- and second-generation devices depending on the presence of an orogastric (OG) decompression port (present in "second-generation" EGDs). The option of gastric decompression may help to reduce the risk of aspiration. Another scheme distinguishes EGDs by the ability to perform tracheal intubation through the lumen of the EGD.

For emergency patients, the ability to intubate through an EGD is an important design feature. After failed laryngoscopy, an intubation-capable EGD should be placed. Many of these have demonstrated high success rates for maintaining oxygenation and ventilation. Once oxygenation is reestablished, intubation through the EGD using the ventilation channel as a conduit for an endotracheal tube (ETT) can often be performed. Some intubation-capable EGDs are designed for blind intubation and all of them can be used in conjunction with a flexible endoscope (FE). The option for blind intubation is particularly important for providers who do not have access to FEs.

Use in emergency settings — EGDs are used widely in emergency airway management. In the prehospital environment, EMS systems that perform rapid sequence airway (RSA) management use EGDs for patient transport. RSA involves giving induction and neuromuscular blocking medications (similar to rapid sequence intubation) but then placing an EGD rather than a tracheal tube [17]. The EGD is exchanged later for an ETT, typically during transport or after the patient arrives in the ED. (See "Rapid sequence intubation in adults for emergency medicine and critical care".)

EGDs are used frequently for primary airway management in patients in cardiac arrest, and as rescue devices after failed laryngoscopy to provide oxygenation and ventilation until a definitive airway can be established. In cardiac arrest patients, placement and ventilation using an EGD can be performed without interrupting chest compressions. Large clinical trials and observational studies show that oxygenation and ventilation during CPR are as effective with an EGD as with an ETT and result in comparable mortality, neurologic outcome, and aspiration rates [18,19].

Following failed laryngoscopy in patients not in cardiac arrest, early placement of an appropriate EGD typically allows for excellent oxygenation, minimal gastric insufflation, little risk of aspiration, decompression of the stomach, and a high likelihood of successful blind intubation. If blind intubation fails, an FE can be passed through some EGDs to assist with tracheal intubation.

Ideally, EGDs can convert a "can't intubate, can't oxygenate" situation into a "can't intubate, can oxygenate" scenario. If placed early in some such situations, oxygenation via the EGD obviates the need for cricothyrotomy. However, it must be emphasized that placement of an EGD should not be attempted if it delays placement of a required surgical airway. (See "Emergency cricothyrotomy (cricothyroidotomy) in adults".)

As emergency clinician experience with EGDs expands, use of these devices is increasing. The reasons for this include the following:

EGDs consistently provide effective oxygenation and ventilation. There is an increasing body of evidence in emergency patients showing oxygenation success rates of 70 to 100 percent on first pass, and 90 to 100 percent following either one or two attempts at placement [3,4].

EGDs may provide more effective oxygenation and ventilation than bag-mask ventilation (BMV). Thus, EGDs may be useful for re-oxygenation between laryngoscopy attempts, or instead of BMV in apneic patients. One prospective multicenter study of EGD use by emergency medical technicians reported a first-attempt success rate for ventilation of 76 percent, compared to 30 percent with traditional BMV [20]. A review of similar studies involving prehospital CPR reported improved ventilation with an EGD compared to BMV [21].

EGDs may be associated with less regurgitation compared to BMV. A retrospective study of 713 patients receiving CPR found less regurgitation with EGDs compared to BMV [22].

EGD placement is easily taught, and skills learned on a manikin transfer readily to patients [23]. This is unlike BMV, which requires more skill and practice to create and maintain a mask seal, particularly in challenging clinical situations (eg, bearded patient, blood or vomit on face).

EGDs are useful if assistants are limited. Placing an EGD frees a provider to perform other needed tasks, since proper BMV often requires two clinicians, whereas an EGD requires only one.

Certain EGDs allow for additional management options, such as gastric decompression or tracheal intubation through the EGD.

Clinicians responsible for emergency airway management should be familiar with the EGDs available at their hospitals and other locations (eg, ambulance). In addition, emergency clinicians should help select the EGDs available to them and be certain that these are well suited to their work environment. As an example, if flexible bronchoscopes are not available it may be important to have access to an EGD through which blind intubation can be performed with a high rate of success.

Relatively few controlled studies assessing and comparing EGDs in emergency department patients have been performed, making it difficult to recommend any specific device, but some evidence suggests that certain EGDs may be more useful in emergency settings. The Fourth National Audit Project from the United Kingdom has reported that aspiration was the most common cause of death in anesthesia cases [24,25]. However, aspiration was rare in patients being managed primarily with EGDs. The authors recommend using EGDs with gastric decompression ports (second-generation EGDs) to reduce the risk of aspiration [26]. The ability to decompress the stomach is likely to be of greater importance in non-fasted patients requiring airway management, who are more common in emergency settings. In addition, it is likely that several episodes of bag-mask ventilation have been performed on patients requiring EGDs for airway rescue following failed laryngoscopy, and these episodes may have filled the stomach with air. Gastric decompression via an EGD may make ventilation easier and regurgitation less likely in such cases.

SUPRAGLOTTIC AIRWAYS — The supraglottic class of EGDs consists entirely of laryngeal masks in design. This means that, instead of making a mask seal on the face as in bag-mask ventilation (BMV), the mask seal is made over the glottic opening. The masks of supraglottic airways seal superiorly around the base of the tongue, laterally around the aryepiglottic folds and piriform recesses, and inferiorly in the upper esophagus (figure 1). The ventilation channel is oriented to send oxygen directly into the glottic opening.

Several manufacturers produce laryngeal mask devices that have been successful in oxygenation and ventilation. Multiple observational studies document the effectiveness of these devices for emergency airway management, including use in difficult airways and challenging environments [1,3-16,20,27-34].

Laryngeal mask airways (LMAs)

Types of LMAs — The laryngeal mask airway (LMA) is designed to create a mask seal over the laryngeal inlet in order to oxygenate and ventilate patients for short to intermediate periods (figure 3). There are multiple types of laryngeal masks, each with specific characteristics:

LMA Classic (picture 1 and picture 2): Standard multiple-use LMA.

LMA Unique: Single-use version of LMA Classic.

LMA ProSeal (picture 4): Similar to an LMA Classic but with a built-in bite block and port for orogastric (OG) tube.

LMA Supreme (picture 5): Single-use LMA with stiffer cuff, integrated bite block, and OG tube port.

LMA Fastrach (intubating LMA) (picture 6): Single- or multiple-use versions available. Designed for blind or endoscope-guided intubation. Includes handle for easier insertion and troubleshooting cuff leaks, stiff tubing, and integrated bite block.

LMA Protector (picture 7): Similar to Supreme but with intubation capability.

Standard LMA placement — A video demonstrating how to place a standard LMA is available in the following reference [35]. The step-by-step process is demonstrated in the following video clip and pictures, and described immediately below (movie 1 and figure 3):

Lubricate both sides of the LMA with a water-soluble lubricant.

Place the LMA Classic or LMA Unique so the cuff lies on a flat surface, and deflate the mask completely by aspirating air from the pilot balloon with a syringe.

Hold the LMA like a pencil with your dominant hand, with the tip of the index finger on the inner-curvature at the wide, proximal portion of the cuff near the junction of the pilot balloon tubing (picture 8).

Stand at the head of the bed and open the mouth using standard airway maneuvers (picture 9). (See "Direct laryngoscopy and endotracheal intubation in adults", section on 'Opening the mouth and inserting the blade'.)

Insert the LMA along the palate, following its curve to the posterior pharynx and hypopharynx, until reaching the full extent of your index finger length.

Using your non-dominant hand, push the LMA into the hypopharynx the remainder of the way using a smooth motion until the LMA comes to a natural stopping point and some resistance is felt. Remove your dominant hand from the patient's mouth.

Inflate the cuff of the LMA with the recommended volume to the minimum cuff pressure to create a seal (<40 cmH2O) in order to create a good seal. Check for proper ventilations using an attached bag mask and in-line end-tidal carbon dioxide (ETCO2) monitor.

LMA Fastrach (intubating LMA) — We feel strongly that for emergency airway management the EGD of choice should include a conduit for intubation. Of such devices, the LMA Fastrach is used most widely and has been used with high success rates as both a primary and rescue technique in the emergency department [36]. It comes in sizes suitable for placement in patients weighing 30 kg or more, and includes a handle designed to facilitate placement and troubleshooting problems with cuff seal. Another notable feature of the LMA Fastrach is the epiglottic elevating bar to facilitate intubation (picture 10).

Given the unique characteristics of the LMA Fastrach, it is helpful to have descriptions of the techniques for placing it in the airway, performing intubation through it and removing it; these are provided below.

Placement of LMA Fastrach — The steps for LMA Fastrach placement are described below and demonstrated in the video clips embedded in the following text:

Place the LMA Fastrach so the cuff lies on a flat surface, and deflate the mask completely by aspirating air from the pilot balloon with a syringe (movie 2).

Lubricate both sides of the LMA with a water-soluble lubricant.

Hold the LMA in your dominant hand by the handle.

Stand at the head of the bed and open the mouth with standard airway maneuvers (picture 9). (See "Direct laryngoscopy and endotracheal intubation in adults", section on 'Opening the mouth and inserting the blade'.)

Keeping the end of the mask in the midline of the oropharynx, place the mask tip on the palate and advance the LMA along the hard palate into the airway, stopping when resistance is felt and the handle is near the patient's face (movie 3). Note that the handle will not reach a horizontal plane but rather will maintain a slight upward angle.

Inflate the cuff of the LMA using the recommended volume to achieve a minimum cuff pressure and create a seal (<40 cmH2O). Check for proper ventilations using an attached bag mask and in-line ETCO2 waveform capnography.

Proper placement of the LMA Fastrach may require some troubleshooting [37]. During placement, the leading edge of the LMA cuff may push the epiglottis tip causing it to fold over, resulting in difficult ventilation or a cuff leak. If this occurs, the "Up-Down Movement" may help. To perform this maneuver, leave the cuff inflated and pull the LMA back about 6 cm with the same rotation used to insert it, then slide it back to its original position (movie 4). This tends to reposition the folded epiglottis.

If the cuff leak persists, better alignment of the cuff and glottic opening can be achieved with the "Chandy maneuver," in which the handle is slightly rotated in the sagittal (up and down) and coronal (side to side) planes. To increase cuff pressure against the glottis, the handle can also be lifted vertically using a "skillet lift," as if the operator is lifting a skillet off the stove (ie, the handle remains roughly parallel to the floor while being lifted). All three maneuvers are shown in the following video clip (movie 5).

Once the cuff leak is corrected, the operator has a few options. First, if the cuff pressure is <40 cm H2O, additional air can be inflated into the cuff to improve the seal and enable adequate ventilation, and the handle released. Alternatively, the operator can continue holding the handle and maintaining the LMA in the optimum position until intubation is completed. The author suggests intubating the patient. With the cuff leak corrected and ventilations successful, the ventilation channel should be lined up well with the glottic opening and passage of an ETT through the lumen of the LMA Fastrach is likely to be successful.

Intubation through LMA Fastrach — Effective oxygenation and ventilation suggest the LMA Fastrach cuff is well aligned with the glottis and intubation can be attempted through the device. To intubate, either the proprietary silicone non-kinking endotracheal tube (ETT) or a standard ETT may be used, with similar success rates [38,39]. If a standard ETT is used, it is helpful to warm the tube slightly to increase flexibility. A standard ETT is introduced into the LMA Fastrach with a reversed curvature (picture 11) so the leading tip emerges from the LMA at a shallower angle, facilitating entry into the trachea. Blind intubation success may be increased by using a Parker Flex-Tip ETT [40].

The intubation procedure is described below and demonstrated in the following video (movie 6):

Insert a well-lubricated ETT to 15 cm depth, at which point the tip of the ETT emerges from the LMA cuff and lifts the epiglottis elevating bar (picture 10). If the LMA proprietary ETT is used, the vertical black line should remain facing the operator (aligns bevel with vocal cords); the horizontal black line marks the 15 cm point, at which the ETT exits the LMA cuff.

Perform a "skillet lift" using the handle of the LMA Fastrach to align the cuff with the glottic opening, and gently advance the ETT. If resistance is felt, then glottic alignment is not adequate. In such cases, use the handle of the LMA Fastrach to adjust the cuff position slightly in either or both the sagittal and coronal planes. These manipulations should enable the clinician to find a place where the ETT advances into the trachea.

When the ETT is at proper depth, inflate the ETT cuff and confirm tracheal placement with bag ventilation and an in-line ETCO2 monitor.

If tracheal placement of the ETT is confirmed, deflate the LMA Fastrach cuff to relieve mucosal pressure.

Removal of LMA Fastrach following successful intubation — Once an ETT has been properly placed through the LMA Fastrach, the operator can stop, as a definitive airway has been established and mucosal pressure from the LMA cuff has been relieved. If the operator knows how to remove the LMA Fastrach properly over the ETT, this procedure may be performed. However, we caution novices against doing this, as the procedure is relatively complicated and can result in displacement of the ETT from the trachea, or ripping the pilot balloon from its tubing which then deflates the ETT cuff. If the clinician wishes to proceed and remove the LMA, the procedure is described below and demonstrated in the following video (movie 7). Ensure the LMA cuff is deflated prior to this removal procedure; it should already have been deflated after successful passage of the ETT passage.

Remove the 15 mm bag connector from the ETT and place in a secure location.

Hold the proximal end of the ETT stationary with your non-dominant hand, then use your dominant hand to rotate the LMA handle gently and pull the LMA Fastrach out of the mouth until the proximal end of the ETT is withdrawn into the lumen of the retracting LMA (movie 7). Stop once the proximal end of the ETT is out of reach, inside the LMA.

Using your non-dominant hand, place the LMA stabilizer bar against the proximal end of the ETT and keep the ETT in place, as you remove the LMA over the ETT with the other hand (movie 7). Pay close attention to stabilizing the ETT only; do not advance it by applying pressure with the stabilizer bar. Retract the LMA about 5 cm.

At this point the stabilizer bar must be removed to allow the ETT pilot balloon to enter the lumen of the LMA. Failure to remove the stabilizer bar will cause both the stabilizer bar and pilot balloon to enter the lumen of the LMA lumen, causing the pilot balloon to be torn from its tubing and the ETT cuff to deflate. Remove the stabilizer bar and stop withdrawing the LMA temporarily.

Place the index finger of your non-dominant hand inside the patient's mouth and press the ETT firmly against the palate (movie 7). Once the ETT is stabilized, continue withdrawing the LMA over the ETT. The ETT pilot balloon is the last part to pass through the LMA lumen.

Once the LMA Fastrach is completely removed, secure the ETT in place with a tie or tape. (See "Direct laryngoscopy and endotracheal intubation in adults", section on 'Post-intubation management'.)

Air-Q — The Air-Q is another type of intubating laryngeal mask (picture 12 and picture 13). It appears similar to the LMA Classic or LMA Unique but has several important differences:

Most importantly, the Air-Q was designed for blind or endoscope-guided intubation using the ventilation lumen as a conduit. The large adult size of the Air-Q can accommodate a size 8.5 ETT. A small triangular ramp in the distal end of the lumen directs the ETT anteriorly into the glottic opening.

The cuff is relatively stiff and designed so airway tissues mold around it, so less air is needed to inflate the cuff and there is less distention of airway structures.

The Air-Q is designed for intubation using a standard ETT. The mild curvature of the device does not require a specialized non-kinking ETT.

Removal of the Air-Q over the ETT is a straightforward process when using the Air-Q Removal Stylet and does not put the pilot balloon tube at risk of tearing.

The Air-Q is available in several models. The Air-Q Blocker (picture 12) has greater tube stiffness to ease placement, increased sidewall rigidity to act as a bite block, and a built-in channel through which a proprietary esophageal catheter can be placed beyond the cuff to decrease the risk of aspiration.

The Air-Q SP model self-regulates cuff pressure (picture 14). During a bagged breath, some air is routed through a short tube from the ventilation channel into the cuff to inflate it when a good glottic seal is required. During passive exhalation, air leaves the cuff into the ventilation lumen to decrease mucosal pressure and reduce distortion of tissues around the cuff.

Placement of the Air-Q involves a technique similar to that used for the LMA Classic, with the exception that the Air-Q does not need to ride against the palate during insertion. The cuff is stiff enough to insert without touching pharyngeal structures. Once the Air-Q is seated at its natural stopping point, ventilation is assessed by bagging and an ETCO2 waveform capnography. If a cuff leak is present, inflate the cuff with a small amount of air (<5 mL). Up to 15 mL of air can be placed in the cuff if needed, while monitoring cuff pressure, which should be kept below 40 cm H2O. The following video demonstrates proper placement of the Air-Q (movie 8).

Intubation through the Air-Q is similar to the LMA Fastrach. A standard (or Parker Flex-Tip) ETT can be used instead of a proprietary ETT because the shallow curve of the Air-Q does not require a non-kinking type of ETT. The procedure requires several steps and should be well practiced before it is performed on a patient. The technique is described below and shown in the following video (movie 9):

Generously lubricate the ETT (appropriately sized according to the directions marked on the side of the Air-Q) with a water-soluble lubricant.

Remove the 15 mm bag connector from the Air-Q and insert the ETT into the lumen of the Air-Q.

Move the ETT up and down the length of the Air-Q to distribute lubricant within the Air-Q lumen.

Gently try to intubate the trachea by fully inserting the ETT into the Air-Q.

Reorient the Air-Q cuff as needed by slightly inserting and/or withdrawing the Air-Q to facilitate tracheal passage of ETT.

When ETT passes easily, advance it to standard depth – centimeter markings are visible through the clear sidewall of the Air-Q.

Inflate the ETT cuff and confirm tracheal placement with ETCO2; if the ETT is not within the trachea, withdraw the ETT and try again.

When tracheal placement of ETT is confirmed, deflate the Air-Q cuff to relieve pressure on the mucosa.

Removal of the Air-Q over the ETT is relatively straightforward, and follows these steps, which are also shown in the following video clip (movie 10):

Remove the 15 mm bag connector from the ETT and place it in a safe place.

Use the appropriately-sized Air-Q removal stylet (three sizes available; appropriate size depends on the size of Air-Q airway) and screw it one-quarter turn into the end of the ETT (picture 15).

Hold the removal stylet in place and slide the Air-Q out of the mouth, over the stylet.

The pilot balloon of the ETT fits through the larger Air-Q sizes, along with the shaft of the removal stylet, so the Air-Q can slide completely out and off the removal stylet without resistance.

If a pediatric size Air-Q is used, the removal stylet may need to be removed in order for the pilot balloon to fit through the lumen of the Air-Q.

Unscrew the removal stylet from the ETT and discard (single use device).

Replace the 15 mm bag adapter onto the end of the ETT and continue ventilations with waveform capnography to confirm tracheal placement of the ETT.

i-gel — The i-gel is an alternative type of laryngeal mask that uses a non-inflatable cuff and wider tubing for stability (picture 16). The device is made from a flexible polymer that seals the glottic opening through its shape. The ventilation lumen is large enough to pass standard ETTs, and a bite block and gastric suction channel are integrated into the device.

Randomized and large observational studies suggest the i-gel may be an effective tool for difficult airway management [41-44], although blind intubation may be more difficult compared with an intubating LMA [2]. The i-gel may be useful for air-medical transport, as it does not use an air-filled cuff that is subject to pressure and volume changes at varying altitudes [45].

Placement of the i-gel is straightforward. After lubrication with a water-soluble lubricant, it is inserted to its natural stopping point and ventilations are begun (movie 11).

Intubation using flexible endoscope — With any of the supraglottic airways designed for ETT passage, it is possible to use a flexible endoscope (FE) to guide the ETT into the trachea under direct visualization and establish a definitive airway, with success rates close to 100 percent [5,6,8,46-49].

The authors recommend that a bronchoscope swivel adapter be used whenever placing an FE through an EGD or ETT. The swivel adapter is placed on the ETT to allow ventilation and oxygenation while the FE is advanced through a diaphragm on the end that aligns with the axis of the ETT (movie 12). By enabling ongoing oxygenation and ventilation during the FE procedure, this technique eliminates the stress associated with the need to perform the procedure rapidly for fear of oxygen desaturation.

The procedure uses the supraglottic airway as a conduit and is described below and demonstrated in the following video (movie 13):

If blind ETT passage has failed, pull the ETT back partially so the distal tip remains within the supraglottic airway (picture 17).

Inflate the ETT cuff just enough to make a seal inside the supraglottic airway and oxygenate the patient through the ETT (picture 18). These two steps are demonstrated in the latter part of the following video clip (movie 12). Note that in the video, a bronchoscope swivel adapter is placed at the end of the ETT to allow for ongoing ventilation and oxygenation throughout the procedure.

Once oxygenation is adequate, insert the FE inside the ETT (picture 19) and steer the FE under direct vision through the vocal cords (picture 20) and into the trachea down to the carina (picture 21).

Deflate the ETT cuff and railroad the ETT over the FE into the trachea, then remove the FE (movie 13). The ETT is advanced into the trachea over the FE while the position of the FE is maintained. Tracheal placement of the ETT is confirmed visually using the FE as it is removed.

Deflate the cuff of the supraglottic airway. This reduces pressure on the mucosa and prevents ischemia and related injury.

If a bronchoscope swivel adapter is available, it can be placed on the ETT to allow oxygenation and ventilations to continue while the FE is advanced (picture 22). This reduces the risk of inadequate oxygenation during the procedure.

It is generally accepted that the EGD may safely stay in place for several hours before it must be removed. If EGD removal over the ETT is attempted, the clinician must be familiar with the proper technique to avoid dislodging the ETT [50-57].

Other supraglottic airways — New supraglottic airways occasionally enter the market, but research is needed to determine their real-world effectiveness. The Aura-I, Aura-Gain, and LMA Protector are three such products (picture 23 and picture 7). Each is designed to serve as a conduit for intubation, but the Aura-Gain and LMA Protector are second-generation devices with OG tube ports and are therefore preferred. The Baska Mask is another second-generation intubating device. Preliminary studies suggest the Baska Mask creates higher cuff seal pressures but may be slightly more difficult to place than other EGDs [58-60]. More studies are needed to evaluate the use of these devices for emergency airway management.

The UEScope Video Laryngeal Mask Airway is a new type of supraglottic airway. It is a second-generation device with a gastric tube placement channel and is designed as a conduit for an ETT. The unique aspect of this product is that a second observation channel exists on the right side of the ventilation lumen (opposite the gastric tube channel) with a lens at the end within the bowl of the cuff. A proprietary FE can then be placed inside the observation channel and advanced to the lens to visualize the laryngeal inlet within the cuff. The view is slightly off-center from the right side, similar to a laryngoscopic view.

Direct laryngeal visualization has the advantages of confirming proper cuff placement, ensuring the epiglottis is not downfolded, and allowing an ETT or ETT introducer ("bougie") to be advanced into the trachea under direct visualization so troubleshooting can be done during the approach in contrast to an endoscopic intubation, in which only the carina is visualized and the approach of the ETT is unseen, sometimes causing the ETT to catch on laryngeal structures, causing difficulty advancing the ETT. Although preliminary data are encouraging (eg, first-pass success of ETT placement, cuff leak pressures, and time and success of intubation compared with FE intubation through an EGD [61-63]), more studies are needed to evaluate use of this device in emergency airway management.

RETROGLOTTIC AIRWAYS

Laryngeal tubes — All retroglottic airway devices are designed as laryngeal tubes. When seated in the airway, they have a large pharyngeal balloon to seal the oropharynx, a small esophageal balloon to seal the esophagus, and lumens between the cuff balloons that align approximately with the glottic opening to provide oxygenation and ventilation [64].

Most complications from retroglottic airway devices stem from soft tissue trauma to the pharynx during placement. To avoid this, laryngeal tubes should be placed gently, or with a laryngoscope to open the airway and allow the device to pass into the esophagus without significant resistance.

Combitube — The Combitube is a dual-lumen, dual-cuff airway designed for esophageal placement (figure 4). One cuff lies above the glottis and the other lies distal to the glottis in the esophagus, thereby isolating the laryngeal inlet and allowing for directed ventilation into the trachea. It has been used extensively for general anesthesia and has been studied in out-of-hospital cardiac arrest [50,65-67]. Despite the documented success of the Combitube in difficult airway management, we prefer EGDs that allow for the establishment of a cuffed endotracheal tube (ETT) in the trachea (ie, definitive airway). It is not possible to establish a definitive airway through the Combitube.

Insertion of the Combitube is a blind technique intended for providers who have not been trained in laryngoscopy. However, a laryngoscope may be used, permitting insertion under direct vision. Although the Combitube can be inserted in almost any patient position, including sitting and semi-prone, the technique described here assumes the patient is in the supine position and that a laryngoscope is not available.

With the patient supine and the head and neck in a neutral position, lift the tongue and jaw upward (jaw lift) with your non-dominant hand.

Insert the Combitube in the midline, allowing the curve of the device to follow the natural curve of the airway, and advance the device until the upper incisors (or alveolar ridge if the patient is edentulous) lie between the imprinted black circular bands on the device. Mild force is required to push the end of the Combitube past the pharyngeal constrictor muscles and into the esophagus.

Inflate the proximal, larger oropharyngeal balloon with approximately 100 mL of air for a 41 French size (85 mL for 37 French) by using the blue pilot balloon port labeled no. 1.

Next, inflate the white, distal balloon with 12 to 15 mL of air using the white pilot balloon port labeled no. 2.

About 90 percent of the time in blind placements, the distal tip of the Combitube will be in the esophagus. With this assumption in mind, begin ventilation using the longer blue connecting tube (labeled no. 1), which ventilates through the fenestrations that should line up with the laryngeal inlet. If the tip of the Combitube is in fact in the esophagus, oxygen will flow into the trachea and end-tidal carbon dioxide (ETCO2) will register on exhaled breaths.

With the Combitube placed in the esophagus, gastric contents can be aspirated and gastric decompression performed by passing the provided suction catheter through the clear connecting tube (labeled no. 2) into the stomach.

If ventilation using the longer blue tube no. 1 causes no breath sounds to be heard in the chest and no ETCO2 to be detected, while sounds of gastric insufflation are present, the distal end of the Combitube is in the trachea (a rare event). In this case, ventilation should be performed through the shorter clear connection tube (labeled no. 2).

Although a definitive airway has been established in this case, the stiff Combitube should be exchanged over an ETT introducer ("bougie") or airway exchange catheter for a conventional ETT within two to four hours to prevent mucosal injuries in the pharynx.

The absence of any sounds on auscultation during ventilation of either port may indicate that the device has been inserted too far. After deflating the proximal balloon, the Combitube should be repositioned more proximally.

King laryngeal tube (LT) — Like the Combitube, the King LT has a pharyngeal cuff and an esophageal cuff, with a port between the cuffs at the level of the laryngeal inlet to allow for gas exchange (figure 2). However, the King LT is shorter than the Combitube, has one large lumen instead of two smaller ones, uses only one inflation valve to fill both cuffs, and has a straight distal segment – instead of the Combitube, which bends slightly anterior – so it almost never enters the trachea and instead goes consistently in the esophagus.

There is a first-generation King LT with a blind distal tip (picture 3) and second-generation model with an open distal tip (King LTS) that permits gastric decompression. There are also single-use, disposable models (King LT-D and LTS-D).

The technique for inserting the King LT is similarly to that used for the Combitube. However, placement and troubleshooting are more straightforward. To insert, open the patient's mouth and place a well-lubricated King LT into the midline of the oropharynx using your dominant hand (movie 14). Advance the King LT until definitive resistance is felt, or the colored 15-mm bag-connector flange touches the incisors. A single pilot balloon port is used to inflate both balloons simultaneously. Once seated, ventilation occurs through the ports between the two cuff balloons.

The first attempt at ventilation after insertion often results in no air movement and high resistance to ventilation. This is because the tube is too deep and the ventilation fenestrations lie within the proximal esophagus. In such case, the King LT should be withdrawn slowly, about 1cm at a time, with the cuffs inflated, while continuing to attempt ventilations. At some point, ventilations will immediately become possible as the fenestrations emerge above the posterior cricoid ring and oxygen enters the glottis. Once ventilations can be performed freely, the King LT should be pulled back another 1 to 2 cm to ensure good alignment of the ventilation fenestrations with the glottis, and prevent air from entering the esophagus. The King LT remains in this position without any further maneuvers, and ventilation and oxygenation via the King LT are generally excellent.

Studies performed on manikins, or in the operating room during management of controlled airways, show that time to ventilation and successful placement of the laryngeal tube is on par with the laryngeal mask airway (LMA) and significantly faster than tracheal intubation using direct laryngoscopy [52-56,65,68,69]. One prospective observational study found that a laryngeal tube maintained effective cuff seals even in the presence of supraglottic tumors in 22 of 23 patients [70].

The King LT has other advantages over the Combitube. It is possible to establish a definitive airway through the King LT, although this requires a flexible endoscope (FE) and an Aintree airway exchange catheter [71]. The FE must be smaller than the internal diameter of the Aintree catheter, which is 4.7 mm. The procedure is performed as follows:

Thread the Aintree catheter over the FE.

Advance the FE down the ventilation lumen of the King LT.

Visualize the vocal cords and while maintaining direct visualization advance the FE tip through the vocal cords, down to the carina.

Leave the Aintree catheter in the trachea and the King LT, then remove the FE from the airway. The Aintree now maintains a path from the oropharynx into the trachea.

Deflate the cuffs of the King LT and remove the King LT over the Aintree.

Railroad the ETT over the Aintree into the trachea. This is the same technique used with an ETT introducer intubation.

Alternatively, if the provider is using a disposable, single-use FE, the FE can be advanced down the King LT into the trachea and the proximal end of the FE (as close as possible to the handle) cut with shears, leaving the flexible tail of the FE as a "railroad track" from the oropharynx to the trachea. Then the King LT can be deflated and removed over the FE tail, and an ETT railroaded over the FE tail into the trachea. A series of photographs depicting this approach is provided (picture 24), and a video of this technique can be found at the following  [72]. Other small-lumen EGDs that are not designed as conduits for ETTs, such as the LMA Unique and LMA Classic, can be exchanged for ETTs using this technique.

Of note, oxygenation and ventilation can be maintained for as long as the FE remains in place by using a bronchoscope swivel adapter (which was not used in the picture sequence and video).

Practitioners are often tempted to insert an ETI blindly through the King LT lumen to "find" the trachea, but the steep angle at which the ETI exits the King LT does not usually allow smooth passage through the vocal cords. Instead, mucosal perforation and other severe complications can occur and we do not recommend this approach [73].

Rusch EasyTube — The Rusch EasyTube is a dual-lumen tube designed for emergency airway management. Like the Combitube, the EasyTube can be placed either in the esophagus (common) or trachea (rare). However, unlike the Combitube, if placed in the esophagus the EasyTube allows the passage of a fiberoptic endoscope through the ventilation lumen. Therefore, a procedure similar to that described above for the King LT (using a single-use FE or an Aintree catheter) can be performed to place an ETT, using the EasyTube as a conduit. If the EasyTube is placed in the trachea, the size and shape of the distal tip are similar to a standard ETT. Additional evidence from human studies is needed to demonstrate the relative success rate of the EasyTube compared with the LMA, Combitube, or King LT.

Intubating Laryngeal Tube Suction Disposable (iLTS-D) — The Intubating Laryngeal Tube Suction Disposable (iLTS-D) is the first laryngeal tube with the capability to serve as a conduit for tracheal intubation with a standard ETT. While promising, available clinical evidence to assess the performance of the iLTS-D is limited.

The device is similar to the King LT in that it has a single pilot balloon port through which both the oropharyngeal and the esophageal cuffs can be inflated. It is passed blindly in the midline of the oropharynx using a jaw thrust to facilitate placement. There is a mark on the iLTS-D that should be aligned with the patient's incisors. Once in position, the cuffs are inflated and ventilation confirmed. An orogastric (OG) tube may be inserted through a dedicated port on the device to decompress the stomach.

After adequate oxygenation and ventilation are confirmed, a standard ETT can be passed through the device into the trachea. This process is ideally performed under continuous visualization using a fiberoptic endoscope but may be attempted blindly, albeit with lower success rates. After confirming successful ETT placement, the iLTS-D may be removed by disconnecting the ETT bag connector, stabilizing the ETT, fully deflating the cuff on the iLTS-D, and removing the iLTS-D over the ETT. The iLTS-D is available in Europe and may soon be available in the United States.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Airway management in adults".)

SUMMARY AND RECOMMENDATIONS

Types of devices and their general use – Extraglottic devices (EGDs) provide an airway for oxygenation and ventilation without entering the trachea. They can be used as either primary or rescue devices but do not provide a definitive airway that protects the trachea from obstruction or aspiration. A table summarizing the basic features of several common EGDs, including their location relative to the glottis and suitability for blind intubation, is provided (table 1). Each of the devices listed is highly effective for providing oxygenation and ventilation. (See 'General indications and contraindications' above and 'Types of devices and their features' above.)

Indications and contraindications – Indications for placing an EGD include the need for oxygenation and ventilation. Contraindications include presence of a gag reflex, trauma or disease of the oropharynx or proximal esophagus that predisposes to perforation or hemorrhage, and airway obstruction by a foreign body.

Use in emergency settings – EGDs are used frequently for primary airway management in patients in cardiac arrest, where they can be placed without causing interruptions in chest compressions, and as rescue devices after failed laryngoscopy until a definitive airway can be established. Particularly in emergency situations, it is important to use an EGD that can decompress the stomach and be used as a conduit for tracheal intubation. Most EGDs require only 2 cm of interdental space for placement; if a laryngoscope and tracheal tube fit in the mouth, an EGD will fit. (See 'Use in emergency settings' above.)

Placement and use of specific devices – Several common EGDs are discussed in the text, including step by step instructions and video clips demonstrating the techniques for placement, intubation, and removal. Among the devices discussed are the following:

Standard laryngeal mask airway (LMA) placement (see 'Standard LMA placement' above)

Intubating LMA (Fastrach) (see 'LMA Fastrach (intubating LMA)' above)

Air-Q LMA (see 'Air-Q' above)

i-gel LMA (see 'i-gel' above)

Intubation via LMA using flexible endoscope (FE) (see 'Intubation using flexible endoscope' above)

Laryngeal tubes (LT) (see 'Laryngeal tubes' above)

Combitube (see 'Combitube' above)

King LT (see 'King laryngeal tube (LT)' above)

Importance of regular practice with select devices – All emergency airway managers must practice regularly with the EGDs that they plan to use to manage critically ill patients. In particular, practice should include placement, intubation via the EGD, and removal of the EGD following intubation.

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Aaron E Bair, MD, MSc, FAAEM, FACEP, now deceased, who contributed to an earlier version of this topic review.

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Topic 106475 Version 16.0

References

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