Alternate Airways in the Prehospital Setting (Resource Document to NAEMSP Position Statement)

Introduction

In the United States, advanced level rescuers often use endotracheal intubation (ETI) to provide oxygenation andventilation to apneic or hypoventilating patients. Alternate airways are devices that facilitate oxygenation andventilation without the use of an endotracheal tube (Table 1). Other terms used to describe an alternate airway include rescue airway device, alternative airway, secondary airway, failed airway device, difficult airway device, salvage airway andbackup airway, among others. Although rescuers typically use alternate airways when ETI is not feasible, these devices are occasionally used as the primary airway device. This resource document reviews the rationale anddata supporting the availability anduse of alternate airways in prehospital airway care.

Table 1 Types of Alternate Airways

Blindly Inserted airways

Laryngeal Mask Airway (LMA)

Esophageal Tracheal Combitube (ETC)

King Laryngeal Tube

Cobra Perilaryngeal Airway (Cobra PLA)

Magboul (Cuffed Oropharyngeal Airway-COPA)

Pharyngeal Tracheal Lumen Airway

Esophageal Obturator Airway (EOA)

Surgical airways

Open Cricothyroidotomy

Percutaneous Cricothyroidotomy

Transtracheal Jet Ventilation

Need andRationale for Alternate Airway Devices

Although paramedics in the United States are trained to perform ETI, the intervention is often unsuccessful or not possible. Prior studies have described unsuccessful ETI rates ranging from 8% to over 30%.[[[1], [2], [3], [4]]] Although unsuccessful ETI may result from inadequate relaxation, many prehospital intubation failures occur on patients in cardiac arrest or without protective reflexes. This suggests that rescuers are often not able to visualize airway structures through laryngoscopy, whether due to the nature of airway anatomy, airway injury, rescuer skill, compromised patient position, or inadequate rescuer access.

Bag-valve-mask (BVM) ventilation is often used in the event of failed ETI efforts. However, despite its perception as a fundamental skill, this technique is extremely difficult to perform both in controlled andclinical settings.[[[5], [6]]] BVM ventilation performance may improve by using a two-rescuer technique, but this may be difficult during prolonged transport or when there is a limited number of rescuers.[[[7]]]

In light of these observations, all prehospital services that perform ETI should have alternate airways available for clinical application. This resource document reviews the current literature andprovides recommendations regarding the use of prehospital alternate airways.

Alternate Airway Devices

Blindly Inserted Airways

Blindly inserted airways are placed in the oropharynx without directly visualizing laryngeal structures. Designed for placement in either the supraglottic or infraglottic positions, these devices use one or more inflatable balloon cuffs to establish andisolate a patent airway.

Esophageal Tracheal Combitube (Esophageal Tracheal Dual Lumen Airway, Combitube)

The Esophageal Tracheal Combitube (ETC, The Kendall Company, Mansfield, Massachusetts) is a dual-lumen airway that is inserted blindly into the oropharynx. The ETC was originally developed as an alternate airway management device for cardiopulmonary resuscitation.[[[8]]] It was designed to provide a temporary airway for providers not skilled in endotracheal intubation.[[[9]]] The ETC was first described as a prehospital alternate device by Atherton andJohnson.[[[10]]]

The ETC has both theoretical andproven features. It can be inserted blindly andmay provide some protection from aspiration.[[[11], [12]]] The ETC protects against aspiration via a distal esophageal balloon.[[[13], [14]]] Hagberg et al. suggested that the ETC protects against aspiration better than the laryngeal mask airway (LMA).[[[15]]] Prior efforts have verified the ease of its use.[[[9]]] Complications associated with ETC use include unrecognized tracheal intubation, pneumomediastinum, pneumoperitoneum, subcutaneous emphysema, perforation of the piriform sinus andthose associated with ventilation of the wrong lumen.[[[16], [17], [18]]] Preliminary evidence suggests that these complications are rare, occurring in less than 1%.[[[17]]]

The ETC is widely recognized in the United States, andits use in prehospital settings has been well described.[[[10], [19], [20], [21]]] Ochs et al. demonstrated that EMT-Ds could successfully manage 79% of the airways in cardiac arrest cases with the ETC alone.[[[20]]] Davis et al. demonstrated the feasibility of ETC use as an alternate airway after failed neuromuscular blockade-assisted intubations.[[[21]]] Several authors have described ETC use by basic-level rescuers.[[[18], [20]]]

Laryngeal Mask Airway

The laryngeal mask airway (LMA, North America, Inc., San Diego, CA, USA) was developed by Brain in 1981 as an alternative to BVM andETI.[[[22], [23]]] It was approved for use in the United States in 1991. Although the LMA is used primarily in the operating room setting, several authors have promoted its use in the emergency department andother in-hospital settings.[[[24], [25], [26], [27], [28]]]

The LMA is believed to cause less damage to the airway than other airway devices.[[[27]]] Because there is no balloon securing the device beneath the vocal cords, the risk of aspiration is theoretically higher with the LMA than the ETC or ETI.[[[15]]] However, there are currently no data specifically evaluating this phenomenon in the prehospital setting. The LMA may be of limited utility in patients with certain anatomic abnormalities or supraglottic airway obstruction.[[[24]]]

Limited studies have described LMA use in the prehospital setting. In a series of 470 prehospital patients, Rumball andMcDonald collected arterial blood gas measurements on patients receiving prehospital ETC, pharygotracheal-laryngoscopy, andLMA; the LMA compared similarly with the other devices.[[[29], [30]]] The LMA is used as a prehospital primary airway device in many countries such as the United Kingdom andJapan.[[[31], [32]]] Experts have suggested the LMA as an alternate to prehospital ETI for pediatric patients, but supportive data are limited.[[[33], [34], [35]]]

King Laryngeal Tube (King LT) Airway

The King LT Airway (King Systems Corporation, Noblesville, Indiana) is a relatively new device that is similar in appearance to the ETC.[[[36]]] Like the ETC, the King LT device is placed blindly. However, the King LT has only a single lumen, andits shape facilitates more consistent placement in the correct esophageal position. The King LT was specifically designed for prehospital use. Anecdotal reports describe King LT use in prehospital andcombat settings, but large-scale clinical data do not yet exist.

Surgical Airways

Surgical airways involve insertion of an airway tube or catheter into the trachea through an incision in the neck. In the United States, three types of surgical airways are commonly available in the prehospital environment: (1) open cricothyroidotomy, (2) percutaneous cricothyroidotomy, and(3) transtracheal jet ventilation.

Open Cricothyroidotomy

Open cricothyriodotomy involves the use of surgical tools (i.e., scalpel, etc.) to facilitate exposure of andinsertion of a tracheal tube through the cricothyroid membrane.[[[37]]] This technique has been used for over 45 years.[[[38]]] Although described as a safe andrapid procedure, the technique requires adequate training for proper execution.[[[39], [40], [41], [42]]] Cricothyroidotomy has been studied in the hospital andemergency department settings as both a primary andalternate airway.[[[43], [44]]] Because of the plasticity of the pediatric airway, it is contraindicated in children less than 8 years old.

Several efforts have described cricothyroidotomy use in the prehospital environment.[[[42], [45]]] Although widely taught, the prehospital application of cricothyroidotomy appears to be rare andassociated with significant complications andpoor outcomes.[[[37], [42], [46], [47]]]

Percutaneous Cricothyroidotomy

Percutaneous cricothyroidotomy uses a modified Seldinger (guidewire) technique to facilitate location of andinsertion of a tracheal tube through the cricothyroid membrane. Commercially packaged kits contain the equipment necessary to perfom the procedure.[[[48]]] The technique is believed to have fewer complications than open cricothyroidotomy.[[[49], [50], [51]]]

Percutaneous cricothyroidotomy was first described as an in-hospital alternate airway by Fischer.[[[52]]] Percutaneous cricothyroidotomy has been described in the anesthesia literature for difficult airway management.[[[53], [54]]] Use of the percutaneous cricothyroidotomy was first described in the emergency department in 1992.[[[55]]]

The prehospital use of percutaneous cricothyroidotomy was proposed over a decade ago.[[[55]]] Several studies using cadavers andhuman simulators have demonstrated the prehospital feasibility of this technique.[[[39], [49], [50]]] However, descriptions of clinical prehospital experience with percutaneous cricothyroidotomy are limited.

Transtracheal Jet Ventilation

Transtracheal jet ventilation involves the insertion of a large bore flexible catheter through the cricothyroid membrane to facilitate insufflation of high-pressure oxygen.[[[56]]] Although some passive exhalation of carbon dioxide occurs, the technique theoretically does not facilitate ventilation. The pressures generated from conventional oxygen regulators andBVM devices are insufficient for TTJV. Special regulators delivering oxygen at 50 psi must be used with TTJV.[[[57], [58]]] TTJV is contraindicated in supraglottic obstruction, because no means of exhalation would be present.[[[59]]] It is the only form of surgical airway that can be used in small children.[[[60], [61], [62]]]

Several authors have described the use of TTJV for alternate airway management in the operating room andemergency department settings.[[[58], [63], [64]]] TTJV has been proposed as an alternative to prehospital cricothryoidotomy.[[[56], [58], [65]]] Field studies of TTJV do not exist.

Bag Valve Mask Ventilation andOther Alternate Airway Techniques

Other alternate airway management techniques merit comment. Although all prehospital rescuers are trained to use Bag-Valve-Mask (BVM) ventilation, the technique is relatively difficult. During BVM ventilation, it may be difficult for a single rescuer to simultaneously open the airway, maintain a mask seal, anddeliver sufficient tidal volume. Two-rescuer BVM techniques may be more effective, but these approaches may not be practical under the constraints of the prehospital environment. Thus, while some services rely on BVM ventilation as a backup for unsuccessful ETI, because of its difficulty, the BVM is not recommended as the sole alternate airway technique.

The Esophageal Obturator Airway (EOA) was developed in the 1970s andused as a prehospital alternate device for many years. The device consists of a single lumen with a large balloon to obstruct the esophagus andindirectly ventilate the trachea. It has fallen out of favor because of significant complications, including inadvertent tracheal intubation andesophageal trauma.[[[69], [70]]]

Other airway management devices include the Cuffed Oropharyngeal Airway (COPA, Mallinckrodt Inc., St. Louis, Missouri, USA), the Cobra Perilaryngeal Airway (Engineered Medical Systems, Inc., Indianapolis, Indiana, USA) andother single andmulti-lumen airways such as the Pharyngeal Tracheal Lumen Airway (PTL). Descriptions of these devices in either in-hospital or prehospital application are limited.

Recommendations for Prehospital Alternate Airways

Availability of Alternate Airways

Alternate airway devices should be available to all prehospital rescuers who perform ETI. In addition to the BVM device, all agencies should have at least one blindly inserted airway device available for clinical use.

The role of andneed for prehospital surgical airway techniques are not clear at this time. Current data allude to significant concerns including complications andpoor outcomes associated with prehospital surgical airway management. In addition, the training needed to maintain these skills is substantial. However, there may be clinical situations where surgical airway management is the only option (e.g., in cases of severe facial trauma). Medical directors must determine the need for prehospital surgical airways on an individual agency basis. Agencies should not rely on surgical airways as the sole alternate airway management technique.

Training in Alternate Airway Use

Medical directors must ensure adequate training in the use of available alternate airways. Acquisition andmaintenance of alternate airway skills are important because their clinical use may occur infrequently andunder emergent conditions. Training should encompass didactic, simulated, andpractical experiences.[[[71], [72], [73]]] Although training on live patients in controlled settings is desirable, this may not be practical for most alternate airways. For example, operating room patients rarely receive elective cricothyroidotomy, andCombitubes are rarely used in the operating room. Although LMAs are used widely in the operating room, rescuers using LMAs should receive additional training in urgent andemergent contexts.

Clinical Indications for Alternate Airway Use

Clinical indications for alternate airway use have not been formally or scientifically derived. However, a practical recommendation is that alternate airways should be used after failed ETI attempts or in situations where initial or ongoing ETI efforts are predicted to be difficult or futile. “Difficult” conditions may include situations involving difficult airway anatomy, severe airway trauma, or inadequate operator skill, among others. Difficult airway conditions may be identified before or after initial intubation attempts. In situations where airway management difficulty clearly exceeds the skill of the operator, it is recommended that rescuers defer ETI efforts andproceed directly to alternate airway insertion.

Clinical protocols should define broad guidelines for alternate airway use. Scientific andconsensus guidelines suggest that ETI efforts should be abandoned (and alternate airway inserted) after no more than three ETI attempts (insertion of blade).[[[74], [75]]] The prompt availability of online medical command may help to facilitate prudent airway management decision making in scenarios involving failed ETI or alternate airway use. However, because of the emergent nature of airway management efforts, clinical protocols should permit alternate airway insertion without online medical command authorization.

Primary Use of Alternate Airways

Many international EMS agencies use alternate airways in a primary capacity.[[[76], [77]]] Several sources describe alternate airway use by basic level rescuers.[[[18], [20]]] Current Advanced Cardiac Life Support recommendations suggest that when adequately skilled personnel are not available, ETI may be substituted with an alternate airway device.[[[78]]] Although this strategy has not been formally evaluated or compared with ETI, this approach does have many appealing features, including the simplification of airway management andthe reduction of potential impact on other concurrent interventions. In a trial using human simulators, Abo et al. showed that compared with traditional ETI, ETC insertion reduced the time to airway placement as well as the time without chest compressions.[[[79]]] This area merits additional scientific study.

Quality Assurance andQuality Improvement

Alternate airway use should be monitored by a comprehensive quality assurance andquality improvement program. EMS medical directors should participate in continuous quality improvement (CQI) activities andhave access to all the reviewed airway data. All uses of alternate andsalvage airways should be documented as described in the NAEMSP position paper “Recommended Guidelines for Uniform Reporting of Data from Prehospital Airway Management.”[[[80]]]

Collection of alternate airway data should include (1) indications for invasive airway management, (2) number of attempts at ETI andalternate airway, (3) relevant clinical andphysiological factors, (4) methods anddevices used, (5) outcomes (success at alternate airway placement), (6) outcomes (success of overall effort), (7) method of confirming proper placement of the airway, (8) physiological changes in patient condition during andafter airway management, (9) critical complications encountered in airway management, and(10) reasons for failed ETI or primary use of the alternate airway device. Patient follow-up including linkage to in-hospital course is strongly recommended; these records often are the only indicators of prehospital airway management complications.

Considerations for Future Research

Additional scientific study is needed to improve our understanding of the use of alternate andsurgical airways. Specific areas requiring evaluation include (1) clinical indications for alternate airway use; (2) device monitoring, including the identification of physiological response to insertion of, andventilation through, alternate airways; (3) clinical outcomes after alternate airway use, including morbidity andmortality; (4) education programs andtraining using both live patients andhuman simulation; and(5) comparisons of cost andoperational impacts.

Conclusion

All prehospital agencies andrescuers that perform endotracheal intubation should have the availability of at least one blindly inserted alternate airway device. All rescuers should receive adequate training in alternate airway use. Medical directors should closely monitor the use of alternate airways.