Student Corner: Supraglottic Airways in Cardiac Arrest

Student Corner is a bimonthly column discussing research projects and interest areas among current EMT and paramedic students. To be featured in this column contact editor@emsworld.com. 

Supraglottic airway devices are airway adjuncts used to provide patients with adequate ventilations and oxygenation. They are commonly used in the surgical setting for patients under general anesthesia. In the prehospital setting these devices are used as alternatives if endotracheal (ET) intubation, the gold standard of airway management, is not successful. 

There are many types of supraglottic airway devices on the market today. The most common are King LTS-D and the i-gel. The King is similar to an ET tube: It’s a simple tube with an oropharyngeal and esophageal cuff. Between the cuffs is an opening to allow air to travel to the larynx. The i-gel, newer and growing in popularity, is a preshaped cuffless device made from a gel-like material. It is inserted into the airway blindly and adapts to the anatomy.¹ 

Airway Management in Cardiac Arrest

The American Heart Association (AHA) in recent years has changed its basic life support algorithm from airway, breathing, circulation to circulation, airway, breathing. The important thing to achieve with CPR efforts during cardiac arrest is adequate circulation through adequate and consistent chest compressions.

Airway management is the second important task; proper ventilation and oxygenation will keep the patient’s brain well oxygenated and improve the probability of stable neurological status if return of spontaneous circulation (ROSC) is achieved. 

During cardiac arrest, the first attempt at securing the airway is by the insertion of a basic airway adjunct. The common types used are the oropharyngeal airway (OPA) and nasopharyngeal airway (NPA). These are initially inserted to temporarily secure the airway before insertion of an advanced airway. An advanced airway consists of either a supraglottic device or an endotracheal intubation. 

Supraglottic Devices vs. Intubation

Supraglottic airway devices are inserted blindly, without a laryngoscope or other means of directing the device into the airway. They usually sit at the hypopharynx area. Supraglottic devices require less training and education to use than endotracheal intubation. The i-gel, which doesn’t need inflation of a cuff for securing, also requires minimal training. 

Endotracheal intubation requires a trained professional who knows the anatomy of the upper and lower airway and can properly identify it during tube placement. The tube placement landmark is the vocal cords in the glottic opening.

Tubes are placed by using a laryngoscope, either video or manual. This is direct laryngoscopy and can be accomplished using either of two types of blades: The Miller blade comes in sizes from 00–4; the Macintosh blade 1–4. These must be placed properly to avoid harm to the airway or patient and thus require training to use. 

Endotracheal tubes come in a variety of sizes for pediatrics to adults. These commonly range from 3–9. All adult tubes have a cuff and require inflation after ET intubation is accomplished. Cuff presence varies on pediatric tubes.

The AIRWAYS-2 trial compared the i-gel to tracheal intubation during cardiac arrest. It enrolled almost 9,300 patients; 4,886 got the i-gel, and 4,410 were intubated. While it found no significant difference in its primary outcome measure of favorable 30-day functional outcomes, among secondary measures it found initial ventilation more successful in the SGA group (87.4% vs. 79%). Two other secondary outcomes, regurgitation and aspiration, were also not significantly different between the groups.² 

The Pragmatic Airway Resuscitation Trial (PART) involved 27 U.S. EMS agencies randomizing use of the King LT vs. endotracheal intubation in adult OHCA, with a primary outcome of 72-hour survival.³ It enrolled more than 3,000 subjects, 1,505 initially getting King LTs and 1,499 ETI.

The King airways were started more quickly after EMS arrival (11 vs. 13.6 mins.) and had a higher initial airway success rate (89.9% vs. 51.3%). Overall airway success rates were 94.2% for the King and 91.5% for ETI, and the ETI group was far more likely to need more than three insertion attempts (18.9% vs. 4.5%).The King’s 72-hour survival was significantly higher (18.3% vs. 15.4%). 

Summary

The AIRWAYS-2 trial showed higher initial ventilation rates with an i-gel during cardiac arrest, and PART showed much faster placement of the King LT than an endotracheal tube. This is important information for EMS providers deciding on an airway management device during cardiac arrest. 

References

1. Almeida G, Costa AC, Machado HS. Supraglottic Airway Devices: A Review in a New Era of Airway Management. J Anesthesia Clin Research, 2016 Jan; 7(7).

2. Benger JR, Kirby K, Black S, et al. Effect of a Strategy of a Supraglottic Airway Device vs. Tracheal Intubation During Out-of-Hospital Cardiac Arrest on Functional Outcome: The AIRWAYS-2 Randomized Clinical Trial. JAMA, 2018; 320(8): 779–91.

3. Idris AH, Mattrisch L, Daya M, et al. ETI vs. SGA: The Verdict Is In. J Emerg Med Serv, 2018 Aug 30; www.jems.com/2018/08/30/eti-vs-sga-the-verdict-is-in/.

Elena Pietrocco  is a recent graduate from the paramedic science program at Bergen Community College in Paramus, N.J. She is a nationally registered paramedic and licensed mobile intensive care paramedic in New Jersey.