The Edge: Supraglottic Airways as Intubation Aids

The Edge is a monthly blog series developed by EMS World and FlightBridgeED that features top EMS medical directors exploring the intricacies of critical care in EMS practice. In this installment FlightBridgeED’s associate medical director of airway and ventilation, James DuCanto, MD, examines the evolution of supraglottic airways. 

When I became an intern 29 years ago, I enrolled in an ACLS class and had my first introduction to the concept of supraglottic airways (SGAs) in the form of the esophageal obturator airway. I found it intriguing this system could assist face mask ventilation; yet I was casually informed by the paramedic instructor that it had already been supplanted by the esophageal Combitube. Combitubes were never introduced into inpatient care in those days, and it wasn’t until 2008 that I saw one utilized for airway management by a regional EMS system transporting cardiac arrest victims. 

Fast-forward to my training in anesthesiology some two years later, where I was introduced to the laryngeal mask airway (LMA). The department in which I served my residency training was careful in its acquisition and use of the LMA: It purchased only one or two models of the size 3 (reusable) LMA masks, and thus my clinical introduction to SGAs was spotty at best. Directions for use were sparse, and the large volume of peer-reviewed literature on how to utilize SGAs effectively was yet to come. 

The size 3 LMA functions well on patients between 30–50 kg. In Chicago in the early 1990s, that meant the mask was appropriate for patients who were either petite women or adolescent children. Most patients at my training institution were well over that size and weight, and as a result I experienced multiple failures to ventilate and maintain patent airways with the LMA during my training. I know now the LMA must be sized appropriately to the body weight of the patient as well as the relative size of their oropharynx and hypopharynx. 

It took nearly eight years for me to become masterful in my use of the LMA in actual clinical practice due to this poor start. Additionally, following the completion of my anesthesia residency, I practiced anesthesia clinically in a tertiary-care facility, and the majority of our cases required tracheal intubation. This held me back in my understanding and clinical ability to utilize SGAs effectively. It wasn’t until 2004 that I began to embrace SGAs as an effective and useful clinical tool. The ability of SGAs to ventilate anesthetized patients is an accepted clinical fact, but it was their ability to assist me in managing difficult tracheal intubations that led me to fully “deep dive” them as a clinical tool.

An Educational Renaissance 

In the days before video laryngoscopy, the “one-eyed man” was king. Flexible bronchoscopy through SGAs simplified difficult airway management. 

The one-eyed man (derived from a quote by philosopher Desiderius Erasmus, “In the land of the blind, the one-eyed man is king”) refers to the use of the flexible fiber-optic bronchoscope (FFB) to manage difficult tracheal intubations (principally in the operating room and intensive care unit). To utilize an FFB, a clinician needs one eye on the lens of the bronchoscope and the other on the rest of the patient. It takes repeated use to become proficient. 

Supported by the faculty at Rush University Medical Center during my clinical years of training, I attempted to master this device prior to leaving training—a skill that has served me well in my clinical career. My original instructor for this device was Peter Murphy, MD, a U.K.-educated anesthetist who published the first clinical case report of fiber-optic bronchoscopic intubation in 1967. Along with other talented clinical faculty, such as Abdel El Ganzouri, MD (who subsequently exported this program to his original training hospital in Cairo), I learned how to manage a variety of difficult airways with one eye on the scope and the other on the patient. In clinical practice I became a resource to many of my colleagues within the operating room and beyond in the management of patients with difficult tracheal intubations. In the mid-1990s there was a growing realization that the LMA-style SGA had a perfect “partner” in the flexible fiber-optic bronchoscope.

There was a sort of renaissance of American airway management education in the mid-1990s regarding the use of the FFB in airway management. It was led by Andranik Ovassapian, MD, at Northwestern University (Ovassapian started the Society for Airway Management circa 1995 in Chicago) and Ray Towey, MD, at Guy’s Hospital in London. Two other U.K. anesthetists, Adrian Pearce and Ralph Vaughan, collaborated to create the Difficult Airway Society, also in 1995, to support the clinical teaching of FFB skills to professionals in their country. These societies individually began to describe and support the use of the LMA-style SGA for use with FFB, and the American Society of Anesthesiology included the LMA as a device to support ventilation in its 1992 difficult airway guidelines and as a potential endotracheal intubation conduit in its 2003 revision. 

I began to regularly utilize the LMA-style SGA as a conduit for FFB-guided tracheal intubation in 2004. Although I acquired my institution’s first GlideScope in 2006, my go-to technique for managing recognized difficult airways remained the SGA-facilitated route for almost another five years due to my familiarity and skill with this technique. As the SGA-facilitated approach to tracheal intubation has multiple advantages beyond simply intubating the trachea (e.g., avoidance of hypoxemia and hypoventilation), I can understand how I was slow to change my practice in the management of difficult tracheal intubations. 

Supraglottic Airway Evolution 

At the current pace of innovation in SGA development, many of us are familiar with the concept of “second-generation” SGAs, which incorporate dedicated channels for venting passive gastric contents out of the hypopharynx. The King LTS-D laryngeal tube features this innovation, as do the Ambu AuraGain and Teleflex LMA Supreme. These improved SGA designs simplified and enhanced the procedure of FFB-guided tracheal intubation. Several second-generation SGA masks have been deliberately engineered for this, including the AuraGain and the Cookgas air-Q (released in fall 2021).

Although there are some services and hospitals that utilize the original LMA design (in the form of the single-use LMA Unique product), commercial improvements to the original LMA design began to enter the medical market space in 2004, and a particular innovation in SGA design from the United States enabled me to more effectively utilize the FFB in clinical practice: the air-Q SGA. Partnering the air-Q with a variety of endoscopes (fiber-optic bronchoscopes as well as optical stylets, such as the Levitan and Shikani optical stylets) provided me with readily available tools to manage difficult tracheal intubations in my institution. In the years prior to the clinical availability of affordable video laryngoscopes, the SGA (partnered with an FFB or optical stylet) was my go-to method for safely managing the airways of patients with difficult tracheal intubations. 

It was only a matter of time until an innovator (in this case Pedro Acha, inventor of the Airtraq laryngoscope) partnered the technology of a second-generation SGA with a video laryngoscope. The TotalTrack appeared in 2018 but has not had widespread success in the United States. It utilizes a second-generation SGA partnered with an illumination and video-imaging system to allow the caregiver the convenience of placing the device with a technique similar to the Airtraq, also utilizing this imaging system to determine if the SGA is properly positioned for ventilation as well as intubation. 

Back up several years from 2018, and an airway-enthusiast colleague of mine, Dutch anesthesiologist Hans Huitink, demonstrated what he called the “one-second intubation” technique, which utilized a video-enabled tracheal tube (the VivaSight) to help demonstrate a video-guided endotracheal intubation method that vastly simplified the process of image-guided tracheal intubation through an SGA.^1,2 Huitink demonstrated more than eight years ago the potential for current technology in medical devices to simplify airway management in cases of difficult tracheal intubation without the use of complicated devices such as FFBs. 

I believe the continued evolution of SGAs will allow their use as tracheal tube introducers when the SGAs are further upgraded to include video imaging systems.³ In the case of Huitink’s technique, he utilized a video-enabled tracheal tube created for the purpose of guiding bronchial-blocking catheters into distal segments of the bronchial tree during thoracic/lung surgery (to allow them to be deflated during surgery). 

However, as in the case of the TotalTrack, video-enabled SGAs are a generation or two away from reality. The advantage of a video-enabled SGA is that it permits the user feedback on proper placement for ventilation, monitoring of airway contamination, and use as a guidance system for endotracheal intubation. Call this the third generation of SGAs. Many of us await this generation, in which the skills of BLS begin to seamlessly merge with those of ALS, and we can all get down to the job of providing the best airway care for our patients when they are in their most vulnerable conditions, such as out-of-hospital cardiac arrest. 

References

1. Huitink JM, Koopman EM, Bouwman RA, et al. Tracheal intubation with a camera embedded in the tube tip (Vivasight(™)). Anesthesia, 2013 Jan; 68(1): 74–8.

2. Huitink J. The one second intubation technique. YouTube, www.youtube.com/watch?v=cUeNp1d1vrY.

3. DuCanto J. Supraglottic airways: their evolution as tracheal tube introducers. Anesthesiology News, 2015 Sep 1; www.anesthesiologynews.com/Review-Articles/Article/08-15/Supraglottic-Airways-Their-Evolution-as-Tracheal-Tube-Introducers/33275.

Dr. James “Jim” DuCanto, MD, is the associate medical director of airway and ventilation for FlightBridgeED, LLC. He is an anesthesiologist whose recent innovations include the SALAD technique and simulation system for airway decontamination from Nasco; the SSCOR DuCanto suction catheter; and the SEADUC, the first fully manual suction unit capable of performing the SALAD technique.