Introducing the First Distal Pharyngeal Airway

Abstract

Airway obstruction during anesthesia is a common occurrence with potentially serious outcomes. Increasingly, patients are older, heavier, and more likely to have obstructive sleep apnea—all heightened risk factors for airway complications. These patients undergo procedures where distal pharyngeal tissues can relax, obstructing the airway. As a result, there is a need for airway devices that can stent open distal pharyngeal tissues to maintain adequate ventilation. To physically address this problem, the new distal pharyngeal airway (DPA) prevents airway obstruction and enables providers to maintain ventilation.

Patients under general anesthesia or deep sedation often require assistance to maintain an open airway.¹ Upper airway obstruction is traditionally relieved by using airway adjuncts, including oropharyngeal or nasopharyngeal airways. Oropharyngeal airways are typically made of rigid plastic and are designed to move the tongue forward. However, they do reach beyond the tongue to stent open the distal pharyngeal tissues near the epiglottis.² Nasopharyngeal airways separate the soft palate tissues, but placement can be traumatic, and there are several contraindications for their use.³ These devices do not reach the distal pharyngeal tissues between the posterior tongue and epiglottis, which is often collapsed in obstructed airways. There is a need for airway devices that can stent open distal pharyngeal tissues and relieve airway obstruction.

To overcome distal pharyngeal obstruction, techniques such as nasal positive airway pressure or continuous positive airway pressure have emerged to assist in opening the airway. These techniques rely on pressure alone, which may have limitations in patients with significant anatomic obstruction of their distal airways. Devices that facilitate these techniques can be expensive and may require additional setup. Given these practical challenges, providers have implemented workarounds such as using nasopharyngeal airways orally, though they are not intended for this purpose. In a survey of 293 anesthesia providers, 52.8% of respondents reported using nasopharyngeal airways orally, and the top reason was to improve airway patency.⁴ Manually opening the airway with a jaw thrust or a chin lift is commonly used as an adjunct to oropharyngeal airway use during deep sedation. In the same study of 293 anesthesia providers, 88.9% reported using a chin lift or jaw thrust maneuver with oropharyngeal airways.⁴ This approach can result in postoperative chin or jaw pain. Additionally, it occupies the provider’s hands, which can lead to hand fatigue and limits the ability to tend to other tasks.

Suboptimal airway management can result in serious patient events. A 2011 analysis of the American Society of Anesthesiologists Closed Claims Database found that 17% of anesthesia closed claims since 1990 were categorized as respiratory events.⁵ One study found an estimated 64% of perioperative cardiac arrests were caused by anesthesia-attributable airway complications, with a mortality of 29%.⁶ When analyzing monitored anesthesia care claims alone, ventilatory depression due to oversedation was responsible for 21% of claims.⁷ These statistics highlight the importance of having sufficient airway devices to maintain adequate ventilation and keep patients safe.

Risk factors for the presence of a difficult airway include increasing body mass index, increasing age, and a history of obstructive sleep apnea (OSA).⁸ Obesity rates are rising, and recent data reveal >40% of American adults qualify as obese, including almost 10% who are severely obese.⁹ Obese patients have increased respiratory demands, increased work of breathing, increased ventilatory muscle inefficiency, and decreased pulmonary compliance.¹⁰ Notably, patients with obesity and OSA have greater neck circumference and more anterior neck soft tissues, which may predispose them to having a difficult airway.^11–13 Due to the unique airway difficulties in these groups, there is a growing need for an airway device that addresses obstructing distal pharyngeal tissues.

This gap in airway management devices led to the development of the distal pharyngeal airway (DPA), which is designed to physically open the DPA and remove anatomic obstruction while supporting maintenance of spontaneous breathing.

The DPA helps maintain a patient’s upper airway and improve safety. Furthermore, it was developed with patient and provider comfort in mind.

DISCUSSION

The DPA (McMurray Enhanced Airway, McMurray Medical) is indicated, and is registered with the Food and Drug Administration for oral use to relieve upper airway obstruction, to facilitate apneic oxygenation, or to facilitate ventilation with assistance (Video 1, Supplemental Digital Content, http://links.lww.com/AACR/A515). The DPA has 5 parts (Figure 1): a distal tip, flexible cannula, elongated cushioned bite block, flange, and optional 15-mm connector. The longer tubing compared to current oropharyngeal airways allows for stenting open redundant distal pharyngeal tissues. An elongated cushioned bite block protects the patient’s teeth, prevents the patient from occluding the device lumen, and allows for sizing variations. Currently, the DPA comes in 1 size and accommodates patients roughly 62 to 70 inches in height. The DPA is sized by measuring from the philtrum to the tip of the earlobe without the connector in place. The flange precludes the device from becoming dislodged. An optional 15-mm connector can be connected to the anesthesia circuit or a manual resuscitator bag. This can help facilitate apneic oxygenation, aid in positive pressure ventilation during routine or difficult mask ventilation, and be a conduit to deliver oxygen directly to the distal pharynx to reduce hypoxemia and limit diffusion of oxygen onto the surgical field.

Figure 1.

DPA design. DPA indicates distal pharyngeal airway.

The DPA differs from oropharyngeal and nasopharyngeal airways and other airway devices in its design, which aims to stent open distal pharyngeal tissues (Figure 2). Unlike oropharyngeal airways, the DPA’s longer tubing is designed to displace redundant distal pharyngeal tissues to provide a patent airway. Since the DPA is placed orally, the gag reflux needs to be blunted, so the patient must be adequately sedated. In a survey of 35 anesthesia providers who used 42 DPAs during deep sedation, the DPA was reported to decrease upper airway obstruction and allow for adequate ventilation in 100% of cases.¹⁴ When compared to oropharyngeal or nasopharyngeal airways, the DPA more readily maintained a patent airway in 88% of cases.¹⁴

Figure 2.

Comparison of nasopharyngeal airway, oropharyngeal airway, and DPA. DPA indicates distal pharyngeal airway.

The DPA’s small diameter allows it to be placed alongside other devices, notably the endoscopy bite block (Figure 3). The “2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway” recommend “supplemental oxygen administration before initiating and throughout difficult airway management, including the extubation process.”⁸ The DPA can fill this role by facilitating apneic or passive oxygenation during intubation. When connected to oxygen, the DPA facilitates continuous oxygen delivery to the patient while still allowing room to work around the device for intubation (Figure 4). A narrow diameter also allows the DPA to be used as a bite block between the molars to prevent collapsing of a supraglottic airway or endotracheal tube.

Figure 3.

DPA alongside the endoscopy bite block (A) and demonstrated in a mannequin (B). DPA indicates distal pharyngeal airway.

Figure 4.

Facilitation of apneic oxygenation during intubation with a DPA. DPA indicates distal pharyngeal airway.

The DPA facilitates intraoral ventilation with a resuscitation bag or breathing circuit, providing an easy means for positive pressure ventilation, especially with bearded patients or patients who are difficult to mask ventilate (Figure 5). In a case study, the DPA was successfully used to provide emergency intraoral ventilation after a patient in a rigid cervical collar and history of difficult intubation became apneic.¹⁵ Additionally, delivery of oxygen directly to the distal pharynx theoretically decreases oxygen diffusion onto the surgical field, thereby decreasing the risk of an operating room fire. All of these potential uses will improve patient safety in the operating room.

Figure 5.

Intraoral ventilation with a DPA. Intraoral ventilation can be delivered using a manual resuscitator bag and 22 mm outer diameter-15 mm inner diameter straight connector using manual occlusion of the mouth and nares (A) or with a mask (B). DPA indicates distal pharyngeal airway.

The DPA is also designed to improve comfort for the patient and provider. The DPA can be navigated past the oral and pharyngeal tissues with minimal trauma due to its smaller diameter (compared to the standard oropharyngeal airway) and flexible nature. This theoretically helps reduce postoperative mouth and throat discomfort. In a study of 243 patients receiving deep sedation, there was an increased incidence of patient-reported postoperative sore throat when an oropharyngeal airway was used compared to when a soft oral airway similar to the DPA was used (40% vs 17%; P < .001).⁴ The DPA’s cushioned bite block is placed between the molars, aiming to decrease the risk of dental damage. By relieving airway obstruction, the DPA’s design aims to decrease the need for chin lifts and jaw thrusts, thereby decreasing chin and jaw discomfort in patients while also freeing the provider’s hands. In a survey of 35 anesthesia providers who used 42 DPAs during deep sedation, 97% of DPA placements allowed for a “hands-off approach” and eliminated the need for chin lift or jaw thrust maneuvers.¹⁴ The DPA is easy to insert and requires no setup or additional equipment. Of 35 surveyed providers, 93% asserted that the device was easy to place, and the remaining 7% felt it was moderately easy to place.¹⁴

Upper airway obstruction during deep sedation and anesthesia is a common problem and typically necessitates the use of an airway device. As described above, the DPA is designed specifically to eliminate issues associated with traditional airway devices. It is able to physically open obstructed distal pharyngeal tissues. The DPA improves ventilation and prioritizes patient and provider comfort.

DISCLOSURES

Name: Roxanne R. McMurray, DNP.

Contribution: This author contributed to writing the original draft, reviewing, and editing.

Conflicts of Interest: R.R. McMurray is a co-owner of McMurray Medical and an inventor of the distal pharyngeal airway.

Name: Megan R. McMurray, DO.

Contribution: This author helped with conceptualization, writing the original draft, reviewing, editing, and revision.

Conflicts of Interest: M.R. McMurray is a relative of R.R. McMurray.

This manuscript was handled by: BobbieJean Sweitzer, MD, FACP.

ACKNOWLEDGMENTS

The authors thank Jana Stender and Jane Nienaber for their contributions.