New Thinking in Airway Management

Anesthesia

By: Daniel Cook

Published: 7/27/2020

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The coronavirus outbreak could change how providers approach difficult intubations.


There's arguably no more dangerous task in surgery during the coronavirus pandemic than intubating patients. Anesthesia professionals work inches from the airway, in the direct path of aerosolized virus particles, as they attempt to insert a laryngoscope blade while decked out in gloves, gowns, N95 masks and face shields.

"COVID-19 has complicated airway management," says Michael Aziz, MD, a professor of anesthesiology and medicine at Oregon Health & Science University in Portland. "Providers must protect themselves with several layers of PPE, which makes the job more physically demanding. Communication is hampered and visualization is more difficult."

The coronavirus outbreak serves as a reset for anesthesia, according to Roxanne McMurray, DNP, APRN, ?CRNA, a clinical assistant professor at the University of Minnesota School of Nursing. "Providers must be more vigilant when securing the airway," she says. "The current challenges will force us to up our game, and that's a good thing."

The use of video laryngoscopes has increased significantly during the pandemic among providers who are increasingly worried about their proximity to the patient's airway, according to Dr. Aziz. "The devices were gaining a stronger foothold because clinical evidence shows higher rates of first pass intubation success," he says. "Some providers had already been using them universally. Many who weren't are now discovering the benefits they provide."

Video laryngoscopes, which provide direct views of the glottis to make intubation much easier, have evolved since first being introduced as a "game-changing" technology about a decade ago. The latest generation of devices are more ergonomic and portable, and feature high-definition imaging that provides clearer views of airway anatomy. They also accommodate various laryngoscope blade designs. Dr. Aziz says providers often use standard blades for routine intubations and acute angle blades to secure anticipated difficult airways.

Screen size matters most to Dr. Aziz. "Units with smaller, attached screens are priced competitively, but the visualization and magnification capabilities afforded by larger screens allow for improved intubation performance," he says.

Dr. Aziz also points out devices with larger, detachable screens let providers keep a healthy distance from the airway. "We're never certain about who's shedding the coronavirus, even with testing in place," he says. "Video laryngoscopes with separate monitors that can be positioned next to the patient let providers stand upright while intubating instead of leaning directly over the airway to perform direct laryngoscopy or manipulate a video laryngoscope with an integrated screen."

Changes in intubating practices during the COVID-19 outbreak could hasten the adoption of these tools, which many providers believe should be the gold standard of airway management. "I still teach direct laryngoscopy to new nurse anesthetists, but video laryngoscopes are fabulous tools," says Dr. McMurray. "There's no doubt video laryngoscopy is developing into the standard of care."

Buying time

SAFE AND SECURE Many intubations are routine, but providers must always have a back-up plan in place to deal with unanticipated challenges.

Dr. Aziz says humidified high-flow nasal oxygenation, which is often used in intensive care units as a bridge to intubation, is emerging as a useful tool for managing the difficult airway. The method provides oxygenation support that's more comfortable for the patient than continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP) or non-humidified nasal oxygen.

"Providers can deliver 70 liters of oxygen quite comfortably," explains Dr. Aziz. "They avoid intubation and effectively maintain oxygenation for shorter duration procedures, which can be done without placing an endotracheal tube.

"Monitoring CO2 and ventilation is the standard of care during sedation," says Dr. Aziz. "Being unable to monitor these levels during the administration of high-flow nasal oxygen is the biggest barrier to widespread implementation of the practice."

Dangerous levels of CO2 are unlikely to accumulate during the time it takes to intubate a patient, according to Dr. Aziz. "The practice can prolong intubation times and potentially improve management of anticipated difficult airways," he says.

We're never certain about who's shedding the virus, even with testing in place.
— Michael Aziz, MD

Administering humidified high-flow nasal oxygen during intubation, instead of preoxygenating with a facemask, significantly prolongs the time it takes a patient to desaturate. "Patients typically begin to desaturate in three minutes with facemask preoxygenation," he says. "Administering high-flow nasal oxygen can extend that time to 20 minutes, which gives providers the flexibility to perform multiple attempts to intubate the patient or retrieve additional airway equipment if it's needed."

CRISIS MANAGEMENT
A Team Approach to Intubation During COVID-19
READY FOR ACTION Anesthesia professionals at Tampa General Hospital run through the process of establishing airways in dedicated rooms.   |  Rebecca Barnett, MD

When Tampa (Fla.) General Hospital lost 80% of its surgical volume during the initial wave of the coronavirus outbreak, the perioperative team put the empty ORs to good use.

"We decided to intubate patients outside of the ORs where procedures were going to take place to avoid exposing surgical team members to aerosolized virus particles," says Rebecca Barnett, MD, medical director at TeamHealth in Tampa, Fla. "Half of the hospital's ORs were left unused, so we converted four of them into dedicated intubation rooms."

Patients who arrived for emergent surgeries were wheeled into an intubation room where a CRNA, who was outfitted in full PPE, secured their airways. A fifth CRNA coordinated the movement of patients between the intubation rooms and the ORs.

The CRNAs administered rapid-sequence intubation to avoid ventilating patients. After they induced a patient and established the airway, they immediately placed a viral filter over the endotracheal tube and taped it in place before transporting the patient to the OR. The CRNAs changed gloves and gowns, and wiped down the face shields between intubations.

At the time, surgical team members had to leave ORs during intubations and wait in the hallway for 20 minutes while the rooms' air filtration systems completed a full cycle. Performing intubations in separate rooms meant surgical teams could get to work as soon as patients arrived in the OR. The system saved significant OR time, conserved PPE and reduced the anxiety of surgical team members, who were constantly worried about being exposed to COVID-19.

"The system was expensive from a staffing perspective, but it was well worth it to protect our staff and increase case efficiencies," says Dr. Barnett.

— Dan Cook

Recognizing red flags

There's no way to know for certain which patients will prove difficult to intubate, but several screening tools can alert providers to airways that are likely to pose a problem. Dr. McMurray shares a few of the methods commonly used to identify potentially problematic intubations:

    STOP-BANG questionnaire. This eight-question tool (osmag.net/Adr8AP) helps providers predict sleep apnea risk factors or determine the likelihood of the airway obstructing when a patient's reflexes are decreased after induction.
  • Visual assessment. Providers determine the patient's Mallampati ?classification (Class I through Class IV). The rating is based on tongue and pharyngeal size, and visualization of the uvula or soft palette, which helps to predict the ease of intubation.
  • Physical assessment. Providers check the distance from chin to the thyroid cartilage. If it's less than three finger breadths, intubation could prove challenging. Providers ask patients to open their mouths wide. If the mandibular opening is less than three finger breadths, there won't be a lot of room to insert and maneuver airway instruments. Additionally, providers could have difficulty establishing the airway in patients who can't bring their lower teeth in front of their top teeth, lack adequate mandibular extension or have limited neck mobility.
  • Voice recognition. Nodules, cysts or polyps can cause unforeseen obstructions after the patient is sedated and tissue around the pharyngeal airway relaxes. These internal structures are impossible to identify before surgery without direct visualization. But a hoarse voice could serve as a warning sign.

A higher percentage of patients are presenting for outpatient surgery with comorbidities, obesity and sleep apnea, factors that increase the complexity of managing the airway. Pre-op screenings can help providers anticipate tricky intubations, but uncertainty always remains about which patients will pose a challenge. "Anesthesia professionals never approach intubations with confidence that they'll be successful," says Dr. Aziz. "They must always have a back-up plan in place for what they'll do when faced with a difficult airway." OSM

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