Grand Rounds: Emergency Airway Management in COVID-19—Concepts from Simulation to Consider

Grand Rounds is a new monthly blog series developed by EMS World and FlightBridgeED that features top EMS physicians exploring the intricacies of critical care in EMS practice. In this installment FlightBridgeED Associate Medical Director Jim DuCanto, MD, considers safety in airway management during COVID-19.

In the interest of improving clinician safety in management of the emergency airway, I recently made some simulation videos to investigate the use of the SALAD technique in the setting of caring for a patient with COVID-19. The videos accompanying this blog entry show how to reproduce the simulation.

The first video involved creating a simulated aerosol plume emanating from the test manikin. This simulation was achieved by linking two nebulizer units together in line with the main stem bronchus of a 7-Sigma Modular Partial Airway Trainer. Utilizing a fresh gas flow of 15 lpm through the nebulizers and diet tonic water as the solution, we were able to visualize a plume aerosol in the presence of two 60-watt UV lights.

In this simulation we sought to investigate reliable and straightforward methods to reduce contamination of the clinical workspace with respiratory droplets with an airborne infectious organism. As a disclosure, I created the SALAD technique. I also invented the SSCOR DuCanto Catheter and receive royalties for its sales.

My colleague in this simulation is Bob Barrix, a paramedic with Sun Prairie (Wisc.) EMS. Bob demonstrates that the suction catheter can visibly reduce the visible aerosolized stream with passage over the face and mouth of the manikin. Furthermore, it also contains the aerosol stream to mainly within the pharynx of the manikin. Bob modifies the SALAD technique to keep the tip of the suction above the upper esophageal inlet (above the larynx to the left) to continue clearing the hypopharynx of aerosolized particles. We further show the influence of parking the suction to the left in the hypopharynx by alternately occluding and opening the flow of suction to the catheter. In the video that follows, Bob shows the basic SALAD technique.

The second video addresses the use of a clinician protection enclosure to manage the aerosol plume during tracheal intubation. The nebulized solution was altered to include a small quantity of Glo Germ to increase its fluorescence under UV light. This video explored the use of a Lexan intubation box connected to an improvised negative pressure shroud, which was powered by a Shop-Vac wet/dry vacuum unit with a vacuum capability of 60 cubic feet per minute.

The aerosol plume is seen to accumulate quickly in the Lexan box until the wet/dry vacuum is activated. Then it disperses haphazardly, with a general flow toward the nozzle connecting the intubation shroud to the vacuum cleaner. Adding the SALAD suction technique further abates the aerosol stream in the simulation.

So It All Means What?

What can we learn from these simulation videos? Reviewing them brings up several questions:

• Is it realistic to assume a suction unit can decontaminate a clinical workspace above the face of a patient during emergency airway management?
• Does utilizing the SALAD technique confer protection to the clinician when caring for patients with infectious diseases?
• Do protective boxes/shrouds have a role in modern airway management? Does the addition of a negative pressure system to these boxes confer extra protection to the clinician?

To answer these questions, let’s consider the following: 

Airborne contamination of a clinical workspace occurs with patient coughing or forceful ventilatory maneuvers into the room air. The volume of air within an ambulance patient compartment area far exceeds the capacity of any suction system, and the safety of the EMS crew relies on their use of appropriate PPE as well as the onboard ventilation system of the ambulance. 

Preemptive use of suction during tracheal intubation and supraglottic airway insertion may contain infectious respiratory droplets to a limited degree in the immediate area of the patient’s mouth. However, this is conjecture based on the performance of modern suction units. Modern portable suction units can draw 30 lpm of flow through the suction canister system and extension hose (which equates to 1 cubic foot per minute—or, in three dimensions, the size of a small microwave oven). To contain the airborne contamination in the ambulance, the airway management procedure must be as swift and definitive as possible, with first-pass success as the primary goal to minimize peri-intubation hypoxemia. The SALAD technique has been written about in at least three simulation-based studies demonstrating improved efficiency of tracheal intubation in simulated contaminated airways.^1–3  

Do protective boxes/shrouds have a role in EMS airway management? Space and operational constraints dictate that protective boxes cannot fit within the patient compartment of an ambulance and furthermore inhibit the performance of the airway management procedure. The addition of a negative-pressure ventilation component is an interesting thought experiment but is not a practical in current EMS airway practice. Indeed, this is a feature ambulance manufacturers would need to engineer into the patient compartment.

Amid the current challenges of the COVID-19 pandemic, efforts to achieve a secure airway on the first attempt in the least amount of time are essential for patient safety and overall caregiver protection.

References

1. Pilbery R, Teare MD. Soiled airway tracheal intubation and the effectiveness of decontamination by paramedics (SATIATED): a randomised controlled manikin study. Br Paramedic J, 2019 Jun; 4(1): 14–21(8); www.ingentaconnect.com/content/tcop/bpj/2019/00000004/00000001/art00003.

2. Lin L-W, Huang C-C, Ong JR, Chong C-F, Wu N-Y, Hung S-W. The suction-assisted laryngoscopy assisted decontamination technique toward successful intubation during massive vomiting simulation: A pilot before–after study. Medicine (Baltimore), 2019; 98(46): e17898.

3. Jensen M, Barmaan B, Orndahl CM, Louka A. Impact of Suction-Assisted Laryngoscopy and Airway Decontamination Technique on Intubation Quality Metrics in a Helicopter Emergency Medical Service: An Educational Intervention. Air Med J, 2020 Mar–Apr; 39(2): 107–10.

James “Jim” DuCanto, MD, is an associate medical director forFlightBridgeED, LLC. He is an anesthesiologist in Wisconsin whose 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.