Editor's note: This article originally appeared as part of our Grand Rounds blog series. Grand Rounds is a monthly blog 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, Jim DuCanto, MD, reviews airway management during the COVID pandemic.
I was recently asked to provide a summary of the tools and techniques relevant to airway management in the COVID-19 pandemic for the 2020 World Trauma Symposium, and this article will summarize that presentation.
To summarize its principal points, we’ll discuss the evolution of personal protective equipment (PPE), the standardized use of HEPA filters in prehospital and hospital respiratory care, and two other techniques to reduce emissions of contaminated aerosols into the clinical working environment. We’ll finish our discussion of aerosol abatement strategies by looking into suction-assisted practices of basic and advanced airway management.
One of our principal concerns with caring for patients during the COVID-19 pandemic is to protect ourselves and our colleagues from airborne infectious agents. Thus, a brief discussion of PPE is warranted.
The highest level of protection for prehospital personnel is afforded by donning an impermeable gown, two layers of disposable gloves, an N95 (or higher) filtering mask, and protective eyewear. This level of PPE matches the current standard of care for COVID-19 patients in intensive care. The prehospital “uniform” may evolve to include an upgrade to respiratory protection for the filtering of infectious aerosols as well as toxic or nuisance odors. Current systems available from heavy industry, such as the 3M Airstream AS-600LBC mining headgear-mounted powered air-purifying respirator system, provide comprehensive protection for the eyes, respiratory system, and head and scalp for up to eight hours per belt-mounted battery pack. It is conceivable that existing protective headgear for fire service personnel, such as MSA’s Cairns XF1 fire helmet, could be adapted to serve as a PAPR. Emergency medical services personnel deserve a substantial upgrade to protect their most valued assets: their heads and respiratory systems.
Beyond PPE, efforts to reduce the emissions of infectious respiratory pathogens from our patients include the standard use of HEPA filters on bag-valve mask (BVM) units, CPAP systems, and, of course, mechanical ventilators. Our goal is to “keep the genie in the bottle” as best as possible to reduce caregiver exposure to infectious agents.
HEPA Filters and Aerosol Abatement
If a HEPA filter is not utilized on a BVM, the patient’s exhalatory gases are expelled through the exhalation port without regard for caregiver safety. The standard placement of the HEPA filter is between the mask, supraglottic airway, or tracheal tube and the BVM device to make this device safe for clinical use during the pandemic.
Suction-assisted aerosol abatement is a potential preemptive method of decontaminating the immediate clinical working area with handheld suction. Commercially available portable medical suction units will mobilize approximately 25 lpm of air through the suction tip and hose and into the suction container. This is equivalent to a cubic foot per minute, the volume of a medium-size microwave oven.
The concept here is to maintain decontamination of the immediate area around the head of the patient. Utilizing handheld suction near the nose and mouth during airway management has been shown in a simulation study to reduce the extent of dispersed particles during simulated coughing bouts in a manikin model.1 The smoke particles emitted from the manikin were generated from a smoke-generating machine, and the exhaled airflow was illuminated with a laser light sheet. This study found continuous use of oral suction during the simulated coughing bouts (650 lpm airflow) reduced the exhaled air dispersion of smoke particles by 32%.
Additionally, this study revealed that caregivers inexperienced with facemask ventilation technique increased the spread of smoke particles as much as 40% due to leaks with the facemask during BVM use. This is directly related to the one-handed mask ventilation technique required during the study—which, of course, is the standard technique for BVM use in prehospital care. A two-handed facemask ventilation technique improves the facemask seal and allows for more effective and robust airway maneuvers during facemask ventilation but requires two rescuers unless automated systems are utilized.
The advantages of using automated systems to assist facemask ventilation are numerous:
It allows a single rescuer to efficiently facemask-ventilate a patient with better implementation of upper airway maneuvers (head tilt, jaw thrust);
It allows control of inspiratory flow rate, peak airway pressure, and minute ventilation;
It reduces gas leak due to the two-handed technique;
It reduces the insufflation of gas to the stomach due to all the above.
In my state automated ventilation equipment intended for basic life support is limited to the Oxylator line of resuscitator equipment. Still, a properly adjusted transport ventilator potentially could fulfill this function.
The Oxylator permits facemask ventilation with a constant flow (30 lpm, 500 ml/second) and an adjustable pressure release selector (HD, EMX, and EM-100 models) so the rescuer sets the pressure release to allow for a one-second inspiratory time (equal to 500 ml). The Oxylator can be used for advanced life support with a supraglottic airway or an endotracheal tube as well. This device requires a HEPA filter between it and the mask, supraglottic airway, or tracheal tube for proper patient and caregiver protection.
In summary, excellent prehospital care depends on maintaining as safe a scene as possible for rescuers, with simple and effective techniques for them to help their patients. In the months to years following the COVID-19 pandemic, I hope we will witness an evolution of PPE and the techniques utilized to manage patients with respiratory pathogens.
1. Chan MTV, Chow BK, Lo T, et al. Exhaled air dispersion during bag-mask ventilation and sputum suctioning—implications for infection control. Scientific Reports, 2018; 8: 198.
James “Jim” DuCanto, MD, is the associate medical director of airway and ventilation for FlightBridgeED. He is also an anesthesiologist in private practice for the past 23 years in Wisconsin. His 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.