Best practices to minimize COVID-19 aerosolization

Prehospital caveats for non-invasive and invasive airway management as we learn more about the pathophysiology of COVID-19


When approaching airway management in the era of COVID-19, several overarching themes emerge that differ significantly from classic teaching.

First of all, every patient care encounter begins with the initial objective of keeping providers protected first and foremost. PPE is essential and should be fully in place before the initiation of patient contact.

Additionally, substantial anecdotal evidence suggests that COVID-19 patients can present with severe hypoxia that is not always reflected in their level of respiratory distress. These patients may indeed eventually need advanced airway management, but this should not be performed based on oxygen saturation values alone. Treat patients, not numbers. Local hospital policies and practices will also guide and potentially limit prehospital treatment options. If a receiving emergency department does not allow non-invasive positive-pressure ventilation (NIPPV) outside of a negative pressure room, then EMS protocols may also need to be adjusted to comply. Teamwork is vital throughout the continuum of care.

Paramedic Bianca Hines works on best airway management practices on a manikin. (Photo/MCHD)
Paramedic Bianca Hines works on best airway management practices on a manikin. (Photo/MCHD)

Finally, COVID-19 best practices are in their infancy. There is still much to learn, and as more data accumulates, practices will likely be adjusted, revised and even reversed. This revision cannot be seen as mistakes or failure, just the natural progression of medical science. Below, the progression of both non-invasive and invasive airway management will be discussed in more detail, with specific attention paid to prehospital COVID-19 caveats.

COVID-19 protection

Sars-COv-2 is believed to be transmitted primarily via large droplet transmission unless these droplets are aerosolized by either the patient or healthcare provider. However, evidence from influenza suggests airborne transmission is likely possible as well [1]. Making a clear distinction between the droplet and aerosol transmission is less important than developing best practices for the overall prevention of healthcare infections.

EMS airway management interventions with the potential to aerosolize COVID-19 include:

  1. BVM
  2. NIPPV
  3. Intubation
  4. Suction
  5. Nebulized Medication
  6. Nasal cannula oxygen >6L
  7. Patient coughing, speaking, sneezing = droplet expulsion

To contain patient-produced droplet dispersal, it is recommended to place a surgical mask on the patient immediately upon contact and to keep that in place throughout transport. These masks should be placed over any canula or oxygen delivery mask if either are added for oxygen supplementation. The primary iatrogenic sources of aerosol generation are high pressure, high flow, and airway manipulation. Viral HEPA filters are a must in any airway management situation, and they should be placed as close to the patient in the expiratory pathway as possible.

While the pathophysiology of COVID-19 is still in many ways a mystery, with continuous new developments, there does seem to be a significant cohort who present severe hypoxia that is not reflected in the expected level of respiratory distress. Again, prehospital providers must be vigilant to treat the patient and not act solely on low oxygen saturation values. This will protect the provider and is likely beneficial to the patient’s clinical course as well.

Bag-valve mask and oxygen considerations

Two-hand bag-valve-mask ventilation technique in the “V-E” fashion is advised in an effort to create the tightest seal possible [2]. The exact oxygen flow that becomes “aerosol generating” is unknown. Several sources, however, reference 6 liters per minute or greater [3]. To avoid confusion and minimize exposure, the best practice is to place a viral filter between the bag and the patient at all times regardless of the oxygen flow rate.

Non-invasive ventilation

The safety and efficacy of NIPPV in COVID-19 is currently quite divisive among emergency medicine and critical care thought leaders. Data from the past MERS epidemic suggest questionable utility of NIPPV with a high failure rate and progression to intubation [4].

Additionally, an increased viral transmission has been documented in the past SARS epidemic [5]. At this time, extreme caution is recommended if the choice is made to utilize NIPPV in the prehospital setting, requiring a viral filter, a non-agitated patient and a tight mask seal, all in an effort to minimize aerosol generation.

Definitive airway management

Droplet and/or aerosol spread are likely to be mitigated by moving the airway manager further away from the patient. Because of this, video laryngoscopy is preferred over direct laryngoscopy [6]. Additionally, devices with a video screen separate from the laryngoscope (allowing an even increased distance) may be safer as well. Intubation has been shown to increase viral transmission in past viral outbreaks [7]. The most experienced operator must intubate as prolonged time in the airway likely correlates with greater viral exposure risk.

There is debate about whether supraglottic airways impart increased droplet exposure risk due to lack of complete glottic seal (as opposed to endotracheal tube balloon occlusion). One could also argue for SGA safety based on decreased time to (and increased ease of) insertion relative to endotracheal intubation. For these reasons, both options may be considered depending on clinical presentation and service characteristics.

Sedation only intubation is strongly discouraged due to the high risk of patient coughing and gagging. For paralysis, rocuronium is advised over succinylcholine due to the increased length of action. This minimizes the risk of the patient waking mid-procedure to cough and/or thrash. However, COVID-19 has not changed the necessity for resuscitation prior to intubation, and avoidance of paralytic administration is vital if the patient is hypoxic after taking maximum pre-oxygenation steps (via BVM or NIPPV with tight mask fit being critical) and/or hypotensive after blood pressure augmentation efforts. Consideration of pre-treatment with lidocaine or fentanyl prior to airway manipulation is reasonable in an effort to minimize patient coughing during manipulation. Barrier devices (plastic boxes/drapes) are not advised during definitive airway placement as there is no clear evidence that these are protective, and they likely inhibit rapid SGA/ETT placement [8]. However, covering the patient’s face/neck and chest following device placement is an option for provider protection during transport.

Following intubation, routine airway suctioning should be avoided unless absolutely needed as the suction can aerosolize viral particles, and it can also stimulate coughing if the patient is not adequately sedated and/or paralyzed. Maintenance of a closed ventilation system is vital following ETT/SGA placement. Keep the SGA gastric port covered (tape is adequate) and clamp the endotracheal tube or cover the opening of the SGA if opening the system for any reason.

Place the viral HEPA as soon as possible pre or post airway procedure to avoid as much contamination as possible [9].

Nebulized medication administration

The nebulization of medication (mainly albuterol) is not advised in the era of COVID-19. This prompts several pharmacologic detours, especially in the moderate to severe, young asthmatic patient. The use of early intramuscular epinephrine is encouraged in these patients to achieve beta-agonist effects. Terbutaline may be considered for asthma exacerbations as well, depending on familiarity and availability.

For both asthma and COPD flares, a metered-dose inhaler (MDI) or HFA albuterol is advised if available. Multiple studies demonstrate equivalence, if not superiority, of MDI albuterol when compared to the nebulized form. Sourcing inhalers is becoming increasingly difficult, so we advise protocol alterations allowing paramedics to bring and administer the patient’s personal inhalers if available. The decision to allow nebulized epinephrine is also controversial as croup season is near. This will definitely be a service-specific decision with minimal, if any, data to use as guidance.

Listen for more: How to safely manage COVID-19 respiratory failure patients: The Montgomery County Hospital District EMS shares its specific airway algorithm and a COVID-19 airway management update

References

  1. Tellier R. Aerosol transmission of influenza A virus: a review of new studies. J R Soc Interface. 2009;6 Suppl 6:S783-790.
  2. Brewster DJ, Chrimes NC, Do TBT, et al. Consensus statement: Safe Airway Society principles of airway management and tracheal intubation specific to the COVID-19 adult patient group. Med J Aust 2020;212(10):472-481.
  3. Yu IT, Xie ZH, Tsoi KK, et al. Why did outbreaks of severe acute respiratory syndrome occur in some hospital wards but not in others? Clinical infectious diseases: An official publication of the Infectious Diseases Society of America. 2007;44(8):1017-1025.
  4. Alraddadi BM, Qushmaq I, Al-Hameed FM, et al. Noninvasive ventilation in critically ill patients with the Middle East respiratory syndrome. Influenza Other Respir Viruses. 2019;13(4):382-390.
  5. Wax RS, Christian MD. Practical recommendations for critical care and anesthesiology teams caring for novel coronavirus (2019-nCoV) patients. Can J Anaesth. 2020.
  6. Hall, D., Steel, A., Heij, R., Eley, A. and Young, P. (2020), Videolaryngoscopy increases ‘mouth‐to‐mouth’ distance compared with direct laryngoscopy. Anaesthesia.
  7. Fowler RA, Guest CB, Lapinsky SE, et al. Transmission of Severe Acute Respiratory Syndrome during Intubation and Mechanical Ventilation. American Journal of Respiratory and Critical Care Medicine. 2004;169(11):1198-1202.
  8. Simpson, J.P., Wong, D.N., Verco, L., Carter, R., Dzidowski, M. and Chan, P.Y. (2020), Measurement of airborne particle exposure during simulated tracheal intubation using various proposed aerosol containment devices during the COVID‐19 pandemic. Anaesthesia.
  9. Peng PWH, Ho PL, Hota SS. Outbreak of a new coronavirus: what anaesthetists should know. Br J Anaesth. 2020.

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