March 1, 2020

COVID-19: Airway Management

The Novel Coronavirus 2019, was first reported on in Wuhan, China in late December 2019.  The outbreak was declared a public health emergency of international concern in January 2020 and on March 11th, 2020, the outbreak was declared a global pandemic.  The spread of this virus is now global with lots of media attention.  The virus has been named SARS-CoV-2 and the disease it causes has become known as coronavirus disease 2019 (COVID-19).  This new outbreak has been producing lots of hysteria and false truths being spread, however the data surrounding the biology, epidemiology, and clinical characteristics are growing daily, making this a moving target.  This post will serve as a summary of airway management in regards to COVID-19. 

To go back to the main post, click on the image below…

Airway Management of COVID-19 Patients [12][34]:

  • This is a list of general recommendations from the North District Hospital in Hong Kong [3]
    • Aerosol generating procedures, such as non-invasive ventilation (NIV), High-flow nasal Cannula (HFNC), bag-mask ventilation (BMV), nebulizers, and intubation are all particularly high risk procedures
    • Airway devices providing 6L/min or more of oxygen are considered high flow and their use should be discouraged if an airborne infection isolation room is unavailable
    • In patients with suspected COVID-19, currently airborne precautions, hand hygiene, and donning of personal protective equipment (PPE) is recommended
    • Double gloving, as a standard practice might provide extra protection and minimize spreading via fomite contamination to surrounding equipment after intubation
    • Early intubation should be considered in a patient with deteriorating respiratory condition
    • Have a backup airway plan ready to go prior to intubation

  • Non-Invasive Oxygenation
    • Supplemental oxygen can be provided with nasal prongs but a surgical mask should be worn over the patients face and prongs to reduce droplet spread
    • HFNC can theoretically increase the risk of viral spread through aerosol generation.  However this plus a surgical mask would be preferred over CPAP/BiPAP [3]
      • HFNC is recognized by World Health Organization (WHO) for treatment of patients with respiratory failure caused by COVID-19 (However, if using airborne isolation is recommended) [Link is HERE]
      • HFNC is being used by clinicians for treatment of patients with respiratory failure caused by COVID-19 in Wuhan within Hubei province, China and Milan in the Lombardy province, Italy (and other countries).
    • In general, CPAP/BiPAP should be avoided (Theoretically, could use if an appropriate viral exhalation filter is available and in the appropriate airborne isolation room)
    • KEY POINT: If you cohort high risk pts and wear appropriate PPE, you can use NIV safely (This is what they are doing in Italy)
    • Also see post on PulmCrit: Could the Best Mode of Noninvasive Support for COVID-19 Be…CPAP??

COVID19 Intubation Packs and Preoxygenation for Intubation via Scott Weingart, MD from the EMCrit Website

  • HiOx Mask [Link is HERE]
    • Potential solution to NIV/HFNC
    • Two head straps create tight seal on patients face
    • No holes in the mask
    • Delivers higher FiO2 with lower flow (8LPM)
    • Exhalation: Patient’s breath flows out one-way exhalation valve (Red arrow) (standard 22mm connector); O2 flowing in fills the inspiratory reservoir at the same time (Blue arrow)
    • Inhalation: Delivers 100% O2 through one-way inspiratory valve to the facemask (Blue arrow); O2 flow creates pressure against dilution valve which allows filling of the inspiratory reservoir (Blue arrow)
    • Increased Inhalation Demand: If demand >0.75L reservoir, dilution valve allows for filling with room air (Yellow arrow)

Improvised CPAP (iCPAP) [8]

  • This may be useful in low-resource settings or during a COVID-19 pandemic where ventilators may not be available
  • Improvised CPAP system from locally available equipment could provide a means of respiratory support (i.e. this is like “Bubble CPAP” in neonates)
  • 10 healthy volunteers used iCPAP set a a pressure of 5cmH20
  • Monitored for 30 minutes
  • iCPAP maintained positive airway pressure in all subjects
    • Mean Expiratory Pressure (EP) = 5.1cmH20
    • Mean Inspiratory Pressure = 3.2cmH20
  • There was a small decrease in average EP (5.28 vs 4.88cmH20) and trend toward decreased IP (3.26 vs 3.07 cmH20) over 30min
  • No difference in heart rate, respiratory rate or EtCO2 over 30 min
  • Limited experimentation with higher pressure values suggested 8.0cmH20 of PEEP could be reliably maintained by this device (pressures above this were not tested
  • CAVEAT: Further studies should trial the iCPAP system in patients with respiratory distress
  • See tweet below for equipment and setup

  • Nebulization of Medications:
    • Should be avoided
    • Bronchodilators should be administered using metered-dose inhalers
    • Mild to Moderate Asthma/COPD: MDI with spacer
    • Severe Asthma/COPD: 0.1 – 0.3mg Epi + early intubation
    • Potential Option: NIPPV mask (unvented) + Multi-Adapter – 15mm x 22mm + Nebulizer setup + Viral filter

Idea and Image from Scott Weingart, MD from EMCrit Website

CPAP without NC O2 and O2 from EtCO2 Port from Scott Weingart, MD from EMCrit Website

  • Intubation:
    • High-Risk Patient + High-Risk Procedure = Higher Level of Precautions (Ideally, want to be in an airborne isolation room with appropriate airborne/droplet PPE plus eye protection with N95 mask or PAPR)
      • Negative pressure ventilation rooms are ideal to minimize exposure to aerosol and droplets.  Where this is not feasible, normal pressure rooms with closed doors are recommended
    • Most skilled person at intubation should perform the procedure to minimize attempts
    • Optimize preoxygenation with non-aerosol generating means: bed up head elevated, airway maneuvers (i.e. jaw thrust), use of positive end expiratory pressure valves, and airway adjuncts [3]
    • Suction: Ensure you are using closed suction systems and not open suction systems to minimize aerosolization
    • Preoxygenation (This assumes full PPE = Gown, gloves, N95/PAPR, eye protection, negative isolation room):
      • Nasal oxygen therapy (via standard or HFNC) should not be used during pre-ox or for apneic oxygenation due to the risk of virus aerosolization. If patients who are receiving HFNC, it should be turned off prior to removal of patient face mask and nasal cannula to minimize aerosolization
      • BVM prior to intubation can generate aerosols and generally should not be used (Again, theoretically could use a viral exhalation filter between the resuscitation bag and mask or endotracheal tube)
        • If BVM is required, a two-handed vice grip + viral filter + gentle ventilation should be used
        • Consider placing a clear drape over the patients face to minimize aerosolization (this can be a patients clear possession bag as an example)

Apneic CPAP via George Kovacs, MD (Twitter: @kovacsgj)

From the Australian Safe Airway Society Consensus Statement [4]

      • Supraglottic Device: Use a second generation device as it has a good seal pressure during PPV.   Although there is no robust evidence, supraglottic devices are likely better options than BVM.  The devices are easy to place, spare man/woman power, have better seal pressure than BVM and thus reduce staff exposure
    • RSI is the treatment of choice for intubation and all patients should get this, as inadequate sedation and paralyzation can produce coughing during laryngoscopy which can also generate aerosols
      • Rocuronium 1.5 – 2mg/kg IV has similar onset of action as succinylcholine, but because of its longer half-life, prevents coughing or vomiting that can occur with succinylcholine
    • Video laryngoscopy is recommended over direct laryngoscopy with a display separate from the blade to avoid placing the face of the intubator close to the patient
      • Disposable equipment is preferred over reusable equipment where available

Infographic from LITFL Blog (Created by Albert Chan, MD Twitter: @gaseousXchange)

From the Australian Safe Airway Society Consensus Statement [4]

From the Australian Safe Airway Society Consensus Statement [4]

Intubation Protocol from COVID Critical Care Website

Intubation Medications

Infographic From The PharmERToxGuy (Link is HERE)

Ventilator Management and Strategies[5]

  • Consider trial of HFNC with moderately severe hypoxemia.  This may avoid intubation and mechanical ventilation. These patients should be monitored closely for clinical deterioration to avoid emergent intubations
  • Things to consider for intubated patients with P/F ratio <100 – 150mmHg:

  • Increase PEEP by 2 – 3 cmH20 every 15 – 30min to help improve O2 saturation to 88 – 90% with the goal of maintaining a plateau airway pressure of <30cmH20
  • Lower driving pressures (plateau airway pressure minus PEEP) with a target of 13 – 15cmH20
  • Recruitment maneuvers (most likely little value), with increasing pressure to 30cmH20 for 20 – 30s can be tried

Lung Injury Ventilation and ARDSnet[6][7]:

Video from Scott Weingart, MD from the EMCrit Site

Images Peer Reviewed by Scott Weingart, MD

  • PDF Version: Lung Injury Mechanical Ventilation
  • Calculating Ideal Body Weight [Link is HERE]
  • If your PIP and Plateau are both elevated then this indicates lung disease and decreased compliance of the lung, but if your PIP is elevated and your Plateau pressure is unchanged then this indicates increased airway resistance

  • Preliminary Observations on Ventilatory Management of ICU COVID-19 Patients from the French Society of Anesthesia and Intensive Care Medicine (SFAR) 2020. [Link is HERE]
    • This paper is contradictory to the ARDSnet protocol for COVID-19 patients
    • COVID-19 ICU patients are NOT similar to ARDS patients.  They have profound hypoxia with a pulmonary compliance that is generally high.
    • High-Pulmonary Compliance: Hypoxic vasoconstriction.  Major issue is lung perfusion.  Increasing PEEP and prone positioning are of minimal help with recruitment of collapsed lungs. In these patients high PEEP (>15cmH20) may compromise right cardiac filling
    • Oxygen Alone vs Ventilation: High FiO2 more important in the short run, other interventions (i.e. intubation) may be more harmful than buying time
    • Management of PEEP: This should be limited at 8 – 10cmH20 as higher levels will not increase pulmonary compliance and will impact venous return and cause more harm.  Further increases in PEEP should be monitored with SvO2 and/or echo to assess right heart function
    • Prone Positioning: Should be considered a rescue maneuver and most likely not beneficial in patients with high compliance
    • Nitric Oxide: Should be considered to maintain lung perfusion
    • Microthrombosis and D-Dimer: Microthrombosis and associated ischemic events are common.
    • Liberal Tidal Volume: In high compliance patients, target TV > 8mL/kg (ideal body weight)
    • Shunt Determination: Shunt fraction is best strategy to assess oxygenation.  etCO2/PaCO2 is a useful tool.  Ratio <1 suggested elevated shunt and dead space (area of lung ventilated and not perfused)
    • Bottom Line:
      • PEEP levels low
      • TV >6mL/kg
      • RR <20BPM
      • Avoid intubation as this is of higher benefit than the costs of intubation
  • COVID-19 patient with ARDS (“CARDS”) and Avoiding the VILI-Vortex [12]

  • Same Virus, Two Phenotypes [8]
    • Despite sharing a single etiology (SARS-CoV-2), COVID-19 pneumonia has two distinct presentations:
    • This is most likely a time-related spectrum of disease:
      • L Type
        • Low elastance (i.e. high compliance)
        • Low ventilation/perfusion ratio
        • Low lung weight
        • Low recruitability
        • CT scan: well aerated lungs (-1000 to -700 HU)
      • H Type
        • High elastance (i.e. low compliance)
        • High right-to-left shunt
        • High lung weight
        • High recruitability
        • CT scan: poorly-aerated lungs (-300 to 100 HU)

    • Differing treatment based on H- and L-type model
      • L Type
        • Increase FiO2
        • NIV options: HFNC, CPAP, or NIV
        • High PEEP can have detrimental effects on hemodynamics
        • Ventilator: TV >6mL/kg (up to 8 – 9ml/kg) – ideal body weight; PEEP reduced to 8 – 10cmH20; Prone positioning as rescue maneuver
      • At some point the L Type can transition to the H Type
        • Swings in CVP or clinical detection of excessive inspiratory effort should be assessed
        • When either are seen, intubation should be considered
      • H Type
        • Ventilator: ARDSnet protocol; Prone positioning

Infographic Created by Mark Ramzy, DO

  • Basing Respiratory Management of Coronavirus on Physiological Principles [10]
    • Dominant respiratory feature of COVID-19 is arterial hypoxemia > decreased compliance
      • Important to base clinical decisions (i.e. intubation) on sound scientific knowledge
      • SpO2 can differ from SaO2 (measured with co-oximeter) by +/-4%
      • SpO2 readings >90% are tough because they can signify a PaO2 of 60 to 200mmHg (different connotations for management)
      • Gas exchange assessment requires FiO2, which is tough in non-intubated pts
      • ABGs can give more precise measure of gas exchange (PaO2, PaCO2, and FiO2 can calculate alveolar to arterial O2 gradient)
        • Hypoxemia + Nl A-a O2 gradient + Increase PaCO2 = Hypoventilation (Uncommon in COVID-19)
        • Hypoxemia + Increased A-a O2 gradient + Nl PaCO2 = V/Q mismatch or intra-pulmonary shunt
        • Diffusion issues cause hypoxemia at high altitude
        • If PaO2 increases with supplemental O2 = V/Q mismatch (Most likely don’t need intubation)
        • If PaO2 does not increase with supplemental O2 = intra-pulmonary shunt (Most likely will require intubation)
    • Decision to use invasive mechanical ventilation (involving ETT) should be based on physician judgment (i.e. clinical gestalt influenced by O2 sat, dyspnea, RR, CXR, and other factors)
      • Tachypnea in isolation should rarely constitute primary reason to intubate
      • Tachypnea is not the same as increased work of breathing which is determined by magnitude of pleural pressure swings and TV (Palpation of sternocleidomastoid muscle with phasic (not tonic) contraction, is the most direct sign on physical exam of increased work of breathing
      • CXR alone should not be an indication for intubation unless there is abnormal gas exchange or increased work of breathing
      • End organ damage is hard to demonstrate in pts with PaO2 >40mmHg (equivalent of SpO2 ≈75%)
    • For patients on the ventilator:
      • Avoid complications (Best way to do this is avoid intubation unless absolutely necessary)
      • Mechanical ventilation in and of itself does not produce lung healing
      • “The surest way to increase COVID-19 mortality is liberal use of intubation and mechanical ventilation.”

LTV Ventilator Setup

LTV Ventilator – Image from Mark Ramzy, DO (Twitter: @MRamzyDO)

LTV Ventilator as CPAP – Image from Mark Ramzy, DO (Twitter: @MRamzyDO)

LTV Ventilator as AC and SIMV Modes – Image from Mark Ramzy, DO (Twitter: @MRamzyDO)

Fairly Rationing ICU Care JAMA Network from March 27th, 2020 (Video Time: 40:49) [Link is HERE]

Solution in Extreme (Last Ditch) Circumstances if Running Out of Ventilators (CAVEAT: Off-label use not studied in humans)

Allocation of Scarce Critical Care Resources During a Public Health Emergency

Stop Intubating Patients for Hypoxemia

References:

  1. Neyman G et al. A Single Ventilator for Multiple simulated Patients to Meet Disaster Surge. Acad Emergency Med 2006. PMID: 16885402
  2. Wax RS et al. Practical Recommendations for Critical Care and Anesthesiology Teams Caring for Novel Coronavirus (2019-nCoV) Patients. Can J Anaesth 2020. PMID: 32052373
  3. Cheung JC et al. Staff Safety During Emergency Airway Management for COVID-19 in Hong Kong. Lancet Respir Med 2020. PMID: 32105633
  4. Safe Airway Society. Consensus Statement: Safe Airway Society Principles of Airway management and Tracheal Intubation Specific to the COVID-19 Adult Patient Group. MJA 2020. [Epub Ahead of Print]
  5. Matthay MA et al. Treatment for Severe Acute Respiratory Distress Syndrome from COVID-19. Lancet Resp Med 2020. [Epub Ahead of Print]
  6. Acute Respiratory Distress Syndrome Network. Ventilation With Lower Tidal Volumes as Compared with Traditional Tidal Volumes for Acute Lung Injury and the Acute Respiratory Distress Syndrome. NEJM 2000. PMID: 10793162
  7. Weingart SD. Managing Initial Mechanical Ventilation in the Emergency Department. Ann Emerg Med 2016. PMID: 27289336
  8. Gattinoni L et al. COVID-19 Pneumonia: Different Respiratory Treatment for Different Phenotypes. Intensive Care Med 2020. [Epub Ahead of Print]
  9. Millner BH et al. A Pilot Study of Improvised CPAP (iCPAP) via Face Mask for the Treatment of Adult Respiratory Distress in Low-Resource Settings. JEM 2019. PMID: 31179948
  10. Tobin MJ. Basing Respiratory Management of Coronavirus on Physiological Principles. AJRCCM 2020. [Epub Ahead of Print]
  11. Kovacs G et al. Just the Facts: Airway Management During the COVID-19 Pandemic. CJEM 2020. PMID: 32223782
  12. Marini JJ et al. Management of COVID-19 Respiratory Distress. JAMA 2020. [Epub Ahead of Print]

For More Thoughts on This Topic Checkout:

Post Peer Reviewed By: Anand Swaminathan, MD (Twitter: @EMSwami) and Mizuho Morrison, DO (Twitter: mizuhomorrison)

Cite this article as: Salim Rezaie, "COVID-19: Airway Management", REBEL EM blog, March 1, 2020. Available at: https://rebelem.com/covid-19-airway-management/.
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Salim Rezaie

Emergency Physician at Greater San Antonio Emergency Physicians (GSEP)
Creator & Founder of REBEL EM
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