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Chapter 1

COVID-19: Fundamentals of Critical Care

MIzuho Morrison, DO and Scott Weingart, MD

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A critical care crash course with Mizuho Morrison and Scott Weingart.

Released 4/21/2020

COVID: The big picture and escalation of care

Bottom line:

  • Respiratory support for COVID “happy hypoxemics”: nasal cannula → non-rebreather → high-flow nasal cannula → CPAP

  • COVID “happy hypoxemics” may require intubation if they have: 

    • Any increased work of breathing (tachypnea is common but they should be a “happy tachypneic”)

    • Any sort of altered mental status

    • Rising CO2 on serial VBGs

    • Oxygen saturation consistently below 80-85%


COVID airway management is different from others because:

  • These patients rapidly desaturate

  • We are concerned about aerosolized virus during intubation and how that affects our safety, our staff’s safety, and the surrounding environment


The “happy hypoxemic”:

  • These COVID patients are hypoxemic (low oxygen level in the arterial blood) but not hypoxic (low oxygen level in the tissues)

  • Monitor these patients closely as they can quickly decompensate 

Step-by step approach to respiratory support for the “happy hypoxemic”:

  • You’ll know if your patient is failing these respiratory support measures and may require intubation if they have: 

    • Any increased work of breathing (tachypnea is common but they should be a “happy tachypneic”)

    • Any sort of altered mental status

    • Rising CO2 on serial VBGs

    • Oxygen saturation consistently below 80-85%

  • Obtunded or crashing on arrival? Just intubate!


Step 1. Start with nasal cannula 

  • Put on nasal cannula at 6 to 10 L/min of oxygen with a surgical mask over the nasal cannula


Step 2. Move to non-rebreather

  • Put on a non-rebreather at 15 L/min (over top of nasal cannula) and reapply surgical mask

    • Why both? Non-rebreather at flow rates around 15L/min supplies 65-70% FiO2; non-rebreather + nasal cannula gets your FiO2 up to around 90%

  • Be sure to have these patients change position (the “rotisserie” method) every 1-2 hours

    • Start with upright in bed (head of bed at 80-90 degrees)

    • Lie on left side for 1-2 hours

    • Lie on right side for 1-2 hours

    • If able to tolerate, lie prone for 1-2 hours


Step 3. Move to high-flow nasal cannula

  • What is high-flow nasal cannula (HFNC)? 

    • Nasal cannula hooked up to a humidifier and heater

  • Scott starts with up to 100% FiO2 at 20 L/min → titrate up the flow by 10 L/min every 10 minutes, as needed

    • Can go up to 60 to 80 L/min; max flow rate depends on the device

  • Can generate a little bit of PEEP (4 to 7 cmH2O) at high flow rates (around the 30-40 L/min)


Step 4. Move to CPAP

  • CPAP provides more PEEP then high-flow nasal cannula, up to 15 cmH2O

  • While we generally do not use BiPAP in COVID, it is still a good choice for those with secondary disease (COPD, asthma)

  • If you do not have a CPAP machine available, see Scott’s CPAP mask + bag-valve-mask (BVM) +/- nasal cannula set-up at


COVID Intubation 

Bottom line:

  • The key is to ensure first-pass success and reduce exposure 


Before entering the room:

  • Highest-level physician should do the intubation; each additional attempt at intubation is a risk for exposure

  • Don PPE

    • Full hood/PAPR is ideal; at a minimum should include N95 covered by a surgical mask, full face visor, hair and neck covering, gown, and double gloves

Upon entering the room:

  • Preoxygenate using CPAP with a viral filter

  • Tools and set-up for first-pass success, including:

    • Video laryngoscopy preferred over direct laryngoscopy, if available (Hippo Education intubation procedure video)

    • Bougie + standard geometry blade OR hyperangulated blade + hyperangulated stylet, whichever you’re comfortable with

    • Endotracheal (ET) tube

    • Back-up plan → Laryngeal mask airway (LMA); scalpel (for cricothyroidotomy)

    • Whatever additional things the respiratory therapist wants to add to the end of the ET tube in order to avoid circuit disconnects (eg, in-line suction, heat moisture exchanger, viral filter)

    • Rapid sequence intubation (RSI) medications:

      • Scott prefers ketamine → can allow for dissociation if the patient is not tolerating preoxygenation 

      • Full dose of paralytic (rocuronium or succinylcholine, user preference)

    • Plastic sheet drape or clear box, only if it makes you comfortable


Intubation tips/tricks:

  • Induce and paralyze while the patient is sitting up

  • Reduce the number of people in the room during intubation (2 to 3 people max)

  • Wipe off the bougie with your gloved hand when removing it from the ET tube to remove COVID secretions

  • Scott does not recommend auscultation checks for ET tube placement

    • Visualize the ET tube passing through the cords

    • If blind intubation, 21 cm for women and 23 cm for men

    • Confirm with CXR and end-tidal CO2 with waveform

  • Do not use BVM until the patient is intubated; must have viral filter proximal to BVM


Additional resources:


COVID Ventilator settings and troubleshooting

Bottom line:

  • Initial COVID ventilator settings → volume AC mode, tidal volume of 8 mL/kg of ideal body weight, respiratory rate of 16 to 18 breaths per minute, FiO2 of 100%, and PEEP of 8 cmH2O

  • Ventilator alarming? Think “DOPE” (displaced tube, obstruction, pneumothorax, equipment failure)

Ventilator Settings: The basics

  • Initial COVID ventilator settings (Hippo Education Initial Vent Settings video)

    • Mode: volume assist control (AC)

    • Tidal Volume: 8 mL/kg of estimated ideal body weight 

    • Respiratory Rate: 16 to 18 breaths per minute

    • Fi02: 100%

    • PEEP: 8 cmH2O, unless they were on a higher PEEP prior to intubation

  • Check a blood gas after 15 to 20 minutes

  • Keep the patient moving → upright, left and right lateral recumbent position

  • Saturation goals should the same as before intubation (SpO2 around 85%)

    • Goals of 90 to 95% may result in lung-injuring ventilator settings

  • Keep tidal volume at 8 mL/kg of estimated ideal body weight

  • Leave on high FiO2 unless hyperoxic (oxygen saturation >95%)

  • Increase PEEP by 2 to 4 cmH2O every 15 to 20  minutes if SpO2 is <85%


Ventilator Alarms: Ventilator troubleshooting

  • “DOPE” - Displaced tube , Obstruction, Pneumothorax, Equipment failure

    • D: Rule out by checking end-tidal CO2 waveform

    • O: Pass in-line suction all the way down; if you cannot pass, you may have an obstruction

    • P: Check for pneumothorax with ultrasound

    • E: Do a circuit run to ensure there is no disconnect

  • If ventilator is still alarming → disconnect proximal to the viral filter, bag patient with a PEEP valve until RT comes, and check end-tidal CO2


Society of Critical Care Medicine’s COVID Guidelines: Scott’s 2-cents

Bottom line: 


IV fluids: 

  • Keep them dry, but not too dry

    • Cover insensible losses

    • Monitor urine output, make sure inferior vena cava (IVC) is not flat

  • Do not give national sepsis guidelines 20-30 mL/kg fluid bolus

  • Scott prefers Lactated Ringer’s 


  • Only if iatrogenically fluid-overloaded


  • Norepinephrine sooner rather than later in a hypotensive COVID patient


  • What Scott is doing:

    • 10 mg dexamethasone daily to any admitted patient with respiratory failure 

    • 60 mg methylprednisolone every 6 hours for those with rising inflammatory markers (CRP, D-dimer)

    • 125 mg methylprednisolone every 6 hours if critically ill


  • COVID seems to be a disease of thrombosis

  • Scott’s team is giving prophylactic enoxaparin to all hospitalized patients

    • If D-dimer is rising, full treatment dose of unfractionated heparin or enoxaparin


Additional resources:

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