COVID-19: Fundamentals of Critical Care
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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:
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Respiratory support for COVID “happy hypoxemics”: nasal cannula → non-rebreather → high-flow nasal cannula → CPAP
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COVID “happy hypoxemics” may require intubation if they have:
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Any increased work of breathing (tachypnea is common but they should be a “happy tachypneic”)
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Any sort of altered mental status
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Rising CO2 on serial VBGs
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Oxygen saturation consistently below 80-85%
COVID airway management is different from others because:
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These patients rapidly desaturate
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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”:
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These COVID patients are hypoxemic (low oxygen level in the arterial blood) but not hypoxic (low oxygen level in the tissues)
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Monitor these patients closely as they can quickly decompensate
Step-by step approach to respiratory support for the “happy hypoxemic”:
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You’ll know if your patient is failing these respiratory support measures and may require intubation if they have:
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Any increased work of breathing (tachypnea is common but they should be a “happy tachypneic”)
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Any sort of altered mental status
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Rising CO2 on serial VBGs
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Oxygen saturation consistently below 80-85%
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Obtunded or crashing on arrival? Just intubate!
Step 1. Start with nasal cannula
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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
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Put on a non-rebreather at 15 L/min (over top of nasal cannula) and reapply surgical mask
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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%
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Be sure to have these patients change position (the “rotisserie” method) every 1-2 hours
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Start with upright in bed (head of bed at 80-90 degrees)
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Lie on left side for 1-2 hours
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Lie on right side for 1-2 hours
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If able to tolerate, lie prone for 1-2 hours
Step 3. Move to high-flow nasal cannula
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What is high-flow nasal cannula (HFNC)?
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Nasal cannula hooked up to a humidifier and heater
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Scott starts with up to 100% FiO2 at 20 L/min → titrate up the flow by 10 L/min every 10 minutes, as needed
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Can go up to 60 to 80 L/min; max flow rate depends on the device
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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
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CPAP provides more PEEP then high-flow nasal cannula, up to 15 cmH2O
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While we generally do not use BiPAP in COVID, it is still a good choice for those with secondary disease (COPD, asthma)
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If you do not have a CPAP machine available, see Scott’s CPAP mask + bag-valve-mask (BVM) +/- nasal cannula set-up at https://emcrit.org/emcrit/covid-airway-management/
COVID Intubation
Bottom line:
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The key is to ensure first-pass success and reduce exposure
Before entering the room:
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Highest-level physician should do the intubation; each additional attempt at intubation is a risk for exposure
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Don PPE
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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:
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Preoxygenate using CPAP with a viral filter
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Tools and set-up for first-pass success, including:
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Video laryngoscopy preferred over direct laryngoscopy, if available (Hippo Education intubation procedure video)
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Bougie + standard geometry blade OR hyperangulated blade + hyperangulated stylet, whichever you’re comfortable with
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Endotracheal (ET) tube
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Back-up plan → Laryngeal mask airway (LMA); scalpel (for cricothyroidotomy)
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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)
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Rapid sequence intubation (RSI) medications:
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Scott prefers ketamine → can allow for dissociation if the patient is not tolerating preoxygenation
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Full dose of paralytic (rocuronium or succinylcholine, user preference)
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Plastic sheet drape or clear box, only if it makes you comfortable
Intubation tips/tricks:
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Induce and paralyze while the patient is sitting up
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Reduce the number of people in the room during intubation (2 to 3 people max)
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Wipe off the bougie with your gloved hand when removing it from the ET tube to remove COVID secretions
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Scott does not recommend auscultation checks for ET tube placement
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Visualize the ET tube passing through the cords
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If blind intubation, 21 cm for women and 23 cm for men
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Confirm with CXR and end-tidal CO2 with waveform
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Do not use BVM until the patient is intubated; must have viral filter proximal to BVM
Additional resources: https://emcrit.org/emcrit/covid-airway-management/
COVID Ventilator settings and troubleshooting
Bottom line:
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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
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Ventilator alarming? Think “DOPE” (displaced tube, obstruction, pneumothorax, equipment failure)
Ventilator Settings: The basics
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Initial COVID ventilator settings (Hippo Education Initial Vent Settings video)
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Mode: volume assist control (AC)
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Tidal Volume: 8 mL/kg of estimated ideal body weight
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Respiratory Rate: 16 to 18 breaths per minute
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Fi02: 100%
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PEEP: 8 cmH2O, unless they were on a higher PEEP prior to intubation
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Check a blood gas after 15 to 20 minutes
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Keep the patient moving → upright, left and right lateral recumbent position
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Saturation goals should the same as before intubation (SpO2 around 85%)
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Goals of 90 to 95% may result in lung-injuring ventilator settings
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Keep tidal volume at 8 mL/kg of estimated ideal body weight
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Leave on high FiO2 unless hyperoxic (oxygen saturation >95%)
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Increase PEEP by 2 to 4 cmH2O every 15 to 20 minutes if SpO2 is <85%
Ventilator Alarms: Ventilator troubleshooting
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“DOPE” - Displaced tube , Obstruction, Pneumothorax, Equipment failure
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D: Rule out by checking end-tidal CO2 waveform
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O: Pass in-line suction all the way down; if you cannot pass, you may have an obstruction
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P: Check for pneumothorax with ultrasound
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E: Do a circuit run to ensure there is no disconnect
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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:
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Here is a summary of the Society of Critical Care Medicine COVID Guidelines
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According to Scott, the guidelines do not mesh with the clinical experience of the front-line providers
IV fluids:
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Keep them dry, but not too dry
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Cover insensible losses
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Monitor urine output, make sure inferior vena cava (IVC) is not flat
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Do not give national sepsis guidelines 20-30 mL/kg fluid bolus
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Scott prefers Lactated Ringer’s
Furosemide:
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Only if iatrogenically fluid-overloaded
Vasopressors:
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Norepinephrine sooner rather than later in a hypotensive COVID patient
Corticosteroids:
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What Scott is doing:
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10 mg dexamethasone daily to any admitted patient with respiratory failure
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60 mg methylprednisolone every 6 hours for those with rising inflammatory markers (CRP, D-dimer)
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125 mg methylprednisolone every 6 hours if critically ill
Anticoagulation:
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COVID seems to be a disease of thrombosis
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Scott’s team is giving prophylactic enoxaparin to all hospitalized patients
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If D-dimer is rising, full treatment dose of unfractionated heparin or enoxaparin
Additional resources: