COVID-19: Fundamentals of Critical Care

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 https://emcrit.org/emcrit/covid-airway-management/

 

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: https://emcrit.org/emcrit/covid-airway-management/

 

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: 

• Here is a summary of the Society of Critical Care Medicine COVID Guidelines

• According to Scott, the guidelines do not mesh with the clinical experience of the front-line providers

 

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 

Furosemide:

• Only if iatrogenically fluid-overloaded

Vasopressors:

• Norepinephrine sooner rather than later in a hypotensive COVID patient

Corticosteroids:

• 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

Anticoagulation:

• 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:

• Initial COVID Ventilator Settings quick reference card 

• Hippo Education Mechanical Ventilator Basics video review

• Hippo Education Ventilator Alarms video review

• https://emcrit.org/wp-content/uploads/2010/05/Managing-Initial-Vent-ED.pdf

• https://emcrit.org/ibcc/COVID19/#invasive_mechanical_ventilation

• https://rebelem.com/benefit-lung-protective-ventilation-ed-lov-ed/