Elsevier Coronavirus Toolkit - Evidence-based content and resources for healthcare professionals

Ventilators Overview

1. General Ventilation


  • CPAP
    • Analogous to PEEP on ventilator
    • keeps from exhaling all the way out, to a certain pressure BiPAP
    • Bi-level: set TWO levels of airway pressure
    • Inhalation (pushes extra amount in) and Exhalation (keeps from collapse)
  • Indications:
    • COPD or Neurmuscular Dz pt’s who need ICU but not intubation right this minute
    • PNA in bone marrow transplant unit; 99% mortaility when intunated
    • Significant pulmonary edema


  • ET Intubation; Indications:
    • #1 – “THE LOOK”
    • “VOPS” mnemonic
      • Ventilation, Oxygenation, Protection [of airway], Secretions

2. Modes of Ventilation

Volume Control (*Preferred Type)

  • Assist Control/Volume Control (“AC/VC”)
    • Set RR and TV; pt gets breath by dropping airway pressure ~2cmH20 -> triggers machine and gives breath of set volume
    • Good default start setting because it accomplishes goal of RESTING PT
  • Intermittent Mandatory Ventilation (“SIMV”)
    • Set RR and TV; pt can take extra breath and machine does nothing (you see big IMV breaths and little pt breaths)
    • Not ideal deafult because might not achieve goal of resting pt’s respiratory muscles

Pressure Control

  • Assist Control/Pressure Control (“AC/PC”)
    • Set RR, PIP, Insp Time; every set amount of time (RR) it will push set amount of pressure in (PIP) and then holds it in (Insp Time)
    • Good for ARDS, refractory hypoxemia (hold it in to try to help gas exchange), refractory hypoxemia, pt comfort (more physiologic). Can switch to this setting
  • Pressure Support (“PS”)
    • ONLY set a pressure (PIP = Peak Insp Press); machine does nothing until pt wants a breath and drops airway pressure (2mmHg). More physiologic
    • Comfortable and no barotrauma BUT no back up rate


Check CXR

  • Ensure ET tube location
    • Want the tip just above carina
    • Right mainstem -> barotrauma

Check Blood Pressure

  • Hypertensive: inadequate sedation; Fentanyl and then Propofol drip if needed
  • Hypotensive: Intubation creates positive intrathoracic pressure -> impedes venous return
  • SOME hypotension expected post-intubation -> give 500cc fluid -> if not work consider pressors

Establish Settings

  • MODE: AC/VC, RR: 12, TV: 6cc/kg of ideal BW, PEEP: 5cm H20, Fi02: 100%
  • Try to get FiO2 <60% ASAP using pulse ox as guide; drop Fi02 q5min O2 stays OK, then check ABG once adequately titrated down

Monitor Resistance and Compliance

  • Resistance: Peak Pr – Plateau/Flow
    • Secretions, biting tube, bronchospasm, kink
    • Check kink, suction, biting block, bronchodilators
  • Compliance: Vol/Pr = TV[cc]/(P[plateau]-PEEP)
    • Right mainstem, tension PNTX, hemothorax, abdominal pathology (perforation)


Ask 5 Questions every day

  1. Is the cause resolved or gone?
  2. No pressor requirement?
  3. Require >40% FiO2 + 5 PEEP
  4. CNS function OK?
  5. No impending doom – does nurse say “are you crazy?!” when you bring up idea of extubating pt?

Check Weaning Parameters

  • Rapid Shallow Breathing Index (RSBI)
    • freq (RR)/TV (L) < 104 = weaning success
    • Best predictor of weaning success
  • Negative Inspiratory Force (NIF)
    • nml = -60cmH20; weak = 0 to -20cmH20
    • Best predictor of weaning failure

Weaning Trial

  • Keep intubated but turn down ventilator support
    • SIMV (5d to extubation)
      • Gradually decreasing RR or “backup rate”
    • Pressure Support (4d to extubation)
      • Switch from whatever they were on to Press Support
      • Gradually decrease PIP
    • *Spontaneous Breathing Trial/”T-Piece” (3d)
      • Vent off, T-piece allows oxygenation to be delivered but no other support (30min=Extbt)


ARDS Criteria:

  1. Acute (<1wk)
  2. p/F ratio <300 (PaO2/FiO2)… <200 = mod, <100 = severe
  3. CXR with diffuse opacities (“bilateral”, “3/4 quadrants”)
  4. NOT 2/2 heart failure or fluid overload = CLINICAL assessment


  1. Tx the cause of the ARDS (#1 = Sepsis; #2 = PNA; #3 = Aspiration)
  2. Increase FiO2 (Shunt pathology will not respond to FiO2)
    • PvO2 = 40mmHg, PaO2 = 100mmHg -> leaky capillaries -> O2 leaks out
      • “v” and “a” even out
    • Don’t leave at toxic FiO2 levels if it’s not helping!
  3. Diurese the pt: less fluid leaking into alveoli if less fluid in capillaries
  4. Increase PEEP: pushes edema out into interstitium -> better gas exchange
    • Go down on PEEP very slowly
  5. Optimize mixed venous PO2… AKA decrease VO2 (consumed O2)
    1. Sedate to decrease skeletal o2 consumption;
    2. Tx fevers;
    3. Consider paralytics;
    4. Increase O2 Delivery (Dobutamine to increase forward flow or transfuse)
  6. Consider PRONE positioning
    • Mortality benefit!
    • Gravity will send blood flow to less involved lung areas
  7. Consider ECMO
    • Re-oxygenate blood outside of body


Still evolving, but preliminary evidence is showing two main scenarios:

  1. COVID-19 infection leading to ARDS or superimposed bacterial infection – 30-40%
    • Use standard ventilator indications and protocols
    • Treat like ARDS
  2. COVID-19 infection with low O2 saturation but no significant respiratory distress -
    • Pt’s do not have the typical air hunger/respiratory distress/”the look”
    • CT and XR imaging shows fairly healthy lung without consolidation/atelectasis/edema
    • Theorize that the virus disrupts hypoxic pulmonary vasoconstriction mechanism -> unable to divert de-oxygenated blood away from lung tissue not providing any gas exchange -> blood flows to damaged lung tissue


Follow physiology; the “art of medicine”, not just protocols

  • 1st consider JUST high flow O2
  • 2nd consider high FiO2 on low pressure Vent setting
    • Barotrauma has become large problem with these pt’s
    • Track resistance and compliance closely
  • Pressure control may have a larger role here