Ventilator Basics

Step 1: Start Patient on Volume Assist-Control Ventilation
  • The most basic mode of ventilation
    • Provides a FIXED VOLUME at a FIXED RATE
  • If the patient over-breaths…
    • The ventilator will give another FULL breath
      • Can cause breath stacking and be uncomfortable in patients who are poorly sedated
      • This is not a problem in the ED because patients are typically deeply sedated
Step 2: Know your oxygenation and ventilation goals
  • Oxygenation (getting oxygen in)
    • Try to keep O2 saturation >92%
  • Ventilation (getting CO2 out)
    • Try to keep pCO2 <40
Step 3: Know the 4 Most Important Settings on a Ventilator
  • FiO2
    • The concentration of oxygen
      • Room air is 21% oxygen (or 0.21 on the vent)
      • Maximum is 100% oxygen (or 1.0 on the vent)
  • PEEP
    • The pressure applied during exhalation
      • Typical starting point is 5 (but can be increased significantly)
    • “Recruits” and opens alveoli
  • Tidal Volume
    • The volume of air moved during each cycle of the vent
  • Respiratory Rate
    • How fast the ventilator cycles/breaths for the patient
Step 4: Improving the patient’s OXYGENATION
  • FiO2
    • Increases the amount of oxygen present for exchange in non-damaged alveoli
  • PEEP
    • Increases the number of alveoli available to exchange oxygen
Step 5: Improving the patient’s VENTILATION
  • FORMULA: Minute Ventilation (MV) = Tidal Volume (Vt) x Respiratory Rate (RR)
  • Increasing either of these will improve ventilation
  • Patients with COPD/asthma
    • Have tendency to not get full breath out (“breath stacking”)
      • “Plateau pressures” will increase above 30
        • Can damage alveoli
        • Can cause pneumothorax
    • Treat by increasing the I:E ratio
      • Quick inhalation
      • Longggggggggggggg exhalation
Additional Reading

1 Comment

  1. Zev

    Hey Zack, this is probably really picking nits, but for breath-stacking obstructive lung disease patients, ain’t we DEcreasing the I:E ratio by increasing the expiratory duration (E) while holding constant (or decreasing) the inspiratory duration (I)?

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