Ventilator Basics

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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

BONUS

• 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

• Breathing (EM Clerkship)
• Dominating the Vent Part 1 (EMCrit)
• Dominating the Vent Part 2 (EMCrit)