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

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)