Vent Settings & Lessons


Steve, Dan, and Holly introduce their guest speaker, Carrie, a respiratory therapist/paramedic from Washington. Carrie discusses the endotracheal tube, and the importance of having a correctly sized and placed tube. Carrie highlights how critical it is to understand the disease processes that resulted in the patient being intubated. Ventilation and oxygenation issues are reviewed, along with the importance of PEEP in intubated patients. 

Carrie talks about PEEP in intubated patients with asthma or COPD, as well as variations in tidal volume settings for various disease processes. The group discusses minute volume, and how a patient’s minute volume is calculated on the ventilator. Carrie discusses her process of titrating ventilator settings to meet a CO2 goal. Do no harm is reviewed in relation to mechanical ventilation, and consequences of a patient working against the ventilator is discussed. 

Assist control (AC) and synchronous intermittent mandatory ventilation (SIMV) modes are compared. Carrie details what modes she prefers for specific patient presentations and disease processes. The group discusses volume and pressure control, and review a trauma scenario where the patient is intubated. Peak inspiratory pressure and peak alveolar pressure are reviewed, along with what abnormal values can indicate. The importance of driving pressure is highlighted. The PF ratio is discussed, along with the importance of weaning patients off of 100% FiO2. 

The group ends on discussing appropriate IE ratios in obstructive patients. Flow rate in both volume and pressure control are reviewed, as well as effect of flow rate on a patient in both volume and pressure control settings. Another scenario is discussed, a COPD patient that has been intubated. Carrie walks through troubleshooting tactics for ventilators, and potential fixes for common issues with mechanical ventilators. 

Learning Points

  • Always check size and depth of the ET tube, because this will effect ventilator effectiveness. 
  • ET tube depth formula: (pt’s height in inches /4) + 4 for a pt greater than 5 feet tall
  • An ET tube placed too deep can effect ventilation and oxygenation, particularly in smaller patients
  • Patients intubated for non-respiratory disease processes should be relatively easy to ventilate and typically require less advanced ventilator settings 
  • Ventilation issues are fixed with changes in tidal volume or respiratory rate
  • Oxygenation issues are fixed with FiO2 and PEEP
  • Minimum PEEP setting is 5 to allow the lungs to remain open and increase oxygenation
  • Obese patients may need a PEEP of 10
  • 6-8 ml/kg ideal body weight is typical tidal volume setting
  • ARDS patients may require smaller tidal volumes (approx. 4-5ml/kg)
  • Minute volume=tidal volume x respiratory rate
  • A higher exhale tidal volume may mean that the pt is working against the ventilator 
  • Metabolic acidosis patients require high rates of ventilation
  • Obstructive patients require low rates of ventilation, and adequate time for expiration
  • There is no difference between AC and SIMV modes in chemically sedated patients 
  • Peak inspiratory pressure (PIP) is directly proportional to resistance in the upper airway
  • Peak alveolar pressure (Pplat) is directly proportional to compliance in the lower airway
  • Driving pressure in pressure control setting: difference between PEEP and PIP
  • Driving pressure in volume control setting: difference between Pplat and PEEP
  • Driving pressure should be less than 14
  • PF ratio for ARDS: 300 equals mild injury to lung, 200 equals moderate injury to lung, 100 equals severe lung injury 
  • 1:4 or 1:5 for IE ratio for obstructive patients 
  • Obstructive patients will have a higher CO2 level than the normal 35-45
  • DOPES: displacement, obstruction, pneumothorax, equipment, stacked breath

    Content Creator: Steve Williams
    CAPCE Course Number: 20-EMTP-F3-3205
    Total CE Hours: 1.5
    Level: Advanced