Review 1.3

• Flow asynchrony


  Inspiratory gas flow from the vent is unable to match the patients inspiratory flow demand
• Flow asynchrony


  • Scoop waveform
• VC/AC mode


  Ventilator mode where flow asynchrony is commonly seen
• Increase the inspiratory flow


  Decrease in I time and increase in E time
• Decrease the inspiratory flow


  Increase in I time and decrease in E time
• For adults, peak flow values are generally kept between 60-80 L/min
• For adults, the typical I-time is 0.8 to 1 second
• Square waveform


  Lower peak flow and decreased inspiratory time, compared to decelerating
• Decelerating waveform


  Mimics more natural breathing pattern, produces high initial peak flow but increased iT, pts are usually placed on this waveform on VC AC mode
• Rise time


  Allows adjustment of the rate
• Rapid rise time


  • Peak is created showing flow being delivered too fast and too high
• Appropriate rise time


  • Just right
• Slow rise time


  • Curve is too low
• Modes that utilize rise time


  • PC & VC+AC
  • PC & VC+ SIMV
  • PSV
  • VS
• Cycle asynchrony


  Occurs when the ventilator does not match the patient breathing pattern
• Long cycling


  iT is too long, excessive and pt may attempt to actively exhale while the ventilator is still in the inspiratory phase resulting in a spike in airway pressure
• Short (double) cycling


  iT is too short due to premature ventilator cycling
• The parameter that allows the patient to exhale while they are on PSV mode is 25%
• Mode asynchrony


  Occurs when the mode of ventilation selected is unable to match pts spontaneous vent pattern