MECH VENT 2

• Flow asynchrony


  Inspiratory gas flow from the vent is unable to match the patients inspiratory flow demand
• be able to identify flow asynchrony from waveforms

  • 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
• Patient-Ventilator Synchrony


  Adequate ventilation and oxygenation, decrease WOB and patient comfort
• Patient-Ventilator Dysynchrony


  Ineffective oxygenation and ventilation, increase WOB and patient discomfort
• Increase in ventilators workload


  Can lead to ventilatory muscle fatigue and structural injury of the lung
• It takes 24 hours to recover from ventilatory muscle fatigue
• Dangers of Controlled Ventilation

  Ventilatory muscle weakness, deconditioning, atrophy
• Things that can worsen patient-ventilator asynchrony

  • Pain
  • Anxiety
  • Procedural interactions
  • Other clinician-patient interactions
• Types of patient-ventilator asynchrony

  • Trigger asynchrony
  • Flow asynchrony
  • Cycle asynchrony
  • Mode asynchrony
• Trigger Asynchrony


  Vent is not triggering breath to patient even though pt demands it
• Flow Asynchrony


  Poor coordination between the pts flow demand and the flow provided by the vent. Common in VC.
• Cycle Asynchrony


  Poor coordination between ventilator and pt respiratory drive
• Mode Asynchrony


  Asynchrony develops when the mode selected does not match the pts spontaneous vent efforts
• Trigger


  Parameter on the ventilator that initiates a breath
• Types of trigger


  • Time trigger
  • Flow trigger
  • Pressure trigger
• Patient-triggered


  Pressure trigger or flow trigger
• Controlled Breaths


  Time trigger
• There would be no dips or jumps on none of the waveforms to identify a time trigger breath
• When will a patient receive a time trigger breath

  Once the preset time interval is met. 60sec/RR=preset time interval
• A jump at the end of exhalation will be shown on the flow-time scalar to identify a flow trigger breath
• How the ventilator knows to deliver a flow trigger breath

  When a change in bias flow is detected
• Flow trigger


  Usually set between 1 to 2 L/min
• There is a dip at the beginning of the pressure-time scalar waveform to identify a pressure trigger breath