Review 1.2

• 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
• Study the effects of patient-ventilator asynchrony (Slide 10)
• 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
• How the ventilator knows to deliver a pressure trigger breath

  Ventilator detects a pressure drop at the proximal airway due to inspiratory effort of the patient and vent begins trigger
• Pressure Trigger


  Usually set between -0.5 to -1.5 cm
• To decrease the patient's sensitivity (make it harder for the patient to initiate a breath)

  Increase the trigger
• To increase the patient's sensitivity (make it easier for the patient to initiate a breath)

  Decrease the trigger
• Trigger Work


  Portion of the WOB performed by the patient to trigger the ventilator to the inspiratory phase
• How to correct autoPEEP

  Increase flow/ Decrease iT, Decrease RR or VT, increase peep, larger diameter ETT, provide bronchodilator, suction secretions
• Types of trigger asynchrony

  • Missed trigger
  • Double trigger
  • Reverse trigger
  • Trigger delay
  • Auto triggering
• Missed Triggering


  Inspiratory effort that does not trigger the vent. Fix By: correcting autoPEEP, adjusting trigger by decreasing trigger
• Trigger Delay


  Occurs when there is increased time interval between diaphragm and ventilators initiation of breath. Fix by: decreasing trigger parameter (easier to breathe)
• Double Triggering


  Most often in VC mode, set VT or IT is less than s neuro vent control center. Second breaths occurs immediately after term of og breath. Fix by: sedation, diff mode, increasing VT, Increasing IT to match neuro-iT
• Reverse Triggering


  Occurs during controlled ventilation, ventilator initiates breath before diaphragm
• Auto Triggering


  Ventilator initiates inspiration without corresponding patient effort due to inappropriate trigger sensitivity. Fix by: increasing vent trigger sensitivity, correct leaks, drain water