Question 11

What is meant by the expression “patient – ventilator  dys-synchrony”?         

What are  the principles of managing this problem?

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College Answer

Patient-ventilator dys-synchrony refers to the situation in which the patient fails to achieve comfortable respiration in synchrony with the ventilator in terms of timing of inspiration, adequate inspiratory flow for demand, timing of the switch to expiration and duration of inspiration.

Managing this problem may be addressed by –

•    treating patient respiratory problems eg sputum, irritable airways

•    checking ETT for kinking, secretion block, impinging on carina or between cords

•    choosing the appropriate ventilator

•    choosing the appropriate mode

•    selecting sensitivity not too low or high

•    choosing the appropriate ventilator rate

•    setting appropriate flow rate

•    sedating the patient to reduce agitation

•    taking over ventilation if fatigue is apparent


Patient-ventilator dyssynchrony is discussed elsewhere. In essence, it is increased work of breathing and decreased patient comfort because of a mismatch between the ventilator gas delivery pattern and the patient's demands.

One can manage patient-ventilator dyssynchrony by

  • Making the mode patient-triggered
  • Improving trigger sensitivity to include patient efforts and exclude cardiac auto-triggering
  • Increasing flow rate if it is inadequate
  • Managing auto-PEEP
  • Increasing flow cycle-off to a higher value, terminating a breath early if the patient wants shorter breaths
  • Decreasing the flow cycle-off to a lower value if the patient requires longer breaths
  • Clearing the airway of sputum and secretions, and ensuring its patency
  • Increasing the sedation
  • Use of neuromuscular blockade