Ventilator Dyssynchrony

Question 1

At what part of the patient airway or connections does the ventilator measure pressure/flow?

Answer 1

The most proximal portion at the level of the machine, not the tubing

Question 2

At what part of the ventilator breath can dyssynchrony occur?

Answer 2

At any phase

Question 3

What is the neural I-time?

Answer 3

The time patient wants to breathe

Question 4

What setting is changed to increase expiratory time?

Answer 4

I-time

Question 5

Describe the mode of ventilation, the abnormality and what type of dyssynchrony it is?

Answer 5

Volume
Flow dyssynchrony / flow starvation
Patient needs more flow, but in volume control, flow is set
Fix: Increase TV, decrease I-time, switch to pressure control

Question 6

What is the mode of ventilation, the abnormality and the type of dyssynchrony in the following scalar? What might be the cause? How do you fix it?

Answer 6

Pressure
Double triggering / Premature cycling (ie trigger dyssynchrony or cycle dyssynchrony)
The patient is still breathing despite the machine terminating the breath, so it immediately re-triggers
Fix: Increase I time, increase peak pressure

Question 7

What would change in the scalars with flow starvation in pressure-control?

Answer 7

You shouldn’t see it. The ventilator in pressure control will give as much flow as needed to reach the set pressure.

Question 8

What mode of ventilation, what type of dyssynchrony, and how do you fix it?

Answer 8

Volume
Flow dyssynchrony due to early spike caused by too much flow
Fix: Increase I-time, decrease TV, change to square wave flow
*Do something to decrease the inhaled extreme pressure

Question 9

What mode of ventilation, what type of dyssynchrony, and how do you fix it?

Answer 9

Pressure control
Delayed cycle dyssynchrony
The increased pressure at the end of the machine-determined breath has to come from the patient
Fix: shorten I-time to synchronize with patient
This will decrease the TV so pay attention- may need to increase PIP or RR

Question 10

What mode of ventilation, what type of dyssynchrony and how do you fix it?

Answer 10

Pressure control
Air-trapping, autopeep
Expiratory dyssynchrony
It’s harder to cause a trigger because increased pressure has to be overcome by the patient
Fix: Shorten I-time, increase PEEP? (not ideal)

Question 11

Name three types of trigger dyssynchrony

Answer 11

1. ineffective
2. double
3. auto

Question 12

Name two types of flow dyssynchrony

Answer 12

1. inadequate
2. excessive

Question 13

Name two types of cycle dyssynchrony

Answer 13

1. Premature (inspiration ends while patient still inhaling, can lead to double triggering)
2. Delayed (starts exhaling before vent switching to exhalation)

Question 14

Name a type of expiratory dyssynchrony

Answer 14

Air-trapping or auto-peep / missed trigger

Question 15

What might cause autotrigger?

Answer 15

Cardiac oscillations, especially in very small dogs
Airway secretions
Fluid in tubes