Ventilation Modes

Question 1

What are the different types of cycling on a ventilator?

Answer 1

• TIme
• Flow
• Pressure
• Volume

Question 2

What are the characteristics of inspiration & expiration on a ventilator?

Answer 2

INSP: Active by positive pressure
EXP: Passive

Question 3

How does volume control work?

Answer 3

For a fixed TV a constant flow is generated as increasing pressure throughout inspiration

Question 4

What is an application of Ohm’s law in ventilation?

Answer 4

For given airway resistance, ig a higher flow is applied, a higher pressure will result as the lungs require time to expan

Question 5

What is a complication of Ohm’s law in ventilation?

Answer 5

Barotrauma

Question 6

Can volume & pressure control compensate for leaks?

Answer 6

V: No
P: Yes

Question 7

What can be optimised using volume control?

Answer 7

PaCO2 - important in brain injury patients

Question 8

What is pressure control dependent on?

Answer 8

Compliance & resistance of the airways

Question 9

How does pressure control work?

Answer 9

Constant inspiratory pressure with a decelerating flow generates a TV dependent on compliance & resistance.

Question 10

What does pressure control ventilation improve?

Answer 10

• Gas exchange - improved oxygenation
• Homogeneity of ventilation particularly in those with ventilatory distribution problems

Question 11

Is the mean airway pressure higher in volume or pressure control?

Answer 11

Pressure control - poor handling of compliance/resistance changes

Question 12

What ventilation mode is helpful in paeds?

Answer 12

Pressure control

Question 13

How do the airways change in a semi-recumbent position?

Answer 13

• FRC increased
• Atelectasis reduced