Basic Ventilator Modes

Question 1

What are the two main ventilator mode categories?

Answer 1

Volume Control and Pressure Control.

Question 2

In volume control, what is constant and what is variable?

Answer 2

Volume is constant, Pressure is variable.

Question 3

In pressure control, what is constant and what is variable?

Answer 3

Pressure is constant, Volume is variable.

Question 4

What triggers both volume and pressure control modes?

Answer 4

Time or patient effort.

Question 5

What is the use case for volume control?

Answer 5

Ensures target volume is delivered.

Question 6

What is the use case for pressure control?

Answer 6

Limits peak airway pressure.

Question 7

What is Tidal Volume (Vt)?

Answer 7

The volume of air delivered with each breath.

Question 8

What is the Frequency or Respiratory Rate (f or RR)?

Answer 8

The number of breaths per minute.

Question 9

How do you calculate interval between breaths?

Answer 9

60 / RR.

Question 10

What does FiO2 stand for?

Answer 10

Fraction of Inspired Oxygen.

Question 11

What is the typical lower limit for FiO2?

Answer 11

0.35 (35%).

Question 12

What is PEEP and its function?

Answer 12

Positive End Expiratory Pressure; prevents alveolar collapse during expiration.

Question 13

What is the minimum PEEP setting?

Answer 13

5 cmH2O (physiologic PEEP).

Question 14

Why is physiologic PEEP important on a ventilator?

Answer 14

Prevents intrathoracic pressure from dropping to zero.

Question 15

What is the typical PEEP range?

Answer 15

5–20 cmH2O.

Question 16

What is Pressure Support (PS)?

Answer 16

Additional inspiratory pressure for spontaneous breaths.

Question 17

What is the typical range for Pressure Support?

Answer 17

5–20 cmH2O.

Question 18

What is a common minimum for PS?

Answer 18

8–10 cmH2O.

Question 19

How is Minute Ventilation (Ve) calculated?

Answer 19

Ve = Tidal Volume × Respiratory Rate.

Question 20

What is the target Minute Ventilation?

Answer 20

5–10 L/min.

Question 21

How does increasing Ve affect CO2?

Answer 21

↑ VE = ↓ CO₂.

Question 22

How does decreasing Ve effect CO2?

Answer 22

↓ VE = ↑ CO₂

Question 23

What is Pip (Peak Inspiratory Pressure)?

Answer 23

Max pressure reached during inspiration.

Question 24

What is the target for Pip?

Answer 24

<35 cmH2O.

Question 25

What is the risk of high PiP?

Answer 25

Barotrauma

Question 26

What is Pplat (Plateau Pressure)?

Answer 26

A reflection of lung compliance.

Question 27

How is Pplat measured.

Answer 27

Measured at the end of inspiration using respiratory pause.

Question 28

What is the target for Pplat?

Answer 28

<30 cmH2O.

Question 29

What does high Pplat indicate?

Answer 29

Decreased lung compliance.

Question 30

What is Assist Control (AC) mode?

Answer 30

Also called Volume Control (VC). Delivers set Vt either on schedule or in response to patient effort.

Question 31

What is set in Assist Control mode?

Answer 31

Vt, RR, Fio2, PEEP

Question 32

What does AC mode not use?

Answer 32

Pressure Support.

Question 33

What can AC mode cause in tachypneic patients?

Answer 33

Hyperventilation and respiratory alkalosis in patient who are tachypneic for non respiratory reasons. (CNS dysfunction, anxiety, pain)

Question 34

How does CMV differ from AC?

Answer 34

CMV delivers preset mandatory breaths at fixed intervals, regardless of patient effort. AC delivers breaths at preset intervals but recognizes spontaneous effort, spontaneous breaths receive full set Vt.

Question 35

What is SIMV mode?

Answer 35

Synchronized Intermittent Mandatory Ventilation.

Question 36

What is set in SIMV mode?

Answer 36

Vt, RR, FiO2, PEEP, Pressure Support

Question 37

What does SIMV allow?

Answer 37

Spontaneous breaths with Pressure Support.

Question 38

How are spontaneous breaths assisted by the ventilator in SIMV?

Answer 38

Does not force full set Vt. Patient will inhale natural Vt. Assisted with pressure support, can increase PS to increase size of breath.

Question 39

What is SIMV used for?

Answer 39

Weaning from the ventilator.

Question 40

What are risks associated with SIMV due to WOB being partially controlled by patient?

Answer 40

Low minute ventilation → respiratory acidosis; Tachypnea → respiratory alkalosis.

Question 41

In sedated patients, how do SIMV and AC behave?

Answer 41

They behave the same as no spontaneous breaths are taken.

Question 42

What is PSV?

Answer 42

Pressure Support Ventilation.

Question 43

Is PSV a volume control mode?

Answer 43

No.

Question 44

What does PSV set?

Answer 44

FiO2, PEEP, and Pressure Support. No set RR or Vt.

Question 45

What is a safety feature of PSV?

Answer 45

Back up rate - default set RR if patient becomes apneic.

Question 46

When is PSV used?

Answer 46

In spontaneously breathing patients and during Spontaneous Breathing Trials.

Question 47

What are common PSV settings?

Answer 47

10/5 or 5/5 (PS/PEEP).

Question 48

Which mode ignores spontaneous breaths?

Answer 48

CMV.

Question 49

Which mode detects spontaneous breaths but delivers full VT?

Answer 49

Assist Control.

Question 50

Which mode supports spontaneous breaths with PS?

Answer 50

SIMV.

Question 51

Which mode is fully spontaneous?

Answer 51

PSV.