Ventilators

Question 1

Minute Ventilation

Answer 1

Respiratory rate x Tidal volume

Normal range: 5-6 L/min

Question 2

I:E

Answer 2

• Inspiratory: Expiratory Ratio
• How much of each ventilation cycle is devoted to inspiration & expiration
• Normal range: 1:2 or 1:3 in COPD patients

Question 3

PIP or PAP

Answer 3

Peak Inspiratory Pressure or Peak Airway Pressure

• Measured by the ventilator in the major airways
• Strongly reflects the airway resistance

Question 4

Ventilator Functions

Answer 4

• Ventilate patient

- Oxygenate patient

Question 5

Plateau Pressure

Answer 5

Positive pressure supplied the small airways and alveoli

Question 6

What pressure should we aim to keep plateau pressure under and why?

Answer 6

Goal is to keep plateau pressure under 30cmH20, because excessive alveoli stretch is thought to be the cause of ventilator induced lung injury

Question 7

Peak Flow

Answer 7

• Determines the rate if tidal volumes delivery to the patient during mandatory volume control breaths.
• It affects the I:E and peak pressure

Question 8

What are the ventilator modes?

Answer 8

• Volume Control Ventilation (VCV)
• Pressure Control Ventilation (PCV)
• Pressure Support Ventilation (PSV)
• Synchronized Intermittent Mandatory Ventilation (SIMV)

Question 9

Volume Control Ventilation (VCV)

Answer 9

Tidal volume is preset and resultant airway pressure is a function of lung compliance and other factors

Question 10

Independent variable(s) of Volume Control Ventilation (things you can set)

Answer 10

Tidal Volume, Respiratory rate , I:E ratio, FiO2, and PEEP (optional)

Question 11

Dependent Variable(s) of Volume Control Ventilation

Answer 11

Peak inspiratory pressure, Plateau pressure

Question 12

Pressure Control Ventilation (PCV)

Answer 12

Peak airway pressure is preset and the delivered tidal volume is a product of lung compliance and other factors

Question 13

Advantage(s) of volume control ventilation

Answer 13

• Guaranteed minute ventilation

- May help lung compliance in certain surgeries (abdominal or chest surgeries)

Question 14

Disadvantage(s) of volume control ventilation

Answer 14

• Patient does not trigger breath but can see patient effort in capnogram
• May need to reduce tidal volumes if you get high PIP/PAP

Question 15

Independent variable(s) of pressure control ventilation

Answer 15

Inspiratory Pressure, Respiratory Rate, I:E Ratio, FiO2, PEEP (optional)

Question 16

Dependent Variable(s) of Pressure Control Ventilation

Answer 16

Tidal volume

Question 17

Advantage(s) of pressure control ventilation

Answer 17

• reduced ventilator induced lung injury
• improved gas distribution because it uses decelerating flow
• more rapid improvement in lung compliance and oxygenation compared to VCV

Question 18

Disadvantage(s) of pressure control ventilation

Answer 18

-Does not guarantee minute ventilation

Question 19

PIP vs Plateau Pressure in VCV

Answer 19

• PIP is determined from tidal volume set
• Plateau pressure is determined by applying an inspiratory hold (0.5 -1 sec). Hold represents no flow, which gives the pressure the alveoli are seeing

Question 20

PIP vs Plateau pressure in PCV

Answer 20

• PIP is usually the same as plateau pressure because of how breath is delivered
• There is an inherent inspiratory pause

Question 21

Pressure Support Ventilation (PSV)

Answer 21

Spontaneous ventilation mode that provides constant pressure once patient inspiratory effort is detected

Question 22

Independent variable(s) of Pressure Support Ventilation

Answer 22

-Support pressure, Inspiratory time, flow trigger, FiO2, PEEP (optional)

Question 23

Dependent Variable(s) of Pressure Support Ventilation

Answer 23

Tidal volume, respiratory rate

Question 24

Advantage(s) of Pressure support ventilation

Answer 24

• Able to have patient breathe spontaneously and not fight the ventilator
• Able to augment tidal volume
• Able to adjust ETCO2 with support pressure

Question 25

Disadvantage(s) of Pressure support ventilation

Answer 25

-requires patient to breathing spontaneously

Question 26

Synchronized Intermittent Mandatory Ventilation (SIMV)

Answer 26

- Breaths are given at preset time intervals - Patient can breathe spontaneously between the ventilator breaths - ventilator will not give a breath if the patient inspires at that same instant

Question 27

Independent Variable(s) of SIMV

Answer 27

Tidal volume, respiratory rate, I:E ratio, FiO2, Pressure support Level, PEEP (optional)

Question 28

Dependent Variable(s) of SIMV

Answer 28

Peak inspiratory pressure, plateau pressure

Question 29

Advantage(s) of SIMV

Answer 29

- Can be used as a way to start building up CO2 | - Back-up mode for PSV

Question 30

Disadvantage(s) of SIMV

Answer 30

-May confuse the patient's brain because it is not physiological

Question 31

If I:E ratio is 1:2 (normal) and RR is 10 breaths/min, how long are the inspiratory and expiratory times?

Answer 31

60 seconds/RR = 6seconds/breath Inspiratory time = I/I+E (6) or 1/3(6) I = 2 seconds E = 6 - I = 4 seconds

Question 32

Inspiratory Pause (Tip)

Answer 32

- holds breath at end of inspiration (before exhalation starts) - Allows breathe to diffuse better - Only available with VCV - Usually 25% of inspiratory time - Takes time from inspiration & adds it as a hold (expiration remains the same)

Question 33

if the I:E ratio is 1:2 and the RR is 10 breaths/min and the inspiratory pause is set at 25%, how much time is spent in inspiration, inspiratory pause, and expiration?

Answer 33

``` I = 1.5 sec Tip = 0.5 sec E = 4 secs ```

Question 34

PEEP

Answer 34

- constant positive pressure applied at the end of exhalation - causes airway pressure to not return to 0cmH20

Question 35

Auto PEEP

Answer 35

- air trapping in the lungs because of insufficient exhalation time - not a setting

Question 36

What are the signs of Auto PEEP?

Answer 36

- Non-zero end expiration pressure | - Increasing PIP/PAP

Question 37

Ventilator settings for tidal volume

Answer 37

500 -700 ml (adults) | 6-10 ml/kg (infants, children, and COPD patients)

Question 38

Ventilator settings for Respiratory Rate

Answer 38

10 breaths/min (initial setting)

Question 39

Ventilator settings for Minute Ventilation (Ve)

Answer 39

- VT x RR - 4 x BSA (Men) - 3.5 x BSA (Women)