Vent Equations

Question 1

Flow=

Answer 1

Tidal Volume (L) / i time seconds
multiply by 60 to get flow in L minute

Question 2

Airway Resistance

Answer 2

RAW = peak - plat / flow L/s (answer is given in L/s/cmH20

Question 3

Ideal body weight- Males

Answer 3

106 + (6 x height-60)

Question 4

Ideal body weight- Females

Answer 4

105 + (5 x height -60)

Question 5

Desired FiO2 formula

Answer 5

PaO2 (desired) x FiO2 (actual) / PaO2 (actual)

Question 6

To determine frequency

Answer 6

Expired Minute volume / Tidal Volume = breaths / minute

Question 7

To calculate cycle time

Answer 7

Ct =60 / frequency

Question 8

I time % =

Answer 8

itime / cycle time

Question 9

To correct respiratory alkalosis in volume control mode (PaCO2 7.35

Answer 9

1st, decrease flow and then if necessary decrease tidal volume
PER JESSICA FIRST MAKE RATE CHANGES
(here - decrease in rate)

Question 10

To correct respiratory alkalosis in pressure control mode

Answer 10

1 decrease flow then if necessary
decrease pressure
PER JESSICA FIRST MAKE RATE CHANGES
(here – decrease)

Question 11

What are the two methods of correcting respiratory acidosis (PaCO2 >45; pH < 7.35

Answer 11

increasing minute ventilation will decrease PaCO2
PER JESSICA FIRST MAKE RATE CHANGES
(here - increase the rate)

Question 12

To correct PaCO2 (calculation for desired frequency)

Answer 12

desired frequency = known freq x known PaCO2 / desired PaCO2

Question 13

To correct PaCO2, (calculation for desired Vt)

Answer 13

Desired Vt= Actual Vt x Actual PaCO2 / Desired PaCO2

Question 14

What is minute ventilation?

Answer 14

the product of tidal volume and resp rate-

in other words the amount of air breathed in in one minute

Question 15

Normal minute ventilation is what?

Answer 15

5 to 6 L/min

Question 16

An elevated minute ventilation indicates what?

Answer 16

elevated work of breathing

Question 17

Alarm settings: High pressure limit

Answer 17

10 to 15 cmH20 above peak pressure

Question 18

Alarm settings: Low pressure limit

Answer 18

5 to 10 below peak pressure

Question 19

Alarm settings: High minute volume

Answer 19

3-5 L/m above consistent observable minute volume

Question 20

Alarm settings: Low minute volume

Answer 20

2 L/m below consistent observable minute volume

Question 21

Alarm settings: Low tidal volume

Answer 21

100 to 200 ml below consistently maintained tidal volume

Question 22

Alarm settings: High respiratory rate

Answer 22

5 to 10 higher than consistently observable

Question 23

Apnea alarm

Answer 23

maximum of 20 seconds

Question 24

For Class/Lab vent tidal volume

Answer 24

8-10 ml/Kg IBW