Calculations

Question 1

Airway Resistance (Raw)

Answer 1

Raw= PIP-Pplat/Flow

If flow is in L/min divide by 60 to get L/sec

Question 2

Alveolar air equation

Answer 2

Pb-PH2O x FiO2-PaCO2 x1.25

PH2O =47

Question 3

Dyanmic Compliance

Answer 3

Dyn=VT/ PIP-PEEP (big # goes on the inside)

Question 4

Static Compliance

Answer 4

VT/ Pplat- PEEP( big # goes on the inside)

Question 5

P/F ratio

Answer 5

PaO2/ FiO2

normal P/F ratio is 400 to 500 mm Hg on room air. ARDS is defined as a P/F ratio <200 mm Hg. ALI is <300 mm Hg

Mild ARDS: 200-300
Moderate ARDS: 100-200
Severe ARDS: <100

Question 6

RSBI

Answer 6

RR/VT

Question 7

VE

Answer 7

VT x RR

Question 8

VA

Answer 8

VT-VD x RR

Question 9

Desired rate

Answer 9

Rate (current) x PaCO2 (current)/ PaCO2 (desired)

Question 10

Optimal PEEP

Answer 10

PPlat -PEEP —-> VT/ sum of pplat and PEEP

IF ALL OF THE VT ARE THE SAME, then you can just subtract the pplat from peep, whichever pressure is the lowest equals the highest compliance

Optimal PEEP must be within 35-45

Question 11

Inspiratory time

Answer 11

1 time = TCT/ sum of I:E ratio

Ex: sum of I:E (1:3-—>1+3=4)

Question 12

I:E ratio

Answer 12

Inspiratory flow rate/VE - 1

Question 13

Duration of flow

Answer 13

DOF= cylinder pressure x cylinder factor/ liter flow

Then divide by 60 for hours

H cylinder: 3.14
E cylinder: 0.28
Full tanks are 2200 psig

Question 14

Desired FiO2

Answer 14

PaO2 (desired) x FiO2 (current)/PaO2 (current)

Question 15

IBW

Answer 15

Females 105+5(H-60)/ 2.2
Males 106+6 (H-60)/2.2

Question 16

CaO2

Answer 16

(1.34 x Hb x SaO2)+ (PaO2 x 0.003)

Question 17

CvO2

Answer 17

(1.34 x Hb x SvO2)+ (PvO2 x 0.003)

Question 18

PVR

Answer 18

MPAP-PCWP/ QT

Question 19

Stroke volume

Answer 19

QT/HR

Question 20

Heliox mixture 80:20 and 70:30

Answer 20

1.8 (80:20)
1.6 (70:30)

Question 21

Cardiac output (QT)

Answer 21

QT = HR x SV

Question 22

Catheter sizes for suctioning

Answer 22

ET x 3/2

next even size up