Calculation Formulas

Question 1

Tobacco use

Answer 1

Pack years= # of pack/day x # of years smoke

Question 2

Cerebral Perfusion Pressure (CPP)

Answer 2

CPP= MAP-ICP

Question 3

Estimating heart rate from ECG tracing

Answer 3

Heart rate = 300/ # of large boxes between R wave
or = 1500/ #small boxes between R waves
or = 10 X number of R waves

Question 4

Pulse pressure

Answer 4

Systolic pressure-diastolic pressure

Question 5

MAP

Answer 5

(2 X diastolic) + systolic
_________________________
3

Question 6

Cardiac output
(Fick equation)

Answer 6

QT=
VO2
_______________
C(a-v)O2 (10)

Question 7

Cardiac output
(Stroke Volume Equation)

Answer 7

QT= heart rate X stroke volume

Question 8

Stroke Volume

Answer 8

QT
_______________
Heart rate

Question 9

Cardiac index

Answer 9

CI= QT
_________
BSA
= Cardiac output
__________________
Body surface area

Question 10

Systemic Vascular Resistance (SVR)

Answer 10

(MAP-CVP)
_______________
Cardiac output

*To convert to Dynes multiply mmHg/L/min by 80

Question 11

Pulmonary Vascular Resistance (PVR)

Answer 11

(MAP-PWP)
_______________
Cardiac output

*To convert to Dynes multiply mmHg/L/min by 80

Question 12

PAO2

Answer 12

(PB-PH2O) X FI02 -PaCO2
________
0.8

or PaCO2 x 1.25

Question 13

A-aDO2

Answer 13

PAO2-PaO2

Question 14

PaO2/FIO2 ratio or P/F ratio

Answer 14

PaO2/FIO2

Question 15

CaO2

Answer 15

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

Question 16

CvO2

Answer 16

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

Question 17

C(a-v)O2

Answer 17

CaO2-CvO2

Question 18

QT

Answer 18

VO2
_____________________
C(A-V)O2 (10)

Question 19

VO2

Answer 19

QT x C(a-v)O2 x 10

Question 20

QS/QT

Answer 20

(A-aD02) 0.003
_________________________
(A-aD02) 0.003 + C(a-v)O2

Question 21

SaO2

Answer 21

PaO2 + 30 (when PaO2 is between 40 and 60 torr)

Question 22

Oxygen index

Answer 22

Paw x FIO2
___________ X 100
PaO2

Question 23

VD/VT

Answer 23

PaCO2-PECO2
________________ x 100
PaCO2

Question 24

Desired minute volume

Answer 24

(VE x PaCO2) = (VE x PaCO2)

Question 25

Suction catheter Size

Answer 25

Catheter size = ID size
_________ x 3
2

Question 26

What should be done to estimate FIO2 for Nasal cannula?

Answer 26

For every 1 L/min increase the flowrate, FIO2 increase by 4%

20 + (4 x liter flow) = approximate FIO2

Question 27

Duration of flow

Answer 27

gauge pressure (psi) x tank factor
_________________________
liter flow

Question 28

E cylinder tank factor

Answer 28

0.28 L/psi

Question 29

H cylinder tank factor

Answer 29

3.14 L/psi

Question 30

D cylinder tank factor

Answer 30

0.16 L/psi

Question 31

G cylinder

Answer 31

2.41 L/psi