Resistance or Raw
|
Ppeak-Pplat/ flow in L per min
|
Static Compliance
|
Vte/Pplat-PEEP
|
Dynamic compliance
|
Vte/Ppeak-PEEP
|
Alveolar ventilation (Va)
|
(Vt-Vd weight in lbs) * f
|
Minute Ventilation (Ve)
|
Vt * f
Male: 4 * BSA
Female: 3.5 * BSA
|
Tidal Volume (Vt)
|
Flow * Ti
Convert flow to L /sec: divide by 60
|
Flow
|
Vt (L)/Ti sec
Convert to L/min; multiply by 60
|
Frequency or rate:
|
Ve/Vt
|
Apnea interval
|
TCT * 2
|
Rapid shallow breathing index RSBI
|
f/ Vte
|
Compliance
|
Change in Volume/Change in Pressure
|
Elastance
|
Change in Pressure/ Change in Volume
|
Arterial O2 content:
|
(hg * 1.34 * SaO2) + (Pao2 * 0.003)
Bound to hg in Plasma
|
Corrected Vt
|
Vt set – {(PIP – PEEP) * CF}
|
Total Cycle Time TCT
|
60/f or Ti + Te
|
Inspiratory Time Ti
|
Vt/ flow (in L per sec)
|
Expiratory Time Te
|
TCT- Ti
|
I:E ratio
|
Te/ Ti
|
A-a gradient
|
PAo2-Pao2
|
P- F ratio
|
Pao2/Fio2
|
Ideal Body Weight IBW
|
106 + 6(ht in inches- 60) male
105 + 5 (ht in inches-60) female
Multiply by 2.2 to convert to kg
|
Body Surface Area BSA
|
Square root of:
Ht inches – actual weight/
3131
|
Shunt equation
|
QS/QT= A-a gradient/
A- Gradient (.003) + C-vO2
Short cut:
Take the A-a gradient and count # if hundreds
Multiply it by 5, add 5, and give as a %
|
Alveolar Air equation
|
(Pb – PH20)* FIO2- Pao2/0.8
|
Work of breathing WOB
|
Change in Pressure * change in volume
|
Desired Co2 from RR
|
PaC02 * f/ Desired PaC02
|
Oxygen Transport
|
Cardiac output * Pao2
|
Anion Gap
|
Na – (Cl + HCO2)
|
Cerebral perfusion pressure CPP
|
MAP- ICP
|
