Math Stuff Flashcards
Calculation for RQ
RQ= CO2 produced
———————
O2 consumed
RQ for average diet
0.8
RQ for all Carbs diet
1.0
RQ for all fat diet
0.7
RQ for all protein diet
0.8
Fick’s Law (Rate of Diffusion)
D x A x 🔺P
Vx= —————-
🔺X
D= Diffusion coefficient
A= surface area
P= partial pressure diff
X= membrane thickness
Inspiratory capacity
IC=
IC= Vt + IRV
Vital Capacity
VC=
VC= IRV + Vt + ERV
Functional Residual Capacity
FRC=
FRC= ERV + RV
Total Lung Capacity
TLC=
TLC= VC+ RV
RV
—— should normally equal=?
TLC
What is it in obstructive?
WHat is it in restrictive?
Should be .25 or less
Increases with both restrictive and obstructive
FEV1
——- should normally equal ?
FVC
How does it change in obstructive?
How does it change in restrictive?
Normally 0.8
Obstructive= lower
Restrictive= higher
Physiological Dead Space (Vd)
2 ways
Vd= anatomical dead space + functional dead space in alveoli
Vd= Vt x PaCO2 - PECO2
———————
PaCO2
PECO2= CO2 in expired air PaCO2= CO2 in arterial blood Vt= tidal volume
Minute ventilation
=Vt x #breaths/min
Alveolar ventilation (Va)
2 ways
Va= (Vt-Vd) x #breaths/min
Or
VCO2 x K
Va= ————-
PACO2
VCO2=rate of CO2 production
K= constant (will be given)
Transmural Pressure
Tp= Alveolar Pressure-Intrapleural Pressure
Compliance
🔺V
C= ——
🔺P
(Or you can measure the slope on a graph (rise over run)
Lap of Laplace (Collapsing Pressure of alveolus)
2T
P=——
r
P=collapsing pressure
T= surface tension
r= alveolar radius
Airflow (Q)
🔺P
Q= ——
R
Q= airflow rate R= airway resistance
Poiseuille’s Law (Resistance)
8 η x L
R=———
πr^4
η= viscosity of inspired air
L= length
r=airway radius
R=resistance
~~note that Resistance is Inversely proportional to r^4~~
Henry’s Law (Concentration of a dissolved Gas, Cx)
Cx= P x solubility
P= partial pressure of the gas
Solubility constant will be given
Dalton’s Law of Partial Pressure of a Gas (Px)
Not corrected for humidified air
Px= Pb x F
Pb= barometric Pressure
F= fractional concentration of a gas
F=0.21 for oxygen!!
What does F= if you are dealing with oxygen
F=0.21
F is the fractional concetration of a gas
Dalton’s Law of Partial Pressure of a gas (Px)
Corrected for humidified air
Px= (Pb- 47) x F
47 is the Pressure of H2O
F will be 0.21 if you’re asked about oxygen
O2 binding capacity
Amount O2 bound to Hb
= ——————————-
100mL
What is the normal concentration of Hb?
15g/dL
1 dL is the same thing as 100mL
How much oxygen will one g of Hb bind?
1.34mL
20.1mL oxygen Normal O2 binding capacity of blood 15 x 1.34= ——————-——-
100mL
What is a normal V/Q
0.8
This means that alveolar ventilation is 80% of pulmonary blood flow
A-a gradient
2 ways
=PAO2-PaO2 (Alveolar- arterial)
Or
= PIO2- PACO2
———- -PaO2
RQ
(This one was hard to format and it’s not quite right. There should be brackets around the PIO2 and the fraction)
