Gas Laws and Gas Cylinders Flashcards
(18 cards)
Daltons Law
total pressure of a gas is equal to the sum of the pressure of individual gases in a mixture
ambient pressure
pressure of the surrounding (ex gas or liquid)
Alveolar Gas Equation
PAO2 = FiO2 x (Pbarometric-PalveolarH2O) - PaCO2/RQ
RQ
(=VCO2-VO2) .8 reflects 8 CO2 molecules produced for every 10 O2molecules burned. means more O2 leaves alveoli than is returned in the form of CO2 to alveoli.
alveolar arterial oxygen gradient
(A-a)DO2
arterial-alveolar ratio
PaO2/PAO2 ratio. better for high FiO2
can also be PaO2/FiO2. for this way, less than 200 means acute RDS. used to quantify hypoxemia
reasons for (A-a)DO2 difference being normal
regional VA/Q mismatch (largest influence)
anatomic shunt of blood, like thespian circulation or bronchial circulation)
pathological A-a O2 difference reasons
significant VA/Q mismatch
intrapulmonary shunts
Alveolar-cap membrane diffusion block
PFO
henrys law
amount of gas dissolved in liquid is directly proportional to pressure applied to that gas as it overlies the liquid.
Concentration of gas = Pressure of gas/KH
(KH is a constant, solubility of gas in particular solvent. measures likelihood to leave liquid to gaseous state.)
(Pressure of gas is partial pressure of gas above liquid)
Boyles Law
at a constant temperature, pressure of a gas is inversely proportional to volume. increased pressure in decreased volume. related to more collisions in a smaller container.
P1 x V1 = P2 x V2
Charles Law
at a constant pressure, the volume of a gas is directly proportional to its absolute temperature. increased temperature (kelvins) = increased volume.
V1/T1=V2/T2
Boyles and Chalres’ Law Combined
P1V1/T1 = P2V2/T2
Gay-Lussacs Law
at a constant volume, pressure of a gas is directly proportional to absolute temp. increased temperature is increased pressure.
P1/T1=P2/T2
Ideal Gas Law
PV=nRT or V=nRT/P
where R is a constant at 62.36L
how to calculate R for ideal gas law
PV/nT=R where 760mmHgx22.4L/1mole x273k = 62.36L mmHg /mole K
Joule Thompson Effect for Compression
endothermic reaction, warmer. KE of molecules increased when compressed and therefore can give off heat.
narrow valve can compress gas.
Joule Thompson Effect for Expansion
exothermic reaction, cooler.
Adiabatic Effect
a gas in a container which is isolated thermally from its environment becomes warmer when it is compressed and cooled when it expands. super rapid, thats why we feel it.
