9 Gas Laws & Gas Cylinders Flashcards Preview

AS - N927 Chem/Physics > 9 Gas Laws & Gas Cylinders > Flashcards

Flashcards in 9 Gas Laws & Gas Cylinders Deck (23)
Loading flashcards...
1

PAO2 Equation

PAO2 = FiO2 x (PB - PH2O) - (PaCO2/RQ)
RQ = 0.8

2

Alveolar/Arterial Ratios

Alveolar-arterial oxygen difference/gradient
(A - a)DO2 or PAO2 - PaO2
Normal 5-15mmHg

Arterial-alveolar ratio
PaO2/PAO2
Normal > 0.75

PaO2/FiO2
Normal >200

3

Henry's Law

Cgas = Pgas / KH

4

Dissolved PaO2

0.003ml O2 dissolved in 100ml blood per 1mmHg PO2 applied
PAO2 = 100mmHg
PaO2 = 0.3ml O2

5

Dissolved CO2

0.067ml CO2 dissolved in 100ml blood per 1mmHg PCO2

6

Arterial O2 Content Equation

CaO2 = ((1.34ml O2/gm Hgb) x (15gm Hgb/100ml blood) x (% saturation)) + (0.003 x PaO2)

7

O2 Delivery

= CaO2 content x CO

8

Boyle's Law

Gas pressure inversely proportional to volume at constant temperature
P1 x V1 = P2 x V2

9

Charles' Law

Gas volume directly proportional to absolute temperature (°K) at constant pressure
V1/T1 = V2/T2

10

Gay-Lussac's Law

Gas pressure directly proportional to absolute temperature (°K) at constant volume
P1/T1 = P2/T2

11

Combined Gas Laws

(P1xV1)/T1 = (P2xV2)/T2

12

Avogadro's Law

Equal gas volumes at same temperature and pressure contain the same number molecules or atoms
V1/n1 = V2/n2

13

Avogadro's Number

1 mole gas @ STP = 6.02 x 10^23 molecules
GMW 1 mole O2 = 32g
2kg tank N2O (44g) = 45.45 Mole

14

1 Mole Gas = x L

22.4L @ STP

15

Ideal Gas Law

Avogadro + Boyle + Charles + Dalton
PV/T = Rn
PV/nT = R
PV = nRT
V = nRT/P
R (constant) = 62.36 L⋅mmHg/Mol⋅K

16

Oxygen Tank

E tank

14.7psi / 5L
(PSI/14.7) x 5L
L/flow = min

Holds 660L
1900psig

17

Nitrous Oxide Tank

Pressure gauge (psig) does not change until N2O unable to move from liquid to gas state (no liquid present)
Open valve → releases gas ↓pressure
Liquid N2O changes to gas state ↑pressure
Equilibrates on pressure gauge Ø change
*Weigh tank to determine N2O remaining
Able to hold more volume w/ less psi than E cylinder tank d/t ↑ Moles (liquid more dense than gas)
Mass N2O present / GMW (44g) = # Moles (n) N2O
V = nRT/P

Holds 1590L
745psig

18

Joule-Thomson Effect

Decrease in temperature as heat loss result when gas expands freely into space
Compression & expansion
Normal conditions compression/expansion occurs slowly enough that heat transfer (exothermic/endothermic reactions) not felt of observed
Heat change dissipates into the environment

19

Compression

Exothermic reaction
↑ kinetic energy when compressed
Heat lost to the environment
Anesthesia machine gas compression via narrow valve = heat
Ignition possible, especially in high O2 environment

20

Expansion

Work requires energy (heat)
Endothermic reaction
Area surrounding rapidly expanding gas will feel cold
Gas cylinder release - cold regulator

21

Adiabatic Compression/Expansion

Rapid compression (exothermic) heat liberation does not have time to dissipate
Things in vicinity or in contact w/ gas will heat up
Rapid expansion (endothermic) surrounding area will feel cold
OR insulated area where compression/expansion occurs ჻ heat trapped and unable to dissipate

22

Concentration Effect

Accelerating alveolar gas concentration by increasing inspired concentration
Alveolar fraction (FA) / Inspired fraction (FI)
Optimal FA/FI ratio = 1
How quickly anesthetic gas enters bloodstream & crosses the blood-brain barrier
Patient who receives higher concentration will feel anesthetic effects sooner

23

2nd Gas Effect

Large volume uptake (highly soluble) gas N2O delivered at high concentration to accelerate alveolar partial pressure increase of anesthetic (ex: Isoflurane)
Concurrent gas administered w/ anesthetic
Oxygen + anesthetic + nitrous oxide
N2O highly soluble and quickly absorbed into blood → leaves void in alveolus
Effect: Concentrates anesthetic gas & suctions in more gas from airways = ↑ anesthetic
Result: Able to anesthetize patient more quickly d/t ↑ anesthetic concentration in the alveolus