Gas and Pressure

Question 0

Gauge measurements

Answer 0

Fsw - feet of sea water

psi - pounds per square inch

Question 1

Absolute Pressure measurement

Answer 1

Ata - atmospheres absolute

mmHg

Question 2

Equivalent pressure measurements

Answer 2

1 atmosphere 
760 mmHg
14.7 psi
33 fsw
10 meters of sea water (msw)
0.99 bar
760 torr
101 kilopascals (kPa)
0.1 Megapascals (mPa)

Question 3

Formula for ata to mmHg

Answer 3

mmHg = ata x 760

Question 4

Formula ata to fsw

Answer 4

fsw = (ata -1) x 33

Question 5

Formula ata to psi

Answer 5

psi = (ata - 1) x 14.7

Question 6

Formula fsw to ata

Answer 6

ata = (fsw + 33) / 33

Question 7

Formula psi to ata

Answer 7

ata = (psi + 14.7) / 14.7

Question 8

Absolute temp for F

Answer 8

Fahrenheit to Rankine (R)

R = F + 460

Question 9

Absolute Temperature for C

Answer 9

Celsius to Kelvin

K = C + 273

Question 10

Boyle’s Law

Answer 10

Pressure and volume. Inverse relationship

Question 11

Gay-Lussac’s Law

Answer 11

Pressure-temperature.

Question 12

Charles’ Law

Answer 12

Volume-Temperature

Significant shrinkage

Question 13

Dalton’s Law

Answer 13

Partial pressure of gases. The total pressure of a mixed gas is equal to the sum of the partial pressures of each of the component gases.

Question 14

Henry’s Law

Answer 14

Dissolved gas in solution. The amount of a gas dissolved in a liquid is directly proportional to the partial pressure of that gas over the liquid.

Question 15

Pascal’s Law

Answer 15

Hydraulics. A bubble deep in the body tissues responds to the pressure applied outside the body.

Question 16

Graham’s Law

Answer 16

Gas diffusion. Gas moves from area higher pressure to an area of lower pressure.

Question 17

Pulmonary oxygen toxicity

Answer 17

Identified by Lorraine Smith (1899)

Difficulty breathing, cough, chest tightness, substernal burning,reduction in vital capacity.

Time/dose relationship

Question 18

Unit pulmonary toxicity dose

Answer 18

UPTD = 100% oxygen at 1 ata for 1 min = 1 UPTD

Question 19

Max UPTD dose in 12 hours

Answer 19

1440

Question 20

Central nervous system (CNS) toxicity

Answer 20

Identified by Paul Bert 1878

Convulsion, nausea, dizziness, muscle twitching, abnormal vision or hearing, anxiety, confusion

Time/dose relationship

Question 21

Threshold for CNS toxicity breathing 100% oxygen

Answer 21

1.6 ata - several hours
2 ata - 4 hours
3 ata - 1 hour

Max oxygen dose - 100% O2 at 3 ata (2280 mmHg)

Question 22

Variables that shorten time to oxygen toxicity seizure

Answer 22

Elevated CO2, fever, exercise, upright position

Question 23

Preventing oxygen toxicity

Answer 23

Intermittent air breathing (air breaks), limit inspired po2 to 2280 mmHg

Question 24

Nitrogen narcosis

Answer 24

Only occurs when breathing air

Sx - euphoria, mood change, idea fixation, slowed reactions, judgement errors, unconsciousness

Can affect inside attendant

Threshold is approximately 4 ata (100 fsw)

Question 25

Isobaric counter-diffusion

Answer 25

When gas inside a bubble is replaced by another gas. Occurs because of pressure gradients of the two gases.

Question 26

Solubility of nitrogen in fat

Answer 26

5xs more soluble in fat than water

Question 27

The amount of time it takes half of nitrogen in tissue to be eliminated is called

Answer 27

Half-time

Question 28

Number of half times required for nitrogen to be completely eliminated in a tissue.

Answer 28

6 units of half time

Question 29

Critical ratio

Answer 29

When ratio of nitrogen to ambient pressure hits critical ratio, bubbles form.