Flight Physiology

Question 1

Barotitis Media

Answer 1

Boyles law, air in middle ear expands on ascent, escapes via Eustachian tube (dumps into nasopharynx).

• on descent, atmospheric pressure increases on ear drum, air is drawn back into ear. If tube is blocked, air cannot get back in,
• descent problem.

Question 2

Barodontalgia

Answer 2

Air trapped beneath dental work. (New or foreign)

• expanding air cannot escape. Pushed down on nerve.
• Ascent problem
• Slow ascent. Analgesics.

Question 3

Barosinusitis

Answer 3

Boyles law.
-air trapped in sinuses.
Ascent / Descent problem. Expanding air cannot escape.
Pressure in sinus tissues,
-slow climb out, nasal decongestions (neosynephrine), analgesics

Question 4

Barobariatrauma

Answer 4

Boyles law

• nitrogen absorbed in adipose tissue, expands on rapid ascent.
• attempts to release into plasma then to lungs.
• cannot blow off quickly enough = nitrogen toxicity, bends
• FiO2 to 100%

Question 5

ETT considerations for Boyles law.

Answer 5

ETT cuff not typically an issue in RW

• 30,000 ft plus requires replacement w/ water
• cabin decompression = cuff rupture.

Question 6

Boyle law Cast considerations

Answer 6

Tissue under cast is rich with air, can expand.

• casts less than 7 days old require bi-valve
• cut on medial and radial aspect, wrap with ace bandage.

Question 7

Chest tube considerations concerning Boyle’s law

Answer 7

Has moving through tube into collection device.

• needs vented to atmospheric air so it can equalize.
• otherwise gas will expand on ascent - escapes into chest.
• pop hemilick valve in line with the atrium.

Question 8

Charles law

Answer 8

At constant pressure, volume of a gas is directly proportionate to the absolute temperature of the gas.

• heat a gas, volume expands,
• cool a gas, volume contracts
• V1/T1 = V2/T2

Question 9

Celsius temp drops 1 degree for q meters climbed.

Answer 9

100 m

Question 10

Boyle’s Law

Answer 10

Volume of a gas is inversely proportionate to its pressure under constant temp.
-P1V1=P2V2

Question 11

Gay-Lussac’s Law

Answer 11

Same as Charles law only vessel is fixed container
-directly proportional between temp and pressure.
Aeromedical application: O2 tank, cools on climb, O2 pressure drops

Question 12

Henry’s law

Answer 12

At constant temp: the amount of a given gas dissolved in a type and volume of liquid is directly proportional to the partial pressure if that gas in equilibrium with that liquid.

Question 13

Henry’s law aeromedical application, cabin decompression

Answer 13

Leer jet at 30k feet- explosive decompression
-partial pressure of plasma O2 is greater than that of lungs
-O2 will not dissolve for, lungs into plasma
-O2 will reverse from plasma into lungs
-Results in sudden LOC
(Another application is decompression sickness)

Question 14

Graham’s law

Answer 14

Law of gaseous diffusion.
-diffusion rate of a gas through a liquid medium is directly related to the solubility of the gas and inversely related to the square root of its density.
-at equal pressures/temps, gases with smaller mass diffuse faster,
O2 smaller than CO2, but CO2 more soluble.
-CO2 diffuses across fluid faster than O2

Question 15

Factors that influence Graham’s law

Answer 15

Surface area, diffusion gradient, diffusion distance, molecular size, solubility.

Question 16

Dalton’s Law

Answer 16

The total pressure of a gas mixture is the sum of the partial pressures of all gases in the mixture.
Pt=P1+P2+P3…
P1 = fractional [P1] x barometric pressure.

Question 17

DEATH - factors effecting flight stressors

Answer 17

Drugs
Exhaustion (predisposes spatial disorientation)
Alcohol
Tobacco
Hypoglycemia

Question 18

Night vision loss, smokers considerations

Answer 18

Loss of night vision: 5000 msl

Smokers loose 4000 ft of night vision capabilities

Question 19

Rods vs cones

Answer 19

Rods: night vision, periphery of eye
Cones: day vision, center of eye.

Question 20

What is most susceptible to hypoxia?

Answer 20

Eyes, eyesight.

Question 21

1 ATM weighs

Answer 21

14. 7 pounds, or 760 Hg (torr)
    - per square inch
    - on perfect day: 59 degrees F

Question 22

Atmospheric change

Answer 22

Greater atmospheric change noted as sea level with ascent than starting at higher elevation.

• ascent, pressure becomes less (0.5 ATM or 389 Hg at 18,000 ft)
• as you dive, 1 ATM = 33 feet under water..

Question 23

Diver has dove 66 feet, how many atmospheres are in him?

Answer 23

3 atmospheres:

• 2 atmospheres of water
• 1 atmosphere of air

Question 24

Physiological Zone

Answer 24

Sea level to 10,000 ft.

Great compensation unless ailments exist

Question 25

Physiological Deficient zone

Answer 25

10k to 50k ft

• healthy individuals notices compensatory attempts
• most would not experience significant symptoms

Question 26

Space-equivalent Zone

Answer 26

50k-250k ft

-requires assistance

Question 27

Space

Answer 27

250k or higher

Question 28

Hypoxia hypoxia

Answer 28

Deficiency in alveolar O2 exchange (aka altitude hypoxia)

-drop in available O2, apnea, altitude, venous mixing

Question 29

Histotoxic Hypoxia

Answer 29

Failure of the tissues ability to use presented O2

• commonly results of poisoning, or metabolic disorders
• cyanide (not only displaces O2 from Hgb, also interferes with mitochondrial ability to utilize O2) interferes wi electron transport chain in cellular respiration.

Question 30

Stagnant hypoxia

Answer 30

Reduced cardiac output, or pooling of blood

• heart failure, PE, Shock
• able to get O2 from lungs, blood is not going anywhere.
• localized stagnant hypoxia: compartment syndrome

Question 31

Hypemic Hypoxia

Answer 31

Reduction in the O2 carrying capacity in the blood