Flight Physiology Flashcards
Barotitis Media
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.
Barodontalgia
Air trapped beneath dental work. (New or foreign)
- expanding air cannot escape. Pushed down on nerve.
- Ascent problem
- Slow ascent. Analgesics.
Barosinusitis
Boyles law.
-air trapped in sinuses.
Ascent / Descent problem. Expanding air cannot escape.
Pressure in sinus tissues,
-slow climb out, nasal decongestions (neosynephrine), analgesics
Barobariatrauma
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%
ETT considerations for Boyles law.
ETT cuff not typically an issue in RW
- 30,000 ft plus requires replacement w/ water
- cabin decompression = cuff rupture.
Boyle law Cast considerations
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.
Chest tube considerations concerning Boyle’s law
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.
Charles law
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
Celsius temp drops 1 degree for q meters climbed.
100 m
Boyle’s Law
Volume of a gas is inversely proportionate to its pressure under constant temp.
-P1V1=P2V2
Gay-Lussac’s Law
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
Henry’s law
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.
Henry’s law aeromedical application, cabin decompression
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)
Graham’s law
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
Factors that influence Graham’s law
Surface area, diffusion gradient, diffusion distance, molecular size, solubility.
Dalton’s Law
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.
DEATH - factors effecting flight stressors
Drugs Exhaustion (predisposes spatial disorientation) Alcohol Tobacco Hypoglycemia
Night vision loss, smokers considerations
Loss of night vision: 5000 msl
Smokers loose 4000 ft of night vision capabilities
Rods vs cones
Rods: night vision, periphery of eye
Cones: day vision, center of eye.
What is most susceptible to hypoxia?
Eyes, eyesight.
1 ATM weighs
- 7 pounds, or 760 Hg (torr)
- per square inch
- on perfect day: 59 degrees F
Atmospheric change
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..
Diver has dove 66 feet, how many atmospheres are in him?
3 atmospheres:
- 2 atmospheres of water
- 1 atmosphere of air
Physiological Zone
Sea level to 10,000 ft.
Great compensation unless ailments exist
