Flight Physiology Flashcards
Boyle’s Law
As altitude increases, the atmospheric pressure decreases, and gas in an enclosed space will expand.
P1V1=P2V2
760mmHg /torr = 1 ATM
29.97 inHg = 1 ATM
0 feet = 1 ATM = 14.7 PSI (water pressure)
Ex. 99 feet = 4 ATM. 0+33+33+33 = 99
Every 33 feet under water = 1 ATM
Body Cavities / Boyle’s Law
Barotitis Media - Expansion of infectious fluid behind the eardrum creating pain and tenderness with altitude. Discomfort on descent. Internal pressures stay the same as external decreases.
Barosinusitis - Massive pain on ascent due to increased sinus pressure not having anywhere to go.
Barobariatrauma - Morbidly obese patients. Fat holds onto nitrogen. Ascent will cause nitrogen narcosis. High flow oxygen will cause nitrogen to diffuse out of lipids. (nitrogen washout). Pain on ascent
Barodentalgia - Inflamed pulp or Abscess. Pain on Ascent.
Charles’ Law
The relationship between temperature and volume is proportional to constant atmospheric pressure. As the temperature goes up, the volume of gas expands. As the temperature goes down, the volume of gas decreases.
For every 1000’ ascended, temperature decreases 2’C.
For every 150 meters ascended, temperature decreases 1’C.
Gay-Lussac’s Law
For a given mass and constant volume of gas, the PRESSURE exerted on the sides of its container is directly proportional to its absolute temperature.
Dalton’s Law
The total pressure of a gas mixture is the sum of partial pressures of all gases. In addition, it describes how pressure is exerted by gas at various altitudes and how that pressure effects the partial pressure of the said gas.
Increase Fi02
Air = 101.3 kilopascals. O2 + N2 + Ar + H20+ Co2 and 14.7 PSI
Henry’s Law
The amount of gas dissolved in a solution is directly proportional to the pressure of the gas over the solution.
Place gas under pressure = BVM, ventilator pressure support
Fick’s Law
The rate of diffusion of a gas across a permeable membrane is determined by the chemical nature of the membrane itself, the surface area of the membrane, and the partial pressure gradient of the gas across the membrane, and the thickness of the membrane. PEEP Increase alveoli surface area.
Graham’s Law
The rate of diffusion of a gas is inversely proportional to the square root of its molecular weight. This means that diffusion will happen at a father rate if the gas is thinner and at a slower rate if the gas is heavier.
High concentration to low concentration
Stressors of Flight
DEATH Acronym:
Drugs. (Not dehydration)
Exhaustion
Alcohol
Tobacco
Hypoglycemia
Hypoxia Stages
Indifferent - 0 - 10,000 90-98%
Reduced night vision at 4000 ft.
Compensatory - 10-15000 80-89%
Drowsy, impaired.
Disturbance - 15-20000 70-79%
Impaired muscle coordination
Slurred speech
Critical - 20-25000 - 60-69%
Dead
Fi02 Equation for altitude
(Fi02 x P1) / P2 = new fi02 at new altitude
P = barometric pressure.
