Flight physiology Flashcards
What three gasses are in the atmosphere?
Nitrogen 78%
Oxygen 21%
Argon 0.93%
How many ATM (atmosphere) are at sea level?
1 ATM or 760 torr
How many feet per 1 ATM (atmosphere)
33 feet
Barometric pressure per altitude?
Sea level- 760 torr or 1 ATM
10k ft msl- 523 torr
18k ft msl- 380 torr/ 1/2 ATM
63k ft msl- o torr/o ATM
Abbreviations for:
Above ground level
Above sea level
Mean sea level
AGL-Above ground level
ASL- Above sea level
MSL- Mean sea level
Physiological zone Altitude and key facts
Sea level to 10k ft MSL
Night vision decreases starting at 5k ft MSL
Physiologic deficient zone altitude and key facts
10k-50k ft MSL
Need O2 or pressurized cabin at this altitude
Time of useful consciousness is cut in half
Time of useful consciousness (TUC)
Effective performance time with poor O2 supply
Normal TUC is 90 seconds with normal decompression
Cut in half at deficient zone with rapid decompression
Space equivalent zone altitude and key facts
50k ft MSL and above
Astronauts
Boyles gas Law
As altitude increases, pressure decreases
Pressure of gas inversely proportional to volume at constant temp
Affects: ETT cuffs, drip chambers, skull fractures, ICP increases, air splints
Charles gas law
As air heats up, molecules spread and make air less dense
Volume of gas is proportional to temp of gas
This will affect how well the aircraft performs at various temps
Ex: when a ball is inflated indoors during the winter, it will shrink when brought outdoors
Dalton’s gas Law
Increased altitude, decreased partial pressure
Total pressure of gas mixture is equal to the pressure of all gasses in mixture
Ex: When ascending to higher altitude, less O2
Fick’s gas law
Inversely proportional to thickness of membranes and difference in partial pressure
Gas diffusion across alveoli
Ex: as altitude increases, pressure decreases and decreased perfusion rate
Henry’s gas law
Solubility of gas in liquid
Affects divers, leads to decompression sickness (the bends)
Nitrogen comes out of tissue and into the venous system
Guy-Lussac’s gas law
Directly proportional to temp and pressure
Ex: why you have to add air to tires when it’s cold out
Graham’s gas law
Gas exchange at cellular level
Heavier gasses diffuse slower
O2 molecules traveling through surfactant, CHF or mucous
what is the O2 adjustment formula
FIO2x P1 / P2 = FIO2 required for ascent
P1 is pressure you are at on the ground
P2 is the pressure you will be flying at
Altitude effects
Cold, dry, higher altitude environment has greatest negative outcome for patient.
Temp is inversely proportional to altitude
Greatest amount of pressure change occurs closest to sea level
For every 1k increase temp will decrease by 2c
Barodontalgia
Occurs on ascent Boyles law (air trapped in fillings)
Barotitis
Occurs on descent
Air trapped in middle ear
Barosinusitis
Occurs on both ascent and descent
Sinus block causing maxillary pain
Decompression sickness (the Bends)
Henry’s law
6 types of decompression sickness
Type 1-Joint and skin, nitrogen related. Painful joints mottled skin and itching
Type 2- Neuro. Rapid ascending paralysis, hypovolemic shock, pulmonary chokes, Preferred method of transport by ground, pressurized cabin or below 1k helicopter
Babrobariotrauma
Obese pt’s, peds or pregnant patients
sudden release of nitrogen stores in lipids
Nitrogen washout before take off at 15 LPM non rebraether
Inherent stressors of flight (8)
Thermal, humidity, G-Forces, fatigue, Pressure change, noise, vibration
Self imposed stressor of flight (5)
Dehydration, exhaustion, alcohol, tobacco, hypoglycemia
Types of hypoxia (4)
Hypoxic hypoxia- not enough O2 in lung (lung level hypoxia)
Stagnant-Blood isn’t moving or moving slowly (cellular level)
Hypemic-Transport problem (blood level) ex: anemia, co2 or fire vict.
Histotoxic- Tissue cannot accept or offload O2 (cellular hypoxia)
Stages of Hypoxia (4)
Indifferent-full reasoning
Compensatory- Increased HR and RR, slowed judgement
Disturbance- Slurred speech, impaired judgment (drunk)
Critical-No longer able to physiologically function, death imminent
O2 is required above 10k ft for any time greater than how many minutes?
30 minutes
What is the body’s PaO2 at 10k ft ASL
61 mmHg (90% SPO2)
Boyle’s law states that as altitude increases, pressure __________?
Decreases
If you set a 2000 psi hot O2 cylinder outside overnight, would you expect the pressure to increase or decrease?
Charles law
DECREASE
If you placed a balloon in a freezer then removed it into a warmer place, would the balloon grow, shrink or stay the same due to which gas law?
Grow
Gay-Lussac’s law
For every 1,000 feet increase in altitude the temp decreases by how many degrees celsius?
2 degrees celsius
Is barodontalgia and ascent or descent problem?
Ascent
Is Barotitis media an ascent or descent problem?
Descent
Is barosinusitis primarily an ascent or descent problem?
60% occur on descent but can happen on both
What 3 main population groups does barobariotrauma effect?
Obese pt’s
pregnant pt’s
Pediatric pt’s
While diving, you will experience 1 additional ATM for how many feet you descent?
Every 33 feet
The greatest pressure changes occur within how many feet below sea level and above sea level?
The first 4 feet while diving and the first 5000 feet while flying
During flight, what amount of low frequency vibrations may you feel? (amount in HZ)
1-12 HZ
What are two examples of stagnant hypoxia?
Cardiogenic shock
High G-Forces
What are 3 causes of hypemic hypoxia?
Anemia
CO poisoning
Sickle cell disease
What are the 4 different stages of hypoxia? (ICDC)
Indifferent
Compensated
Disturbance
Critical
What gravitational force is best tolerated?
GX (anterior/posterior force)
Like accelerating in your car
Which gravitational force is least tolerated?
(Lateral) GY
Like being t-boned
What are the 4 different types of hypoxia?
Hypoxic hypoxia
Stagnant hypoxia
Hypemic hypoxia
Histotoxic hypoxia
PaO2 decreases ____mmHg for every 1000 feet increase in altitude?
5 mmHg
Space altitude in feet?
250,000 feet and above
