CFRN: Flight Physiology 40 Questions with Verified Answers
What is Boyle's Law? - CORRECT ANSWER Boyle's Balloon
Balloon expands as rises 2/2 less pressure against it.
*Think of things ABOVE sea-level*
Closer t
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CFRN: Flight Physiology 40 Questions with Verified Answers
What is Boyle's Law? - CORRECT ANSWER Boyle's Balloon
Balloon expands as rises 2/2 less pressure against it.
*Think of things ABOVE sea-level*
Closer to sea-level, more barometric pressure.
Gas volumes expands as barometric pressure ↓
Temperature is the same
What are the common medical problems associated with Boyle's law? - CORRECT ANSWER ~Arterial gas embolism (needs to be in a pressurized aircraft)
*~pneumocephalus 2/2 depressed skull Fx*
~Barotitis Media (middle ear)
~Barodontalagia (air under tooth)
~Barosinusitis (sinus)
~Barobariatrauma (like the bends)
Barotitis Media - type of problem & Tx - CORRECT ANSWER A *descent* problem
Tx: Easiest way to fix, go back to altitude
Valsava maneuver
Neosyneprhine or Afrin to vasoconstrict
Treat pain symptomatically
Barodontalagia- type of problem & Tx - CORRECT ANSWER An *ascent problem*
Seen with newer dental work
Tx: analgesics, slower descent, Boyle's Law
Barosinusitis- type of problem & Tx - CORRECT ANSWER An *ascent (more so) but can be decent* problem
Seen with sinusitis
Tx: analgesics, Afrin and slower ascent.
Barobariatrauma- type of problem & Tx - CORRECT ANSWER An *ascent problem*
Seen with morbidly obese patients (more lipid tissue=more nitrogen)
Gases in adipose tissue released into plasma causing nitrogen narcosis "bends"
Tx: 100% O₂ to wash nitrogen from lungs (pre-oxygenated for at least 15 minutes prior to ascent and high concentration for duration of transport)
What are some aeromedical considerations of Boyle's law? - CORRECT ANSWER *air in tubes*
~ETT (create minimal air leak - can replace with water, but would need to change out ETT once landed)
~IV drips - may see rate accelerate with ascent and converse
~MAST pants - ↑ in altitude, air ↑ - OK if have pop-off valves (as descend, ↓ in air pressure)
~Casts <7 days old bivalved, ace wrapped and
neuro checked frequently
~IABP
~Chest tubes: vent chamber to atmosphere or air will be forced back into patient. (can place heimlick valve in between pt and pleurovac to prevent air backing up to)
~Foleys can push air or dirty urine back into patient but does not affect foley cath balloon
What is Charles's Law? - CORRECT ANSWER A Law of VOLUME proportional to temperature
(e.g. football inflated inside, shrinks when outside in the cold)
~for every 100 m climb = 1°C ↓ drop
~heated gas expands volume (e.g. can of shaving cream into a fire)
*THINK TEMPERATURE*
Law has little effect on human body (we are at a relatively constant temperature)
What is Gay-Lussac's Law? - CORRECT ANSWER "Charles Gay brother"
*SAME law except, except Gay is about PRESSURE*
Volume is the same, lower temp - lower pressure, higher temp - higher pressure
e.g. *heat applied to an O₂ tank, O₂ cylinder is fixed vessel; so with temp change throughout day will change pressure*
e.g. put nitrogen in tires in CO - b/c it does not change w/ temp - so you don't have to add air in winter, take it out in the summer
What is Henry's Law? - CORRECT ANSWER Henry's Heineken (solubility of gas in a liquid)
*Think BELOW sea-level - the bends, nitrogen*
MOST IMPORTANT GAS LAW TO UNDERSTAND - *the way we treat hypoxia*
How to manipulate Henry's Law:
(1) ↑ concentration of gas (↑ % O₂)
(2) Pressurize the gas (BiPAP/CPAP/ET-vent)
(3) Change surface area (add PEEP - prevents alveoli from collapsing when they exhale)
Partial pressure in capped Heineken beer bottle is equalized with air in neck of bottle until you pop the top and a gas gradient exists
What is Graham's Law? - CORRECT ANSWER Graham's grape jelly
(opposite of Henry's Law) *gas bubbles coming out of grey matter at altitude*
Law that governs what the resistance is, when you are trying to put the gas in the first place. *Dictates gas exchange at cellular level - always about equality*
1) How big is the gas molecule? (helium vs O₂)
2) What is the density of the fluid? (more dense, harder to move aside for gas)
~Gases with lower mass diffuse faster than those with high density
~Dictates gas exchange at molecular level
~Always goes from higher to lower gradient
~CO₂ travels through water 20-40x faster than O₂
Pt with PNE - takes more time for O2 to diffuse across membrane 2/2 all the shit in the way
What is Dalton's Law? - CORRECT ANSWER Dalton's Gang
(multiple gasses, like a gang that needs multiple people)
*tissue swelling at altitude*
TOTAL pressure of gas mixture is the SUM of the partial pressures of ALL THE GASES in the mixture
The percentage of oxygen does NOT change with altitude, what changes is how crammed the molecules are together
Sum of all partial pressures added together will give total pressure of the environment
What are 8 stressors of flight? - CORRECT ANSWER All of these are *INHERENT stressors*
1. G forces
2. Decreased humidity
3. Thermal changes
4. Noise
5. Vibration
6. Decreased partial pressure of oxygen (Dalton's Law)
7. Fatigue
8. Barometric pressure
What does DEATH stand for in relation to factors effecting stressors of flight? - CORRECT ANSWER All of these are *SELF-imposed*
~*D*rugs (benadryl, BB, +big ones like fentanyl)
~*E*xhaustion (dehydration adds to this as well)
~*A*lcohol
~*T*obacco (reduce NV by 4000')
~*H*ypoglycemia
What does *MSL* stand for? - CORRECT ANSWER *Mean Sea-Level*
4300 MSL is 4300 ft ↑ sea-level.
Takes into account tides - most common term
ASL - above sea-level - does not account for tides
What does *AGL* stand for? - CORRECT ANSWER *Above Ground Level*
You can be 1000 AGL but 7400 ↑ sea -evel.
Distance below the plane to the ground
What does *ATM* stand for? - CORRECT ANSWER *Atmosphere*
1 ATM weighs:
14.7 lbs or
*760 mmHg* (torr) - measurement used in aviation
Closer to sea-level - more pressure there is
(Denver 7000' to 8000' not nearly as significant as Florida sea-level to 1000')
What does torr stand for? - CORRECT ANSWER Measurement of pressure in mmHG
What does psi stand for? - CORRECT ANSWER Pressure per square inch.
A measurement of pressure, in psi
What is atmospheric pressure? - CORRECT ANSWER The weight of 1 square inch column of air extending from sea-level into space - it actually has a weight
*@ sea-level* = *1 ATM*
*33 ft*↓ sea-level = *2 ATM*
*66 ft* ↓ sea-level = *3 ATM*
(1) ATM weighs how much torrr? - CORRECT ANSWER 760 torr
As you ascend what happens to pressure? - CORRECT ANSWER It ↓
(lessens)
What are the 4 zones of altitude? - CORRECT ANSWER 1. *Physiologic zone* (sea-level to 10,000 ft)
2. *Physiologic deficient zone* (10,000-50,000 ft) when even a healthy person starts to see physiologic changes (body is compensating - not used to it)
3. *Space equivalent zone* (50,000-250,000 ft)
(65,000 ft - Armstrong's Line - point where barometric pressure in atmosphere is↓ than the barometric pressure in the body - you can't on-gas and all gas you have in the body, escapes - leaves your body!)
4. *Space* (250,000 ft.)
CAMES guidelines recommend supplemental O2 for prolonged duration at greater than 9000 ft
As you dive what happens to pressure? - CORRECT ANSWER It ↑
*Every 33 ft ↓ + one ATM*
If you dive ↓ 66 ft = 2 water ATM & 1 air ATM ∴ total 3 ATMs
*Related to Henry's Laws*
What is *hypoxic hypoxia*? - CORRECT ANSWER *Suffocation*
Can't get O₂ into body
Only hypoxia you can r/o with an SpO₂
What is *stagnant hypoxia*? - CORRECT ANSWER *Blood is stagnant, so O₂ isn't going anywhere*
Think of train station, lots of Pts (O₂), lots of cars (Hgb) - train isn't moving
i.e. CHF, PE, shock @global level= compartment syndrome - @ local level=tourniquet)
What is *histotoxic hypoxia*? - CORRECT ANSWER Failure of body tissue to use available oxygen
*histotoxic = toxic*
i.e. cyanide poisoning, metabolic disorder, CO, sodium nitroprusside (it goes into the liver and when metabolized - it turns into cyanide)
What is *hypemic hypoxia*? - CORRECT ANSWER Decrease in oxygen carrying capacity in the blood.
*Think hypemic = anemic*
One of the most powerful forms of hypoxia in the body - cut Hgb in ½, cut O₂ in ½
i.e. anemia, hemorrhage, CO poisoning, sickle cell
What are the 4 stages of hypoxia? - CORRECT ANSWER 1. Indifferent stage
2. Compensatory stage
3. Disturbance stage
4. Critical stage
What S&S do you have with *indifferent stage of hypoxia*? - CORRECT ANSWER Person can still compensate
Only stage where you will still be able to think critically
↑ HR and RR
↓ night vision
Whats S&S do you have with *compensatory stage of hypoxia*? - CORRECT ANSWER ↑ BP
Impairment of task performance occurs - loose critical thinking - get stoned
~You won't recognize that you are hypoxic
What are the S&S of *disturbance stage hypoxia*? - CORRECT ANSWER Dizziness
Sleepy
Tunnel vision
Cyanosis
What are the S&S of the *critical stage of hypoxia*? - CORRECT ANSWER Marked mental confusion
Incapacitatation
Death unless fixed
PaO₂ ↓ by how much for every 1000 ft of altitude? - CORRECT ANSWER *↓5mmHg*
What is the formula for *FiO₂ adjustment* calculation? - CORRECT ANSWER This formula allows you to keep the same O₂ concentration at a different altitude.
P1 = barometric pressure the Pt is currently at
P2 = barometric pressure the Pt will be GOING
% FiO₂ x P1
----------- = FiO₂ for new altitude
P2
(30 % x 760 torr)
-------------- = 37%
620 torr
What is effective performance time? - CORRECT ANSWER EPT = amount of time a person is able to perform useful flying duties in an inadequately oxygenated environment
What is time of useful consciousnesses? - CORRECT ANSWER TUC = the *time from exposure to O₂ deprivation to point deliberate function is lost*
How LONG can you protect yourself in an inadequately oxygenated environment?
Most important for us in air/medical
Higher we go, the more it goes down
How is time of useful consciousness affected, in the setting of an explosive decompression? - CORRECT ANSWER *It is cut in half*
They hear a pop from rush of air and see fog in cabin from condensation (2/2 temperature change from outside of cabin to inside of cabin)
What is the difference between Type 1 and Type 2 Decompression Sickness? - CORRECT ANSWER *Type 1* - nitrogen related, painful joints, mottled skin, pruritic (itching)
*Type 2* - neurological S&S, hypoglycemic shock
*Difference is neurological*
What type of G-forces are best tolerated by people? - CORRECT ANSWER Gx - *anterior/posterior* force, best tolerated, e.g. accelerated in your car (+Gx when a dragster takes off and - Gx when they deploy a parachute)
Gz - vertical force, e.g. falling from roof, landing on feet
Gy - lateral force, LEAST tolerated, e.g. T-bone MVA
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