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"Boyle's Balloon" If you let a balloon go, as it goes up and there is less pressure on the outside it expands. As it goes down, there is more pressure on the outside and it contracts.
Air trapped in the teeth from new dental work or poorly done work. Gas expanding during ascent causes pain. Ascent problem.
Air in the middle ear expands during ascent and escapes. During descent, as gas is contracting, it is more difficult for air to move back into the ear especially if it is clogged which causes pain. Descent problem.
Air trapped in sinuses. As you go up it expands causing pressure. Usually corrects itself as you go down. Ascent problem.
Gas (mostly nitrogen 78%) that is trapped in tissues expands during ascent and is released into the blood stream. Obese patients have more adipose tissue therefore they can have a fast release of large amounts of gas into their bloodstream which they cannot exhale fast enough causing nitrogen narcosis. Treatment - all obese pts get high-flow O2 prior to take-off to displace nitrogen in the lungs.
"Charles-Centigrade-Volume" Heated gas expands, cooling gas contracts. Approximately for ever 100 meters climbed, the temp drops about 1 degree C.
"Charles Gay Brother" If the temperature increases so does it's pressure but the volume does not change. For instance, if you have an O2 tank that will not allow for expansion/contraction of a gas, the pressure in the O2 tank will change with the temp.
"Henry's Heineken" Like beer in a bottle. When the cap is on the partial pressures of gas inside the liquid and outside the liquid will equalize. When you remove the cap, the gas will escape creating a lower partial pressure of the gas outside than inside, therefore the gas inside the liquid will move to outside. Therefore, the partial pressure of gas inside the lungs must be higher than the blood otherwise the gas in the blood will move outward. (In a rapid decompressure, gas will move out of the blood rapidly which is why you can lose consciousness in seconds.)
"Graham's Grape Jelly" At equal pressures and temperatures gases with a smaller mass will diffuse faster than gases with a larger mass. O2 has a smaller mass than CO2 but CO2 diffuses through liquids better than O2. Therefore, in flight you want the alveoli as thin as possible (PEEP), the least liquid as possible, and partial pressures to be optimal.
"Dalton's Gang" P(t)=P(1)+P(2)+P(3).... The pressure of the atmosphere at sea level on a perfect day is 760 torr. That is the pressure of all the gases in the atmosphere pushing down on you at one time. You can calculate the partial pressure of any gas. For example O2 is 21%. At sea level it is 760 x 0.21 = 160. The percentage make-up doesn't change with altitude (still 21% O2 at 30,000 feet).
All things that stress the body in flight that can burn up energy. Such as noise, vibration, barometric pressure, temperature, G-forces.
What is the weight of one atomosphere?
760 mmHg (Torr)
What is the depth of one atmosphere in water?
For every 33 feet of water you add one atmosphere.
If you are 66 feet down in water, how many atmospheres are above you?
Three. You are two atmospheres down and you have one atmosphere of air above you.
What is the partial pressure of oxygen at sea level with an atomosphere of 760 mmHg?
b. 760 mmHg
c. 380 mmHg
d. None of the above
- d. None of the above
- Reasoning: 760 x .21 = 159
What is the partial pressure of oxygen entering your nose at 0.5 atmospheres?
a. 159.6 mmHg
b. 79.8 mmHg
d. None of the above
- b. 79.8
- Reasoning: 760 x 0.5 = 380
- 380 x .21 = 79.8
Seal level to 10,000 feet
Physiologically Deficient Zone
10,000 - 50,000 feet
Space Equivalent Zone
50,000 - 250,000 feet
Deficiency in alveolar O2. Any drop in available PO2 such as anemia, altitude, venous mixing, etc.
Reduced cardiac output or pooling of blood. O2 can get to the blood but not to the tissues. Examples are heart failure, PE, shock, tourniquets, compartment syndrome.
A failure of the tissue's ability to use O2 presented. Commonly as a result of poisoning or metabolic disorders. Examples are cyanide or carbon monoxide poisoning.
Reduction int he O2 carrying capacity of the blood such as hemorrhage, anemias, or CO posioning. Hemoglobin is a HUGE factor in moving oxygen.
What are the stages of Hypoxia?
- 1. Indifferent stage - slightly increased HR and RR. Decreased night vision.
- 2. Compensatory stage - Increased BP and impairment of task performance.
- 3. Disturbance stage - Dizziness, slieepiness, tunnel vision, cyanois
- 4. Critical stage - marked mental confusion, incapacitation. Possibly seizure, coma, death.
What is the oxygen adjustment calculation formula?
(FIO2 x P1)/P2
Effective Performance Time
The amount of time you are able to perform useful flying duties in an inadequately oxygenated environment. Could be hours or days.
Time of Useful Consciousness
The elapsed time from exposure to an oxygen deprived enviroment to the point where deliberate function is lost. (Based on military studies of sudden decompression.) Usually seconds to minutes. The TUC in an explosive decompression is half the time in a controlled decompression. (Hint, if it is explosive, choose the smallest amount of time given.)
What is the ultimate test for shock?
Lactate Level. Normal Lactate is 1 mmol/L +/- 0.5 mmol. Any lactate above 2 in a critically ill pt signals significant lactic acidosis.
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