Lecture 22: Extreme Conditions (Final Exam) Andy's Cards

Question 1

What is the oxygen concentration level at the peak of Mt. Everest?

Answer 1

• 21%

[O2] doesn’t change, but there will be ↓ partial pressure due to lower barometric pressure.

Question 2

What is the term used for a body adapting to higher altitudes?

Answer 2

Acclimatization

Question 3

How does the body trigger acclimatization when climbing Mt. Everest?

Answer 3

• The kidney will sense a drop in PaO₂ levels in the blood.
• The kidneys will ↑ release EPO in response to the O2 drop.
• ↑ Hb will ↑ CaO₂ (blood thickens up)

Question 4

What is the downside of acclimatization?

Answer 4

• The thickened blood makes it much harder for the heart to pump
• ↑ Risk of right heart failure

Question 5

What is our PiO₂ at sea level?

Answer 5

• 150 mmHg

Question 6

What is our PiO₂ at the Base Camp of Mt. Everest?

Answer 6

75 mmHg

Question 7

How will our SaO₂ change to a lower PiO₂ at the Base Camp (5500 meters) of Mt. Everest?

Answer 7

Lower SaO2 reading

The body will compensate for this by increasing Hb to increase CaO₂.

Question 8

What is barometric pressure at the summit of Mt. Everest?

What is our Pi_O2 at the Summit of Mt. Everest?

Answer 8

• Barometric Pressure = 253 mmHg
• 43.1 mmHg

You will need supplemental oxygen to survive the summit of Mt. Everest.

Question 9

A Nepalese ethnic group renowned for its rich culture, superior climbing skills, and extreme endurance for high altitudes.

Answer 9

Sherpas

Question 10

If you are born or grew up in a high altitude environment the lungs will typically have a higher ___________.

Answer 10

Surface area

There will be more alveoli and a greater ability to extract oxygen from the environment.

Question 11

What is the cruising altitude for most commercial airlines?

Answer 11

• 30,000 - 45,000 feet

Question 12

Why do we need to pressurize commercial airplanes?

Answer 12

Airplanes are pressurized because the air is very thin at the altitude they fly. The average passenger jet has a cruising altitude of about 30,000 to 45,000 feet. At this altitude, humans can’t breathe very well and our body gets less oxygen.

Question 13

Calculate the PiO2 if you are inspiring 100% FiO₂ at the summit of Mt. Everest.

Answer 13

• Atmospheric Pressure at Summit = 253 mmHg
• 253 mmHg - 47 mmHg (water vapor) = 206 mmHg
• 206 mmHg x 100% = 206 mmHg
• PiO2 = 206 mmHg

(102:00)

Question 14

Commercial Planes are pressurized to mimic an altitude of __________ ft.

Why not just pressurize to plane to sea level?

Answer 14

• 15,000 ft
• Dangerous to pressurize the plane to sea level, the plane can explode.

Question 15

When will you see these drop during your flight?

Why do the flight attendants instruct you to put on your own oxygen mask first before helping others?

Answer 15

• Oxygen masks are released whenever there’s a drop in cabin pressure.
• So you don’t pass out first from the lack of oxygen.

FYI: The oxygen from the yellow mask doesn’t come from O2 tanks. It is from an exothermic chemical reaction instead. The oxygen will only last about 10 minutes.

Question 16

Describe the relationship between water depth and pressure.

Answer 16

• Proportional relationship.
• Increase water depth = Increase pressure

Question 17

1 liter of air at sea level can be compressed to 1/2 Liter of air at how many feet underwater?

Compressed to 1/4 Liter of air?

Compressed to 1/8 Liter of air?

Answer 17

• 33 ft (atmospheric pressure x2)
• 100 ft (atmospheric pressure x4)
• 233 ft (atmospheric pressure x8)

Question 18

What happens to nitrogen in our body as we dive under?

What happens if there is a sudden decompression?

Answer 18

• Increased pressure will force more nitrogen into a dissolved state in our blood.
• Nitrogen will convert into gas form in the blood if rapidly decompressed.

Question 19

When deep-water diving, why is sudden decompression dangerous?

Answer 19

• Rapid decompression will result in nitrogen rapidly converting from dissolved to a gas state (Air).
• Nitrogen air can end up in the wrong places, like the coronary artery or brain.

Question 20

What is the treatment for sudden decompression?

Answer 20

• Hyperbaric Chamber

A hyperbaric chamber will allow gas to slowly come out of the system. Usually, it’s able to work its way out without any damage being done.

Question 21

How many hours would it take to come up safely from a 233 ft dive?

Answer 21

~ 6 hours

Question 22

At a depth of 500 ft, what pressure would be see?

Give answer in both mmHg and atm.

Answer 22

16 atm = 12160 mmHg

Question 23

What altitude equivalent are airplanes pressurized to?

Answer 23

~ 15,000ft

Question 24

What two methods are available to decrease the risk of decompression illness?

Answer 24

• Replace N₂ w/ He
• Replace N₂ w/ 100% O₂

Question 25

What risks are incurred by utilizing 100% O₂ instead of atmospheric air for scuba diving?

Answer 25

At 4 atm (3040mmHg) and 100% O₂ we will have seizures and CNS toxicity.